Crustacea Glossary Complete List

Introduction

Joel Martin

jmartin@nhm.org

Because crustaceans are the most morphologically diverse group of animals on the planet, it comes as no surprise that there exists a huge number of morphological terms that are being used, or that have been used in the past, to describe them. As far as I have been able to determine, there is no single, standard glossary that is widely accepted. This is in part because different terms may mean different things for different groups of crustaceans, and in part because many existing glossaries tend to deal with selected subgroups or local faunas rather than with the taxon as a whole. More general glossaries do exist, and include McLaughlin's (1980) book on crustacean morphology and the glossary in the Treatise on Invertebrate Paleontology (Moore and McCormick, 1969), upon which McLaughlin's glossary seems to have been largely based.

The following glossary includes terms and their definitions taken verbatim from a variety of sources. In all cases, the reference is given in brackets [ ] following the definition. In cases where the same term is defined in slightly different ways, both definitions are given and both references are listed. If the definitions are identical, I have simply cited both references after the definition. The references also include the name of the group or groups of crustaceans with which that reference primarily deals. For example, the terms taken from Williams (1984) deal only with the Decapoda, specifically those of the east coast of the United States, and this is so indicated. In some publications, the glossary also contains more adjectival terms and non-morphological entries, in addition to the strictly descriptive terms. I have opted to list everything found in the original publication, so that you will occasionally find unusual entries that seem to deal not with crustacean morphology in general but with descriptive terms or even more specialized topics (e.g., "Moult to puberty").

References to figures refer to original illustrations in the original publications, and not to any figures in this computer file. Perhaps some day we will be able to add appropriate figures to this file as well, as in some cases the figures are much more clear than the verbal definitions given.

Please be sure to cite the original source of the definition, and not this electronic file, as your source for these definitions.

I have not made any attempt to correct definitions, grammar, or spelling, preferring instead to list each entry as it originally appeared without inserting my own biases or judgment. An obvious exception with regard to biases is that my specialty is the Decapoda, and so initially most terms will have been taken from publications on this group. I hope that as time goes by and more definitions are received by other workers in the field, this bias will correct itself.

Some descriptive adjectival terms are included here as well, and definitions for some of these have been taken from the American Heritage Dictionary of the English Language, third edition [AHD].

If you are aware of other publications that contain good glossaries for crustaceans, please let us know so we can add them to our list.

Corrections? Additions? Comments? Please send them to me. I promise to at least consider them.

Joel Martin
jmartin@nhm.org

Definitions

Current as of 23 January 2025

Note that this is a web reference, and hence may change over time.
Please send us corrections.

This resource is found at: http://research.nhm.org/glossary

Abdomen

Posterior part of body, of six segments or somites, sometimes including tailfan. [Poore, 2004]
Region of the body posterior to cephalothorax, consisting of six body segments and telson (see Fig. 13). [Hobbs and Jass, 1988]
That part of the body posterior to the cephalothorax, consisting of six body segments or somites plus the telson (Fig. 1).
(syn. Tail) [Perez Farfante and Kensley, 1997]
That portion of the body posterior to the cephalothorax, consisting of the telson and six body segments ot somites; the "tail". [Hobbs, Hobbs, and Daniel 1977]
The "tail or that part of the body posterior to the cephalothorax, consisting of six body segments or somites and the telson. [Chace and Hobbs, 1969]
The part of the body posterior to cephalothorax, the 'tail." [Butler, T. H.]
The posterior region of the trunk (body). [Brusca and Brusca, 2002]
The segmented hindmost part of the body held flexed forward beneath the thorax. Composed of six segments and a telson, referred to here as seven-segment. [Ingle, 1983]
Trunk somites (tagma) between thorax and telson; somites with or without limbs.
(syn. pleon) [McLaughlin, 1980]
Trunk tagma following thorax and including telson; somites either without limbs or (in Malacostraca) bearing pleopods or uropods or both; in crabs bent sharply forward under thorax and much wider in females than in males.
(syn. pleon)
See: Metasome, Urosome [Moore and McCormick, 1969]
(Taxon-specific: ) Trunk. [Stachowitsch, 1992]
Posterior division (tagma) of body (head, thorax, abdomen), Consists of large and variable number of segments (body rings), the anterior abdominal rings each bearing several appendages. [Stachowitsch, 1992]
Trunk. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Posterior division (tagma) of body (head, thorax, abdomen). Consists of eight segments (somites) and bears terminal telson with caudal rami. lacks appendages except for anterior two somites, which are fused (genital somite) and bear reproductive structures. [Stachowitsch, 1992]
Posterior division (tagma) of body (cephalon, thorax, abdomen). Consists of 11 segments (somites) and bears terminal telson (anal somite) with caudal furca, With the exception of a reduced pair of appendages ("genital appendages"), abdomen lacks limbs. Thorax and abdomen together occasionally termed trunk. [Stachowitsch, 1992]
Pleon. [Stachowitsch, 1992]
Pleon. [Stachowitsch, 1992]
Posterior division (tagma) of body (cephalothorax, abdomen). Consists of six somites (pleomeres), each bearing pair of appendages (pleopods). Sixth pleomere (with uropods) bears posterior telson. (extended, bent upon itself, folded under cephalothorax, spirally coiled; symmetrical, asymmetrical; compressed, depressed; acutely triangular, broadly triangular, broadly oval, subcircular, T-shaped; smooth, sculptured).
(syn. pleon) [Stachowitsch, 1992]
Pleon. [Stachowitsch, 1992]
Pleon. [Stachowitsch, 1992]
Posterior of three basic divisions (tagmata) of body (head, thorax, abdomen). Consists of six somites (pleomeres) bearing posterior telson.
(syn. pleon) [Stachowitsch, 1992]
Posterior division (tagma) of body (cephalon, thorax, abdomen). Consists of six somites (pleomeres), each bearing pair of appendages (pleopods). Sixth pleomere (with uropods) bears or is fused with telson. (compressed, depressed).
(syn. pleon) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Posterior division (tagma) of body (cephalon, thorax, abdomen). Consists of seven segments (somites), the first six each bearing pair of pleopods; bears telson and caudal furca posteriorly. Anterior region of abdomen covered, along with thorax and posterior part of head (cephalon), by carapace.
(syn. pleon) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Unsegmented posterior division (tagma) of body (cephalothorax, abdomen, or cephalon, pereon, abdomen). Relatively small, dorsoventrally flattened, and drawn out posteriorly into two lobes; bears pair of caudal rami and anus in cleft (sinus) between two lobes. (acorn-shaped, broadly elliptical, cordate, obcordate, obovate, spindle-shaped; lobes: acutely pointed, bluntly pointed, rounded).
(syn. pleon) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In ascothoracican, posteriormost division (tagma) of body (head, thorax, abdomen). Consists of four or five segments (somites), the last bearing caudal furca. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Posterior and typically narrowest of three basic divisions of body (cephalon, thorax, abdomen). Consists of five somites (pleomeres), the first often being termed genital somite, the last termed anal somite (posterior to caudal rami). Typically lacks appendages. (symmetrical, asymmetrical; segmented, unsegmented).
(syn. pleon) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) That part of the body of a copepod posterior to the somite bearing the genital opening. The abdomen includes four somites, three of which do not bear a paired appendage; the posterior somite bears the caudal rami and is the first abdominal somite to appear during development. [Ferrari and Dahms, in press]
According to interpretation dividing body into cephalon, thorax, and abdomen, last five somites of body. Lacks appendages yet bears telson and caudal furca. [Stachowitsch, 1992]
Rudimentary region of body bearing caudal rami; indistinguishably fused to thorax. [Stachowitsch, 1992]
Posterior of three divisions (tagmata) of body (head, throrax, abdomen). Consists basically of six somites (pleomeres) bearing posterior telson, although in bathynellacean, last pleomere is fused with telson to form pleotelson. Bears varying number of pleopods.
(syn. pleon) [Stachowitsch, 1992]
Posterior of three divisions (tagmata) of body (cephalon, thorax, abdomen). Consists basically of six somites (pleomeres) bearing posterior telson. (See also pleotelson).
(syn. pleon) [Stachowitsch, 1992]
Posterior division (tagma) of body (cephalo-thorax, abdomen); consists of six somites (pleomeres), the first first five bearing pleopods, the sixth bearing uropods. Bears posterior telson. [Stachowitsch, 1992]

Abdominal aorta

Posterior aorta. [Stachowitsch, 1992]

Abdominal appendage

Pleopod. [Stachowitsch, 1992]

Abdominal ganglion

(Taxon-specific: Order Monhysterida) Ganglion adjoining last thoracic ganglion in anterior region of thorax (forming last lobe of six-lobe ganglion mass). May bear smaller pair of lobes; gives rise to two pairs of nerves extending into abdomen. [Stachowitsch, 1992]

Abdominal limb

See: Pleopod, Uropod [Martin, 2005]

Abdominal process

Finger-like projection ( one to several ) on dorsal surface of cladoceran abdomen; may help to retain eggs in brood chamber. [Moore and McCormick, 1969]
(Taxon-specific: ) Finger-like projection(s) on dorsal surface of abdomen. [McLaughlin, 1980]
(Taxon-specific: ) One of typically two dorsal processes projecting from border of trunk and postabdomen. Considered to serve in closing off brood chamber posteriorly.
(syn. abdominal outgrowth) [Stachowitsch, 1992]

Abdominal segment

Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]

Abdominal seta

(Taxon-specific: ) One of two elaborate setae located on small protuberance on dorsal surface of postabdomen.
(syn. setae natatoriae) [Stachowitsch, 1992]

Abdominal somite

Any single division of body behind thorax.
(syn. pleomere, pleonite) [Moore and McCormick, 1969]
Any single division of body between thorax and telson.
(syn. pleomere, pleonite) [McLaughlin, 1980]
One of 11 segments of abdomen. First abdominal somite ( = 9th postcephalic segment) bears reduced pair of appendages ("genital appendages"). Last abdominal somite (19th postcephalic segment) bears telson. [Stachowitsch, 1992]
Pleomere. [Stachowitsch, 1992]

Abdominal spine

(Taxon-specific: Family Pycnogonidae) Spine-shaped projection on each side of abdominal somite. [Stachowitsch, 1992]

Abreptor

Postabdomen of cladocerans, bent forward from junction with body and terminating in 2 claws with spines and teeth on their concave sides. [Moore and McCormick, 1969]
(Taxon-specific: ) Postabdomen, bent forward from junction with body, terminating in 2 claws. [McLaughlin, 1980]
(Taxon-specific: ) Postabdomen. [Stachowitsch, 1992]

Acanthopod

In Cirripedia (Thoracica), appendage where rami of cirrus have setae along lesser curvature much reduced; setae of greater curvature arranged in transverse row, as strong sharp spines at each articulation (cf., ctenopod, lasiopod). [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Appendage (cirrus) with short row of strong sharp spines distally at each articulation of greater curvature and few or no spines along lesser curvature. [McLaughlin, 1980]

Acanthosoma

Zoea. [Stachowitsch, 1992]

Accessory Antennule

(Taxon-specific: Family Cyatholaimidae) The atrophied and offset terminal segment of the antennary endopod. [Boxshall and Halsey, 2004]

Accessory flagellum

Small inner flagellum of antennule (as opposed to larger primary flagellum). Number of articles is of taxonomic importance. [Stachowitsch, 1992]
In antenna of certain isopods, small, many-segmented flagellum projecting from fourth segment of peduncle. [Stachowitsch, 1992]

Accessory flexor muscle

A small muscle which flexes the leg at the MC joint. It is in two parts, proximal and distal, and inserts on a long thin apodeme in the merus (Fig. 19). [Warner, 1977]

Accessory gill

One in a series of I small respiratory structures projecting from bases of coxal gills. [Stachowitsch, 1992]

Accessory gland

In male reproductive system, pair of slender glands in thorax under heart; fused anteriorly and opening at tips of penes (via ducts running parallel to sperm ducts). [Stachowitsch, 1992]

Accessory heart

Cor frontale. [Stachowitsch, 1992]

Accessory lobe

Small lobe at base of median lobe, on anterior surface of petasma in the genus Gennadas. [Perez Farfante and Kensley, 1997]
One posteriorly directed part of epipod of first maxilliped pair, single respiratory projection set apart from series of remaining branchial lobules. [Stachowitsch, 1992]

Accomodation groove

Hinge structure; longitudinal groove above median hinge element. Receives dorsal edge of opposite valve. [Stachowitsch, 1992]

Acicle

Antennal scale reduced to a spine. [Williams, 1984]
Small scaphocerite or antennal scale. [Poore, 2004]
Spine-shaped outer branch (exopod) of antenna; represents reduced antennal scale (scaphocerite). May also refer to spine-like ophthalmic scale on eyestalk. (unarmed, spinose). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Ocular scale. [Stachowitsch, 1992]

Acron

Anteriormost part of body carrying eyes, not considered to be true cephalic somite.
(syn. ophthalmic somite, presegmental region. [Some authors recognize as protocephalon anterior part of h) [Moore and McCormick, 1969]
Anteriormost part of the body carrying the eyes; not considered true cephalic somite.
(syn. opthalmic somite, presegmental region) [McLaughlin, 1980]
Anterior segment of body (although not considered to be a true somite); bears eyestalks (ocular peduncles). Acron and first cephalic somite occasionally interpreted as representing protocephalon.
(syn. ophthalmic somite, pre-segmental region) [Stachowitsch, 1992]
Anteriormost segment of body (although not considered to be a true somite); divided into three plates-fastigial, ocular, and postocular- of which the median ocular plate bears the eyestalks (ocular peduncles). Not covered by carapace, although rostrum may partially or entirely extend across acron.
(syn. opthalmic somite) [Stachowitsch, 1992]

Acumen

Pointed apical part (tip) of rostrum, frequently delineated basally by marginal spines (see Fig. 14). [Hobbs and Jass, 1988]
The apical part of the rostrum frequently delimited basally by marginal spines. [Hobbs, Hobbs, and Daniel 1977]

Acute

Tapering to sharp point. [Butler, T. H.]

Adductor muscle (of carapace)

Muscle attached to carapace for pulling it to the body (thorax) or connecting halves of bivalve shell (e.g. Conchostraca, Ostracoda, Leptostraca) or valves of cirriped capitulum for closure of them. In Cirripedia, any transverse muscles, particularly that of maxillary segment, for closure of aperture; in Thoracica, adductor (adductor scutorum) acts upon scutal plates or valves. [Moore and McCormick, 1969]
Well-developed muscle attaching each side of head region to carapace. (See also ligament). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Carapace adductor muscle. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Conspicuous transverse muscle joining both scuta and serving to close aperture. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Muscle attached to carapace for pulling it to body or connecting halves of bivalve carapace. [McLaughlin, 1980]
Well-developed transverse muscle extending from body to inner surface of each valve. Forms characteristic muscle scars on valves and serves to close carapace. [Stachowitsch, 1992]

Adductor muscle scar pattern

Rather central pattern of scars (raised or depressed) indicating where central adductor muscles attach to valves; not always clearly visible. [Cohen, Peterson, and Maddocks, in press]

Adductor pit

In cirripeds, depression on interior of scutum for attachment of adductor muscle, located between adductor ridge and occludent margin. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: on inner surface of scutum, depression marking attachment point of adductor muscle. In unstalked barnacle, located between adductor ridge and occludent margin. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Depression on inner surface of scutum between adductor ridge and occludent margin for attachment of adductor muscle (thoracic Cirripedia). [McLaughlin, 1980]

Adductor ridge

In cirripeds (Balanomorpha), linear elevation on interior of scutum between adductor pit and tergal margin. [Moore and McCormick, 1969]
Linear elevation on inner surface bounding adductor pit on tergal pit in sessile barnacles. [McLaughlin, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: on inner surface of scutum in unstalked form, linear elevation between adductor muscle pit and tergal margin. [Stachowitsch, 1992]

Adhesion pads

(Taxon-specific: Family Cyatholaimidae) Raised areas of specialised integument, ornamented with fine ridges, found in some siphonostomatoids parasitic on fish. [Boxshall and Halsey, 2004]

Adhesive gland

(Taxon-specific: Order Rhabditida) Cement gland. [Stachowitsch, 1992]

Adont hinge

Single element hinge, bar on one valve fits into groove of other valve. [Cohen, Peterson, and Maddocks, in press]

Adrostal carina

Ridge flanking the rostrum, sometimes nearly reaching the posterior margin of the carapace (Fig. 2B). [Perez Farfante and Kensley, 1997]

Adrostral ridge

Ridge parallel to and separated by narrow groove from rostrum (Penaeoidea). [Poore, 2004]

Adrostral sulcus

Groove flanking the rostrum mesial to the adrostral carina, sometimes nearly reaching the posterior margin of the carapace (Fig. 2B). [Perez Farfante and Kensley, 1997]

Aesthetasc seta

Confined to antennule; thin-walled, smooth, non-tapering seta, rounded tip; without pore; annulus not evident. [Ingle, 1992]

Aesthetascs

See: Esthetasc [Martin, 2005]
A long, tubular, sensory seta having thin cuticle, found on the antennula or antenna. Aesthetascs may have a chemosensory function, because males generally have more of these structures than females. [Wilson, 1989]
Sensory seta covered by delicate cuticle, often projecting from antenna or antennule.
(syn. olfactory hair, esthetasc, esthete...) [McLaughlin, 1980]
Simple, tubular, thin-walled, chemosensory seta often found on the antennular flagellum. [Holdich and Jones, 1983]
Spinelike cuticular processes often occurring in clumps or rows and functioning in chemoreception, usually located on the antennules. [Brusca and Brusca, 2002]
(Taxon-specific: ) One in a tuft of sensory projections at tip of each antennule.
(syn. esthete, olfactory seta) [Stachowitsch, 1992]
Elongate sensory projection at tip of each antennule.
(syn. esthete) [Stachowitsch, 1992]
One in a series of sensory projections on main flagellum of antennule. [Stachowitsch, 1992]
One in a series of sensory projections on flagella of antennules. [Stachowitsch, 1992]
One in a series of small sensory projections on outer flagellum of antennule.
(syn. esthetasc, esthete, olfactory hair) [Stachowitsch, 1992]
One in a series of thin-walled sensory projections on antennule.
See: Calceolus [Stachowitsch, 1992]
One in a series of sensory projections on antennules. (uniramous, biramous, triramous). [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Thin-walled chemosensory seta usually found on antennular flagellum. [Wetzer et al. 1997]
Thin-walled sensory seta usually on flagellum of antennule. [Kensley and Schotte, 1989]
(Taxon-specific: Class Secernentea) One in a series of sensory projections on antennules and ocasionally also on antennae. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A thin-walled, sensory element with putative chemoreceptive function, found on the antennules. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) A transformed seta of antenna 1 or another oral appendage of copepodids. An aesthetasc usually has a sclerotized base but otherwise is poorly sclerotized; it often is considered to have a chemosensory function. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) One in a series of small sensory projections along antennule.
(syn. esthetasc, esthete) [Stachowitsch, 1992]
Small sensory projection at tip of each antennule.
(syn. aesthete) [Stachowitsch, 1992]
One in a series of small sensory projections along antennule or antenna; considered to be modified setae. [Stachowitsch, 1992]
One of numerous robust, long sensory projections aggregated in several dense rows at base of antennules (on pad on first article of peduncle); directed posteriorly and partially covering antennae.
(syn. esthetasc, esthete, olfactory hair) [Stachowitsch, 1992]
One of several senory projections on larger of two flagellaf antennule. [Stachowitsch, 1992]
One in a series of small sensory projections on each antennule. [Stachowitsch, 1992]

Afferent branchial channels

Pair of channels between ridges, supplying water to branchial cavity and opening in front of chelipeds or alongside epistome (some Brachyura). [Poore, 2004]

Afferent channels

Opening through which water passes to gills. [McLaughlin, 1980]
Openings through which water passes to gills, in brachyuran crabs generally located in front of bases of chelipeds. [Moore and McCormick, 1969]
Openings through which water passes to gills. In brachyuran crabs, usually opening behind pterygostomian regions and in front of chelipeds except in certain Oxystomata in which they open at anterolateral angles of palate or endostome. [Williams, 1984]

Afferent respiratory channels

Channels through which water passes to the gills, that open in front of the chelipeds and behind the pterygostomial region except in some oxystomata where they open at the sides of the endostome.
(syn. afferent branchial channels) [Ingle, 1980]
Opening through which water enters branchial chamber under carapace. Typically applied to more restricted opening in crab-like (brachyuran) decapod; located anteroventrally on each side of body, either behind pterygostomial regions or in front of chelipeds.
(syn. afferent branchial channel)
See: Efferent respiratory channels [Stachowitsch, 1992]

Ala

One of pair of posteriorly directed cephalic-shield extensions; in cirripeds (Balanomorpha), triangular lateral part of compartment plate delimited from paries, which is overlapped by adjacent compartment plate with or without radius.
(pl. alae) [Moore and McCormick, 1969]
(Taxon-specific: Order Monhysterida) One of two posterolateral extensions of carapace. (broad, broadly rounded, narrowly rounded, elongate and coiled behind thorax, greatly elongated; extending to second, third, or fourth thoracomere, to abdomen, beyond abdomen). [Stachowitsch, 1992]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, triangular lateral part of compartmental plate. Delimited from median part (paries) and overlapped by lateral part (radius) of adjoining compartmental plate. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of pair of posteriorly directed cephalic-shield extensions (Branchiura and some parasitic Copepoda); triangular lateral part of compartmental plate, with or without radii, overlapped by adjacent compartmental plate (balanomorph Cirripedia).
(pl. alae) [McLaughlin, 1980]
(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, one of two posterolateral extensions of cephalic shield. [Stachowitsch, 1992]
Wing-like extension of valve, typically located ventrally and directed posteriorly. (simple, carinate). [Stachowitsch, 1992]

Aliform apophyses

Incurved anterior and posterior extremities of growth lines (e.g., Conchostraca, characteristic of Ipsilonia). [Moore and McCormick, 1969]
Incurved anterior and posterior extremities of growth lines. [McLaughlin, 1980]

Alimentary tract

Tubular organ comprising the oesophagus, foregut, hepatopancreas, and hindgut. [Holdich and Jones, 1983]

Allometric growth

Growth of one part of the body relative to another part in which there is a change in relationships of proportions and/or shape. [Ingle, 1983]

Ambulatory leg

See: Pereiopod [Moore and McCormick, 1969]
See pereopod. [McLaughlin, 1980]
(as applied to pereopods). Used for walking. [Kensley and Schotte, 1989]

Ambulosome

The part of the thorax of munnopsid isopods that bears the walking legs. It consists of pereonites 1-4. [Wilson, 1989]

Ambulosomite

A body segment of the ambulosome. [Wilson, 1989]

Amphidont hinge

A modified entomodont hinge in which the four elements are well differentiated (Families Hemicytheridae, Trachyleberididae). [Cohen, Peterson, and Maddocks, in press]

Ampulla

One in a series of spinose and setose ridges surrounding border between esophagus and stomach. [Stachowitsch, 1992]
One of two spinose or setose internal ridges on each side of foregut. Serves in crushing food. [Stachowitsch, 1992]
In digestive tract, diverticulum at junction of posterior (pyloric) stomach, digestive ceca, and midgut.
(syn. pars ampullaris) [Stachowitsch, 1992]

Anal flap

Small lobe covering anus at posterior end of anal segment. [Stachowitsch, 1992]

Anal furca

(Taxon-specific: Order Monhysterida) Caudal ramus. [Stachowitsch, 1992]

Anal operculum

(Taxon-specific: Family Cyatholaimidae) A small median process on dorsal surface of the anal somite protecting the anus. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) Lid-like structure covering anus. (smooth, toothed). [Stachowitsch, 1992]

Anal papilla

(Taxon-specific: Order Monhysterida) Caudal ramus. [Stachowitsch, 1992]

Anal segment

Telson.
(syn. anal somite) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Telson.
(syn. anal somite) [Stachowitsch, 1992]
Telson.
(syn. anal somite) [Stachowitsch, 1992]
Posteriormost segment of body; partially fused to reduced last trunk segment and bearing both anus and caudal rami. Occasionally also referred to as telson. (Length longer than, equal to, or shorter than width). [Stachowitsch, 1992]

Anal somite

Postsegmental plate or lobe bearing anus. [Brusca and Brusca, 2002]
(Taxon-specific: Class Secernentea) Telson.
(syn. anal segment) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Last (fifth) segment of abdomen; bears anus dorsally and pair of caudal rami posteriorly. Occasionally termed telson. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The posterior somite and abdominal somite onto which the anus opens. The anal somite bears a paired appendage called the caudal rami. The anal somite is considered the first abdominal somite, despite its posterior position, because it is the first abdominal somite to appear during post-embryonic development. [Ferrari and Dahms, in press]
Telson. [Stachowitsch, 1992]

Anal spines

Single row of spines on either side of cladoceran postabdomen (e.g., Sididae, Holopedidae, Daphniidae). [In addition, some cladocerans possess lateral spines (e.g., Macrothricidae, Chydoridae).]. [Moore and McCormick, 1969]
Single row of spines on either side of postabdomen (cladocera) or prominent telsonal spines (Conchostraca). [McLaughlin, 1980]
(Taxon-specific: ) One in a series of spines along (morphological) dorsal surface of postabdomen.
(syn. anal tooth) [Stachowitsch, 1992]
One of two blade-like, serrate spines projecting from posterodorsal end of telson. [Stachowitsch, 1992]

Anameric

The addition of only one somite to the body at each molt during development. [Ferrari and Dahms, in press]

Anamorphic development

In which a series of similar larval stages are passed through after hatching. [Ingle, 1992]
Indirect development in which the embryo hatches as a nauplius larva and the adult form is achieved via a series of gradual changes in body morphology as new segments and appendages are added. [Brusca and Brusca, 2002]

Androdioecy

Rare type of mixed mating system in which males coexist with hermaphrodytes but there are no true females. [Brusca and Brusca, 2002]

Androgenic gland

In male, small gland associated with terminal end of each vas deferens. Secretes hormones stimulating spermatogenesis and development of secondary sex characteristics. [Stachowitsch, 1992]

Anecdysis

A prolonged period without ecdysis; occurs in crustaceans that molt seasonally. [Bliss, 1982]
An intermoult stage in which all tissue growth has been completed. [Ingle, 1983]

Angulate

Having an angle or an angular shape. [Kensley and Schotte, 1989]

Annulate seta, with setules

These are always mechanoreceptors; they always form in invaginated pockets, may be of a variety of sizes and shapes, may have the setules distributed along the shaft in many kinds of patterns, and may have denticules distally along the shaft. [Watling, 1989]

Annulate seta, without setules

These usually are chemoreceptive, but may be mechanoreceptive in large groups; they always form in invaginated pockets and may be smooth or denticulate, elongate and stiff, or short and robust. [Watling, 1989]

Annulations

Spaced rings on a segment of appendage, not articulated, yet wth flexability. [Butler, T. H.]

Annulus

A faint ring circumscribing the shaft; may be located near the base or well along the shaft. [Watling, 1989]

Annulus ventralis

Crayfish seminal receptacle, consisting of median sclerite between fourth and fifth pereiopods; the spermatophore receptacle on sternum of female (see Fig. 23d). [Hobbs and Jass, 1988]
Seminal receptacle of cambarids, consisting of a median sclerite between the fourth and fifth pereiopods. [Hobbs, Hobbs, and Daniel 1977]
Seminal receptacle of female crayfish. [McLaughlin, 1980]

Anomura

A suborder of decapod crustaceans in which the fifth pair of pereiopods are extremely reduced and often concealed beneath the carapace; the antennae are placed to the outside of the eyestalks and the sub-hepatic regions of the carapace are not fused with the endostome. (Hermit crabs, Porcelain crabs, Lithodid crabs). [Ingle, 1980]

Anomuran crabs

Hermit crabs; coconut crab; also crab-like members of the infraorder Anomura, in which the last (fifth) pair of thoracic legs is very small and often kept hidden within the branchial chambers. [Bliss, 1982]

Anomuran seta

A small (pappose-type seta in species studied) occuring on or near the outermost part of the telson posterior margin in anomuran larvae (and also Dromia), and distinct from all other types of telson setae. [Ingle, 1992]

Antenna

Antennal peduncle consisting of 5 articles, based on Uroptychus. [Baba, 2005]
(Figure only.) [Baba, 2005]
Mobile sensory appendages arising below the eyes at the front of the head. There are two pairs of these appendages, the first and second antennae. The first antennae are uniramous and may have two or three flagellae each. The second antennae are biramous, one branch being similar in gross form to the first antenna, the other being flattened and scale-like (referred to as a scale). [Mauchline, 1984]
More lateral of the two paired, usually flagellate appendages projecting distally from the anterior end of the cephalothorax (Fig. 1).
(pl. antennae) [Perez Farfante and Kensley, 1997]
One of pair of anterior appendages of head region placed morphologically next behind antennule, uniramous in some crustaceans but biramous in all nauplii and in adults of most classes; may be extremely long and composed of multitudinous small segments or reduced to mere rudiment or lacking.
(syn. second antenna) [Moore and McCormick, 1969]
One of pair of appendages of second cephalic somite.
(syn. 2nd antenna) [McLaughlin, 1980]
Second cephalic appendage, usually with peduncle of five articles and multiarticulate flagellum (sometimes antenna 2); plural sometimes used to refer to both antennules and antennae.
(pl. antennae) [Poore, 2004]
Second pair of cephalic appendages (antenna 2). [Holdich and Jones, 1983]
The appendages of the second and third head segments are the first and second pairs of antennae respectively. The first antennae are secondarily biramous (Fig. 3) Both pairs of antennae are sensory. [Warner, 1977]
The more lateral of the the two paired flagellate appendages projecting anteriorly from anterior end of the body.
(pl. antennae) [Butler, T. H.]
The more lateral of the two paired flagellate appendages projecting anteriorly from the anterior end of the body.
(pl. antennae) [Chace and Hobbs, 1969]
The second pair of appendages situated between the antennules and the orbits, sometimes referred to as second antennae. [Ingle, 1983]
The second, paired, cephalic appendage. It consists of four short, robust, proximal segments, two long, intermediate segments, and a long series of tapering annuli, called the flagellum. The third basal segment bears a smaller, lateral appendage called the antennular scale that is homologous to the exopod in other Crustacea.
(syn. second antenna) [Wilson, 1989]
Whiplike, generally long sensory organ arising from anterior region of cephalothorax (see Figs. 13, 14). [Hobbs and Jass, 1988]
(Taxon-specific: ) Second and much larger pair of antennae; located laterally near posterior margin of head. Biramous, consisting of relatively large basal part (peduncle) bearing two- to four-segmented dorsal and ventral branches (rami). Serves as principle locomotory organ and moved by relatively large muscles (antennal muscles). (biramous and flattened, simple and cylindrical, branched, not branched).
(syn. second antenna) [Stachowitsch, 1992]
Second and smaller pair of antennae; uniramous, extending from each side of labrum on underside of head. (very small, vestigial, absent).
(syn. second antenna) [Stachowitsch, 1992]
Second and much larger pair of antennae on head; biramous, consisting of long, terminally annulate basal part (protopod, with basal lobe) and pair of segmented branches (flagella, rami).
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Second and larger of two pairs of antennae; uniramous, projecting ventrally from head. In female, typically unsegmented and reduced. In male, forms clasper generally consisting of exapanded basal segment (with antennal appendage) and more slender distal segment. (fused at base, not fused at base; basal segment: with/without hand; with/without finger-like process on median surface near midlength; with prominent, dorsally directed, peg-like process on median surface just below mid-length; with row of spines along median margin; with spinous pad, median protuberance, and many small distal spines; distal segment: laminate, not laminate, with/without calcar) (See also clypeus, hand).
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae. Biramous, consisting of two-segmented protopod, relatively short, two-segmented endopod, and longer, multi-segmented exopod. Serves in locomotion and feeding.
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae; uiramous. If fully developed, consisting of proximal five-segmented peduncle and distal flagellum.
(syn. second antenna) [Stachowitsch, 1992]
Second, relatively small pair of antennae.
(syn. second antenna) [Stachowitsch, 1992]
Second and typically larger pair of antennae. Originates from second (antennal) somite of head. Biramous, consisting of basal peduncle (typically composed of protopod, endopod, and scaphocerite) and distal flagellum. Bears pore of antennal gland. (elongate, spatulate, squamiform).
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae. Uniramous, consisting of proximal five-segmented peduncle and distal flagellum. May bear sensory structures (aesthetascs, calceoli). (short, long; slender, robust; naked, setose, spinose; similar, sexually dimporphic; pediform).
(syn. second antenna) [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
(pl. antennae) [Wetzer et al. 1997]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Paired appendage of the third cephalon segment; sometimes referred to as antenna 2. [Kensley and Schotte, 1989]
Second, usually longer appendage of cephalon. Uniramous, consisting of basal peduncle and distal lagellum. (pediform).
See: Accessory flagellum, Antennal scale [Stachowitsch, 1992]
Second pair of antennae. Biramous, consisting of peduncle bearing scale-like outer branch (antennal scale, squama, exopod) and elongate inner branch (flagellum).
(syn. second antenna) [Stachowitsch, 1992]
Second and smaller pair of antennae; originating from second somite of head (cephalon). Biramous, consisting of basal, two-segmented peduncle, two-segmented exopod (distal segment = antennal scale), and three-segmented endopod (with distal flagellum). (See also antennule).
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Second pair of antennae. Uniramous, relatively long, and consisting of three- or four-segmented peduncle and variously shaped endopod (flagellum). (peduncle: three-/four-segmented; flagellum: long with many small joints, small with few large joints).
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Second pair of appendages on underside of head. Relatively short, uniramous, and consisting of four to six segments. Armed basally with large spines/hooks, terminally with smaller spines. Serves in attachment to host.
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Biramous second pair of antennae. Present, with the exception of certain ascothoracicans, only in early larval stages (nauplius).
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Second and typically shorter pair of antennae on underside of head. Highly setose and serving in suspension feeding or, in certain parasitic copepods, with terminal claw and serving in attachment to host. If uniramous, outer branch (exopod) is missing. The term second antenna is often preferentially applied. (biramous, uniramous; prehensile).
(syn. second antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The limb of the cephalon posterior to antenna 1; on most naupliar stages, it bears a distinct protopodal masticatory arthrite which is not present on copepodid stages or on non-feeding naupliar stages, especially those of species with lecithotrophic embryos.
(syn. antenna 1) [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The second cephalic appendage. [Boxshall and Halsey, 2004]
Second and smaller pair of antennae. Biramous, consisting of basal protopod bearing nine-segmented exopod and four-segmented endopod. Serves in locomotion and feeding.
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae on head. Basically biramous, consisting of basal protopod and distal endopod and exopod (the latter often being reduced). Serves, along with antennules, as chief locomotory appendage. Carapace margin may be indented (rostral notch) for antenna. (biramous, uniramous).
(syn. second antenna) [Stachowitsch, 1992]
Second and smaller, more paddle-shaped pair of antennae on underside of head (cephalon); biramous and consisting of protopod (with two articles) bearing scale-like exopod and three-segment endopod. Endopod articles arc around anterior aspect of exopod. Setae on antenna are plumose.
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae. Consists of basal peduncle and either single flagellum (stygocaridacean), single or paired (flagellum and small exopod) branches (bathynellacean), or flagellum and scaphocerite (anaspidacean). (uniramous, biramous).
(syn. second antenna) [Stachowitsch, 1992]
Second, relatively small pair of antennae. Uniramous, consisting of peduncle and flagellum.
(syn. second antenna) [Stachowitsch, 1992]
Second pair of antennae. Biramous, consisting of proximal single-segmented peduncle, scale-shaped outer branch (exopod = scaphocerite), and inner branch (endopod) consisting of three larger segments and multiarticulate flagellum. Peduncle bears opening of antennal gland.
(syn. second antenna) [Stachowitsch, 1992]

Antennae

The second pair of antennae. [Brusca and Brusca, 2002]

Antennal acicle

Acicle. [Stachowitsch, 1992]

Antennal appendage

(Taxon-specific: Family Pycnogonidae) Variously shaped process extending from basal segment of each antenna; more common in male. (conical, lamelliform, robust, slim; extending/not extending beyond basal segment of antenna; with small teeth, with large teeth; with teeth longer on one side, with teeth not greatly different in size; with/without conical processes).
(syn. basal antennal appendage) [Stachowitsch, 1992]

Antennal artery

Artery.
(syn. antennary artery) [Stachowitsch, 1992]

Antennal carina

See: Carapace carina a [Martin, 2005]
Ridge extending posteriorly along dorsal extremity of antennal region, often continuous with antennal spine (Fig. 2B). [Perez Farfante and Kensley, 1997]
On each side of carapace, narrow, longitudinal ridge extending posteriorly from antennal spine.
(syn. postannular crest) [Stachowitsch, 1992]

Antennal flagellum

Multiarticulate, whiplike terminal part of the antenna (Fig. 1).
(pl. antennal flagella) [Perez Farfante and Kensley, 1997]

Antennal gland

See: Green glands [Martin, 2005]
Excretory gland situated in the basal article of the antennal peduncle. [Holdich and Jones, 1983]
Nephridial excretory organs exiting via a pore at the base of the antennae. [Brusca and Brusca, 2002]
One of pair of complex excretory glands in many malacostracans with duct opening on antenna.
(syn. green gland) [McLaughlin, 1980]
One of two glands located in anterior region of head and consisting basically of end sac (divided into saccule and labyrinth), bladder, and excretory duct. Opens via excretory pore on basal segment (coxa) of each antenna. Functions in excretion and controls internal fluid pressure as well as ion concentration.
(syn. green gland, excretory organ) [Stachowitsch, 1992]
Pair of excretory glands in head, one opening to exterior at base (peduncle) of each antenna.
See: Gland cone [Stachowitsch, 1992]
Pair of poorly developed excretory organs in head of certain isopods, one opening at base of each antenna. [Stachowitsch, 1992]
Excretory gland located in head; consists of long, coiled excretory canal and bladder. Opens to exterior on basal segment of either antenna. (See also maxillary gland). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Pair of excretory glands in head, one opening to exterior at base of each antenna. (See also maxillary gland). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Excretory organ, one opening at each base of antenna. Characteristic for larval stages and cetain parasitic copepods. (See also maxillary gland). [Stachowitsch, 1992]
One of two excretory glands opening at base of antennae (See also maxillar gland). [Stachowitsch, 1992]
Pair of excretory glands in head, one opening to exterior at base (peduncle) of each antenna. [Stachowitsch, 1992]

Antennal groove

See: Carapace groove a [Martin, 2005]
See: Carapace grooves a [McLaughlin, 1980]
On each side of carapace, longitudinal groove extending posteriorly from vicinity of antennal spine. [Stachowitsch, 1992]

Antennal muscle

(Taxon-specific: ) One of several well-developed muscles spanning from antenna to dorsal part of head. According to position and function one may distinguish, e.g., antennal levator muscle and antennal adductor muscle. [Stachowitsch, 1992]

Antennal notch

On each side of carapace, notch in anterior border below pseudorostrum. Antennules and occasionally antennae project through antennal notch. Lower extension of notch termed anterolateral angle or corner. (deep, shallow).
(syn. antennal sinus) [Stachowitsch, 1992]

Antennal peduncle

Basal segments of antennule from which the flagella arise. [Butler, T. H.]
Five basal segments of the antenna, from which the antenna arises distally. [Perez Farfante and Kensley, 1997]
The basal segments of the antenna, from which the flagellum arises. [Chace and Hobbs, 1969]

Antennal region

See: Carapace region a [Martin, 2005]
See: Carapace regions a [McLaughlin, 1980]
Area on lateral surface of the carapace posterior to and encompassing antennal spine. [Butler, T. H.]
Area on the lateral face of the carapace posterior to and encompasing the antennal spine. [Perez Farfante and Kensley, 1997]
The area on the lateral surface of the carapace of shrimps posterior to and encompassing the antennal spine. [Chace and Hobbs, 1969]
In shrimp-like (natantian) decapod, one of two relatively small regions along anterolateral margin of carapace; corresponds to position of antenna. Adjoining regions include orbital, hepatic, and pterygostomial regions. [Stachowitsch, 1992]

Antennal scale

See: Stylocerite, Scaphocerite [Martin, 2005]
Bladelike exopod of antenna situated at base of antenna (see Figs. 13, 14). [Hobbs and Jass, 1988]
See scaphocerite. [McLaughlin, 1980]
See scaphocerite.
See: Scaphocerite [Poore, 2004]
The laterally ragid lamellar exopod of the antenna. [Butler, T. H.]
The laterally rigid lamellate exopod of the antenna of shrimps and crayfishes. [Chace and Hobbs, 1969]
The plate-like exopod of the antenna. [Hobbs, Hobbs, and Daniel 1977]
Scale-like structure projecting from second segment of peduncle of antenna. Considered to represent outer branch (exopod). [Stachowitsch, 1992]
Scaphocerite. [Stachowitsch, 1992]
Projection extending from base (peduncle) of antenna; considered to represent reduced outer branch (exopod).
(syn. squama) [Stachowitsch, 1992]
Scale-shaped outer branch (exopod) of antenna, frequently with terminal articulation. (Scale-shaped, spine-shaped).
(syn. exopod, scaphocerite, squama) [Stachowitsch, 1992]
On each (second) antenna, large, flattened terminal segment of exopod; bears setae.
(syn. scaphocerite) [Stachowitsch, 1992]
Scaphocerite. [Stachowitsch, 1992]
Scaphocerite. [Stachowitsch, 1992]

Antennal setae formula

(Taxon-specific: ) Notation specifying number of segments and number of setae per segment in dorsal and ventral branches (rami) of antenna. Example: 0-0-1-3/1-1-3.
(syn. setation formula) [Stachowitsch, 1992]

Antennal spine

See: Carapace spine a [Martin, 2005]
See: Carapace spines a [McLaughlin, 1980]
Anterior part of carapace, including ocular peduncles, based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
A short spine usually present on or near the anterior margin of the carapace of shrimps just ventral to the orbit. [Chace and Hobbs, 1969]
A spine on, or adjacent to, the anterior margin of the carapace, immediately ventral to the orbit. [Hobbs, Hobbs, and Daniel 1977]
Short spine usually present on or near anterior margin of carapace just ventral to orbit. [Butler, T. H.]
Spine on anterior edge of carapace immediately below orbit adjacent to base of antenna (fig. 2). [Williams, 1984]
Spine on anterior margin of carapace ventral or lateral to orbit (antennal angle if spine absent). [Poore, 2004]
Spine on, or adjacent to, anterior margin of carapace and ventral to orbit (see Fig. 13). [Hobbs and Jass, 1988]
Spine situated on the anterior margin of the carapace just ventral to the orbital margin (Fig. 2A). [Perez Farfante and Kensley, 1997]
Anteriorly directed, spine-like projection on anterior region on each side of carapace; located below orbit, adjacent to base of antenna, and may extend beyond carapace margin. [Stachowitsch, 1992]
Spine. [Stachowitsch, 1992]

Antennary nerves

Nerves extending from the tritocerebrum to the antennae. [Brusca and Brusca, 2002]

Antennula

The first paired cephalic appendage. In munnopsids, it consists of a wide, flattened basal segment, two segments of intermediate thickness, and distal annular segments of varying lengths. The most distal segments generally bear aesthetascs.
(syn. first antenna, antennule) [Wilson, 1989]

Antennular artery

Artery. [Stachowitsch, 1992]

Antennular flagellum

Multiarticulate paired filaments (sometimes flattened and lamellate) of the antennule (Fig. 3B).
(pl. antennular flagella) [Perez Farfante and Kensley, 1997]

Antennular fossette

On each side of carapace, anteroventral depression containing basal portion of antennule.
See: Orbito-antennulary pits [Stachowitsch, 1992]

Antennular lamella

In antennule of certain mysidaceans, term occasionally applied to scale-like process projecting from last (third) peduncular segment. [Stachowitsch, 1992]

Antennular lappet

On each antennule, small lobe extending dorsally from end of first peduncular segment. (bifid, laminar, obtuse, triangular).
(syn. leaflet) [Stachowitsch, 1992]

Antennular peduncle

Proximal segments of antennule, from which flagella arise. [Hobbs and Jass, 1988]
The basal segments of the antennule, from which the flagella arise. [Chace and Hobbs, 1969]
The proximal segments of the antennule, from which the flagella arise. [Hobbs, Hobbs, and Daniel 1977]
Three basal segments of the antennule, from which the flagella arise distally (Fig. 3B). [Perez Farfante and Kensley, 1997]

Antennular process

Tapering dorsolateral extension on each side of first head somite (antennular somite). [Stachowitsch, 1992]

Antennular scale

See: Stylocerite [Martin, 2005]
See stylocerite. [McLaughlin, 1980]
Stylocerite. [Stachowitsch, 1992]

Antennular somite

First true somite of head (cephalon); located between acron and second (antenna-bearing) somite. Bears pair of anteriorly directed antennules as well as dorsolateral antennular processes. Not covered by carapace, although rostrum may partially or entirely extend across it.
(syn. posterior dorsal plate) [Stachowitsch, 1992]

Antennular spine

Stylocerite. [Stachowitsch, 1992]

Antennulary nerves

Nerves that innervate the antennules and connect them to the deuterocerebrum. [Brusca and Brusca, 2002]

Antennulary part

Region of head (cephalon) anterior to cephalic constriction. Bears antennules, four ocelli, two anteromedian lobes (rostral plate), and two anterolateral (lateral) lobes. (posterolateral corner: obtuse, right-angled). [Stachowitsch, 1992]

Antennule

First cephalic appendage, usually with peduncle of three articles and two multiarticulate flagella (sometimes antenna 1). [Poore, 2004]
First pair of cephalic appendages (antenna 1). [Holdich and Jones, 1983]
First pair of feelers, or antennae. [Bliss, 1982]
Inner of two paired flagelate appendages projecting from anterior end of body. [Butler, T. H.]
More mesial of the two paired, usually flagellate appendages projecting from the anterior end of the cephalothorax (Fig. 1, 3B). [Perez Farfante and Kensley, 1997]
One of a pair of appendages of the first cephalic somite.
(syn. 1st antenna) [McLaughlin, 1980]
One of pair of appendages of the first cephalic somite; "first antenna" (Figs. 13, 14). [Hobbs and Jass, 1988]
One pair of morphologically frontmost appendages of head region, usually filiform and multiarticulate, uniramous except in Malacostraca where it is generally biramous or even triramous; may be larger or smaller than morphologically next following appendages named antennae.
(syn. antennula, first antenna) [Moore and McCormick, 1969]
The first pair of antennae. [Brusca and Brusca, 2002]
The first pair of appendages situated medially close together under the frontal region. [Ingle, 1983]
The more mesial of the two paired flagellate appendages projecting from the anterior end of the body. [Chace and Hobbs, 1969]
(Taxon-specific: ) First and typically much smaller pair of antennae; located ventrally near posterior margin of head. Uniramous, unsegmented, with tuft of terminal aesthetascs. (movable, immovable = fixed; fused/ not fused with rostrum; insterted/ not inserted at anterior end of ventral edge of head).
(syn. first antenna) [Stachowitsch, 1992]
First and larger pair of antennae; relatively short, uniramous and slender. Extends from each side of labrum anterior to antennae. (simple, obscurely segmented).
(syn. first antenna) [Stachowitsch, 1992]
First and much smaller pair of antennae; uniramous, typically with series of dorsal sensory papillae. (short, long; unsegmented = unjointed, with two segments, multijointed).
(syn. first antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) First and smaller of two pairs of antennae, projecting from anterior end of head. Uniramous, either unsegmented or only superficially segmented. (with/without tuft of terminal setae).
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae. Uniramous, consisting of six segments; bears terminal aesthetasc. With locmomotory and sensory functions.
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae. Basically biramous, consisting of proximal three-segmented peduncle bearing larger outer (main) and smaller inner (accessory) flagellum. May bear aesthetascs. (uniramous, biramous; geniculate).
(syn. first antenna) [Stachowitsch, 1992]
First, relatively large pair of antennae. If fully developed, biramous, consisting of proximal four-segmented peduncle and two flagella. (uniramous, biramous).
(syn. first antenna) [Stachowitsch, 1992]
First and typically smaller pair of antennae. Originates from first (antennular) somite of head, each consisting of basal peduncle and one or more distal flagella. Peduncle bear statocysts and stylocerites, flagella bear aesthetascs. In crab-like (brachyuran) decapod, may be folded into orbitoantennulary pit of carapace. (biramous, triramous).
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae. Basically biramous, consisting of proximal three-segmented peduncle bearing large outer (primary) and smaller inner (accessory) flagella. (short, long; slender, robust; naked, setose, spinose; geniculate; with/without accessory flagellum = biramous/uniramous).
(syn. first antenna) [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Antennae 1 or first antennae; anteriormost paired appendages of head (= antennula). [Wetzer et al. 1997]
First, usually shorter appendage of cephalon; typically uniramous,
consisting of basal peduncle and distal flagellum. (uniramous, biramous).
(syn. first antenna) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Paired appendage of the second cephalon segment; sometimes referred to as antenna 1. [Kensley and Schotte, 1989]
First pair of antennae. Biramous, consisting of three-segmented peduncle and pair of flagella. Antennule of male may bear processes masculinus and, rarely, an additional unsegmented accessory process.
(syn. first antenna) [Stachowitsch, 1992]
First and larger pair of antennae; originating from first (antennular) somite of head. Consists of slender, three-segmented peduncle and three short flagella.
(syn. first antenna) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) First pair of antennae. Relatively long, basically biramous, typically consisting of four-segmented peduncle with flagelliform inner branch (endopod) and scale-like outer branch (exopod). (biramous, uniramous; fourth segment of peduncle: with/without process, with tuft of bristles). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) First pair of appendages on underside of head. Relatively short and basically four-segmented. Bears palp and several large spines/hooks; anterior antennular spine/hook is associated with gland or sensory organ. Serves in attachment to host.
(syn. first antenna) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) First pair of antennae. Present in larval (nauplius, cyprid) stages, yet typically reduced or absent in adults. Used in attachment by barnacle larvae and associated with cement glands. Well developed in adult acrothoracican and ascothoracican. (prehensile, raptorial, subchelate, uniramous).
(syn. first antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) First and typically larger pair of antennae on underside of head. Uniramous, consisting of up to 26 articles. In male, one or both may be equipped with hinge joint for grasping female during copulation. Bears aesthetascs. Number of articles is of systematic importance. The term first antenna is often preferentially applied. (geniculate).
(syn. first antenna) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The anterior limb of the cephalon; it is uniramous in copepods.
(syn. antenna 1) [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The first cephalic appendage. [Boxshall and Halsey, 2004]
First and larger pair of antennae. Uniramous, consisting of eight setose segments and occasionally bearing terminal aesthetasc.
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae on head. Uniramous, typically consisting of five to eight segments. Bears setae and claws for swimming, digging, and copulation; bears one or more aesthetascs. Carpace margin may be indented (rostral notch) for antennules.
(syn. first antenna) [Stachowitsch, 1992]
First and larger pair of antennae on underside of head (cephalon); biramous and consisting of basal peduncle (with two articles and bearing aesthetasc pad) and distal (dorsal and ventral) flagella. Setae on antennae are simple.
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae. Consists of basal peduncle and distal flagellum (or flagella). Biramous, with tiny lappet in bathynellacean interpreted as representing second branch. (with/without statocyst).
(syn. first antenna) [Stachowitsch, 1992]
First, relatively large pair of antennae. Uniramous, consisting of peduncle and flagellum.
(syn. first antenna) [Stachowitsch, 1992]
First pair of antennae. Biramous, consisting of proximal three-segmented peduncle and two distal flagella. Antennules joined to each other by setae on first peduncular segment. (with/ without antennular lappet).
(syn. first antenna) [Stachowitsch, 1992]

Antepenultimate

Second from the last; third from the end in a series. [AHD]
Third from last, as a segment of appendage. [Butler, T. H.]

Anterioposterior axis

(Taxon-specific: Family Cyatholaimidae) An imaginary line through the rostral area of the head and the anal segment. [Ferrari and Dahms, in press]

Front end of organism "head end." [Hobbs and Jass, 1988]
Of, pertaining to, or toward the front. [Butler, T. H.]

Anterior aorta

Aorta. [Stachowitsch, 1992]
Aorta.
(syn. cephalic aorta) [Stachowitsch, 1992]
Major unpaired blood vessel arising from anterior end of heart and extending into head. May bear accessory heart (cor frontale); gives rise to series of smaller arteries supplying brain and eyestalks.
(syn. ophthalmic artery) [Stachowitsch, 1992]
Aorta. [Stachowitsch, 1992]
Major unpaired blood vessel arising from anterior end of heart and extending over stomach into head. Bears accessory pumping organ (cor frontale). [Stachowitsch, 1992]
Aorta.
(syn. anterior dorsal aorta) [Stachowitsch, 1992]
Major unpaired blood vessel arising from anterior end of heart and extending over stomach into head. Bears accessory pumping organ (cor frontale) and gives rise to series of smaller arteries supplying brain and eyes.
(syn. first antenna) [Stachowitsch, 1992]

Anterior chamber

Second portion (after the esophagus) of the chitin-lined foregut; has often been called the cardiac stomach. [Bliss, 1982]

Anterior process

Anterior part of an elongate median protuberance lying on the penultimate (XIII) thoracic sternite (Fig. 4A). [Perez Farfante and Kensley, 1997]

Anterior tubercle

Swelling or small protuberance in anterior region of carapace of Archaeostraca; polygenetic, includes the "optic tubercle" of some authors. [Moore and McCormick, 1969]

Antero-lateral teeth

Teeth situated on the antero-lateral margin of the carapace; i.e., the margin between the outer region of the orbit and the widest part of the carapace. [Ingle, 1983]

Anterolateral

Front side of a structure. [Butler, T. H.]

Anterolateral angle

On each anterolateral margin of carapace, lower extension of antennal notch. (acute, rounded; armed, unarmed).
(syn. anterolateral corner) [Stachowitsch, 1992]

Anterolateral carina

Longitudinal ridge extending along the anterior part of carapace, ventral to gastro-orbital carina. [Perez Farfante and Kensley, 1997]

Anterolateral margin

Margin of carapace between orbit and lateral angle or spine. [Poore, 2004]

Anterolateral region

See: Carapace region a [Martin, 2005]
See: Carapace regions b [McLaughlin, 1980]
In crab-like (brachyuran) decapod, relatively small region along each anterolateral margin of carapace. Adjoining regions include hepatic or subhepatic regions.
See: Posterolateral region [Stachowitsch, 1992]

Anterolateral spine

Anterior part of carapace, including ocular peduncles, based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]

Anterolateral tooth

On carapace of crab-like (brachyuran) decapod, one (or one in a series of) projection(s) along each anterolateral margin. (acute, conical, obtuse, quadrangular, spiniform, subtriangular; ciliated, denticulate, spiny; tip: acuminate, rounded). [Stachowitsch, 1992]

Antimerodont hinge

A median bar or groove differentiated, usually with all elements crenulate. [Cohen, Peterson, and Maddocks, in press]

Antizoea

A modified zoeal stage exhibited by some stomatopods. [Brusca and Brusca, 2002]
Early larval stage of certain stomatopods; characterized by uniramous antennules, five pairs of biramous thoracopods, and no pleopods. (See also pseudozoea). [Stachowitsch, 1992]

Antorbital spine

The spine at the postero-lateral corner of the supraorbital eave in Majidae. [Ingle, 1983]

Antrum

(Taxon-specific: Family Cyatholaimidae) Atrium. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In female reproductive system, invagination of ventral surface (sternite) of first abdominal segment (genital somite). Recieves common opening of both oviducts and openings of seminal receptacles.
(syn. atrium, genital atrium) [Stachowitsch, 1992]

Anus

(Taxon-specific: ) Posterior opening of digestive tract at end of postabdomen. (terminal, on dorsal margin). [Stachowitsch, 1992]
Posterior opening of digestive tract at end of telson; located between caudal rami and may be covered dorsally by supra-anal plate. [Stachowitsch, 1992]
Posterior opening of digestive tract at end of telson. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Posterior opening of digestive tract; located terminally on telson (between caudal rami). [Stachowitsch, 1992]
Posterior opening of digestive tract. Located at end of last (sixth) pleonite or on ventral surface of telson (in the latter case occasionally divided telson into preanal and postanal parts). Flanked by pair of anal valves. [Stachowitsch, 1992]
Posterior opening of digestive tract to exterior. Located on ventral surface of telson. [Stachowitsch, 1992]
Posterior opening of digestive tract; located on ventral surface of telson. [Stachowitsch, 1992]
Posterior opening of digestive tract to exterior; located ventrally at base of telson. [Stachowitsch, 1992]
Posterior opening of digestive tract to exterior; located ventrally at base of telson. [Stachowitsch, 1992]
Posterior opening of digestive tract; located on ventral surface of telson. [Stachowitsch, 1992]
Posterior opening of digestive tract; located anteroventrally on telson. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Posterior opening of digestive tract; located ventrally on telson between caudal rami. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Posterior opening of digestive tract. Located at posterior end between two lobes of abdomen; typically flanked on each side by minute caudal ramus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Posterior opening of digestive tract. Located near posteriormost thoracic appendages. i.e., between sixth pair of cirri; in ascothoracican at end of abdomen. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Posterior opening of digestive tract. Located terminally, on dorsal surface of last abdominal segment (anal somite); covered by anal operculum. [Stachowitsch, 1992]
Posterior opening of digestive tract; located on ventral surface of telson (anal somite). [Stachowitsch, 1992]
Posterior opening of digestive tract at end of body (thorax/abdomen). May be located either dorsal or ventral to caudal rami. [Stachowitsch, 1992]
Posterior opening of digestive tract. Located on telson. (terminal, ventral). [Stachowitsch, 1992]
Posterior opening of digestive tract to exterior; apparently terminal. [Stachowitsch, 1992]
Posterior opening of digestive tract; located ventrally at posterior margin of last (sixth) abdominal somite (pleomere). [Stachowitsch, 1992]

Aorta

(Taxon-specific: ) Heart. [Stachowitsch, 1992]
(Taxon-specific: ) Unpaired blood vessel extending ventroposteriorly from heart. Separated from heart by anteroventral aortic valve and splits distally into several branches. [Stachowitsch, 1992]
In circulatory system, major blood vessel exending from end of heart. One may distinguish 1) an unpaired anterior aorta extending into head and bearing a cor frontale and 2) paired posterior aortas extending to end of abdomen. [Stachowitsch, 1992]
In circulatory system, major blood vessel extending from end of heart. One may distinguish an anterior aorta extending into head and paired posterior aortas. Anterior aorta bears cor frontale.
See: Lateral artery [Stachowitsch, 1992]
Anterior aorta, dorsal aorta. [Stachowitsch, 1992]
In circulatory system, major blood vessel extending from end of heart. One may distinguish an anterior aorta extending into head and a paired or unpaired posterior aorta extending to end of abdomen. [Stachowitsch, 1992]
In circulatory system, major unpaired blood vessel extending from anterior end of heart. Extends into head and bears small accessory heart (corfrontale). [Stachowitsch, 1992]
In circulatory system, major blood vessel extending from heart. According to position one may distinguish an anterior aorta (bearing cor frontale), a posterior aorta, and a descending aorta. [Stachowitsch, 1992]
Major blood vessel leading from heart. According to position one may distinguish an anterior aorta (giving rise to antennal, antennular, opthalmic, and other cephalic arteries) and a posterior aorta. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In circulatory system, major unpaired blood vessel extending from end of heart. One may distinguish an anterior aorta extending into head and a posterior aorta extending into abdomen; each is branched distally. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Unpaired dorsal blood vessel extending anteriorly from heart. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Unpaired dorsal blood vessel extending anteriorly from heart.
(syn. anterior aorta) [Stachowitsch, 1992]
In circulatory system of anaspidacean, major blood vessel extending from heart. According to position one may distinguish an anterior aorta extending into head, a posterior aorta extending into abdomen, and a descending aorta at level of eighth thoracic somite. (See also artery). [Stachowitsch, 1992]
In circulatory system, blood vessel extending from end of heart. One may distinguish short anterior and posterior aortas. [Stachowitsch, 1992]
Anterior aorta, descending aorta, posterior aorta. [Stachowitsch, 1992]

Aortic valve

(Taxon-specific: ) Anteroventral opening in heart through which blood is pumped into aorta. (See also hepatic valve). [Stachowitsch, 1992]

Apertural hook

(Taxon-specific: Order Rhabditida) In acrothoracican, hook-like structure protecting aperture. (See also apertural spine). [Stachowitsch, 1992]

Apertural spine

(Taxon-specific: Order Rhabditida) In acrothoracican, spine-like structure protecting aperture. (See also apertural hook). [Stachowitsch, 1992]

Aperture

Posteroventral opening into cirriped mantle cavity. [Moore and McCormick, 1969]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) In barnacle, opening through which thoracic appendages (cirri) are protruded. In stalked barnacle, bordered on each side by scutum and tergum; bordered in unstalked barnacle by operculum (paired scuta and terga in symmetrical forms, single scutum and tergum in asymmetrical forms). (See also occludent margin).
(syn. orifice) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Posteroventral opening into mantle cavity. [McLaughlin, 1980]

Apex

Upper angle of scutum or tergum of cirripeds. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature; uppermost point (angle) of plate. Typically refers to scutum, tergum, or carina. (beaked). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Upper angle of scutum or tergum (thoracic Cirripedia). [McLaughlin, 1980]

Apical

Apex; tip. [Hobbs and Jass, 1988]
At the distal end. [Butler, T. H.]
Relating to the apex or tip. [Kensley and Schotte, 1989]

Apicobasal ridge

In cirripeds longitudinal feature which divides tergal slip (tergum) from rest of valve.
(syn. apicobasal furrow) [Moore and McCormick, 1969]

Apicoumbonal ridge

(Taxon-specific: Order Rhabditida) Barnacle plate feature; in scutum of stalked form, ridge extending from upper point (apex) to umbo. [Stachowitsch, 1992]

Apodemal pit

Any of several often unpigmented depressions on the carapace of many crabs indicating the origin of an invaginated element that forms part of the internal thoracic skeleton. [Chace and Hobbs, 1969]

Apodeme

A cuticular, usually calcified invagination upon which muscles insert and which, itself, inserts by means of tough flexible cuticle onto that part of the skeleton which is moved by its muscles (Figs. 12, 13). [Warner, 1977]
Any cuticular ingrowth of body wall. [Williams, 1984]
Infold of exoskeleton for attachment of muscles. [McLaughlin, 1980]
Infold of exoskeleton serving for attachment of muscles. [Moore and McCormick, 1969]
Any one of numerous infolds of exoskeleton serving for attachment of muscles (e.g., head apodeme). May be highly developed as endopleurites and endosternites to form endoskeleton. [Stachowitsch, 1992]

Apophysis

(Taxon-specific: Family Cyatholaimidae) A spinous process on a swimming leg segment, typically sexually dimorphic (present in male only); ma y originate as produced segmental margin, or may be derived by modification of setal element present in female. [Boxshall and Halsey, 2004]
Type of valve sculpture: extension of wall (murus) in reticulate pattern. May lead to pore. [Stachowitsch, 1992]

Appendage

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
An articulated structure used for feeding, locomotion, sensory reception, e.g., mouthparts, antennae, pereopods, pleopods, uropods. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) Paired extensions of a somite along a proximodistal axis and usually composed of serially repeated elements. Appendages of copepods include the limb of the five cephalic somites, the limb of the seven thoracic somites plus the caudal ramus of the anal segment (see also limb and swimming leg). [Ferrari and Dahms, in press]

Appendix interna

A slender rodlike lappet on the mesial ,argin of the endopod of the second through fifth pleopods of shrimps; it is provided with terminal hooked setae by which the two pleopods of a pair must be joined mesially.
(pl. appendices internae) [Chace and Hobbs, 1969]
A slender rodlike structure on the mesial border of the endopod of the second through fifth pleopods of shrimps; terminal and/or subterminal hooked setae allow the mesial joining of two pleopods of a pair. [Hobbs, Hobbs, and Daniel 1977]
Medial projection stemming from pleopodal endopods, serving to unite members of each pair of pleopods.
(syn. stylamblys) [Moore and McCormick, 1969]
Median process of pleopodal endopod uniting members of each pair.
(syn. stylamblys) [McLaughlin, 1980]
Slender lappet, sometimes rodlike, at the mesial base of the endopod of the second pleopod (dorsal to the appendix masculina) of many males.
(pl. appendices internae) [Perez Farfante and Kensley, 1997]
Slender rodlike flap on inner margin of endopod of the second to fifth pleopods of shrimp.
(pl. appendices internae) [Butler, T. H.]
Slender, rodlike structure on mesial border of endopod of second through fifth pleopods of shrimp. [Hobbs and Jass, 1988]
Small branch on inner margin of pleopod 2, triangular or rod-like, usually with clusters of hooks to attach to its pair.
(pl. appendices internae) [Poore, 2004]
Small separate branch on mesial side of pleopodal endopodite, usually tipped with hooks which interlock with opposite member in swimming. [Williams, 1984]
Projection of inner branch (endopod) of each pleopod; serves to hook pleopod to its opposite member (for swimming).
(syn. stylamblys) [Stachowitsch, 1992]
Projection of inner branch (endopod) of each pleopod. Bears hooks (retinacula) and, in first pleopod pair of male, hook-shaped and tubular processes (petasma).
(syn. stylamblys) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In each of the four well-developed anterior pairs of pleopods, medially (inwardly) directed process at base of endopod. Serves to link pleopods together for swimming. [Stachowitsch, 1992]
Medially (inwardly) directed process of each pleopod. Serves to link pleopods of each somite together for swimming. [Stachowitsch, 1992]

Appendix masculina

A lappet inserted between the appendix interna and the mesial margin of the second pleopod of most male shrimps. The presence or absence of an appendix masculina is the easiest way to distinguish males and females in most caridean shrimps, and in some families, such as the Atyidae, it is greatly enlarged, dwarfing the superimposed appendix interna, and it offers important taxonomic characters.
(pl. appendices masculinae) [Chace and Hobbs, 1969]
A setiferous lobe or rodlike structure situated between the appendix interna and the mesial margin of the mesial ramus (endopod) of the second pleopod of male shrimps. Often an important taxonomic character, the presence or absence of an appendix masculina is the easiest means of distinguishing males and females of most freshwater shrimps. [Hobbs, Hobbs, and Daniel 1977]
Accessory male organ located mesially on second pair of pleopods between endopodite and appendix interna. [Williams, 1984]
An alternative name for a stylet-like copulatory structure on the male pleopod II. This structure is not homologous to similarly named structures found in non-isopod Eumalacostraca. [Wilson, 1989]
Complex median process of 2nd ploepodal endopod of male Caridea and some other Eucarida used in copulation or spermatophore transfer. [McLaughlin, 1980]
Complex median process of endopod of second pleopods of male Caridea and some isopods; serves in copulation. [Moore and McCormick, 1969]
Flap inserted between appendix interna and inner margin of endopod of the second pleopod in most male shrimps.
(syn. appendices musculinae) [Butler, T. H.]
Lappet, sometimes scalelike, at the mesial base of the endopod of the second pleopod (ventral to the appendix interna if latter present) in some males.
(pl. appendices masculinae) [Perez Farfante and Kensley, 1997]
Lobe or rodlike structure, bearing setae, situated between appendix interna and mesial margin of endoopod of second pleopod of male shrimps. The presence or absence of this structure provides easiest means of distinguishing males from females; an important taxonomic character for palaemonids (see Fig. 73j,k). [Hobbs and Jass, 1988]
Small branch on inner margin of pleopod 2 of males, usually rod-like, proximal to appendix interna.
(pl. appendices masculinae) [Poore, 2004]
Median process of inner branch (endopod) of second pleopod in male; serves in copulation or spermatophore transfer. [Stachowitsch, 1992]
Copulatory stylet arising from medial margin of male pleopod 2 endopod, used for transfer of spermatophores in at least some species.
(pl. appendices masculinae) [Wetzer et al. 1997]
Rod-shaped median process on endopod of second pleo-pod in male; serves in sperm transfer.
(syn. male stylet) [Stachowitsch, 1992]

Aquaculture

Large-scale cultivation of aquatic organisms under controlled conditions, for use of food or for other economic purposes. [Bliss, 1982]

Area

(Taxon-specific: ) One in a number of somewhat arbitrarily delimited regions on lateral surface of valve. According to position one may distinguish anterior, anterodorsal, anteromedian, anteroventral, dorsal, dorsomedian, median, midanterior, middorsal, midposterior, posterior, posterodorsal, posteromedian, posteroventral, ventral, and ventromedian areas. [Stachowitsch, 1992]

Areola

Area between branchiocardiac grooves and posterior to cervical groove on dorsal surface of carapace (Astacidea and Austroastacidea). [McLaughlin, 1980]
Dorsomedial area (usually hourglass-shaped) of thoracic region of carapace of crayfishes, bounded laterally by paired arched (branchiocardiac) grooves delineating dorsomedial limits of gill chamber (see Fig. 14). [Hobbs and Jass, 1988]
See "Cardiac region". [Chace and Hobbs, 1969]
The dorsomedian area of the thoracic part of the carapace of crayfishes, bound laterally by paired arched (branchiocardiac) grooves. [Hobbs, Hobbs, and Daniel 1977]
On dorsal surface of carapace, area between two longitudinal branchiocardiac grooves and posterior to transverse cervical groove. [Stachowitsch, 1992]

Areolation

Demarcated and usually elevated regions of the brachyuran carapace. [Martin, 2005]

Armature

(Taxon-specific: Family Cyatholaimidae) The setae and spines carried on the paired limbs and caudal rami. [Boxshall and Halsey, 2004]

Artery

One of numerous blood vessels originating from aorta or directly from heart. According to position or body region/appendages supplied, one may distinguish, among others, antennal, antennular, hepatic, lateral cephalic, ophthalmic, optic, pleopodal, rostral, segmental, sternal, and subneural arteries. [Stachowitsch, 1992]
One of numerous blood vessels originating from heart or aortas. According to position one may distinguish anterior lateral or facial artery as well as three pairs of lateral arteries. [Stachowitsch, 1992]
One of numerous blood vessels originating from heart or aorta. According to position one may distinguish anterior and posterior arteries as well as a subneural artery. [Stachowitsch, 1992]
One of numerous blood vessels originating from aorta or directly from heart. According to position and mysidacean group, one may distinguish hepatic, (anterior and posterior) lateral, sternal, subneural, and ventral arteries. [Stachowitsch, 1992]
One of numerous blood vessels originating from heart or aorta. According to position or appendages supplied, one may distinguish antennal, antennular, opthalmic, lateral, and subneural arteries. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of numerous blood vessels originating from heart or aortas. According to position or organ supplied, one may distinguish dorsal, labral, median, and segmental arteries, the latter with podial and visceral branches. [Stachowitsch, 1992]
In anaspidacean, one of numerous blood vessels originating from heart or aorta. According to position one may distinguish seven pairs of lateral arteries and a subneural artery (arising from descending aorta). [Stachowitsch, 1992]
One of numerous blood vessels originating from aorta or directly from heart. According to position or body region/appendages supplied, one may distinguish, among others, abdominal, antennal, antennular, anterior lateral, mandibular-maxillary, ophthalmic, posterior lateral, and sternal arteries. [Stachowitsch, 1992]

Arthrite

(Taxon-specific: Family Cyatholaimidae) A movable endite, used for the praecoxal endite of maxillule. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) A ventrally articulating, sclerotized extension of a protopodal segment that is moved by muscles. [Ferrari and Dahms, in press]

Arthrobranch

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
A decapod gill associated with the articular membrane between the coxa and the body wall; "joint gills." [Brusca and Brusca, 2002]
A gill arising from the articular membrane at the proximal base of the coxa of an appendage. [Hobbs, Hobbs, and Daniel 1977]
A gill arising from the junction of the limb with the body. [Ingle, 1983]
Gill attached to the articular membrane between body wall and coxa of an appendage. [Butler, T. H.]
Gill attaching to membrane between coxa and side of body, 1 or 2 pairs per somite and usually pointing upwards. [Poore, 2004]
Gill of decapods attached to articular membrane between limb and body.
(syn. arthrobranchia) [Moore and McCormick, 1969]
Gill attached to articular membrane between appendage and body.
(syn. arthrobranchiata) [McLaughlin, 1980]
Type of gill attached to point of articulation (articular membrane) between thoracopod and body wall. If full complement is developed, may be found associated with first through seventh thoracopods (i.e., all except last pereopods).
(syn. arthrobranchia)
See: Pleurobranch, Podobranch [Stachowitsch, 1992]

Arthrobranchia

Branchia (gill) attached to the joint area between the body and the first podomere of the leg (Fig. 3C).
(pl. arthrobranchiae) [Perez Farfante and Kensley, 1997]

Arthrobranchiae

Gills attached to articular membrane between coxa of appendage and body wall. [Williams, 1984]

Arthrodial membrane

Tough flexible cuticle occurring between skeletal elements and allowing relative movement. [Warner, 1977]
(Taxon-specific: Family Cyatholaimidae) An unsclerotized, flexible section of the exoskeleton between the sclerotized parts of two somites or two segments. [Ferrari and Dahms, in press]

Arthrophragm

See: Endophragm [Martin, 2005]
A cuticular calcified invagination, usually in the form of a plate, which provides a rigid orgin for muscles. [Warner, 1977]
See endophragm. [McLaughlin, 1980]

Article

A segment of any limb, but usually applied to the antennula or antenna. [Wilson, 1989]
Any of the segments of a limb or appendage.
See: Coxa, Basis, Ischium, Merus, Carpus, Propodus, Dactylus [Poore, 2004]
Any one of the subdivisions of an appendage segment. [Perez Farfante and Kensley, 1997]
Individual element of crustacean appendage.
(syn. joint, segment) [Moore and McCormick, 1969]
Subdivision of antennal or antennular flagella or appendage.
See: Segment [McLaughlin, 1980]
One of up to 25 segments of antennal branches (rami, flagella). May also refer to segment of other appendages. [Stachowitsch, 1992]
Segment of appendage. [Stachowitsch, 1992]
Any segment of appendage, although often applied to segment of flagellum of antennule or antenna.
(syn. joint, segment) [Stachowitsch, 1992]
One in a series of numerous segments of flagellum at end of antenna or antennule. May also refer to segment of pereopod.
(syn. joint, segment) [Stachowitsch, 1992]
Any segment of an appendage, although often applied to segments of flagella of antennules or antennae.
(syn. joint, segment) [Stachowitsch, 1992]
A single section of an appendage, with an articulation at one or both ends. [Kensley and Schotte, 1989]
Any segment of an appendage, although often applied to segments of flagellum of antennae or antennules.
(syn. joint, segment) [Stachowitsch, 1992]
One in a series of numerous segments of flagellum at end of antennule or antenna. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One in a series of segments of flagellum of antennule or antenna. May also refer to segment of other appendages.
(syn. joint, segment) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One in a series of segments of thoracic appendage (cirrus) or other appendage.
(syn. joint segment) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) One in a series of up to 26 segments of flagellum of antennule (few in antenna). Number of articles is of systematic importance. May also be used to refer to segments of other appendages.
(syn. segment, joint) [Stachowitsch, 1992]
See podomere.
See: Podomere [Cohen, Peterson, and Maddocks, in press]
In antennule, one of 11 or 12 segments of larger dorsal flagellum or 3 or 8 segments of smaller ventral flagellum. Each article bears tuft of several setae at distoventral end as well as scattered setae along shaft. Last article bears terminal tuft of setae . Also synonymous with any appendage segment.
(syn. joint, segment) [Stachowitsch, 1992]
Any segment of appendage, although often applied to segment of flagella of antennules and antennae.
(syn. joint, segment) [Stachowitsch, 1992]

Articular furrow

In cirripeds, groove on tergal margin of scutum or scutal margin of tergum forming part of articulation between the plates. [Moore and McCormick, 1969]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, linear elevation on tergal margin of scutum or scutal margin of tergum. Ridge and furrow of scutum (or tergum) articulate with corresponding structures in tergum (or scutum). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Groove near tergal margin of scutum or scutal margin of tergum forming part of articulation between the two valves (balanomorph Cirripedia). [McLaughlin, 1980]

Articular knob

A swelling or irregularity in the integument at a joint, as on either side of a chela at the base of the movable finger or between the abdominal somites at the juncture of the terga and the pleura. [Chace and Hobbs, 1969]
Swelling or irregularity in the shell at a joint of an appendage, or between abdominal somites at the juncture of pleuron and tergum. [Butler, T. H.]

Articular membrane

The uncalcified integument at a joint, permitting movement of the exoskeleton, as between the podomeres of a pereiopod. [Chace and Hobbs, 1969]
The uncalcified integument, permitting movement of the shell, as between segments of a periopod, or between abdominal somites. [Butler, T. H.]
Uncalcified integument of a joint, permitting movement of the exoskeleton, as between the segments of a pereopod. [Perez Farfante and Kensley, 1997]

Articular ridge

In cirripeds (Balanomorpha), linear elevation on tergal margin of scutum or scutal margin of tergum close to articular furrow and with it forming articulation between these plates. [Moore and McCormick, 1969]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Linear elevation on scutum or tergum bordering articular furrow and with it forming articulation between with two valves (balanomorph Cirripedia). [McLaughlin, 1980]

Ascending

Growing or directed upward. [Butler, T. H.]

Atrium oris

Preoral cavity, bounded ventrally by posteriorly directed labrum, dorsally by ventral surface of cephalon just behind mouth, and laterally by paragnaths and mandibles. [Moore and McCormick, 1969]
Preoral cavity, bounded ventrally by posteriorly directed labrum, dorsally by ventral surface of cephalon just behind mouth, and laterally by paragnaths and mandibles. [McLaughlin, 1980]
Large preoral cavity formed by upper lip (labrum) extending over mouth. Tips (molar processes) of mandibles extend into atrium oris. [Stachowitsch, 1992]
Large preoral cavity formed by labrum extending over mouth. Mandibles (and to a lesser extent the endites or gnathobases of maxillules) extend into atrium oris. [Stachowitsch, 1992]
Cavity around mouth formed by projecting posterior margin of labrum and paragnaths; masticatory ends (incisor process, lacinia mobilis, molar process) of mandible project into atrium oris. [Stachowitsch, 1992]

Attachment disc

(Taxon-specific: Order Rhabditida) In female acrothoracican, anteroventral horny structure used in attachment to burrow. If somewhat elevated, referred to as attachment knob. [Stachowitsch, 1992]

Attractor epimeralis muscle

Important muscle in many decapods, inserted along line of branchiocardiac groove in carapace. [Moore and McCormick, 1969]
Prominent muscle in many decapods, inserting along line of branchiocardiac groove. [McLaughlin, 1980]
In each side of cephalothorax, prominent muscle extending from epimeral fold to carapace, where it inserts along branchiocardiac groove (or lateral gastrocardiac marking).
(syn. tergoepimeral muscle) [Stachowitsch, 1992]

Autotomy

The voluntary shedding of a limb by snapping it off the base. [Ingle, 1983]

Bar

(Taxon-specific: ) Hing structure: Ridge-like projection extending along and set off from dorsal margin of one valve. Fits into accommodation groove of opposite valve. (smooth, crenulate).
(syn. hinge bar) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One in a series of chitinous skeletal elements supporting distal end of proboscis. According to position on may distinguish groove, lateral, lateral marginal, anterior and posterior lateral oblique, and inner and outer mandibular bars. [Stachowitsch, 1992]

Basal margin

In cirripeds, lower edge of scutum or tergum or other plate. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: lower edge of plate. Typically refers to lower edge of scutum or tergum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Lower edge of scutum or tergum or other plate (thoracic Cirripedia). [McLaughlin, 1980]

Basal plate

(Taxon-specific: Order Monhysterida) Spine-studded, plate-like structure on basal segment of each maxilla. (spines: alike, unlike; close together, well-separated; blunt, curved, scale-like, sharp).
(syn. maxillary plate) [Stachowitsch, 1992]

Baseoendopod

(Taxon-specific: Family Cyatholaimidae) The fused basis and endopod, particularly of the fifth leg in harpacticoids. [Boxshall and Halsey, 2004]

Basi-ischium

The second podomere from the base of a limb, formed from the fusion of the basis and the ischium of the primitive appendage (Figs. 1, 2). [Warner, 1977]
Ischiobasis. [Stachowitsch, 1992]

Basial spine

Spine projecting from basis of a thoracic appendage. [Perez Farfante and Kensley, 1997]

Basicarinal angle

Intersection of basal and carinal margins of cirriped tergum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: corner of tergum formed by junction of basal and carinal margins. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Intersection of basal and carinal margins of tergum (thoracic Cirripedia). [McLaughlin, 1980]

Basicerite

Second or distal segment of the protopodite of antenna, to which are attached the scale and peduncle. [Butler, T. H.]
Second segment of antennal peduncle (in Caridea bearing scaphocerite). [Moore and McCormick, 1969]
Second segment of antennal peduncle, bearing scaphocerite (Caridea). [McLaughlin, 1980]
Spine on dorsal side of basis of antenna; sometimes more lateral than dorsal. [Martin, 2005]
In antenna, term applied to second of two segments (coxicerite, basicerite) of peduncle; may bear antennal scale (scaphocerite).
See: Carpocerite, Ischiocerite, Merocerite [Stachowitsch, 1992]

Basidorsal point

(Taxon-specific: Order Rhabditida) In certain unstalked barnacles, cone-shaped projection at base of penis. [Stachowitsch, 1992]

Basilateral angle

In cirripeds, intersection of lateral and tergal margins of scutum.
(syn. basitergal angle) [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Basitergal angle. [Stachowitsch, 1992]

Basioccludent angle

Intersection of basal and occludent margins of cirriped scutum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: corner of scutum formed by junction of basal and occludent margins. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Intersection of basal and occludent margins of scutum (thoracic Cirripedia). [McLaughlin, 1980]

Basiophthalmite

Proximal segment of eyestalk, articulating with distal segment (podophthalmite) which bears corneal surface of eye. [Moore and McCormick, 1969]
Proximal segment of eyestalk, articulating with distal segment (podopthalmite) bearing corneal surface of eye. [McLaughlin, 1980]
Proximal of typically two segments (basiophthalmite, podophthalmite) of eyestalk. [Stachowitsch, 1992]

Basipod

See: Basis [Martin, 2005]
See basis. [McLaughlin, 1980]

Basis

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Article 2 of thoracic and abdominal appendages. [Holdich and Jones, 1983]
Limb segments adjoining coxa on its distal side and commonly bearing endopod and exopod; in nonpedunculate cirripeds comprises basal calcareous or membranous plate which furnishes anchorage to foreign body or substrate.
(syn. basipod(ite)) [Moore and McCormick, 1969]
Second article (from body) of leg or maxilliped. Sixth segment from distal end of limb.
(syn. basipodite) [Williams, 1984]
Second article of limb.
(pl. bases) [Poore, 2004]
Second podomere or segment, from the proximal end of a typically 7-segmented appendage (Fig. 3C).
(pl. bases) [Perez Farfante and Kensley, 1997]
Second segment (from proximal end) of segmented appendage. [Hobbs and Jass, 1988]
Second segment from the proximal end of a typically 7-segmented appendage.
(pl. bases) [Butler, T. H.]
Second segment of a pereiopod or maxilliped counted from the proximal end, immovably united with the ischium. [Ingle, 1983]
Segment of protopod adjoining coxa and carrying exopod and endopod distally; also basal calcareous or membranous plate furnishing anchorage to substrate in sessile cirripeds.
(pl. bases) [McLaughlin, 1980]
The second segment from the proximal end of a segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
The second segment from the proximal end of a typically 7-segmented appendage.
(pl. bases) [Chace and Hobbs, 1969]
The second segment of a thoracic limb.
See: Pereopod [Wilson, 1989]
(Taxon-specific: ) Second segment of appendage; from distal segment of protopod (coax, basis). Often fused and indistinguishable.
(syn. basipodite) [Stachowitsch, 1992]
Protopod. [Stachowitsch, 1992]
Elongate second segment of thoracopod (maxillipeds and pereopods) or pleopods. May bear five-segmented endopod and smaller exopod. (See also epipod). [Stachowitsch, 1992]
Second of seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod. Bears endite in maxillae and maxillipeds.
(syn. basipodite) [Stachowitsch, 1992]
Second segment of appendage (thoracopod); forms distal segment of protopod (coxa, basis) and bears variously developed branches (endopod, exopod). May be fused to following segment (ischium) to form ischiobasis.
(syn. basipodite) [Stachowitsch, 1992]
Second of seven segments of thoracopod (coxa, basis, ischium, merus, carpus, propodus, dactylus); represents first movable (free) segment.
(syn. basipodite) [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
(Figure only.) [Wetzer et al. 1997]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Article of appendage adjoining coxa proximally, and carrying endopod distally, i.e., article 2 of pereopod. [Kensley and Schotte, 1989]
Second segment of pereopod; located between coxa and ischium.
(syn. basipodite) [Stachowitsch, 1992]
Second of two segments (coxa, basis) of proximal part (protopod) of appendage.
(syn. basipodite) [Stachowitsch, 1992]
Third segment of thoracic appendage (thoracopod); located between coxa and merus. Also interpreted as being second segment (between coxa and ischium).
(syn. basipodite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In thoracopod, third of three segments (precoxa, coax, basis) of protopod; may also be applied to segment of antennule.
(syn. basipodite) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Basal element by which unstalked barnacle is attached to substratum. (calcareous = solid, membranous). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Second segment of appendage; forms distal segment of protopod (coxa, basis).
(syn. basipodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The distal segment of the protopod of postantennulary appendages, bearing the rami. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) The distal segment of the protopod; it bears no more than two ventral, setose endites. The rami, exopod and endopod of a limb, originate on the basis (see coxa and praecoxa). [Ferrari and Dahms, in press]
Protopod. [Stachowitsch, 1992]
Distal part of divided protopod (separated from coxa by suture). [Cohen, Peterson, and Maddocks, in press]
Second of two segments (coxa, basis) of proximal part (protopod) of appendage.
(syn. basipodite) [Stachowitsch, 1992]
Second of two segments (coxa, basis) of proximal part (protopod) of appendage. Frequently interpreted as being fused with following segment (ischium) in maxilliped endopod.
(syn. basipodite) [Stachowitsch, 1992]
Second segment of appendage; forms distal segment of protopod (coxa, basis) and bears variously developed branches (endopod, exopod). Typically specified only when referring to thoracopods.
(syn. basipodite) [Stachowitsch, 1992]

Basiscutal angle

Intersection of basal and scutal margins of cirriped tergum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature; corner of tergum formed by junction of basal and scutal margins. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Intersection of basal and scutal margins of tergum (thoracic Cirripedia). [McLaughlin, 1980]

Basitergal angle

Intersection of basal and tergal margins of cirriped scutum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature; corner of scutum formed by junction of basal and tergal margins.
(syn. basilateral angle) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Intersection of basal and tergal margins of scutum (thoracic Cirripedia). [McLaughlin, 1980]

Bathypelagic

Zone in the ocean deeper than 1000 m below the surface, or pertaining to its inhabitants. [Butler, T. H.]

Beak

Downwardly directed (anteroventral) projection of carapace margin. Not equivalent to rostrum and not associated with rostral notch. [Stachowitsch, 1992]

Beaked apex

In cirripeds (Balanomorpha), upper angle of tergum produced into long narrow point. [Moore and McCormick, 1969]

Bellonci organ

Organ projecting from forehead or naupliar (medial) eye of most Myodocopa. [Cohen, Peterson, and Maddocks, in press]

Bender muscle

The muscle which bends the leg forward at the CP joint.
See: Abdominal spine, Cephalothorax [Warner, 1977]

Biarticulate

Consisting of two articles or segments. [Wilson, 1989]
Composed of two articles. [Kensley and Schotte, 1989]

Bidentate

Having two teeth. [Kensley and Schotte, 1989]

Bifid

A structure with two distal tips, as in unequally bifid seta. [Wilson, 1989]
Split in two, as in spines. [Butler, T. H.]
Divided into two lobes or parts by a cleft. [Kensley and Schotte, 1989]

Biformes

Carapaces reflecting sexual dimorphism (e.g., Conchostraca), marked by differing valve proportions for each sex of same species (DADAY); a given species may have carapaces that are "biformes.". [Moore and McCormick, 1969]
Carapaces reflecting sexual dimorphism (e.g., Conchostraca), marked by differing valve proportions for each sex of the same species. [McLaughlin, 1980]

Bifurcate

Forked, divided into two branches. [Butler, T. H.]

Bilobed

Composed of two lobes. [Kensley and Schotte, 1989]

Bioluminescene

Production of light by living organisms; occurs in several genera of shrimps. [Butler, T. H.]

Biramous

Having two branches or rami (exopodite and endopodite). [Holdich and Jones, 1983]
Having two branches, a typical condition for most primitive crustacean appendages. [Wilson, 1989]
Having two branches, as a pleopod. [Butler, T. H.]
Having two branches, as in the basic appendage (Fig. 2). [Warner, 1977]
Having two branches. Crustacean appendage with two rami; also antennule or antenna with two flagellar elements. [McLaughlin, 1980]
Two-branched; crustacean limb in which basis bears both exopod and endopod. [Moore and McCormick, 1969]
Composed of two rami or branches. [Kensley and Schotte, 1989]
Composed of two rami or branches. [Wetzer et al. 1997]
(Taxon-specific: Family Cyatholaimidae) Two-branched, used of limbs possessing both endopod and exopod. [Boxshall and Halsey, 2004]

Biserial branch

Primary branch of dendrobranchiate gill subdivided into two rows or series. [McLaughlin, 1980]

Biunguiculate

Having two claws, as in a bifid dactylus. [Kensley and Schotte, 1989]

Bladder

Expanded section of antennal gland between end sac and excretory pore. Consists of simple vesicle or is subdivided into a number of lobes or elongate diverticula extending into different regions of body. [Stachowitsch, 1992]

Blind capsule

(Taxon-specific: Order Monhysterida) In male reproductive system, pair of glands in anterior region of thorax. Duct from each blind capsule connects to vas deferens and leads to common ejaculatory duct and gonopore.
(syn. blind gland) [Stachowitsch, 1992]

Blood pump

(Taxon-specific: Order Rhabditida) Rostral sinus. [Stachowitsch, 1992]

Blood rooms

Network of anastomosing cavities in body of conchostracans which provide for circulation of blood (SARS). [Moore and McCormick, 1969]

Body articulation

(Taxon-specific: Family Cyatholaimidae) Point at which body is capable of bending to greatest extent. Region of body anterior to flexure point is termed prosome, that posterior to it, urosome. According to group, it is located either between third/fourth, fourth/fifth, fifth/sixth thoracic somites or between sixth thoracomere and genital somite.
(syn. body flexure, flexure point) [Stachowitsch, 1992]

Body chamber

In cirripeds, interior of shell contaning soft parts of animal. [Moore and McCormick, 1969]

Body of mandible

See: Mandible body [Martin, 2005]

Body ring

Combined tergite and sternite of single somite, bearing legs or legless (as used by some specialists on Notostraca, not equivalent to somite). [Moore and McCormick, 1969]
One in a series of divisions of thorax and abdomen. Posterior body rings may bear more than one pair of appendages each and are therefore considered to consist of several fused segments. May be modified to form half rings or spiral rings. (with leg, apodous).
(syn. ring) [Stachowitsch, 1992]

Body somite

Generally refers to unit division of thorax + abdomen in contrast to cephalic somite. [Moore and McCormick, 1969]

Boletate

A tubercle with a thick stem that is expanded distally into a convex or flat-topped surface with a circumference broader than the stem and that is usually punctate or marginally striate. [Ingle, 1980]

Bopyridum

Postlarva of epicaridean isopod that is attached to permanent host. [McLaughlin, 1980]

Boss

A globular, often polished, protrusion from the carapace surface. [Ingle, 1983]
An expanded portion (rounded protuberance) on mesial surface of coxa of fourth pereiopod of male crayfish (see Fig. 14). [Hobbs and Jass, 1988]

Brachium

(Taxon-specific: Family Cyatholaimidae) The digital segment of the maxilla of some siphonostomatoid copepods, corresponding to the basis plus basal endite. [Boxshall and Halsey, 2004]

Brachyura

An infra-order of decapod crustaceans. Used by Latrielle (1802) for the 'short tail' decapods, and now having the following restricted definition. Epistome always fused laterally with carapace and usually also medioanteriorly, pereiopod 1 chelate, 2-4 alike, abdomen reduced in size, bent under thorax. [Ingle, 1992]

Brachyuran crabs

Members of the infraorder Brachyura, in which all five pairs of thoracic legs are well developed.
(syn. true crabs) [Bliss, 1982]

Brain

Main concentration of nreve tissue in head; consists of supraesophagael ganglion (protocerebrum and deutocerebrum) and, posterior to mouth, tritocerebrum (ganglion of antennal somite). Continues posteriorly as ladder-like ventral nerve cords. [Stachowitsch, 1992]
Main concentration of nerve tissue in head. Consists basically of ganglion (supraesophageal ganglion = protocereberum + deutocerebrum) anterior to esophagus and ganglion (tritocerebrum) to side of or posterior to esophagus. Continues posteriorly as ladder-like ventral nerve cord. [Stachowitsch, 1992]
main concentration of nerve tissue in head. Consists basically of ganglion (supraesophageal ganglion = protocerebrum and deuterocerebrum) anterior to esophagus and ganglion (tritocerebrum = circumesophageal ganglion = ganglion of antennal somite) to each side of or posterior to esophagus. Continues posteriorly as ladder-like ventral nerve cord. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Main concentration of nerve tissue; consists of supraesophageal ganglion (protocerebrum, deuterocerebrum) and, posterior to mouth, tritocerebrum (ganglion of antennal somite). [Stachowitsch, 1992]
Main concentration of nerve tissue in cephalon. Connected with "eyes" by optic nerves and continues posteriorly to form subesophageal ganglion. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Supraesophageal ganglion. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Supraesophageal ganglion. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Supraesophageal ganglion. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Supraesophageal ganglion. [Stachowitsch, 1992]
Main concentration of nerve tissue in cephalon. Consists of anterior protocerebrum, median deutocerebrum (ganglion of antennular somite), and, at some distance posterior to deutocerebrum, a tritocerebrum (ganglion of antennal somite). Surrounds esophagus and gives rise to pair of ventral nerve cords. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Main concentration of nerve tissue located above foregut in anterior region of head (cephalon); connected to ventral nerve cord by pair of circumesophageal commissures.
(syn. supraesophageal ganglion) [Stachowitsch, 1992]
Main concentration of nerve tissue above (anterior to) esophagus. Continues posterior to esophagus as ventral nerve cord.
(syn. supraesophageal ganglion) [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]

Branchia

Gills, usually thoracic. [Poore, 2004]
Respiratory organ (gill) associated with an appendage or with the body wall.
(pl. branchiae) [Perez Farfante and Kensley, 1997]
Thin-walled finger-like or leaf-like structure extending outward from limb or secondarily from side of body, functioning for respiration.
(syn. gill. [Special types are termed arthrobranchs, pleurobranchs, and podobranchs, depending on their pl) [Moore and McCormick, 1969]
Thin-walled, fingerlike or leaflike structure extending outward from appendage or secondarily from side of body, functioning in respiration.
(pl. branchiae) (syn. gill) [McLaughlin, 1980]
Gill. [Stachowitsch, 1992]
Coxal gill. [Stachowitsch, 1992]
Respiratory structure on or modification (thin cuticle, folding, etc.) of pleopod for gas exchange. [Stachowitsch, 1992]
Gill. [Stachowitsch, 1992]
Gill. [Stachowitsch, 1992]
Branchial plate, gill. [Stachowitsch, 1992]

Branchial

Pertaining to the gills. [Butler, T. H.]

Branchial apparatus

Term applied to epipods of first maxilliped pair (or, in an alternate interpretation, to epipods and exopods). Modified for respiration, the posteriorly directed part extending into branchial cavity and bearing branchial lobules, the anteriorly directed part ("exopod") forming part of exhalant cephalon. [Stachowitsch, 1992]

Branchial carina

See: Carapace carina b [Martin, 2005]
See: Carapace carina b [McLaughlin, 1980]
On each side of carapace in shrimp-like (natantian) decapod, narrow, longitudinal ridge extending posteriorly from orbit over branchial region. [Stachowitsch, 1992]

Branchial cavity

See: Branchial chamber [Martin, 2005]
Space between thorax and lateral flap of carapace (branchiostegite) enclosing branchia or gills. [Poore, 2004]

Branchial chamber

A chamber limited primarily by the lateral folds of the carapace, the inner surface of which performs a respiratory function. [Holdich and Jones, 1983]
Area between body and carapace enclosing branchiae.
(syn. gill chamber) [McLaughlin, 1980]
Chamber between carapace and body wall (pleura) that contains gills in most decapods. [Brusca and Brusca, 2002]
On either side of the cephalothorax of shrimps, lobsters, crabs and certain other crustaceans; formed from a deep lateral fold of the carapace; house the gills. [Bliss, 1982]
Space between body and wall of carapace enclosing branchiae.
(syn. gill chamber) [Moore and McCormick, 1969]
The chamber formed by the lateral region of the carapace enclosing the gills. [Ingle, 1983]
Space on each side of cephalothorax between body and inner wall of carapace. Contains posteriorly directed part of epipods of first maxillipeds. Closed posteriorly, with water entering anteriorly and exiting frontmedially via siphon. [Stachowitsch, 1992]
Space on each side of head between body and inner wall of carapace. Epipods of maxillipeds extend into branchial chamber. Water enters chamber primarily at posteroventral margins of carapace and exits ventrally at bases of maxillipeds.
(syn. branchial cavity) [Stachowitsch, 1992]
Lateral or dorsolateral space on each side of cephalothorax between body wall and carapace; encloses gills. In shrimp-like (natantian) decapod, water enters branchial chamber along posterior or ventral edges of carapace; in crab-like (brachyuran) decapod, it typically enters via afferent respiratory channels near bases of chelipeds.
(syn. gill chamber)
See: Epibranchial space, Hypobranchial space [Stachowitsch, 1992]
Area on ventral surface of abdomen (pleon) containing branchiae; may be covered by expanded pleopods or uropods. [Stachowitsch, 1992]

Branchial count

The number of gills and epipodites present on one side of the cephalothorax. [Hobbs, Hobbs, and Daniel 1977]

Branchial filament

(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, one element in tuft-like aggregations of slender processes of abdomen. [Stachowitsch, 1992]

Branchial glands

masses of connective-tissue cells surrounding venous channels in branchiae and devoid of ducts. [Moore and McCormick, 1969]
Masses of connective-tissue cells without ducts surrounding venous channels in branchiae. [McLaughlin, 1980]

Branchial lobe

A boss located at the anteriomesial angle of the mesobranchial region on the carapace of certain crabs. [Chace and Hobbs, 1969]
One in a series of respiratory projections along posteriorly directed part of epipods of first maxillipeds. Located in branchial chamber. (finger-like, lamelliform) (See also accessory lobule). [Stachowitsch, 1992]

Branchial plate

Enlarged, flattened modification of outer branch (exopod) of either mandible, maxillule, maxilla, or first thoracic limb. Bears long setae along margin and maintains water circulation within carapace.
(syn. vibratory plate, respiratory plate) [Stachowitsch, 1992]
Flat setose epipod, used to circulate water through the domicilium.
(syn. vibratory plate) [Cohen, Peterson, and Maddocks, in press]

Branchial region

See: Carapace region c [Martin, 2005]
See: Carapace regions c [McLaughlin, 1980]
Area of the carapace overlying the branchial cavity. [Perez Farfante and Kensley, 1997]
Paired regions of dorsal carapace between hepatic regions in front posterior margin behind, sometimes bearing branchial spine(s), defined laterally in crabs by posterolateral margin. [Poore, 2004]
Portion of the carapace overlying the branchial cavity. [Butler, T. H.]
The portion of the carapace overlying the branchial cavity, in the true crabs comprising the epibranchial, mesobranchial, and metabranchial regions and the branchial lobe. [Chace and Hobbs, 1969]
One of two relatively larger lateral regions of carapace overlying branchial chamber.
(syn. branchial area) [Stachowitsch, 1992]
One of two relatively large, lateral regions of carapace overlying gills (branchiae). May be subdivided (from anterior to posterior) into epibranchial, mesobranchial, and metabranchial regions/ lobes/areas. [Stachowitsch, 1992]

Branchiocardiac carina

See: Carapace carina c [Martin, 2005]
See: Carapace carinae c [McLaughlin, 1980]
Ridge extending along posterodorsal limit of branchiostegite (Fig. 2A). [Perez Farfante and Kensley, 1997]
On each side of carapace, narrow ridge separating branchial region from cardiac region. [Stachowitsch, 1992]

Branchiocardiac groove

See: Carapace groove b [Martin, 2005]
See: Carapace grooves b [McLaughlin, 1980]
Groove separating branchial and cardiac regions. [Williams, 1984]
Line along dorsal limit of branchiostegite.
(syn. branchiocardiac ridge) [Poore, 2004]
On each side of carapace, oblique groove separating branchial and cardiac regions. Considered to represent former transverse border between two cephalic somites. May also refer to pair of grooves connecting cervical and postcervical grooves or extending posteriorly from post-cervical groove. [Stachowitsch, 1992]

Branchiocardiac sulcus

Groove extending along dorsal limit of branchiostegite, running parallel to branchiocardiac carina. [Perez Farfante and Kensley, 1997]

Branchiostegal area

Part of carapace extending laterally and downward over branchiae. [Moore and McCormick, 1969]
Part of carapace extending laterally and ventrally over branchiae. [McLaughlin, 1980]

Branchiostegal carina

Longitudinal ridge extending along anteroventral part of carapace, usually continuous with branchiostegal spine. [Perez Farfante and Kensley, 1997]

Branchiostegal spine

See: Carapace spine b [Martin, 2005]
See: Carapace spines b [McLaughlin, 1980]
A short spine located on or near the anterior margin of the carapace, ventral to the antennal spine in the shrimps; in crayfishes, immediately ventral to the anterior extremity of the cervical groove. [Hobbs, Hobbs, and Daniel 1977]
A short spine on or near the anterior margin of the carapace of some shrimps ventral to the antennal spine and dorsal to the anterolateral angle of the carapace. [Chace and Hobbs, 1969]
Short spine on or near the anterior margin of the carapace ventral to the antennal spine and dorsal to the anteroventral angle of the carapace (Fig. 2A). [Perez Farfante and Kensley, 1997]
Short spine situated on or near anterior margin of carapace, ventral to antennal spine in shrimps; in crayfishes, located immediately ventral to anterior extremity of cervical groove (see Fig. 13). [Hobbs and Jass, 1988]
Spine on anterior edge of carapace, or near it, immediately below branchiostegal groove (Fig. 2). [Williams, 1984]
Spine on or near anterolateral margin of the carapace of some shrimps, ventral to antennal spine and dorsal to pterygostomian spine. [Butler, T. H.]
Anteriorly directed, spine-like projection on branchial region on each side of carapace in shrimp-like (natantian) decapod; located at anterior margin, below branchiostegal groove and between antennal and pterygostomial spines. [Stachowitsch, 1992]
Spine. [Stachowitsch, 1992]

Branchiostegal sulcus

Groove often accompanying branchiostegal carina, located on the anteroventral part of the carapace. [Perez Farfante and Kensley, 1997]

Branchiostegal-hepatic carina

Longitudinal ridge consisting of the fusion of the branchiostegal and hepatic carinae. [Perez Farfante and Kensley, 1997]

Branchiostegite

Expanded dorsal and lateral branchial region of carapace. [McLaughlin, 1980]
Expanded ventro-lateral part of the carapace covering the gills (Fig. 2A). [Perez Farfante and Kensley, 1997]
Expanded ventrolateral part of carapace covering gills. [Poore, 2004]
Part of carapace extending over top and side of branchial chamber. [Moore and McCormick, 1969]
Part of carapace not coalesced ventrally with thoracic somites, but overhanging on each side as covering for gill chamber. [Williams, 1984]
The anterior and lateral margins of the carapace extending ventrally on either side. [Ingle, 1983]
Lateral or dorsolateral part of carapace extending over gills and forming outer wall of branchial chamber. [Stachowitsch, 1992]

Branchiostegites

The anterior and lateral margins of the carapace extend ventrally on either side forming the walls of the cephalothorax and enclosing the branchial chambers (Fig. 1). [Warner, 1977]

Bristle

Indefinite term for short, stiff seta or spinule. [Butler, T. H.]

Brood chamber

In female, chamber formed on ventral surface of pereon by oostegites on last (third) maxillipeds and on first three pereopod pairs.
(syn. brood pouch, marsupium) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In female, space between thoracopods and carapace in which eggs are brooded. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In female rhizocephalan, pouch-like structure projecting from body of host; contains eggs and seminal receptacle and serves as site of attachment of male. May also refer to brood pouch of ascothoracican.
(syn. externa) [Stachowitsch, 1992]

Brood plate

Oostegite. [Stachowitsch, 1992]

Brood pouch

Marsupium. [Stachowitsch, 1992]
In female, chamber formed on ventral surface of pereon by oostegites on second to fifth pereopods.
(syn. marsupium) [Stachowitsch, 1992]
Chamber formed on ventral surface of pereon in female by three to five pairs of oostegites.
(syn. brood chamber, marsupium) [Stachowitsch, 1992]
Marsupium. [Stachowitsch, 1992]
An expanded region of the female domicilium, usually posterior, for protecting developing eggs and instars. [Cohen, Peterson, and Maddocks, in press]
In female, dorsal chamber between thorax and carapace. Serves to brood eggs.
(syn. marsupium) [Stachowitsch, 1992]

Brood sac

A pouch formed from either one or two oostegites. [Holdich and Jones, 1983]

Brooding female

An adult female with fully extended oostegites on the coxae. In specimens from deep-sea samples, the developing embryos are often lost during sample processing, so it is generally not possible to tell whether the female was in fact brooding embryos, or whether she released the young before sampling. [Wilson, 1989]

Broom seta

A sensory seta that has a distinctly articulated pedestal, and two distal rows of long, extremely thin setules. It may be found on the antennulae or any of the pereopods. [Wilson, 1989]

Brush

Clump or band of setae or spinules, usually on distal flexor margin of propodus of fifth pereiopod; used by shrimp for grooming. [Butler, T. H.]

Brush-shaped organ

Rudimentary third pair of thoracopods (ninth paired appendage of body). Consists of basal part (stem) bearing distal cluster of hairs. Typically restricted to male and considered to be sensory.
(syn. brush-like structure) [Stachowitsch, 1992]
Small pair of lobes bearing numerous fine setae; found between the fifth limbs in males of most Cytherocopina and some Cypridocopina; might represent vestigial appendages. [Cohen, Peterson, and Maddocks, in press]

Buccal cavern

Space, especially in crabs, enclosing the mouthparts and more or less covered by third maxillipeds, defined anteriorly by epistome and laterally by pterygostomial region, sometimes by ridges.
(syn. buccal frame) [Poore, 2004]

Buccal cavity

Cavity on ventral surface of body in which mouth parts are situated; bounded anteriorly by epistome, laterally by free edges of carapace. Within this "frame" lie the mouth parts, which in most Brachyura are covered by operculiform third maxillipeds. [Williams, 1984]
Hollow space on ventral side of body containing mouth parts, in Malacostraca bounded by epistome in front and free edges of carapace on sides. [Moore and McCormick, 1969]
The area on the ventral surface of the carapace in which the mouth parts are situated. Bounded anteriorly by the epistome, laterally by the inner margin of the pterygostomial region and posteriorly by the anterior margin of the first thoracic sternite. [Ingle, 1983]
Area of cephalon containing mouthparts; bounded by epistome anteriorly and free margins of carapace laterally. [McLaughlin, 1980]
On underside of head, cavity in which mouthparts (labrum, mandibles, maxillules, maxillae, maxillipeds, labium) are located. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In front of mouth, chamber formed by lip-like extensions of proboscis margins. Contains mandibles. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, term applied to space formed around mouth by prolonged upper lip (labrum) and lower lip (labium). (See also mouth cone). [Stachowitsch, 1992]

Buccal frame

structure of brachyuran decapods enclosing mouth parts, its sides formed by free anterolateral edges of carapace, its front delimited by epistome, and commonly closed by operculiform third maxillipeds. [Moore and McCormick, 1969]
In crab-like (brachyuran) decapod, well-defined, frame-like depression on underside of head; contains mouthparts (labrum, mandibles, maxillules, maxillae, maxillipeds, labium) and may be covered by expanded (operculiform) maxillipeds. (quadrate, triangular).
See: Endostome [Stachowitsch, 1992]
Structural region of cephalon enclosing mouthparts. [McLaughlin, 1980]

Buccal groove

See: Carapace grooves c [McLaughlin, 1980]
On each side of carapace, transverse groove behind antennal spine; connects gastroorbital and antennal grooves. [Stachowitsch, 1992]

Bud

(Taxon-specific: Family Cyatholaimidae) The earliest step of a developing limb; a limb bud does not articulate with its somite and bear setae including at least the crown group of terminal setae. A limb bud often is considered functionless on immature stages although limb 6 of podopleans is a bud which covers the genital opening of the adult male (see transformed limb and secondary bud). [Ferrari and Dahms, in press]

Bulb

Type of valve sculpture: relatively large, subspherical projection. [Stachowitsch, 1992]

Bulla

(Taxon-specific: Family Cyatholaimidae) A small, chitinous anchor-like structure fused to the tips of the maxillary arms in lernaeopodid copepods, that is embedded in the surface of the host fish to serve as an anchor. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, attachment disc formed at fused end of both arm-like maxillae. (club-shaped, elliptical, spherical).
(syn. button) [Stachowitsch, 1992]
Type of valve sculpture: tubercle-like projection whose summit is elongated into a transverse or radial direction. May be considered to be type of verruca. [Stachowitsch, 1992]

CB

The junction between the coxa and the basi-ischium (Fig. 12). [Warner, 1977]

CP

The junction between the carpus and the propodus (Fig. 12). [Warner, 1977]

Calamus

(Taxon-specific: Family Cyatholaimidae) The main claw on the apex of the basis of the maxilla of some siphonostomatoids. [Boxshall and Halsey, 2004]

Calathus

See Optic Calathus. [Perez Farfante and Kensley, 1997]

Calcar

(Taxon-specific: Family Pycnogonidae) Spur-like process on distal segment of antenna. (one-half as long/one-eighth or less as long as basal segment of antenna). [Stachowitsch, 1992]

Calceolus

Complex sensory filaments on antennules of some amphipods. [Moore and McCormick, 1969]
Complex sensory filaments on antennules.
(pl. calceoli) [McLaughlin, 1980]
One in a series of club-shaped sensory projections on antennules and antennae. More common in male.
See: Aesthetascs [Stachowitsch, 1992]

Calcified inner lamella

Calcified part of the inner (medial) lamella of valve margin. [Cohen, Peterson, and Maddocks, in press]

Calyptopis

First larval stage following the nauplius stage in euphausids, corresponding roughly to the the protozoea stage. [Brusca and Brusca, 2002]
Larval stage of euphausiids. There are three successive calyptopes, distinguished by the increasing degree of development of the abdomen. [Mauchline, 1984]
Third larval stage in euphausiaceans, characterized by differentiation of abdomen and appearance of compound eyes. [Moore and McCormick, 1969]
Third larval stage, characterized by differentiation of abdomen and appearance of compound eyes (Euphausiacea); see also zoea. [McLaughlin, 1980]
Third of several larval stages (nauplius, metanauplius, calyptopis, furcilia). Characterized by development of carapace, elongation of abdomen, differentiation of somites, and development of eyes under carapace.
See: Cyrtopia [Stachowitsch, 1992]

Canna

(Taxon-specific: Family Cyatholaimidae) The armature element representing the basal endite of the maxilla of some siphonostomatoids. [Boxshall and Halsey, 2004]

Caperation

Type of valve sculpture: fine wrinkle. [Stachowitsch, 1992]

Capitate

Enlarged or globular at end. [AHD]

Capitulum

In pedunculate cirripeds portion of carapace enclosing trophic structures, commonly armored by calcareous plates. [Moore and McCormick, 1969]
Portion of carapace enclosing body, commonly protected by calcareous plates (lepadomorph cirripeds); or anterior prominence in complex tooth and socket hingement (Ostracoda). [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) In stalked barnacle, one of two external divisions of body (capitulum, peduncle). Consists of mantle and associated plates enclosing body. [Stachowitsch, 1992]

Carapace

Carapace, spines, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
"Head Shield" cuticular structure arising from posterior margin of cephalon, extending anteriorly and posteriorly, and covering the cephalothoracic somites of the body (Fig. 1). [Perez Farfante and Kensley, 1997]
"Shield" (exoskeleton) overlying cephalothoracic somites of body (see Figs. 13,14) [Hobbs and Jass, 1988]
'Head shield" covering the cephalothoracic somites of the body. [Butler, T. H.]
A more expansive structure than the head shield (cephalic shield) , comprising the head shield and a large fold of the exoskeleton that probably arises (primitively) from the maxillary somite. [Brusca and Brusca, 2002]
A sheet of cuticle extending back from the head to enclose the dorsal and lateral parts of the thorax; the 'shell' of a crab (Fig. 1). [Warner, 1977]
A shield that covers the head and thorax. [Mauchline, 1984]
an extension of the exoskeleton which covers and fuses with the head and the first two thoracic somites. [Holdich and Jones, 1983]
Cuticular, usually calcified, structure arising from posterior margin of cephalon, extending anteriorly and posteriorly, often covering head and thorax (cf. Eucarida); also fold of integument extending from maxillary segment, forming bivalved shell of cyprid larvae and of ascothoracicans and mantle of other cirripedia; mantle usually with calcified plates in thoracicans. [McLaughlin, 1980]
Cuticular, varyingly calcified structure comprising cephalic shield and fold of integument arising from posterior border of maxillary somite extending over trunk, usually covering it laterally as well as dorsally; commonly fused to one or more thoracic somites and in may forms having mid-dorsal hinge. [Moore and McCormick, 1969]
Shield arising from posterior margin of head and comprising lateral extensions of thoracic somites covering all or most of cephalothorax. [Poore, 2004]
The "head shield" covering the cephalothoracic somites of the body. [Chace and Hobbs, 1969]
The "head shield" overlying the cephalothoracic somites of the body. [Hobbs, Hobbs, and Daniel 1977]
The exoskeleton that covers the dorsal and ventro-lateral portions of the cephalothorax. [Ingle, 1980]
The portion of the hard exoskeleton, or shell, that covers all or part of the body of many crustaceans; in shrimps, lobsters, and crabs, the carapace covers the head and thorax. [Bliss, 1982]
(Taxon-specific: ) Single-piece (univalved) shield which, if fully developed, covers only posterior part of body (trunk). Laterally compressed, with ventral gape, and therefore occasionally described as bivalved (i.e., consisting of two "valves" ). (angular, circular, elongate, oval, ovate, ovoid, spherical, subcircular, subquadrate; laterally compressed, thick-bodied; with/without carapace spine, with/without crest, narrowed and prolonged/not narrowed and prolonged posteriorly into short tube, anterior portion swollen/not swollen, with/without projection on anteroventral margin, ventral margin smooth/with fine spines, dorsal margin smooth/serrate; sculpture: reticulated, smooth; longitudinally, obliquely, transversely striated; with/without hairs, with polygonal or rhomboid markings).
(syn. shell) [Stachowitsch, 1992]
Large broad shield covering dorsal surface of head, thorax, and anterior part of abdomen. Consists of single element (univalve) and is emarginated (notch, sinus) posteriorly. Bears median eye, compound eyes, and dorsal organ anteriorly and is sculptured by median keel and transverse mandibular and cervical grooves.
(syn. dorsal shield) [Stachowitsch, 1992]
Bivalved, laterally compressed shield typically enclosed entire body; consists of two valves with dorsal hinge line, although occasionally interpreted as representing a single continuous element. Joined to body by ligament and pair of adductor muscles in head region. (broadly oval, compressed, globose = globular, oblong, ovate, subovate, subrectangular, subspherical, swollen, thick and globose, thin and pellucid; with/without growth lines; with/without umbones; with/without keel; sculpture: polygonal, punctate, reticulate, with dendritic or radial grooves, with striae).
(syn. shell) [Stachowitsch, 1992]
Large, shield-like structure covering head and three to six thoracic somites. Extends laterally to enclose branchial chamber. Regionated to form anterior pseudorostrum, frontal lobe, ocular lobe, as well as branchial and cardiac regions. (inflated, laterally compressed; dorsal outline: straight, arched, with slight undulations; with/without lateral horns; smooth, sculptured: hairy, rugose, with denticles, with median/lateral carina, with longitudinal depressions, with dorsal crest: serrate, smooth, with teeth). [Stachowitsch, 1992]
Shield-like structure covering head and first two thoracic segments (thoracomeres). Extends laterally to enclose branchial chamber.
See: Cephalothorax [Stachowitsch, 1992]
Large, shield-like cuticular structure covering cephalothorax; bears rostrum anteriorly and is typically regionated and sculptured with various carinae, grooves, spines, and teeth. Encloses gill-bearing bases of thoracopods and thus forms branchial chambers. (general form: cylindrical, compressed, depressed; shape: convex, circular, globular, hemispherical, hexagonal, octagonal, orbicular, oval, ovate triangular, pentagonal, polygonal, pyriform, quadrilateral, rectangular, subcircular, subcylindrical, subglobose, subhexagonal, suborbicular, subovoid, subpenta-gonal, subquadrate, subquadrilateral, sub-triangular, transversely oval, tumid; surface: areolated, carinate, eroded, glabrous, granulate, nodular, nodulose, plicate, polished, pubescent, punctuate, with rugae, smooth, squamose, tuberculate, wrinkled). [Stachowitsch, 1992]
Shield-like structure coving head and most of thorax. Typically fused to first three thoracic segments (thoracomeres) and typically bearing rostrum. (with/without rostrum; undecorated, ornamented: spinose, with keels; posterior margin: indented, produced into spines, with lobes) (See also cervical sulcus). [Stachowitsch, 1992]
Shield-like cuticular structure covering cephalon (except for anterior acron and antennular somite) as well as first four thoracic somites (thoracomeres); overlaps but does not enclose bases of first five thoracopods. Broad, flattened, and typically sculptured with various carinae and grooves. Bears rostrum anteriorly. (with/without carinae; anterolateral corners: armed, unarmed, rounded). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Large shield covering thorax, posterior part of head, and anterior part of abdomen. Laterally compressed and therefore often described as being bivalved (although no dorsal hinge is present). Two halves of carapace can be drawn toward each other by carapace adductor muscle. Bears rostral plate anteriorly. (elliptical and posterodorsally truncate, subtriangular and posteriorly acuminate; smooth, with polygonal ornamentation). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Dorsoventrally flattened, shield-like structure covering head and first thoracic somite (thoracomere); characterized by pair of posterolateral wing-like extensions (alae). Bears pair of compound eyes dorsolaterally and set of median nauplius eyes. (circular, cordate, elliptical, trifoliate). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Mantle. [Stachowitsch, 1992]
Lateral outfolds of dorsal epithelium and cuticle, bivalved and enveloping the entire body. [Cohen, Peterson, and Maddocks, in press]
Shell-like outer covering; consists of pair of valves joined dorsally by hinge and entirely enclosing body. (calcareous, uncalcified; ornate, smooth; amplete, postplete, preplete). [Stachowitsch, 1992]
Shield-like structure fused to and covering head and first thoracic somite (thoracomere). Extends posteriorly and laterally to cover additional thoracomeres. Serves in respiration and forms brood pouch in female. [Stachowitsch, 1992]
Shield-like, relatively thin structure fused to thoracic somites and covering cephalothorax. Does not enclose gill-bearing bases of thoracopods. Typically bears cervical groove. (with/without rostrum). [Stachowitsch, 1992]

Carapace angles

In Leaiidae (Conchostraca), angle made by straight dorsal margin with anterior rib (a) and with posterior rib (b); these angles may have utility in tracing evolutionary development and in stratigraphic zonation. [Moore and McCormick, 1969]
Intersection of straight and dorsal margin by anterior rib (alpha) and posterior rib (beta). [McLaughlin, 1980]

Carapace carina

Narrow ridge on surface of carapace (cf. decapod carapace and stomatopod integumental ornamentation). [McLaughlin, 1980]
Narrow ridge variously located on surface of decapoda carapace — named types:
a) antennal. Narrow ridge extending backward from antennal spine.
b) branchial. Narrow ridge extending backward from orbit over branchial region.
c) branchialcardiac. Narrow ridge marking off branchial from cardiac regions of carapace.
d) gastroorbital. Narrow ridge extending backward from supraorbital spine.
e) lateral. Narrow ridge on side margin of carapace.
f) orbital. Narrow ridge on margin of orbit.
g) posterior. Transverse narrow ridge in front of carapace marginal groove.
h) postorbital. Narrow ridge slightly behind orbital margin and parallel to it.
i) postrostral. Narrow ridge behind rostrum extending along dorsal mid-line of carapace.
j) rostral. Longitudinal narrow ridge continuous with lateral margin of rostrum.
k) subhepatic. Narrow ridge extending backward from branchiostegal spine.
l) submedian. Narrow ridge on either side of postrostral carina and parallel to it; may join rostral carina.
m) supraorbital.
See: Gastroorbital carina [Moore and McCormick, 1969]

Carapace carinae

(a) antennal. Extending posteriorly from antennal spine.
(b) branchial. Extending posteriorly from orbit over branchial region.
(c) branchiocardiac. Dividing branchial from cardiac region.
(d) gastroorbital. Extending posteriorly from supraorbital spine; syn., supraorbital.
(e) lateral. On lateral margin of carapace.
(f) orbital. On margin of orbit.
(g) posterior. Transverse ridge anterior to marginal groove.
(h) postorbital. Slightly posterior and parallel to orbital margin.
(i) postrostral. Posterior to rostrum along dorsal midline.
(j) rostral. Continuous with lateral margin of rostrum.
(k) subhepatic. Extending posteriorly from branchiostegal spine.
(l) submedian. On either side of, and parallel to, postrostral carina, sometimes joining rostral carina.
(m) supraorbital. See gastroorbital. [McLaughlin, 1980]

Carapace costae

Closely spaced radial ridges, grading from fine to coarse, that become obsolete near umbo and do not cross it (=radial lirae, radial riblets, accessory ribs) (e.g., Conchostraca, especially Estheriellidae, in which valves generally have more than 5 costae). [Moore and McCormick, 1969]
Closely spaced radial ridges, grading from fine to coarse, not crossing to umbo.
(syn. radial lirae) [McLaughlin, 1980]

Carapace costellae

Fine radial ridges that run from ventral margin to and across umbo, and are usually numerous on any given valve (e.g. Conchostraca). [Moore and McCormick, 1969]
Fine radial ridges extending from ventral margin across umbo. [McLaughlin, 1980]

Carapace groove

Furrow on surface of decapod, generally dorsal — named types:
a) antennal. Furrow on carapace extending backward from vicinity of antennal spine.
b) branchiocardiac. Oblique furrow approximately in middle of posterior half of each side of carapace, separating branchial and cardiac regions and reaching dorsomedian part of carapace well behind cervical or postcervical grooves; may be longitudinal, connecting cervical and postcervical grooves, or extending backward from submedian point on postcervical groove.
c) cervical. Transverse furrow in median part of carapace between gastric and cardiac regions, curving forward toward antennal spine.
d) gastroorbital. Short longitudinal furrow branching from cervical groove at level of orbit and running toward it.
e) hepatic. Short longitudinal furrow connecting cervical with postcervical and branchiocardiac grooves, more or less continuing antennal groove.
f) inferior. Transverse furrow extending from junction or hepatic and cervical grooves toward side margin of carapace, more or less continuous with cervical groove.
g) marginal. Furrow close to posterior edge of carapace and parallel to it.
h) postcephalic. one of three transverse furrows on carapace of many fossil decapods.
i) postcervical. Furrow located behind cervical groove and parallel to it, dividing cardiac region into two parts.
j) submedian. Longitudinal furrow in submedian dorsal part of carapace closely adjacent to post-rostral carina. [Moore and McCormick, 1969]

Carapace grooves

(a) antennal. Extending posteriorly from vicinity of antennal spine.
(b) branchiocardiac. Oblique groove approximately in middle of posterior half on each side of carapace, separating branchial and cardiac regions and reaching dorsomedian part well posterior to cervical or postcervical grooves; sometimes longitudinal, connecting cervical and postvcervical grooves or extending posteriorly from submedian point on postcervical groove.
(c) buccal. Transverse groove crossing mandibular elevation behind antennal spine, connecting gastroorbital and antennal grooves.
(d) cervical. Transverse groove medially between gastric and cardiac regions, curving toward antennal spine; syn., cervical suture, cervical furrow.
(e) dorsomedian. Longitudinal groove extending from tip of rostrum to posterior carapace margin dorsomedially.
(f) gastroorbital. Short, longitudinal groove branching from cervical groove at level of orbit and directed toward it.
(g) hepatic. Short, longitudinal groove connecting cervical with postcervical and branchiocardiac grooves, more or less continuous with antennal groove.
(h) inferior. Extending from junction of hepatic and cervical grooves toward lateral margin, more or less continuous with cervical groove.
(i) intercervical. Oblique groove connecting postcervical and cervical grooves.
(j) intestinal. Short, transverse groove in median part of posterior carapace, interrupted by intestinal tubercle.
(k) marginal. Close to, and parallel with, posterior margin.
(l) parabranchial. Groove below, behind and almost parallel with branchiocardiac and postcervical grooves, joining latter in lower part.
(m) postcephalic. One of three transverse furrows on carapace of many fossils.
(n) postcervical. Posterior to, and parallel with, cervical groove, bisecting cardiac region.
(o) sellar. Short transverse groove dorsally anterior tp cervical groove.
(p) submedian. Longitudinal groove in submedian dorsal part, contiguous with postrostal carina.
(q) urogastric. Short transverse groove in median or submedian region posterior to postcervical groove, sometimes joining upper part of postcervical groove. [McLaughlin, 1980]

Carapace growth line

Peripheral margin of successive membranes added to shell during each molt. [Moore and McCormick, 1969]

Carapace horn

Anterodorsal termination of carapace valves in some Archaeostraca; may be indurated (e.g., Ceratiocaris) or produced into long process (e.g., Caryocaris). [Moore and McCormick, 1969]

Carapace length

In shrimps, distance from the posterior margin of orbit to midcaudodorsal margin of carapace; in crayfishes, distance from tip of rostrum to midcaudodorsal margin of carapace (see Fig. 14). [Hobbs and Jass, 1988]
In shrimps, the distance from the posterior margin of the orbit to the mid-caudodorsal margin of the carapace; in crayfishes, the distance from the tip of the rostrum to the mid-caudodorsal margin of the carapace. [Hobbs, Hobbs, and Daniel 1977]

Carapace lirae

Linear concentric edges parallel to and between growth lines. [McLaughlin, 1980]
Raised, linear, fine concentric ridges parallel to growth lines and occupying an interspace. [Moore and McCormick, 1969]

Carapace region

Differentiated portion of decapod carapace surface distinguished in descriptions and used in classification — named types:
a) antennal. Anterior marginal part of carapace bordering orbital region laterally and also touching hepatic, pterygostomial, and, in some forms, frontal region.
b) anterolateral. Lateral part of carapace bordering subhepatic or hepatic regions.
c) branchial. Lateral part of carapace behind pterygostomial region and overlying branchiae, divided by some authors into epibranchial, mesobranchial, and metabranchial subregions.
d) cardiac. Median part of carapace behind cervical groove or suture, between urogastric and intestinal areas.
e) frontal. Anteromedian part of carapace including rostrum and area behind it.
f) gastric. Median part of carapace in front of cervical groove and behind frontal region; divided by some authors into epigastric, mesogastric, metagastric, protogastric, and urogastric subregions.
g) hepatic. Part of carapace which may touch antennal, cardiac, and pterygostomial regions.
h) intestinal. Short transverse part of carapace behind cardiac region, designated by some as posterior cardiac lobe.
i) jugal. See: Pterygostomial region
j) orbital. Part of carapace behind eyes, bordered by frontal and antennal regions.
k) pterygostomial. Anterolateral part of carapace on ventral surface located on opposite sides of buccal cavity.
l) subhepatic. Part of carapace below hepatic region and extending below lateral edge of latter.
(syn. carapace area) [Moore and McCormick, 1969]
Differentiated portion of carapace surface.
See: Carapace regions [McLaughlin, 1980]
One of numerous, more or less clearly delimited and elevated subdivisions of carapace. According to position or underlying internal organs, as well as according to group, one may distinguish antennal, anterolateral, branchial, cardiac, epibranchial, epigastric, frontal, gastric, hepatic, intestinal, mesobranchial, mesogas-tric metabranchial, metagastric, orbital, pos-terolateral, protogastric, pterygostomial, subhepatic, and urogastric regions. [Stachowitsch, 1992]

Carapace regions

(a) antennal. Anterior marginal part bordering orbital region laterally, adjoining hepatic, pterygostomial, and occasionally also frontal regions.
(b) anterolateral. Lateral part bordering subhepatic or hepatic regions.
(c) branchial. Lateral part posterior to ptergostomial region, overlying branchiae; epibranchial, mesobranchial, and metabranchial lobes or areas sometimes distinguished.
(d) cardiac. Median part posterior to cervical groove between urogastric and intestinal regions.
(e) frontal. Anteromedian part including rostrum and region behind it.
(f) gastric. Median part posterior to cervical groove and posterior to frontal region; sometimes epigastric, mesogastric, metagastric, protogastric, and urogastric (genital) areas distinguished.
(g) hepatic. Part adjoining antennal, cardiac, and pterygostomial regions.
(h) intestinal. Short traverse part posterior to cardiac region; sometimes referred to as posterior cardiac lobe.
(i) jugal. See pterygostomial region.
(j) orbital. Part posterior to eyes bordered by frontal and antennal regions.
(k) pterygostomial. Anterolateral part on ventral surface located on opposite sides of buccal cavity; syn., jugal region, pterygostome.
(l) subhepatic. Part on ventral surface below hepatic region, bounded by pterygostomial and suborbital regions.
(m) suborbital. Part on anteroventral surface beneath orbit. [McLaughlin, 1980]

Carapace spine

Sharp projection of carapace important for classification — chief types:
a) antennal. Spine on front margin of carapace slightly below orbit.
b) branchiostegal. Spine on front margin of carapace or slightly behind it about halfway between antennal and pterygostomial spines.
c) hepatic. Spine in hepatic region of carapace below lower branch of cervical groove and behind it.
d) infraorbital. Spine on lower angle of orbit.
e) postorbital. Spine at moderate distance behind middle of orbit.
f) postrostral. Dorsomedian spine immediately behind rostrum.
g) pterygostomial. Spine on anterolateral angle of carapace.
h) suborbital. Spine at moderate distance below middle of orbit and slightly beneath it.
i) supraorbital. Spine at moderate distance obliquely behind and above orbit (may be placed at postorbital carina). [Moore and McCormick, 1969]
(Taxon-specific: ) Large, posteriorly directed, spine-like structure formed by posterodorsal extension of carapace. Relative length may be of taxonomic importance.
(syn. apical spine, posterior spine, shell spine) [Stachowitsch, 1992]
Sharp projection from carapace.
See: Carapace spines [McLaughlin, 1980]

Carapace spines

(a) antennal. On anterior margin slightly below orbit.
(b) branchiostegal. On or clsoe to anterior margin medially between antennal and pterygostomial spines.
(c) hepatic. Below and posterior to lower branch of cervical groove.
(d) infraorbital. On lower angle of orbit.
(e) postorbital. At moderate distance posterior to middle of orbit.
(f) postrostral. Immediately posterior to rostrum.
(g) pterygostomial. On anterolateral angle.
(h) suborbital. Slightly below and posterior to middle of orbit.
(i) supraorbital. At moderate distance obliquely behind and above orbit; somtimes on postorbital carina. [McLaughlin, 1980]

Carapace teeth

(a) cardiac. On midline of carapace just posterior to cervical groove.
(b) gastric. On midline of carapace immediately anterior to cervical groove.
(c) lateral. On lateral margin of carapace; anterolateral, mediolateral, and posterolateral teeth distinguished.
(d) orbital. On orbital margin.
(e) posterior. On midline of carapace between posterior margin and marginal groove.
(f) pregastric. On midline of carapace between gastric tooth and rostrum.
(g) rostral. On rostrum, either single or multiple; upper, lower, and lateral teeth distinguished. [McLaughlin, 1980]

Carapace tooth

Generally blunt projection of carapace, often broader than spine.
See: Carapace teeth, Stomatopod integumental ornamentation [McLaughlin, 1980]
Small sharp spinous projection in varied locations — named types:
a) cardiac. Tooth on mid-line of carapace just behind cervical groove.
b) gastric. Tooth on mid-line of carapace just in front of cervical groove.
c) lateral. Tooth placed on lateral margin of carapace (includes anterolateral, mediolateral, posterolateral teeth).
d) orbital. Tooth on orbital margin.
e) posterior. Tooth on mid-line of carapace just in front of posterior margin between it and marginal groove.
f) pregastric. Tooth on mid-line of carapace between gastric tooth and rostrum.
g) rostral. Tooth on rostrum; may be single (e.g., scyllarid palinurans) or multiple and classified as upper, lower or lateral (e.g., nephropid astacideans and natantian crabs). [Moore and McCormick, 1969]

Carcinisation

Tendency for decapods to evolve towards a crab-like form. [Poore, 2004]

Cardiac

A median region of the carapace, between the gastric and intestinal regions. [Poore, 2004]

Cardiac notch

Indentation on posterior margin of carapace (e.g., some Alpheidae).
(syn. cardiac incision) [Moore and McCormick, 1969]
Indentation on posterior margin of carapace. [McLaughlin, 1980]
In shrimp-like (natantian) decapod, notch on posterior margin of carapace. [Stachowitsch, 1992]

Cardiac region

See: Carapace region d [Martin, 2005]
See: Carapace regions d [McLaughlin, 1980]
Dorsolateral region of carapace bounded anteriorly by gastric region and laterally by branchial regions. [Butler, T. H.]
The dorsomedian area on the carapace bounded anteriorly by the gastric region, laterally by the branchial regions, and (in the crabs) posteriorly by the intestinal region. This area is often very narrow in the crayfishes and commonly called the areola. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by parts or the margins of the urogastric, mesobranchial, metabranchial and intestinal regions. [Ingle, 1983]
Unpaired median region in posterior half of carapace; overlies anterior region of heart. (See also branchial region). [Stachowitsch, 1992]
Relatively large, unpaired median region in posterior half of carapace; overlies heart. Adjoined anteriorly by gastric, posteriorly by intestinal, and laterally by branchial regions. [Stachowitsch, 1992]

Cardiac stomach

Anterior region of the decapod foregut. [Brusca and Brusca, 2002]
Anterior and larger cuticle-lined division of stomach; separated from smaller posterior pyloric stomach by cardiopyloric valve and characterized by variously developed grinding apparatus (gastric mill). [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Anterior and larger division of stomach occupying most of head (cephalon). Separated from smaller posterior pyloric stomach by filtering apparatus; contains only small pairs of plates (ossicles). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Stomach. [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Anterior and larger division of stomach; separated from smaller posterior pyloric stomach by cardiopyloric valve. Serves to grind food. (with/without denticles). [Stachowitsch, 1992]

Cardiac tooth

See: Carapace tooth a [Martin, 2005]
See: Carapace teeth a [McLaughlin, 1980]
On midline of carapace, tooth-like projection in cardiac region just posterior to cervical groove. [Stachowitsch, 1992]

Cardial sulcus

Transverse groove across posterior region of carapace at level of heart. (See also cervical sulcus). [Stachowitsch, 1992]

Cardiopyloric valve

In digestive tract, valve-like structure between anterior cardiac stomach and posterior pyloric stomach. [Stachowitsch, 1992]
In digestive tract, valve-like structure between anterior cardiac stomach and posterior pyloric stomach. [Stachowitsch, 1992]

Cardo

Basal segment of maxillula articulating with head. [Moore and McCormick, 1969]
Basal segment of maxillule articulating with cephalon. [McLaughlin, 1980]

Caridean lobe

External rounded projection on basal part of exopod of 1st maxilliped (Caridea). [McLaughlin, 1980]
External rounded projection on basal part of exopod of first maxilliped (e.g., Caridea). [Moore and McCormick, 1969]
In first maxilliped, setose broadening or lobe at base of outer branch (exopod). [Stachowitsch, 1992]

Caridean shrimps

Higher shrimps, members of the infraorder Caridea; include the majority of shrimps and prawns. [Bliss, 1982]

Caridoid escape reaction

"Tail-flip" behavior resulting from rapid contraction of the ventral abdominal (flexor) muscles, causing the animal to shoot quickly backward from the force of water displaced by the large propulsive surface provided by the tail fan. [Brusca and Brusca, 2002]

Caridoid facies

Aspect of primitive Eumalacostraca distinguished by enclosure of thorax by carapace, movably stalked eyes, biramous antennules, scaphocerite-bearing antennae, thoracopods with natatory exopods, elongate abdomen ventrally flexed and powerfully muscled, and caudal fan. [Moore and McCormick, 1969]
Basic group of characters distinguishing eumalacostracan crustaceans: enclosure of thorax by carapce, movable stalked eye, biramous antennules, antennae with scaphocerites, thoracopods with natatory exopods, ventrally flexed abdomen, and tailfan. [McLaughlin, 1980]

Carina

A raised ridge on the surface of the exoskeleton. [Ingle, 1980]
A ridge or keel of the exoskeleton (Fig. 1, 2).
(pl. carinae) [Perez Farfante and Kensley, 1997]
Any keel-like structure, as on dorsum of pleon on some amphipods; in cirripeds, single compartment plate at end of shell where cirri are protruded, or adjacent to tergum, possessing alae only.
See: Carapace carina [Moore and McCormick, 1969]
Any keellike structure; any well-defined projecting ridge on outer surface of carapace (podocopan Ostracoda); unpaired posterodorsal plate of thoracic Cirripedia (in lepadomorphs 1 of up to 4 unpaired plates of capitulum; in verrucomorphs compartmental plate between rostrum and fixed tergum; in balanomorphs compartmental plate, with alae on each side, opposite rostrum). [McLaughlin, 1980]
Keel, acute ridge, crest. [Poore, 2004]
Keel, or ridge.
(pl. carinae) [Butler, T. H.]
Keel-like ridge or prominence. [Williams, 1984]
Median middorsal ridge on rostrum; oriented parallel to lateral margins of rostrum (see Figs. 37,47). [Hobbs and Jass, 1988]
Median keel. [Stachowitsch, 1992]
One of a number of narrow, elevated ridges along carapace or abdomen. According to position and according to group, those on carapace may be termed antennal, branchial, branchiocardiac, gastroorbital, lateral, orbital, posterior, postorbital, postrostral, rostral, subhepatic, submedian, and supraorbital carinae.
(syn. ridge, keel) [Stachowitsch, 1992]
A keel, or acute ridge. [Wetzer et al. 1997]
A keel, or an acute ridge. [Kensley and Schotte, 1989]
One in a series of longitudinal, keel-like elevations on dorsal surface of either carapace, thoracic somites (thoracomeres), abdominal somites (pleomeres) or telson. According to position (from midline outward) one may distinguish median, submedian, intermediate, lateral, marginal, and various accessory carinae or secondary ridges. Refers also to ventral elevations (e.g., postanal carina). (sharp, swollen/rounded; posteriorly spined, posteriorly rounded; straight, curved; median carina: bifurcate, not bifurcate). [Stachowitsch, 1992]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) One of five primary plates (carina, two scuta, two terga) on outer surface of barnacle: unpaired posterior plate. In stalked form, posterior plate on capitulum. In unstalked barnacle, compartmental plate between rostrum and fixed tergum (asymmetrical form) or plate opposite rostrum (symmetrical form); consists of median paries and lateral alae. [Stachowitsch, 1992]
Type of valve sculpture: prominent ridge or keel. (disconnected, excavate, ponticulate = perforate, simple, undercut; dorsal, marginal, median, ventral). [Stachowitsch, 1992]

Carinal

In cirripeds (Thoracica), toward or adjacent to compartment plate termed carina. [Moore and McCormick, 1969]

Carinal latus

See: Latus (carinal) a [Martin, 2005]
See latus. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: in stalked form, paired plates (latera), one on each side of carina. Homologous with carinolateral of unstalked form.
(syn. carinolatus) [Stachowitsch, 1992]

Carinal margin

In cirripeds (Thoracica) , edge of tergum adjacent to carina, occluding with carinal margin of opposed tergum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Edge of any plate adjacent to carina; occluding with carinal margin of opposed tergum (thoracic Cirripedia). [McLaughlin, 1980]

Carinate

Conchostracan valve bearing rib(s), chiefly applicable to Leaiidae. [Moore and McCormick, 1969]
Having a carina, keeled. [Butler, T. H.]
Valve bearing rib(s). [McLaughlin, 1980]
Having one or more carinae or acute ridges. [Kensley and Schotte, 1989]

Carinolateral

Compartment plate of cirripeds located on either side of carina, with radii on cardinal side and alae on rostral side.
(syn. latus (cardinal)) [Moore and McCormick, 1969]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: in unstalked form, paired posterolateral plate, one between carina and each lateral plate. Consists of median paries with radius on one (carinal) side, ala on other (lateral) side.
(syn. carinolatus) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of pair of compartmental plates typically overlapping carina on each side, with radius on carinal side and ala on lateral side, sometimes absent; homologous with lepadomorph carinal latus (balanomorph Cirripedia). [McLaughlin, 1980]

Carpocerite

Distal (5th) segment of antennal peduncle. [Moore and McCormick, 1969]
Distal (5th) segment of antennal peduncle. [McLaughlin, 1980]
In antenna, term applied to last of three segments (ischiocerite, merocerite, carpocerite) of endopod (alternate interpretation: fifth segment of peduncle). [Stachowitsch, 1992]

Carpochelate

Having a chela or pincerlike structure formed by the seventh (dactylus) and fifth (carpus) articles of an appendage. [Kensley and Schotte, 1989]

Carpopod

See: Carpus [Martin, 2005]
See carpus [McLaughlin, 1980]

Carpoprodus

On inner branch (endopod) of thoracopod, multisegmented unit formed by carpus and propodus. [Stachowitsch, 1992]

Carpus

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Antepenultimate segment of thoracopod or pereopod.
(syn. carpopod) [McLaughlin, 1980]
Article 5 of pereopod (article 4 of cheliped). [Holdich and Jones, 1983]
Fifth article of limb (first article of palp in maxilliped 3). [Poore, 2004]
Fifth podomere from the proximal end of a typically 7-segmented appendage (Fig. 3C).
(pl. carpi) [Perez Farfante and Kensley, 1997]
Fifth segment from proximal end of a typically 7-segmented appendage.
(pl. carpi) [Butler, T. H.]
Fifth segment from proximal end of segmented appendage. [Hobbs and Jass, 1988]
Segment of limb located next distally from merus and joined to propodus proximally.
(syn. carpopod(ite), wrist) [Moore and McCormick, 1969]
The fifth segment from the proximal end of a segmented appendage; in some shrimps, consisting of several articles (that of the second pereiopod of alpheids and hippolytids consisting of a number of articles). [Hobbs, Hobbs, and Daniel 1977]
The fifth segment from the proximal end of a typically 7-segmented appendage.
(pl. carpi) [Chace and Hobbs, 1969]
The fifth segment of a thoracic limb.
(syn. carpopodite)
See: Pereopod [Wilson, 1989]
The third podomere from the tip of the endopod of a limb (Figs. 1, 2). [Warner, 1977]
Third article from distal end of leg.
(syn. carpopodite) [Williams, 1984]
Third segment of a pereiopod or maxilliped, counted from the distal end. [Ingle, 1983]
Third of five segments (ischium, merus, carpus, propodus, dactylus) of endopod of thoracopod (maxillipeds and pereopods).
(syn. carpopodite) [Stachowitsch, 1992]
Fifth of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod.
(syn. carpopodite) [Stachowitsch, 1992]
Fifth segment of thoracopod; located between merus and propodus. (simple, multiar-ticulated = subdivided).
(syn. carpopod, carpopodite, wrist) [Stachowitsch, 1992]
Fifth of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod; represents fourth movable (free) segment. In certain amphipods, may form part of subchela (i.e., dactyl and propodus bearing down on carpus).
(syn. carpopodite) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Article 5 or pereopod. [Kensley and Schotte, 1989]
Fifth segment of pereopod; located between merus and propodus.
(syn. carpopodite) [Stachowitsch, 1992]
Fourth of basically six segments (preischium, ischium, merus, carpus, propodus dactylus) of inner branch (endopod) of thoracopod, May form a multiarticulate unit with propodus (carpopropodus). (multiarticulate, one-segmented).
(syn. carpopodite) [Stachowitsch, 1992]
Fifth segment of thoracic appendage (thoracopod); located between merus and propodus.
(syn. carpopodite) [Stachowitsch, 1992]
Fourth of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Main bend (knee) of thoracopod typically occurs between carpus and propodus.
(syn. carpopodite) [Stachowitsch, 1992]
Third of basically five segments (ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. carpopodite) [Stachowitsch, 1992]
Fifth segment of thoracopod (third segment of five-segmented endopod); positioned between merus and propodus.
(syn. carpopodite) [Stachowitsch, 1992]

Catalepsis

Bridging of the dorsal surface of the shrimp, as if telson is about to touch rostrum; a defensive position. [Butler, T. H.]

Caudal

Posterior (rear,tail) end of organism. [Hobbs and Jass, 1988]

Caudal appendage

In cirripeds, one of terminal, multiarticulate or uniarticulate, uniramous paired appendages, homologous with caudal furca of other crustaceans. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) One of terminal, multiarticulate or simple, uniramous paired appendages homologous with caudal furca. [McLaughlin, 1980]

Caudal fan

Combination of laterally expanded uropods and telson turned backwards to form powerful swimming structure or means of steering and balancing.
(syn. tail fan, rhipidura) [Moore and McCormick, 1969]
Powerful swimming structure formed of laterally expanded uropods and telson.
(syn. tailfan) [McLaughlin, 1980]
Tailfan. [Stachowitsch, 1992]
Tailfan. [Stachowitsch, 1992]

Caudal filament

See: Caudal ramus [Martin, 2005]

Caudal furca

Pair of caudal rami. [Moore and McCormick, 1969]
Paired caudal rami of terminal abdominal segment or telson.
(syn. furca) [McLaughlin, 1980]
(Taxon-specific: ) Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Caudal ramus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
Subapical spine. [Stachowitsch, 1992]

Caudal process

Posterior extension of carapace.
(syn. keel) [Cohen, Peterson, and Maddocks, in press]
Posterior projection of valve border generally above midheight, or posteroventral, directed upward. [McLaughlin, 1980]
Posterior projection of valve margin. (posterodorsal, posteroventral and upwardly directed). [Stachowitsch, 1992]

Caudal rami

Pair of appendage-like or spine-like processes borne on anal somite in primitive crustaceans. [Brusca and Brusca, 2002]

Caudal ramus

One of paired appendages constituting caudal furca, usually rodlike or bladelike, sometimes filamentous and multiarticular.
(syn. caudal filament, caudal style, cercus, cercopod, furcal ramus, stylet) [McLaughlin, 1980]
Single appendage of terminal abdominal somite paired with another to form caudal furca, both articulated with telson; usually rod-like or blade-like but may be filamentous and multiarticular (caudal filament).
(syn. cercus, cercopod, caudal style, stylet) [Moore and McCormick, 1969]
(Taxon-specific: ) One of two relatively short, claw-shaped projections at end of postabomen. May bear up to three series (pectens) of minute spines. Both caudal rami together are termed caudal furca. (denticulate, pectinate, with/without basal spine, with/without pectin).
(syn. claw, postabdominal claw, terminal claw) [Stachowitsch, 1992]
One of two posteriorly directed projections of last segment (telson). Long and segmented ( = annulate, multiarticulate). Both caudal rami together are termed caudal furca. (unarmed, armed with minute spinules and setae).
(syn. furca ramus) [Stachowitsch, 1992]
One of two relatively short, posteriorly directed of projections of telson. Both caudal rami together are termed caudal furca. (claw-like, styliform) (See also uropod).
(syn. cercopod, furcal claw) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two posteriorly directed projections of last segment (telson). Unsegmented, typically fringed with setae. (freely movable/variously fused with last segment; thin and slender, broadly leaf-like or plate-like).
(syn. furcal ramus, cercopod) [Stachowitsch, 1992]
One of two posteriorly projections of last body segment (telson). Consists of single element with terminal setae (ramal setae, caudal setae). Both rami together are termed caudal furca. If telson is interpreted as representing anal somite, then caudal ramus may be termed uropod. (length relative to telson width: equal to or less than, less than twice, equal to twice). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of two posteriorly directed projections of last body segment (telson). Both rami together termed caudal furca. (dorsoventrally flattened and leaf-like, rod-like) (see also uropod).
(syn. furcal ramus) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Pair of minute projections between posterior lobes of abdomen; rami flank anus. (basal, lateral, subbasal, subterminal, terminal).
(syn. anal furca, anal papilla) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In ascothoracican, one of two posteriorly directed projections of last segment of abdomen. Both caudal rami together termed caudal furca. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) One of two posteriorly directed projections of last abdominal segment (anal somite); typically bears a number of setae (caudal setae). (length greater than, equal to, or less than width; margins: hairy, smooth, spinulose).
(syn. furcal ramus) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The appendage of the posterior abdominal somite of a copepod. It does not have a propodal/ramal configuration and its homologies to serially repeated limbs of the cephalon and thorax have not been determined. The caudal ramus bears setae in a pattern similar to an exopod. Its axial orientation is not known. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The paired, setiferous and usually articulated structures carried on the anal somite. [Boxshall and Halsey, 2004]
One of two relatively large, posteriorly directed projections of last segment (telson). Claw-shaped, with serrate inner margin and bearing several major setae. Both rami together are termed caudal furca.
(syn. furcal ramus, furcal claw) [Stachowitsch, 1992]
One of two projections of posterior end (thorax/abdomen) of body; extends anteroventrally due to curvature of body. (paired, unpaired; symmetrical, asymmetrical; lemelliform, rod-shaped, claw-like).
(syn. furcal ramus) [Stachowitsch, 1992]
One of two unbranched processes projecting posteriorly from anal segment; each ramus bears setae along median margin and terminally. (shorter than, longer than anal segment). [Stachowitsch, 1992]
In bathynellacean, one of two small protuberances at end of telson. Both caudal rami together termed caudal furca. May also be interpreted as representing lobes of telson.
(syn. furcal ramus) [Stachowitsch, 1992]

Caudal siphon

Posteroventral gape in valve margin; may be extended as tubular structure. [Stachowitsch, 1992]
Posteroventral opening in valve border; sometimes produced as tubular structure (Ostracoda). [McLaughlin, 1980]

Caudal style

See: Caudal ramus [Martin, 2005]
See caudal ramus. [McLaughlin, 1980]

Cecum

(Taxon-specific: ) Digestive cecum. [Stachowitsch, 1992]
One of two outpocketings of midgut. Elongate and extensively branched with carapace. Opens into digestive tract posterior to esophagus/midgut border.
(syn. midgut diverticulum, digestive gland) [Stachowitsch, 1992]
Digestive cecum. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Midgut diverticulum. [Stachowitsch, 1992]
Hepatic cecum. [Stachowitsch, 1992]
Midgut cecum. [Stachowitsch, 1992]
Dorsal cecum, lateral cecum. [Stachowitsch, 1992]
Digestive gland. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Midgut cecum, rectal cecum. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Highly branched diverticulum, one extending from each side of anterior midgut. Fills greater part of carapace after fish louse feeds on host tissues. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Digestive cecum.
(syn. caecum) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Unpiared anterior extension of stomach. (See also lateral midgut diverticulum).
(syn. midgut cecum, anterior midgut cecum) [Stachowitsch, 1992]
Pair of large outpocketings or one of numerous smaller outpocketings of anterior section (stomach) of midgut.
(syn. caecum, liver) [Stachowitsch, 1992]
In anaspidacean, one of numerous relatively thin tubules arising at anterior end of midgut and extending posteriorly to end of thorax. Also refers to short dorsal ceca of midgut, one at level of first abdominal somite, the other level at fifth.
(syn. digestive cecum) [Stachowitsch, 1992]

Celation

Type of valve sculpture: elaboration (tegmen) of outer layer which overlapsand obscures underlying ornamentation. [Stachowitsch, 1992]

Cement gland

Special concentrations of cells in dermal cover of cirripeds which function for secreting calcareous substance of valves; possibly equivalent to dermal glands of other crustaceans. [Moore and McCormick, 1969]
(Taxon-specific: Family Pycnogonidae) Pair of glands dorsal and proximal to eggs in ovisac; produces outer cover of eggs. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Glandular structure, one associated with and opening at base of each antennule. Used by cyprid larva in attachment to substratum.
(syn. adhesive gland) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Special concentration of cells in dermal cover that secretes calcareous substances of valves (Cirripedia). [McLaughlin, 1980]

Central projection

Terminal projection on crayfish male gonopod formed by fusion of two processes; poorly developed in second form male; located centrally on apex of Procambarus gonopod, distally on that of Cambarus, Fallicambarus, and Orconectes (Figs. 23,32,63). [Hobbs and Jass, 1988]

Cephalasome

Fused five head segments and additional first one or two fused thoracic segments in some copepods. [Brusca and Brusca, 2002]

Cephalic

Pertaining to head; of head. [Hobbs and Jass, 1988]

Cephalic constriction

Constriction delimiting anterior antennulary part of head from posterior part. [McLaughlin, 1980]
Transverse groove dividing head (cephalon) into anterior (antennulary) and posterior parts. [Stachowitsch, 1992]

Cephalic dorsal length

The length of the cephalon measured in a straight line along the dorsal midline from the posterior edge to the anterior vertex or rostrum, depending on which is present. [Wilson, 1989]

Cephalic flexure

Forward or even upward deflection of anterior sterna of some decapods. [Moore and McCormick, 1969]
Foward, or sometimes upward, deflection of anterior sterna. [McLaughlin, 1980]
On underside of cephalothorax, forward, or occasionally upward, deflection of anterior sternum. [Stachowitsch, 1992]

Cephalic hook

One in a series of minute, anteriorly directed hooks located on underside of head (cephalon); restricted to anterolateral margins. [Stachowitsch, 1992]

Cephalic shield

Chitinous or more or less calcified covering of the head region, formed of fused tergites of cephalic somites, commonly having pleura. [McLaughlin, 1980]
Chitinous, more or less calcified covering structure of head region formed of fused tergites of cephalic somites commonly having pleura. [Moore and McCormick, 1969]
Head shield; the dorsal head tergites fused to form a solid cuticular plate, often with ventrolateral folds ("pleural folds"). [Brusca and Brusca, 2002]
Broad, semicircular shield covering dorsal surface of head. Formed by fusion of dorsal surfaces (tergites) of first five segments.
(syn. head shield) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Dorsal cuticular shield covering head and thoracic somites (thoracomeres) fused to it. May project anteriorly to form rostrum, posteriorly to form pair of alae. (convex, flat, regionated).
(syn. head shield, dorsal shield) [Stachowitsch, 1992]
Shield-like cuticular structure dorsally convering and folding over front of head (cephalon) and extending somewhat laterally and posteriorly; tapers anteriorly (in one case with narrowest part in middle) and is marked by one or two transverse grooves. (subquadrangular, subrectangular, subtrapezoidal).
(syn. head shield) [Stachowitsch, 1992]

Cephalic somite

One unit of cephalon bearing distnctive pair of appendages.
(syn. cephalomere) [McLaughlin, 1980]
Unit division of head region, generally recognized as one of five such parts which bear distinctive paired appendages (antennules, antennae, mandibles, maxillules, maxillae) in addition to "precephalic" acron bearing eyes. [Moore and McCormick, 1969]
Any one of five segments (somites) of head (not including anteriormost acron). According to appendages borne, one may distinguish an antennular, antennal, mandibular, maxillular, and maxillar somite. Fused to each other and to thoracic somites to form cephalothorax.
(syn. cephalomere) [Stachowitsch, 1992]

Cephalomere

Cephalic somite. [Moore and McCormick, 1969]
See cephalic somite. [McLaughlin, 1980]
Cephalic somite. [Stachowitsch, 1992]

Cephalon

A term that refers to the head of a crustacean. [Brusca and Brusca, 2002]
Anterior region of the body bearing the antennules, antennae, eyes, mandibles, maxillules, and maxillae. [Holdich and Jones, 1983]
Anteriormost tagma, bearing eyes, mouth, two pairs of antennae, and three pairs of mouthparts.
(syn. head) [McLaughlin, 1980]
Head, body segments bearing eyes, antennules, antennae, mandibles, maxillules, and maxillae. [Poore, 2004]
Most anterior tagma, bearing eyes, mouth, 2 pairs of antennae, and 3 pairs of mouth-part appendages (e.g., Branchiopoda, Ostracoda, Leptostraca, Bathynella).
(syn. head) [Moore and McCormick, 1969]
The head, or anteriormost body unit. In isopods, the cephalon bears the eyes, mouth, antennulae, antennae, and four pairs of mouthparts (mandibles, maxillulae, maxillae, and maxillipeds). [Wilson, 1989]
(Taxon-specific: ) Head. [Stachowitsch, 1992]
Head. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Head. [Stachowitsch, 1992]
Anterior of three basic divisions (tagmata) of body (cephalon, thorax, abdomen). Relatively short and covered dorsally by cephalic shield. Consists of five fused segments (somites) bearing antennules, antennae, mandibles, maxillules, and maxillae.
(syn. head) [Stachowitsch, 1992]
Anterior of three basic divisions (tagmata) of body (cephalon, thorax, abdomen = pleon). Fused with three thoracic somites to form cephalothorax; accordingly, body may be interpreted as being divided into cephalothorax and pleon or into cephalon, pereon and pleon.
(syn. head) [Stachowitsch, 1992]
Anterior part of cephalothorax. Consists of anterior acron and five cephalic somites and bears eyes, antennules, antennae, labrum, mouth, mandibles, maxillules, maxillae, and labium. First three thoracic appendages (maxillipeds) closely associated with head. Covered, along with thorax, by carapace.
(syn. head) [Stachowitsch, 1992]
Anterior of three major divisions (tagmata) of body (cephalon, pereon, pleon). Typically laterally compressed and fused with first (occasionally also second) thoracic somite to form cephalothorax. The term head is often used synonymously with cephalothorax. (with/without rostrum, anteriorly truncate; laterally compressed, dorsoventrally flattened).
(syn. head)
See: Lateral lobe, Postantennal sinus [Stachowitsch, 1992]
Anterior division (tagma) of body bearing eyes, mouth, two antennules, two antennae, and three pairs of mouthparts; fused with first thoracic segment, in certain cases also with second, and therefore occasionally referred to as a cephalothorax.
(syn. head) [Stachowitsch, 1992]
Anterior region of body or head; more correctly the cephalothorax in isopods, as the first pereonal segment is usually fused with the head. [Kensley and Schotte, 1989]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Head; strictly speaking the cephalon of an isopod is a cephalothorax, as it is always fused with the first thoracomere (and also with the second thoracomere in the Gnathiidea). [Wetzer et al. 1997]
Anterior division (tagma) of body (cephalon, thorax, abdomen). Consists of an anterior acron and five somites and bears eyes, antennules, antennae, epistome, labrum, mouth, mandibles, maxillules, and maxillae. Covered, along with first four somites (thoracomeres) of thorax, by carapace.
(syn. head) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Anterior of three divisions (tagmata) of body (cephalon, thorax, abdomen). Consists of five somites bearing antennules, antennae, mandibles, maxillules, and maxillae. Covered by rostral plate and, posteriorly, by carapace.
(syn. head) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Anterior part of cephalothorax (or anterior of three tagmata of body: cephalon, pereon, abdomen). Partially fused to first thoracic somite and delimited from last three thoracic somites (pereon) by cervical groove and ridges on carapace. Bears antennules, antennae, preoral sting, proboscis with mandibles, mouth and modified lips, maxillules and maxillae.
(syn. head) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A complex of all of the somites of the head. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Anterior of three basic divisions of body (cephalon, thorax, abdomen). Consists of five (cephalic) somites and bears antennules, antennae, labrum, mouth, labium, mandibles, maxillules, and maxillae. Fused with one or more thoracic somites (thoracomeres) to form cephalosome.
(syn. head) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Head: the anterior region of the body, comprising the first five somites (antennulary to maxillary somites). [Boxshall and Halsey, 2004]
Anterior of three basic division of body (according to interpretation, either cephalon, maxillipedal somite, thoracoabdomen, or cephalon, thorax, abomen). Relatively large and divided into anterior (antennulary) and posterior parts by groove (cephalic constriction). Bears antennules, antennae, mandibles, maxillules, and maxillae.
(syn. head) [Stachowitsch, 1992]
Head. [Stachowitsch, 1992]
Anterior division of body (cephalon, trunk) bearing frontal processes, antennules, anteannae, labrum, mouth, mandible, maxillules, maxillae, and maxillipeds; covered dorsally by cephalic shield. First trunk segment fused to cephalon.
(syn. head) [Stachowitsch, 1992]
Head. [Stachowitsch, 1992]
Anterior of three basic divisions (tagmata) of body (cephalon, thorax, abdomen). Fused with first thoracic somite, leading to alternate interpretation (cephalon, pereon, abdomen). Covered by carapace. (See also cephalothorax).
(syn. head) [Stachowitsch, 1992]
Anterior part of cephalothorax. Consists of five cephalic somites bearing antennules, antennae, mandibles, maxillules, and maxillae. Covered, along with thorax, by carapace.
(syn. head)
See: Protocephalon [Stachowitsch, 1992]

Cephalosome

Head region when this includes only somites bearing maxillipeds or gnathopods, or both. [Moore and McCormick, 1969]
(Taxon-specific: Family Cyatholaimidae) Head region with one or two fused thoracic somites (Copepoda). [McLaughlin, 1980]
(Taxon-specific: Family Cyatholaimidae) One of three divisions (tagmata) of body (cephalosome, metasome, urosome); consists of head and one or two thoracic somites (thoracomeres) fused to it. Cephalosome and metasome together from prosome. (See also cephalothorax). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The anterior tagma of the body in copepods, covered by the dorsal cephalic shield and comprising 5 cephalic somites and the first thoracic (maxilliped-bearing) somite. [Boxshall and Halsey, 2004]

Cephalothoracic ganglion

In crab-like (brachyuran) decapod, large concentration of nerve tissue posterior to esophagus. Consists of fused ganglia of thoracic somites (thoracomeres).
(syn. postesophageal ganglion) [Stachowitsch, 1992]

Cephalothorax

A fused dorsal covering resulting when the carapace extends dorsally and laterally and/or posteriorly and fuses dorsally with one or more thoracic segments. [Brusca and Brusca, 2002]
All fused somites of the cephalon (head) and thorax, covered in Decapoda by carapace. [Poore, 2004]
Anterior part of body composed of fused cephalic and thoracic somites; latter with appendages modified as mouthparts, sometimes also with relatively unmodified appendages. [McLaughlin, 1980]
Anterior part of body composed of united cephalic and thoracic somites, latter comprising not only those with appendages modified as mouth parts or for food capture but others with relatively unmodified appendages, all forming a fused complex. [Moore and McCormick, 1969]
Anterior part of the body consisting of the fused cephalon (head) and thorax, bearing all the apendages except the pleopods and uropods. [Perez Farfante and Kensley, 1997]
Cephalon and first two thoracomeres. [Holdich and Jones, 1983]
Fused anterior part of the body bearing all body appendages except pleopods and uropods. [Butler, T. H.]
Portion of body bearing eyes and all appendages through fifth pereiopod (fused head and thorax). [Hobbs and Jass, 1988]
Region of the body in decapod crustaceans that is covered by the carapace, with the boundary between head and thorax indicated by the cervical groove. In lobsters the cephalothorax is called the "body;" in shrimps it is called "head.". [Bliss, 1982]
The body of a crab; formed from the fusion of the head and thorax, enclosed dorsally and laterally by the carapace and ventrally by the sternum. [Warner, 1977]
The fused anterior part of the body bearing all of the appendages except the pleopods and uropods. [Chace and Hobbs, 1969]
The fused head and thorax, enclosed dorsally and laterally by the carapace and ventrally by the sternum. [Ingle, 1983]
The fused head and thorax. [Ingle, 1980]
The portion of the body bearing the eyes and all of the appendages through the fifth pereiopod. [Hobbs, Hobbs, and Daniel 1977]
Expanded anterior section of body consisting of head (cephalon) fused with first three thoracic somites. Covered by and fused dorsally and laterally with carapace. [Stachowitsch, 1992]
Term applied to anterior section of body consisting of head and first two thoracic segments (thoracomeres); covered dorsally by carapace. [Stachowitsch, 1992]
Anterior division (tagma) of body (cephalothorax, abdomen). Consists of head (cephalon) fused with thorax and is largely or entirely covered by carapace. [Stachowitsch, 1992]
Term applied to anterior section of body consisting of head (cephalon) fused with first (and occasionally with second) thoracic somite.
(syn. head) [Stachowitsch, 1992]
Term applied to anterior section of body consisting of head (cephalon) fused with first (and occasionally second) thoracic segment. [Stachowitsch, 1992]
Anterior section of body consisting of head and, according to interpretation, either those anterior thoracomeres fused to head or entire thorax. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Anterior division (tagma) of body (cephalothorax, abdomen). Consists of head (cephalon)-fused with thoracic somite-and remaining three thoracomeres; anterior position covered by carapace. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A complex of the cephalic somites plus at least one thoracic somite. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Anterior region of body including head (cephalon) and thoracic somites (thoracomeres) fused to it. Cephalosome and metasome together form prosome. (See also cephalothorax). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The anterior tagma of the body in copepods in which the first pedigerous somite (=second thoracic) is incorporated into the cephalosome and covered by an extended dorsal shield. [Boxshall and Halsey, 2004]
Term occasionally applied to major part of body comprising fused head (cephalon) and thorax. [Stachowitsch, 1992]
Term occasionally applied to part of body consisting of head and fused first thoracomere. [Stachowitsch, 1992]
Term applied to anterior section of body consisting of cephalon and first thoracic somite (thoracomere). This unit may also be expressed by term cephalon. [Stachowitsch, 1992]
Anterior division (tagma) of body (cephalothorax, abdomen). Consists of head (cephalon) fused with thorax. Covered dorsally (incompletely on sides) by carapace. [Stachowitsch, 1992]

Cercopod

See: Caudal ramus [Martin, 2005]
See caudal ramus [McLaughlin, 1980]
Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Caudal ramus. [Stachowitsch, 1992]

Cercus

See: Caudal ramus [Martin, 2005]
See caudal ramus
(pl. cerci) [McLaughlin, 1980]

Cerebral ganglion

(Taxon-specific: Order Rhabditida) Supraesophageal ganglion. [Stachowitsch, 1992]

Cervical carina

Mesially transverse and laterally oblique ridge extending from the anterior limit of the hepatic region towards middorsal line of carapace (Fig. 2A). [Perez Farfante and Kensley, 1997]

Cervical furrow

See: Cervical groove [Martin, 2005]
See: Carapace grooves d [McLaughlin, 1980]

Cervical groove

See: Carapace groove c [Martin, 2005]
A groove or series of grooves sometimes present on the carapace; it is mesially transverse, laterally oblique, and separates the gatric and hepatic regions from the cardiac and branchial regions. [Chace and Hobbs, 1969]
Groove across the middle of the carapace between gastric and cardiac regions, curving forwards laterally, sometimes incomplete medially, sometimes accompanied by cervical ridge and ending laterally in cervical incision in some lobsters, sometimes with paired postcervical spines. [Poore, 2004]
Major arclike suture (groove) on carapace of crayfish, dividing it into anterior (cephalic) and posterior (thoracic) regions (see Fig. 14). [Hobbs and Jass, 1988]
The complex groove running along the dorsal surface of the carapace, being transverse in the middle and turning obliquely forward on each side to the lateral margins. [Ingle, 1983]
The major arc-like suture on the carapace of a crayfish, dividing it into cephalic and thoracic regions. [Hobbs, Hobbs, and Daniel 1977]
Somewhat curved, transverse groove in anterior third of carapace; corresponds to border of head and thorax. (See also mandibular groove). [Stachowitsch, 1992]
transverse groove across dorsal surface of head; corresponds to level of mandibles. [Stachowitsch, 1992]
See: Carapace grooves, Stomatopod integumental ornamentation [McLaughlin, 1980]
On carapace, well-defined, transverse groove separating gastric and cardiac regions. Considered to represent former border between two cephalic somites.
(syn. cervical suture, cervical furrow) [Stachowitsch, 1992]
Transverse groove across posterior third of carapace. (See also gastric groove). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In carapace, transverse groove delimiting cephalon (including first thoracic somite) from remaining three thoracic somites (pereon).
(syn. transverse groove) [Stachowitsch, 1992]
In anaspidacean, transverse groove across head.
(syn. mandibular groove, mandibular sulcus) [Stachowitsch, 1992]
Transverse groove across anterior region of carapace. [Stachowitsch, 1992]

Cervical notch

Strong indentation of carapace at level of cervical groove (e.g., scyllarid palinurans).
(syn. cervical incision) [Moore and McCormick, 1969]
Strong indentation of carapace at level of cervical groove. [McLaughlin, 1980]
(Taxon-specific: ) Transverse groove between head and trunk (with/without conspicuous folds).
(syn. cervical sinus) [Stachowitsch, 1992]
On dorsal surface of carapace, strong indentation at level of cervical groove.
(syn. cervical incision) [Stachowitsch, 1992]

Cervical sinus

Rounded to angular indentation at front of cladoceran carapace along dorsal edge, exposing rear part of head. [Moore and McCormick, 1969]
(Taxon-specific: ) Cervical notch. [Stachowitsch, 1992]
(Taxon-specific: ) Rounded to angular indentation anteriorly along dorsal edge of carapace (Cladocera). [McLaughlin, 1980]

Cervical spine

Spine on lateral surface of carapace immediately posterior to cervical groove of crayfishes (see Fig. 14). [Hobbs and Jass, 1988]
Spine on the lateral surface of the carapace immediately posterior to the cervical groove in crayfishes. [Hobbs, Hobbs, and Daniel 1977]

Cervical sulcus

Groove or series of grooves sometimes present on carapace; mesially transverse, laterally oblique, and separates gastric and hepatic regions from cardiac and branchial regions.
(syn. (or groove)) [Butler, T. H.]
Mesially transverse and laterally oblique groove of the carapace extending from the anterior limit of the hepatic region towards the midline of the carapace (Fig. 2B). [Perez Farfante and Kensley, 1997]
Transverse groove across anterior region of carapace at level of mandibles.
(syn. cervical groove) [Stachowitsch, 1992]

Cervical suture

See: Cervical groove [Martin, 2005]
See cervical groove. [McLaughlin, 1980]
Cervical groove. [Stachowitsch, 1992]

Chaetotaxy

The form, number, and shapes of the setae. [Wilson, 1989]

Chalimus

(Taxon-specific: Family Cyatholaimidae) One of up to four stages in copepodid phase of development of caligid-like parasitic copepods; the chalimus usually is attached to the host, often by a frontal filament held by maxilla 2. The first chalimus is molted from the first copepodid stage; the four chalimus stages correspond to the second to fifth copepodid stages. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The post-copepodid developmental stage of most siphonostomatoid fish parasites, characterised by possession of a frontal filament for attachment to the host. [Boxshall and Halsey, 2004]

Chela

A claw formed by the dactyl and propodus or a limb. Incorrectly used in euphausiids to describe setae in the configuration of a claw. [Mauchline, 1984]
A claw, or the claw-like terminus of a cheliped. [Bliss, 1982]
A forceps-like structure consisting of the two distal-most podomeres of a pereiopod. [Hobbs, Hobbs, and Daniel 1977]
A pincer formed by the two distal podomeres of a pereiopod in which the movable finger or dactyl opposes a fixed finger formed by a distal extension of the propodus.
(pl. chelae) [Chace and Hobbs, 1969]
A pinching claw composed of a moveable finger, the dactylus, and a fixed finger, a distal extension of the propodus (Fig. 1). If a pair of chelae differ in size the larger is called the major chela and the smaller the minor. [Warner, 1977]
Appendage ending in chela (claw).
(pl. chelae) [Perez Farfante and Kensley, 1997]
Arrangement of distal 2 articles of crustacean limb in which terminal article is opposed to article preceding it in an adaptation for grasping. In true chela, terminal 2 articles shaped as fingers, one closing against other. In subchela, terminal article (dactyl) usually closes against distal surface of penultimate article (propodus). [Williams, 1984]
Claw formed by the two distal segments of a periopod, in which the movable finger or dactylus opposes a fixed finger formed by the distal extension of propodus.
(pl. chelae) [Butler, T. H.]
Claw or pincer, derived from interacting fixed finger (extension from palm of propodus) and moveable finger (dactylus); palm refers. [Poore, 2004]
Distal part of appendage; pincerlike, with opposable movable and immovable fingers; occasionally both fingers moveable.
(pl. chelae) [McLaughlin, 1980]
Forcepslike structure ("claw" or "pincer"), consisting of two opposed distal podomeres of first, second and third pereiopods of crayfishes, first and second pereiopods of shrimps; dactyl (moveable finger) and propodus (see Figs. 13,14). [Hobbs and Jass, 1988]
Pincer-like distal part of limb consisting of opposed moveable, and immovable fingers. [Moore and McCormick, 1969]
The two distal segments of a cheliped forming a pinching claw. [Ingle, 1983]
Pincer-like structure at end of cheliped (first pereopod). Formed by movable finger (dactylus) opposed by immovable distal extension of propodus. Highly variable according to sex and stage of maturity.
See: Subchela [Stachowitsch, 1992]
Pincer-like structure at end of appendage. Formed by movable finger (dactylus) opposed by immovable distal extension (fixed finger) of expanded propodus (manus). (heterochelous, crushing, tearing).
(syn. pincer, claw)
See: Subchela [Stachowitsch, 1992]
Pincer-like structure of first two pereopod pairs (gnathopods). Formed by movable finger (dactylus) opposed by immovable distal extension of propodus.
See: Subchela [Stachowitsch, 1992]
Distal pincerlike part of appendage, often formed by a mobile and an immobile finger. [Kensley and Schotte, 1989]
In maxilla of certain male, hook-like structure formed by segments of inner branch (endopod); used to hold female during copulation. May also refer to pincer-like structure formed by middle segment of endopod in second (last) pair of thoracopods; used to clean food from maxillule.
(syn. pincer) [Stachowitsch, 1992]
Pincer-like structure at end of third thoracopod in certain euphausiaceans. Formed by movable dactylus bearing down on rigid spine(s) projecting distally from propodus. [Stachowitsch, 1992]

Chelate

An appendage in which the movable dactylus is apposed to an equally well-developed distal prolongation of the propodus. [Ingle, 1980]
Bearing a chela. [Butler, T. H.]
Bearing chela (chelae). [Moore and McCormick, 1969]
Pincer-like condition in which dactylus closes against fixed forward projection of propodus. [Holdich and Jones, 1983]
Pincerlike. [McLaughlin, 1980]
The dactyl and distal part of the propodus of a pereiopod forming a pinching claw. [Ingle, 1992]
Having a chela; modified to form a pincer. [Kensley and Schotte, 1989]
Having a chela; the propodus and dactylus forming a pincerlike structure wherein the latter articulates submedially on the former to produce a "moveable and fixed finger" arrangement. (True chelae are extremely rare in isopods.). [Wetzer et al. 1997]

Cheliped

A pereiopod bearing a chela. [Chace and Hobbs, 1969]
A pereiopod bearing a chela; in crayfishes, the first pereiopod. [Hobbs, Hobbs, and Daniel 1977]
Any thoracopod bearing chela. [McLaughlin, 1980]
Pereiopod bearing chela (see Figs. 13,14), in crafish literature applied almost exclusively to first pereiopod. [Hobbs and Jass, 1988]
Modified second thoracopod (= first pereopod). Typically consists of only five segments (basis, merus, carpus, propodus, dactylus), with coxa and ischium being absent. (chelate, subchelate; symmetrical, asymmetrical).
(syn. chelipede) [Stachowitsch, 1992]
Any chela-bearing thoracopod; typically refers to first pair(s) of pereopods. (equal, unequal: major, minor). [Stachowitsch, 1992]

Chelipeds

A limb bearing a chela. In crabs this limb is borne on the fourth thoracic segment (Fig. 1). [Warner, 1977]
Any thoracopod bearing chelae. [Moore and McCormick, 1969]
One or more pairs of thoracic legs of decapod crustaceans that terminate in a chela, or claw. Often the entire cheliped is referred to as a claw. [Bliss, 1982]
Pair or pairs of thoracic legs behind maxillipeds; bearing chelae, or pincer-like claws, and often stouter, sometimes much stouter, than other legs. [Williams, 1984]
Pereiopod bearing a chela. [Butler, T. H.]
Second pair of thoracic appendages; chelate in form. [Holdich and Jones, 1983]
The first pair of pereiopods arising opposite the first (or fourth) sternite and bearing the chelae. [Ingle, 1983]

Chirocerate

(Taxon-specific: Family Cyatholaimidae) Used of male antennules with one very swollen, thick walled segment and with only one segment distal to the geniculation. [Boxshall and Halsey, 2004]

Chitin

A resistant complex chemical compound, the chief constituent of the exoskeleton, or shell, of crustaceans. [Bliss, 1982]
Constituent of the shell or integument of a shrimp. [Butler, T. H.]

Chromatophore

A cell (simple or branched), usually in shell (cuticular or subcuticular), containing pigment granules, usually capable of being dispersed or concentrated. [Butler, T. H.]
Cell containing pigment. [Holdich and Jones, 1983]
Cells whose cytoplasm contains pigment that can be rapidly concentrated or dispersed, producing an overall effect of altering the color or tone of the whole or part of the animal. [Ingle, 1983]
Pigmented cell in exoskeleton. [Poore, 2004]
Pigment-filled, sac-shaped cell; contraction and expansion of chromatophores result in color changes. (bichromatic = dichromatic, monochromatic, polychromatic). [Stachowitsch, 1992]

Cicatrix

Longitudinally disposed ridge(s) often present on lateral part of sixth abdominal somite (Fig. 1).
(pl. cicatrices) [Perez Farfante and Kensley, 1997]

Cincinnuli

Minute hooked processes interlocking halves of petasma (Dendrobranchiata). [Poore, 2004]
Minute interlocking processes projecting from the dorsomesial margins of the petasmal endopods (Fig. 4B).
(pl. cincinnulus) [Perez Farfante and Kensley, 1997]

Cincinnulus

See: Retinaculum [Moore and McCormick, 1969]
See retinaculum. [McLaughlin, 1980]

Circumboreal

Pertaining to geographical distribution that encompasses all marine areas in colder parts of the northern hemisphere. [Butler, T. H.]

Circumesophageal connective

One of two strands of nerve tissue surrounding esophagus and connecting dorsal supraesophageal ganglia with posterior subesophageal ganglia. May bear ganglia (paraesophageal ganglia).
(syn. esophageal connective) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two short, relatively thick strands of nerve tissue surrounding esophagus and connecting dorsal supraesophageal ganglion with subesophageal ganglion. Innervates antennae.
(syn. paraesophageal connective) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) One of two strands of nerve tissue surrounding esophagus and connecting supraesophageal ganglion to ventral nerve cord.
(syn. esophageal connective) [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and forming lateral part of circumesophageal nerve ring. Joins supraesophageal ganglion and complex formed by subesophageal ganglion and more or less concentrated ventral nerve cord. [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding foregut and joining dorsal brain to ventral nerve cords. [Stachowitsch, 1992]

Circumesophageal ganglion

Brain. [Stachowitsch, 1992]

Circumesophageal nerve ring

Well-developed ring of nerve tissue surrounding esophagus; consists anteriorly of supraesophageal ganglion, laterally of circumesophageal connective, and posteriorly of complex formed by subesophageal ganglion and more or less concentrated central nerve cord. [Stachowitsch, 1992]

Circumgenital body cavity

(Taxon-specific: Order Monhysterida) Genocoel. [Stachowitsch, 1992]

Circumgnathal

Around the biting or grinding surface, as in circumgnathal denticles. [Wilson, 1989]

Circumoral connective

One of two long strands of nerve tissue surrounding anterior section of digestive tract and joining supraesophageal ganglion to postoral ganglion.
(syn. esophageal connective) [Stachowitsch, 1992]

Cirral fan

Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: cirri V, III, II, and I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Cirri

Feathery thoracopods used for suspension feeding in many barnacle groups. [Brusca and Brusca, 2002]
Long, feathery biramous thoracopods of sessile thoracican barnacles. [Brusca and Brusca, 2002]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: cirri V, III, II, and I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Cirrus

Multiarticulate food-gathering appendage of "thoracic" region of cirriped, normally one of six pairs, each with two long hairy rami curled towards mouth. [Moore and McCormick, 1969]
Penes; specialized reproductive organ of pentastomids; the term penes can also refer to reproductive appendages or structures in other taxa. [Brusca and Brusca, 2002]
Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) One of up to six pairs of elongate appendages of thorax regions (those of ascothoracican being termed thoracopods). Biramous, basically consisting of proximal protopod and distal endopod and exopod. Reduced and set-off pair of cirri in acrothoracican are termed mouth cirri. (uniramous, biramous; acanthopodus, ctenopodous, lasiopdous). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Thoracic, usually biramous, multiarticulate appendage generally flattened laterally and curled anteriorly, with food-gathering function; anterior and posterior margins designated lesser and greater curvature respectively.
(pl. cirri) [McLaughlin, 1980]

Clasper

Appendage, including antenna, modified for holding female during copulation; or an organ for fixation in parasites. [McLaughlin, 1980]
Appendage, including antenna, that serves for attachment in copulation or as organ for fixation in parasites. [Moore and McCormick, 1969]
Modified first and occasionally also second pair of trunk appendages in male; distal endites elongated and hook-like. Serves in grasping female during copulation. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Term applied to well-developed antennae in male; used to clasp famale during copulation. [Stachowitsch, 1992]

Class

A major subdivision of a phylum in the classification of animals, usually consisting of several subclasses and orders. [Bliss, 1982]

Clava

Type of valve sculpture: tubercle-like projection elongated in longitudinal direction or parallel to margin. If arranged in a series, clavae may represent disconnected ridge (carina). (cruciform). [Stachowitsch, 1992]

Clavate

Club shaped; having one end thickened. [Kensley and Schotte, 1989]

Clavus

(Taxon-specific: Family Cyatholaimidae) An accessory spiny process on the apex of basis of the maxilla of some siphonostomatoids. [Boxshall and Halsey, 2004]

Claw

a modified seta found on the distal segment of the walking legs that is heavily sclerotized and has a sharp tip. [Wilson, 1989]
(Taxon-specific: ) Caudal ramus. [Stachowitsch, 1992]
One of up to several claw-like projections from last segment of inner branch (endopod) of maxillae or thoracopods. Inner border may bear series of fine denticles. Largest claw occasionally termed "dactyl."
(syn. endopodal claw) [Stachowitsch, 1992]
Chela. [Stachowitsch, 1992]
Any claw-shaped projection of limb or caudal ramus. (subterminal, terminal; smooth, toothed) (See also chela). [Stachowitsch, 1992]
Claw-like tip of last segment of maxillules, maxillae, and maxillipeds. one may distinguish the talon of the maxillules, which has a pore for the maxillulary glands, and the claws of the maxillae and maxillipeds, which usually have secretory? or sensory? pores. (arcuate, horseshoe-shaped, talon-like, trifid, 10-pronged).
(syn. fang) [Stachowitsch, 1992]

Cleaning setae

Unusual setulate setae used to clean the antennae or antennulae. These setae are located on the distal segment of the mandibular palp. [Wilson, 1989]

Closed petasma

The lateral lobes are heavily sclerotized, sometimes making structure virtually rigid, with the ventral costae situated ventromesially, almost abutting, and delimiting a small, sometimes extremelyso, space; lateral lobe usually produced distally into lateral sprouts or horns.
See: Petasma [Perez Farfante and Kensley, 1997]

Closed thelycum

One in which the seminal vesicles are present.
See: Thelycum [Perez Farfante and Kensley, 1997]

Closer muscle

The muscle which moves the dactlyus downwards relative to the propodus (Fig. 12, 13). [Warner, 1977]

Clypeus

An unpaired dorsal unit of the cephalon bearing the labrum medially and the mandibular fossae laterally. The fossae articulate with the dorsal condyle of the mandibles. [Wilson, 1989]
Part of head carrying labrum; plate on anterior medial part of head formed by fusion of basal segments of antennae (e.g., Branchipus, also Hexapoda). [Moore and McCormick, 1969]
(Taxon-specific: Family Pycnogonidae) Part of cephalon carrying labrum; plate anteromedially on head formed by fusion of basal segments of antennae. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Plate-like structure fromed by medial fusion of bases of antennae. (with/without digiform process).
(syn. frontal plate) [Stachowitsch, 1992]
On underside of head, plate-like structure bearing upper lip (labrum). Separated from labrum by suture. [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
In most (but not all) isopods the labrum consists of two pieces; the anteriormost (proximal) piece is referred to as the clypeus, the posteriormost (distal) piece as the labrum proper. [Wetzer et al. 1997]
Part of head (cephalon) bearing upper lip (labrum). [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Platelike structure of cephalon, anterior to upper lip or labrum, sometimes fused with frontal lamina. [Kensley and Schotte, 1989]

Colleteric gland

In Cirripedia (Rhizocephala), a single or paired sac-like gland in female or hermaphrodite, producing viscid material binding eggs together. [Moore and McCormick, 1969]
(Taxon-specific: Suborder Enoplina) Single or paired gland in female or hermaphrodite producing viscid material for binding eggs together. [McLaughlin, 1980]

Comb

Ventral comb. [Stachowitsch, 1992]
Telsonic comb. [Stachowitsch, 1992]

Comb collar

In Cirripedia (Acrothoracica), retractable membranous collar supporting row of numerous uniform setae at superior angle of aperture. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) In acrothoracican, collar-like structure surrounding upper part of aperture. Retractable, consisting of membranous fold with fringe of setae. [Stachowitsch, 1992]
(Taxon-specific: Suborder Leptolaimina) Retractable membrane supporting row of uniform setae, at superior angle of aperture. [McLaughlin, 1980]

Combinatorial stages

Larvae exhibiting a combination of characters from the preceding and succeeding stages so that the resulting stage appears generally more (or less) advanced than the normal numeric stage. [Ingle, 1992]

Commensal

An association in which food is shared or taken by one partner from the other without greatly harming it. [Ingle, 1983]

Compartment plate

In sessile cirripeds (Verrucomorpha, Balanomorpha), rigid articulate skeletal element (valve) forming part of shell wall.
(syn. mural plate) [Moore and McCormick, 1969]
One of several rigidly articulated plates forming wall in sessile cirripeds. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) In unstalked barnacle, one of up to eight overlapping/articulating plates forming wall which encircles body. May include form anterior to posterior end: single rostrum, paired rostrolaterals, laterals, carinolaterals, single carina, and in asymmetrical form, also fixed scutum and fixed tergum.
(syn. compartmental plate, mural plate) [Stachowitsch, 1992]

Complemental plate

(Taxon-specific: Order Rhabditida) In barnacle, term applied to relatively small male attached to hermaphroditic individual. (See also dwarf male). [Stachowitsch, 1992]

Complex

(Taxon-specific: Family Cyatholaimidae) Two or more unarticulated somites or segments resulting from the failure of an arthrodial membrane to form between the somites or segments comprising the complex. [Ferrari and Dahms, in press]

Compound eye

Array of contiguous ommatidia having common optic nerve trunk; paired. [Moore and McCormick, 1969]
Paired array of contiguous ommatidia having common optic nerve trunks. [McLaughlin, 1980]
(Taxon-specific: ) One of two large photosensitive organs on head; sessile, typically fused, and enclosed within optic vesicle. Movable by series of optic muscles. Relative position of compound eye on head (e.g., anterior, in middle near ventral margin) may be of taxonomic importance. [Stachowitsch, 1992]
One of two larger photosensitive organs located on sloping anterior part of carapace; sessile. (See also eye tubercle, nauplius eye).
(syn. lateral eye) [Stachowitsch, 1992]
One of two large photosensitive organs located on anterior end of head; sessile, either closely adjoining or partially fused. Enclosed almost entirely within optic vesicle. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two relativel large, stalked photosensitive organs projecting from each side of head. (See also nauplius eye). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Eye. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two organs of vision suspended in a blood sinus on dorsal surface of carapace; each movable eye consists of numerous ommatidia, yet lacks true outer cornea. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Cypris larva. [Stachowitsch, 1992]
One of two more complex anterodorsal organs of vision. Each is contained in ocular sinus beneath eye tubercle. (See also nauplius eye). [Stachowitsch, 1992]
Pair of larger organs of vision, each located distally on eyestalk (ocular peduncle), (divided = bilobed = multilobed, undivided = single-lobed = spherical, imperfect). [Stachowitsch, 1992]

Compound rostrum

In cirripeds (Balanomorpha), projection formed by fusion of rostrolateral plates, forming compound compartment overlapping latera, and on which radii may develop (cf. rostrum). [Moore and McCormick, 1969]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Compartmental plate formed by fusion of rostrolaterals with rostrum or of rostrolaterals, with rostrum missing (balanomorph Cirripedia). [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Rostrum. [Stachowitsch, 1992]

Compressed

Flattened from side to side, or laterally. [Butler, T. H.]

Conchostracan carapace interspace

Area between any 2 growth lines of conchostracan carapace.
(syn. used interchangeably include intervales, growth zone, growth band) [Moore and McCormick, 1969]

Conchostracan carapace interval

Space between any 2 ribs, costae, or costellae on conchostracan carapace. [Moore and McCormick, 1969]

Conchostracan carapace ribs

Strong radial ridges radiating from and across umbo of conchostracan carapace, with intervals of variable width between any pair and commonly nodose at intersections of growth lines; may be partial or embryonic in expression; synonyms include longitudal striae, carinae, radials, diagonal ridges, radial costae, and keels. [Characterize Leaiidae, never exceeding five in number on any given leaian valve; ribs also occur in Protomonocarina and Limnadiopsileaia.]. [Moore and McCormick, 1969]

Condyle

A heavily sclerotized projection of the mandible's dorsal surface that articulates with the cephalon in the clypeal fossa. [Wilson, 1989]
Knob; rounded process at base of central projection of male first pleopod (gonopod); "condyl length" as presented in Tables 4,6,8,10 is measured distance between base of condyl and distal tip of central projection (Fig. 32). [Hobbs and Jass, 1988]

Conglobate

Able to roll up into a ball, as in some sphaeromatid and oniscidean isopods. [Kensley and Schotte, 1989]

Conspecific

Belonging to the same species. [Kensley and Schotte, 1989]

Contiguous

Touching. [Kensley and Schotte, 1989]

Conulus

Type of valve sculpture: conical spine. [Stachowitsch, 1992]

Copepodid

Postnaupliar developmental stages of copepods. [Moore and McCormick, 1969]
(Taxon-specific: Family Cyatholaimidae) A developmental stage without a naupliar arthrite on antenna 2, usually with articulating thoracic somites and more than three transformed limbs, and often with articulating abdominal somites. Copepodid stages are designated by Roman numerals. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Postnaupliar developmental stage (Copepoda). [McLaughlin, 1980]
(Taxon-specific: Family Cyatholaimidae) The postnaupliar phase in copepod development. [Boxshall and Halsey, 2004]

Copepodite

Postnaupliar stage (= a small juvenile) recognized in some copepod groups. [Brusca and Brusca, 2002]

Copulation

Joining of male and female for transference of spem; sexual union. [Hobbs and Jass, 1988]

Copulatory limbs

Male limbs modified for copulation, at least in most Myodocopa, usually the 8th limb pair.
See: Hemipenes [Cohen, Peterson, and Maddocks, in press]

Copulatory male

A fully adult male. In the janiroidea isopods, the male is identified by a sperm tube on the second pleopod's stylet, which is open at its sharp distal tip. In some specimens at this terminal stage, the vas deferens is visible through the cuticle connecting to the penile papilla. [Wilson, 1989]

Copulatory organ

Third pair of trunk limbs, bearing the gonopores, in ostracodes. [Brusca and Brusca, 2002]

Copulatory pore

(Taxon-specific: Family Cyatholaimidae) In female reprductive system, pore on ventral surface (sternite) of first abdominal segment (genital somite). Opens into seminal receptacle and thus represents, along with two gonopores, third opening of reproductive system. [Stachowitsch, 1992]

Copulatory stylet

Structure situated on endopod of pleopod 2 in males, used for transfer of spermatophore in some species; also referred to as appendix masculina. [Kensley and Schotte, 1989]

Cor frontale

Anterior accessory circulatory pump that helps maintain blood pressure in large or active crustaceans. [Brusca and Brusca, 2002]
Special pulsating structure or accessory heart formed from enlargement of blood vessel; contraction caused by outer tangential muscles or internal muscles derived from muscles having other functions. [McLaughlin, 1980]
In circulatory system, small, muscular expansion of anterior aorta. Located in head; supports heart in pumping blood anteriorly.
(syn. cephalic heart) [Stachowitsch, 1992]
In circulatory system, small muscular expansion of anterior aorta. Located in head; supports heart in pumping blood anteriorly.
(syn. cephalic heart) [Stachowitsch, 1992]
In circulatory system, muscular expansion of anterior aorta. Supports heart in pumping blood to anterior region of head.
(syn. accessory heart) [Stachowitsch, 1992]
In circulatory system, small, muscular expansion of anterior aorta. Located at border of cephalon and pereon; supports heart in pumping blood to anterior region of head.
(syn. accessory heart) [Stachowitsch, 1992]
In circulatory system, muscular expansion of anterior aorta. Supports heart in pumping blood to anterior region of head.
(syn. anterior heart, frontal heart) [Stachowitsch, 1992]
In circulatory system, muscular expansion of anterior aorta. Supports heart in pumping blood to anterior region of head. [Stachowitsch, 1992]

Cordate

Heart shaped in outline. [Kensley and Schotte, 1989]

Cormopod

See: Thoracopod [Martin, 2005]
See thoracopod. [McLaughlin, 1980]

Cormus

See: Thorax [Martin, 2005]

Cornea

Anterior part of carapace, including ocular peduncles, based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
A transparent horny membrane forming the distal covering of the eye. [Ingle, 1980]
Faceted portion of the eye. [Butler, T. H.]
Faceted, usually pigmented portion of the eye (Fig. 3A). [Perez Farfante and Kensley, 1997]
Facetted and pigmented part of eyestalk. [Poore, 2004]
The faceted portion of the eye. [Chace and Hobbs, 1969]
The terminal cap of the eye, faceted except in most troglobites. [Hobbs, Hobbs, and Daniel 1977]
Transparent cuticle covering ommatidia of compound eye. [Moore and McCormick, 1969]
Transparent cuticle covering ommatidia of compound eye. [McLaughlin, 1980]
Transparent cuticle covering ommatidia of each eye. [Stachowitsch, 1992]
Outermost layer of compound eye; may be divided into upper and lower units. (bilobed, cylindrical, globular, subglobular, laterally expanded; at right angle to stalk, oblique on stalk). [Stachowitsch, 1992]

Corneous

Structures that are horny (sclerified), particularly as related to reproductive appendages (modified first pleopod) of first form males. [Hobbs and Jass, 1988]

Corpus

(Taxon-specific: Family Cyatholaimidae) The massive proximal part of the subchelate maxilliped in some parasitic copepods, corresponding either to the basis or fused basis plus syncoxa. [Boxshall and Halsey, 2004]

Corpus mandibulae

See: Mandible body [Martin, 2005]
See mandible body. [McLaughlin, 1980]

Costa

Type of valve sculpture: prominent rib. Also used as synonym for carina. [Stachowitsch, 1992]

Coupling seta

One in a series of cuticular projections on inner branch (endopod) of maxilliped or on medial margin of pleopods; serves to hook maxilliped or pleopod to its opposite member.
(syn. coupling hook) [Stachowitsch, 1992]

Coupling spine

Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
When present, coupling spines (or hooks) occur on the maxillipedal endites and pleopodal peduncles, and serve to lock the opposing appendages together, allowing them to function as a single unit. [Wetzer et al. 1997]

Coxa

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Article 1 of thoracic and abdominal appendages. [Holdich and Jones, 1983]
First article of limb, usually short. [Poore, 2004]
First or proximal article of leg or maxilliped.
(syn. coxopodite) [Williams, 1984]
First or proximal podomere of a typically 7-segmented appendage (Fig. 3C).
(pl. coxae) [Perez Farfante and Kensley, 1997]
First or proximal segment of a typically 7-segmented apendage.
(pl. coxae) [Butler, T. H.]
Proximal (first) segment of segmented appendage. [Hobbs and Jass, 1988]
Segment of appendage adjoining sternite, except in forms having precoxa.
(syn. coxopodite) [McLaughlin, 1980]
Segment of limb directly attached to sternite of body (except rarely in forms having distinguishable precoxal segment).
(syn. coxopod(ite)) [Moore and McCormick, 1969]
Seventh segment of a pereiopod, counted from the distal end. [Ingle, 1983]
The basal podomere of a limb (Fig. 1). [Warner, 1977]
The first (proximal) segment of a segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
The first or basal segment of a thoracic appendage.
See: Pereopod [Wilson, 1989]
The first or proximal segment of a typically 7-segmented appendage.
(pl. coxae) [Chace and Hobbs, 1969]
Protopod. [Stachowitsch, 1992]
First segment of thoracopod (maxillipeds and pereopods) or pleopod. May be more or less fused with ventral surface (sternites) of body. Coxae of second maxillipeds fused to one another.
(syn. coxopodite) [Stachowitsch, 1992]
First of seven segments (coxa, basis, ischium, mercus, carpus, propodus, dactylus) of thoracopod. Bears well-developed epipod in maxillipeds (= first thoracopods) and may be indistinct or absent in chelipeds (= second thoracopods).
(syn. coxopodite)
See: Precoxa [Stachowitsch, 1992]
First, most proximal segment of appendage; forms protopod together with following segment (basis). Depending on appendage, coxa may bear opening of antennal gland, epipodite, gill (podobranch), or gonopore.
(syn. coxopodite) [Stachowitsch, 1992]
First of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod; typically developed as large, immovable coxal plate.
(syn. coxapodite) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Basal article of an appendage, attached to sternite, sometimes expanded into a lateral coxal plate. [Kensley and Schotte, 1989]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Basal article of an appendage. [Wetzer et al. 1997]
First segment of pereopod; often expanded to form projecting coxal plate.
(syn. coxapodite) [Stachowitsch, 1992]
First of two segments (coxa, basis) of proximal part (protopod) of appendage.
(syn. coxopodite) [Stachowitsch, 1992]
Second segment of thoracic appendage (thoracopod). Also interpreted as being first segment (forming fused precoxa and coxa).
(syn. coxopodite) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Most proximal segment of appendage. Gonopores located on coxae of sixth (female) or eighth (male) thoracopods. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In thoracopod, second of three segments (precoxa, coax, basis) of protopod; may also be applied to segment of antennule.
(syn. coxopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) First, most proximal segment of appendage. Typically forms protopod together with following segment (basis). Generally specified only in maxillules (where it bears endites and exites) and pereopods (coxae of opposed limbs united).
(syn. coxopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The middle segment of the 3-segmented protopod of postmandibular limbs, the proximal segment of the 2-segmented protopod of the antenna and mandible. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) The middle segment of the protopod, proximal to the basis and distal to the praecoxa, with a single setose endite; the mandibular gnathobase of copepods includes the coxal endite with its single seta (see basis and praecoxa). [Ferrari and Dahms, in press]
Protopod. [Stachowitsch, 1992]
First, most proximal segment of appendage; typically forms protopod together with following segment (basis). Forms ganthobase in mandibles. (See also precoxa).
(syn. coxopodite) [Stachowitsch, 1992]
Proximal part of divided protopod (separated from basis by suture).
See: Protopod [Cohen, Peterson, and Maddocks, in press]
First of two segments (coxa, basis) of proximal part (protopod) of appendage. May bear lateral lobes (endites, epipods).
(syn. coxopodite) [Stachowitsch, 1992]
First of two segments (coxa, basis) of proximal part (protopod) of appendage.
(syn. coxopodite) [Stachowitsch, 1992]
First, most proximal segment of appendage; forms protopod together with following segment (basis). Typically specified only when referring to thoracopods. Coxae of maxillae bear endites, those of thoracopods bear gills (epipodites), with coxae of second and seventh thoracopods (occasionally more) containing photophores.
(syn. coxapodite) [Stachowitsch, 1992]

Coxal endite

Lobe produced from inner margin of coxa. [McLaughlin, 1980]

Coxal exite

Lobe produced from outer margin of coxa.
(syn. coxepipod) [McLaughlin, 1980]

Coxal gill

Respiratory structure projecting from basal segment (coxa) of pereon appendage (peropod); consists of modified epipod. Six pairs of coxal gills (on pereon segments 2-8) represent full complement. (digitiform, foliate, sac-like; walls: simple = smooth, convoluted, pleated).
(syn. branchia)
See: Accessory gill, Sternal gill [Stachowitsch, 1992]

Coxal gland

Segmentally arranged series of small excretory structures, one pair in each somite (pereonite) of pereon as well as in first four abdominal somites. [Stachowitsch, 1992]

Coxal plate

Lateral expansion of coxa broadly joined to lateral mergin of tergite. [McLaughlin, 1980]
Lateral expansion of pereiopod coxa joined broadly to lateral margins of tergites. [Moore and McCormick, 1969]
Pereopodal coxae that are expanded as lateral side plates in some of the more derived groups of isopods and in some amphipods. [Brusca and Brusca, 2002]
Modification of proximal segment (coxa) of appendage (e.g., pereopod) into immovable, plate-like structure. Serves protect gills and accentuates laterally compressed shape of body, (contiguous, discontiguous; bilobed, rectangular, rounded, spiniform; margin: setose, serrate, smooth; ornamentation: setose, with ridges, spines, tubercles). [Stachowitsch, 1992]
Coxae of the pereopods laterally expanded into flattened lamellar structures extending freely (as "plates") to overhang the coxa-basis hinge of the leg. [Wetzer et al. 1997]
Lateral extension of proximal segment (coxa) of pereopod; may be fused to body wall.
(syn. epimere) [Stachowitsch, 1992]

Coxal spine

Spine projecting from the coxa of a thoracic appendage. [Perez Farfante and Kensley, 1997]

Coxepipod

Coxal exite. [Moore and McCormick, 1969]
See coxal exite. [McLaughlin, 1980]

Coxicerite

In antenna, term applied to first of two segments (coxicerite, basicerite) of peduncle. [Stachowitsch, 1992]

Coxite

See: Protopod [Martin, 2005]

Coxobasis

(Taxon-specific: Family Cyatholaimidae) A compound protopodal segment representing coxa plus basis. [Boxshall and Halsey, 2004]

Coxopod

See: Coxa [Martin, 2005]

Crenulate

Having a scalloped edge with rounded teeth, usually used to refer to the margin of a structure. [Kensley and Schotte, 1989]

Crested

With elevated and irregular or toothed ridge. [Butler, T. H.]

Crista

(Taxon-specific: Family Cyatholaimidae) A group of small spinules or setules on the apex of the maxilla of some siphonostomatoids. [Boxshall and Halsey, 2004]

Crista dentata

In third maxilliped, toothed median margin of third segment (ischium). [Stachowitsch, 1992]
Toothed crest on ischium of 3rd maxilliped. [McLaughlin, 1980]

Cristate

Sharply emarginate. [Ingle, 1980]

Crop

(Taxon-specific: Order Monhysterida) Midgut. [Stachowitsch, 1992]

Crustaceans

Members of the superclass Crustacea of the phylum Arthropoda. Examples are shrimps, lobsters, crabs, amphipods, copepods, isopods, and barnacles. [Bliss, 1982]

Cryptoniscus

Planktonic larval stage of epicaridean isopod with pereopods modified as holdfasts. Stage at which larva seeks a permanent host. [McLaughlin, 1980]
Third of three larval stages (epicaridium, microniscus, cryptoniscus) in certain parasitic isopods. Free-living, more elongate, and characterized by seven pairs of grasping pereopods. Swims by means of antennae pleopods and attaches to final host. [Stachowitsch, 1992]

Ctenopod

Appendage (cirrus) usually with long paired setae on segments of lesser curvature and few setae distally on each articulation of greater curvature. [McLaughlin, 1980]
In cirripeds, appendage where rami of cirrus have setae arranged in linear series along lesser curvature , like a comb (cf. acanthopod, lasiopod). [Moore and McCormick, 1969]

Cuspate

Having a sclerotized surface or margin with one or more rounded projections. [Wilson, 1989]

Cuspidate seta

Shaft varying from thin to stout; setules prominent and often extending post-annularly, setules with setulettes; setules sometimes grading into denticles and setae may grade into plumodenticulate type; socket usually prominent; annulus usually apparent; pore usually present. [Ingle, 1992]

Cuticle

(Taxon-specific: Family Pycnogonidae) Noncellular, multilayered structure forming outer layer of body and lining esophagus and hindgut; relatively thin and not calcified. Secreted by epidermis. [Stachowitsch, 1992]
Noncellular, multilayered, relatively thick layer forming exoskeleton and endoskeleton and lining foregut and hindgut. Secreted by epidermis. [Stachowitsch, 1992]
Noncellular, multilayered layer forming exoskeleton and lining foregut and hindgut. (smooth, spinose, with plate-like projections). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Noncellular, multilayered, relatively thick layer forming exoskeleton and lining both foregut and hindgut. Secreted by epidermis. Forms plate-like structures (cephalic shield, sternites, tergites). [Stachowitsch, 1992]
Noncellular, multilayered structure forming outer layer of body and lining foregut (stomodeum) and hindgut (proctodeum); relatively thin and pigment-free. Secreted by epidermis. [Stachowitsch, 1992]
Noncellular, multilayered, relatively thick layer forming valved, endoskeleton, and exoskeleton, and lining foregut and hindgut. Secreted by epidermis. [Stachowitsch, 1992]
Noncellular, multilayered outer layer of body; secreted by epidermis and equipped with numerous pores and sensory organs. Also lines foregut and joining dorsal brain to ventral nerve cords. [Stachowitsch, 1992]

Cuticular

Of the cuticle. [Wilson, 1989]
Pertaining to, or part of the integument or shell; structurally, cuticle is complex, made up of four layers of differing chemical composition. [Butler, T. H.]

Cuticular combs

Tiny, arc-shaped or linear groups of cuticular spines, most easily Seen on the distal parts of the mandibular palp. They may occur elsewhere on the cephalic appendages. [Wilson, 1989]

Cuticular organ

The paired female copulatory organ of Asellota, found either ventrally or on the anterior dorsal margin of pereonite 5. [Wilson, 1989]

Cycladiformes

Conchostracan carapaces having dorsal margin of valves forming obtuse with posterior margin. [Moore and McCormick, 1969]
Carapace with dorsal margin of valve forming obtuse angle with posterior margin. [McLaughlin, 1980]

Cyclomorph

(Taxon-specific: ) Any one of variously modified individuals in a population. These modifications are seasonal and generally involve the head (development of helmet) or changes in eye size or carapace spine length. [Stachowitsch, 1992]

Cyclomorphism

Seasonal changes in body form through succeeding generations of parthenogenetically produced individuals. [Brusca and Brusca, 2002]

Cyclops stage

Post-metanaupliar stage in ontogeny in some copepods. [Moore and McCormick, 1969]
(Taxon-specific: Family Cyatholaimidae) Post-metanaupliar stage. [McLaughlin, 1980]

Cyprid

(Taxon-specific: Order Rhabditida) Cypris larva. [Stachowitsch, 1992]

Cypris adductor muscle

Transverse muscle that attaches the two sides together in the cypris larva of cirripedes. [Brusca and Brusca, 2002]

Cypris larva

"Bivalved" larval type following the naupliar stage in most cirripedes. [Brusca and Brusca, 2002]
Unique larval stage that follows the nauplius stage in cirripedes. [Brusca and Brusca, 2002]
(Taxon-specific: Order Rhabditida) Final larval stage, common to all cirripeds, characterized by bivalved carapace, compound eyes, prehensile antennules, and series of locomotory thoracic appendages (cirri). (See also nauplius).
(syn. cyprid, cyprid larva) [Stachowitsch, 1992]

Cypris stage

Bivalve larval stage. [McLaughlin, 1980]
Ostracode-like larval stage (e.g., Cirripedia). [Moore and McCormick, 1969]

Cyrtopia

Furcilia. [Stachowitsch, 1992]

Cyrtopia stage

Fifth larval stage in euphausiaceans in which antennae no longer serve for locomotion. [Moore and McCormick, 1969]
Formerly considered 5th larval stage with antennae no longer used in locomotion; currently included in furcilia stage. [McLaughlin, 1980]

Dactyl

Article 7 of pereopod (article six of cheliped). [Holdich and Jones, 1983]
Diastalmost segment of limb.
(syn. dactylopod(ite)) [Moore and McCormick, 1969]
Distalmost segment of usually 7-segmented appendage; smaller, mesially situated, and moveable part of chela (moveable finger). (see Fig. 14) [Hobbs and Jass, 1988]
Terminal or distal article of leg; movable finger of cheliped.
(syn. dactylus or dactylopodite) [Williams, 1984]
Terminal podomere of a typically 7-segmented appendage (Fig. 3C). [Perez Farfante and Kensley, 1997]
The distalmost segment of a usually 7-segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
The first segment of a pereiopod, counted from the distal end. [Ingle, 1983]
The most distal segment of a limb. [Mauchline, 1984]
The seventh or distal segment of a thoracic appendage, bearing one or more distal claws.
See: Pereopod [Wilson, 1989]
The seventh or terminal segment of a typically 7-segment appendage. [Chace and Hobbs, 1969]
The terminal podomere of the endopod of a limb (Figs. 1, 2). [Warner, 1977]
Claw. [Stachowitsch, 1992]
Seventh and terminal segment of thoracic appendage (thoracopod). In first five thoracopods, folded back on propodus to form subchela. Particularly well developed on second thoracopod to form raptorial claw. (inner margin: armed, unarmed; outer margin: curved, sinuate; base: inflated, no inflated).
(syn. dactylus) [Stachowitsch, 1992]

Dactylus

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Seventh article of limb (last article interacting with fixed finger to form chela in chelate limb).
(syn. dactyl) [Poore, 2004]
Seventh or terminal segment of a typically 7-segmented appendage.
(pl. dactyli) [Butler, T. H.]
Ultimate segment of thoracopod.
(syn. dactylopodite) [McLaughlin, 1980]
Fifth and most distal of five segments (ischium, merus, carpus, propodus, dactylus) of endopod or thoracopod (maxillipeds and pereopods).
(syn. dactyl) [Stachowitsch, 1992]
Seventh, most distal of basically seven segments (coxa, basis, ischium, mercus, capus, propodus, dactylus) of thoracopod. In second pair of thoracopods (= chelipeds or first pereopods) forms movable distal element in chela or subchela.
(syn. dactyl) [Stachowitsch, 1992]
Seventh and terminal segment of appendage (thoracopod). Follows propodus and may serve as distal element in subchela or as movable finger in chela. (simple, many jointed; bifurcate, curved, falcate, falciform, obtuse, rounded, sharply pointed, spatulate, subacute, straight; ciliate, furred, grooved, hairy, smooth, spinose).
(syn. dactyl, dactylopodite) [Stachowitsch, 1992]
Seventh and most distal of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) thoracopod. In gnathopod, may form moveable distal element in chela or subchela. (oriented anteriorly/posteriorly).
(syn. dactyl) [Stachowitsch, 1992]
Seventh and terminal segment of perepod. In gnathopod, may form movable distal element in subchela. (biunguiculate, triunguiculate).
(syn. dactyl, dactylopodite) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Terminal (7th) article of a pereopod or thoracic appendage. [Kensley and Schotte, 1989]
Sixth and most distal segment (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Usually minute, with claw. May form movable distal element in subchela.
(syn. dactyl) [Stachowitsch, 1992]
Sixth, most distal segment (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. dactyl) [Stachowitsch, 1992]
Fifth and most distal of basically five segments (ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. dactyl) [Stachowitsch, 1992]
Seventh segment of thoracopod (fifth or last segment of endopod); may serve as movable element in terminal pincer (chela).
(syn. dactyl) [Stachowitsch, 1992]

Decapod crustaceans

Members of the order decapoda, class Malacostraca, superclass Crustacea, phylum Arthropoda; have five pairs of thoracic legs. Examples are shrimps, lobsters, crabs, and hermit crabs. [Bliss, 1982]

Decapodid stage

Postlarva. [Stachowitsch, 1992]

Decurved

Curved downward. [Butler, T. H.]

Deflected

Bent or turned, usually abruptly. [Butler, T. H.]

Deflected front

Broadly downturned front margin of carapace in some decapods. [McLaughlin, 1980]

Deflexed front

Broadly downturned front marginal part of carapace in some decapods. [Moore and McCormick, 1969]

Delayed development

A moulting sequence producing one or more larval forms showing little or no morphological progress towards a more advanced stage. [Ingle, 1992]

Dendrobranch

A type of decapod gill bearing two principal branches off the main axis, each of which is divided into multiple secondary branches. [Brusca and Brusca, 2002]
Type of gill having tubes divided into arborescent bundles. [Moore and McCormick, 1969]
Type of gill with lamellae divided into arborescent bundles. [McLaughlin, 1980]
Type of gill whose axis bears series of highly subdivided branches.
See: Phyllobranch, Trichobranch [Stachowitsch, 1992]

Dendrobranchiate

(noun) A decapod bearing dendrobranch gills, or (adjective) the condition of having dendrobranch gills. [Brusca and Brusca, 2002]

Dendrobranchiate gill

Gill with paired primary branches subdivided. [Poore, 2004]
One in which the paired primary branches are subdivided, sometimes highly so. [Perez Farfante and Kensley, 1997]

Dentate

With sharp spines directed outward from margins. [Butler, T. H.]
Edged with teeth. [Kensley and Schotte, 1989]

Denticle

A small tooth. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) A solid extension of the epicuticle of a segment (see seta and setule). [Ferrari and Dahms, in press]

Denticulate

A surface invested with denticulettes. [Ingle, 1992]
Having denticles. [Wilson, 1989]
Having fine teeth. [Kensley and Schotte, 1989]

Denticulate seta

A generally robust seta with either a row of denticles or a group of distal denticles. [Wilson, 1989]

Denticule

A non-articulated extension of the shaft of a seta or spine. [Watling, 1989]
A short, pointed, tooth-like projection of the cuticle. [Wilson, 1989]
In cirripeds (Balanomorpha), primary or secondary toothlet on sutural edge of radius of compartment plate or opposed buttress of adjoining plate, serving to strengthen articulation of plates. [Moore and McCormick, 1969]
(Taxon-specific: ) One in a series of small, tooth-like projections along postabdomen. Number, position, and relative size are of taxonomic importance. (equal, subequal; smooth, serrate; lateral, marginal). [Stachowitsch, 1992]
One of numerous smaller tooth-like projections between larger teeth on telson margin; according to position one may distinguish submedian, intermediate, and lateral denticles. [Stachowitsch, 1992]
Small, tooth-like projection on outer surface or hinge of valve. [Stachowitsch, 1992]

Depressed

Flattened from above downwards, or dorsoventrally. [Butler, T. H.]

Depressor muscle

In Cirripedia (Balanomorpha), muscle inserted at basicarnial angle of tergum, for which depressor muscle crests are usually developed. [Moore and McCormick, 1969]
Muscle inserted at basicarinal angle of tergum (balanomorph Cirripedia). [McLaughlin, 1980]
The muscle which moves the limb downwards by rotating it about the CB joint. [Warner, 1977]
(Taxon-specific: Order Rhabditida) In stalked barnacle, one of several paired muscles spanning from tergum and scutum to basis; serves in closing aperture. [Stachowitsch, 1992]

Depressor muscle crests

In cirripeds (Balanomorpha), elevated denticles on interior of tergum near basicarinal angle for attachment of depressor muscles (crests may extend apically). [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: on inner surface of tergum in unstalked form, elevated denticles or ridges near basicarinal angle. Serves as site of attachment of depressor muscle. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Elevated denticles or ridges on inner surface of tergum near basicarinal angle for attachment of depressor muscles (balanomorph Cirripedia). [McLaughlin, 1980]

Depressor muscle, lateral

In Cirripedia (Balanomorpha), muscle inserted on basitergal angle of scutum, for which lateral depressor muscle pit, depression or crests may develop. [Moore and McCormick, 1969]

Dermal

See: Cuticular [Butler, T. H.]

Dermal gland

Cell or concentration of cells in epidermis traversed by canals communicating with surface through fine ducts. [McLaughlin, 1980]
Single cell or concentration of cells in epidermis of body and limbs, traversed by canals and communicating with surface by fine ducts, their functions various and possibly corresponding to cement glands of cirripeds. [Moore and McCormick, 1969]
One of numerous glands in epidermis underlying cuticle; opens to exterior through long ducts traversing cuticle. [Stachowitsch, 1992]

Descending

Directed downward. [Butler, T. H.]

Descending aorta

Major unpaired blood vessel arising ventrally near posterior end of heart. Variously branched ventrally. [Stachowitsch, 1992]
Aorta. [Stachowitsch, 1992]
Major blood vessel arising from ventral surface of heart. Extends around gonads and branches above ganglia of thorax into an anteriorly and posteriorly directed artery (sternal and abdominal arteries). (paired, unpaired). [Stachowitsch, 1992]

Detritus

Non-living particulate organic matter inhabited by decomposer organisms; also, including dissolved carbon-containing substances excreted by plants and animals as well as soluble organic materials released from decaying plant and animal tissues. [Hobbs and Jass, 1988]

Deuterocerebrum

See: Mesocerebrum [Martin, 2005]
One of two anterior dorsal supraesophageal ganglia in the crustacean brain; receives the antennulary nerves. [Brusca and Brusca, 2002]
See mesocerebrum. [McLaughlin, 1980]
(Taxon-specific: ) Supraesophageal ganglion. [Stachowitsch, 1992]

Deutocerebrum

Supraesophageal ganglion. [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]

Diacresis

Transverse groove on posterior of exopod (rarely also endopod) of uropod appendage, in some forms dividing exopod into 2 movably connected parts. [Moore and McCormick, 1969]
Transverse groove on posterior part of exopod (also rarely of endopod) of uropod; sometimes dividing exopod into 2 movable parts. [McLaughlin, 1980]

Diaeresis

Transverse groove across outer branch (exopod) of uropod; may divide exopod into two movable parts. [Stachowitsch, 1992]
Transverse suture superficially subdividing one or both branched of uropod, or antennal scale. [Stachowitsch, 1992]
In anaspidacean, transverse suture superficially dividing outer branch (exopod) of uropod. [Stachowitsch, 1992]
Transverse groove across outer branch (exopod) of uropod in certain euphausiaceans. [Stachowitsch, 1992]

Diapause

A period of suspended development. [Ingle, 1983]
Extreme state of anaerobic quiescence (seen in encysted embryos of some large-bodied branchiopods and eggs or cysts of some copepods). [Brusca and Brusca, 2002]
(Taxon-specific: Family Cyatholaimidae) A significant period of quiescence during development. [Ferrari and Dahms, in press]

Digestive cecum

(Taxon-specific: ) One of two lateral outpocketings of midgut; located in head posterior to border of esophagus and midgut. An additional unpaired cecum may open into posterior end of digestive tract.
(syn. cecum, hepatic cecum, midgut diverticulum) [Stachowitsch, 1992]
One of two lateral outpocketings of midgut near border of esophagus and midgut. Highly branched, with lobe-shaped branches extending ventrally and dorsally and anterior part of head.
(syn. caecum) [Stachowitsch, 1992]
Dorsal cecum, lateral cecum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of up to several pairs of outpocketings of anterior region of midgut.
(syn. digestive gland, gut diverticulum, hepatic cecum) [Stachowitsch, 1992]
Pair of elongate digestive glands opening into digestive tract at border of stomach and midgut. Extends posteriorly to end of abdomen.
(syn. hepatopancreas) [Stachowitsch, 1992]

Digestive diverticulum

One or two pairs of digestive glands opening into digestive tract at border of stomach and midgut. [Stachowitsch, 1992]

Digestive gland

Hepatic cecum. [Stachowitsch, 1992]
Pair of large glands, one originating from each side of pyloric stomach and extending along midgut. Fills most of body, giving rise to pair of lateral pouches in posterior four throacomeres, in all pleomeres, and branching into telson.
(syn. Digestive cecum, cecum) [Stachowitsch, 1992]

Digitiform

Fingerlike. [Kensley and Schotte, 1989]

Direct development

See Epimorphic development [Ingle, 1992]

Distad

(Taxon-specific: Family Cyatholaimidae) Toward the distal end of a limb. [Ferrari and Dahms, in press]

Distal

Away from body mid-line; toward apex (tips) of appendages. [Hobbs and Jass, 1988]
Direction away from central part of body; opposite of proximal. [Moore and McCormick, 1969]
Part of structure farthest from midline of body or base of attachment; opposed to proximal. [McLaughlin, 1980]
Situated away from the base or point of attachment. [Butler, T. H.]
Situated away from the base or point of origin or attachment. [Kensley and Schotte, 1989]
Situated away from the base or point of origin or attachment. [Wetzer et al. 1997]

Distal fold

Distal pleat in the dorsolateral lobule of the petasma. [Perez Farfante and Kensley, 1997]

Distolateral

Outer side of margin of an appendage, e.g., uropod. [Butler, T. H.]

Distolateral projection

Distolateral, ventrally inclined projection or spur of the basis of the endopod of the male second pleopod. [Perez Farfante and Kensley, 1997]

Distomedian projection

Distal, relatively narrow extension of the dorsomedian lobule of the petasma. [Perez Farfante and Kensley, 1997]

Distoventral projection

Outer distal flap articulating with the distal extremity of ventrolateral lobule of petasma in members of the genus Metapenaeopsis. [Perez Farfante and Kensley, 1997]

Diverticulum

(Taxon-specific: Family Pycnogonidae) Midgut diverticulum. [Stachowitsch, 1992]
One of two simple glandular outpocketings of digestive tract; located in head and opening into anterior region of midgut. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Midgut cecum. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Lateral midgut diverticulum, oviducal diverticulum. [Stachowitsch, 1992]
One of a pair of lateral outpocketings of midgut in each trunk segment; each diverticulum extends into pleurite of segment. Diverticula become smaller toward posterior end of body and almost completely disappear in posterior-most region.
(syn. gut diverticulum) [Stachowitsch, 1992]

Domicillium

The volume between the two valves of the carapace and occupied by the soft body and limbs. [Cohen, Peterson, and Maddocks, in press]

Dorsad

Toward dorsal surface. [Butler, T. H.]

Dorsal

Of, or pertaining to, the back or upper surface. [Butler, T. H.]
Top or back of shrimp crayfish. [Hobbs and Jass, 1988]

Dorsal abdominal artery

Dorsal aorta. [Stachowitsch, 1992]

Dorsal artery

Major unpaired blood vessel arising from posterior end of heart. Extends to posterior end of abdomen and gives rise to series of segmental arteries in abdominal somites (pleomeres).
(syn. dorsal abdominal artery, posterior aorta, superior abdominal aorta) [Stachowitsch, 1992]

Dorsal cecum

Typically unpaired dorsal outpocketing of digestive tract at border of pyloric stomach and midgut. (paired, unpaired) (See also lateral cecum).
(syn. dorsal diverticulum) [Stachowitsch, 1992]
One of two small dorsal outpocketings of digestive tract at border of pyloric stomach and midgut.
See: Hepatic gland [Stachowitsch, 1992]

Dorsal keel

Keel. [Stachowitsch, 1992]

Dorsal organ

Poorly understood glandular-sensory structures (actually several different structures that may or may not be homologous) on the head of many crustaceans. [Brusca and Brusca, 2002]
Thickened glandular area of hypoderm of dorsal surface just behind head in various branchiopods, isopods, amphipods, mysidaceans, tanaidaceans, and syncarids, its function obscure. [Moore and McCormick, 1969]
Thickened glandular area of hypoderm on dorsal surface, usually in posterior of cephalon, sometimes in anterior part; not homologous in all taxa. [McLaughlin, 1980]
Unpaired organ of unknown function located behind compound eyes on dorsal surface of carapace. (considerably behind eye tubercles, anterior part between eye tubercles; circular, somewhat triangular).
(syn. nuchal organ) [Stachowitsch, 1992]

Dorsal orifice

The distal opening of the sperm tube in the janiroidean male's first pleopod. [Wilson, 1989]

Dorsal oval

Dorsal region of carapace defined by linea thalassinica laterally, cervical groove posteriorly and oblique semicircle anteriorly (Thalassinidea). [Poore, 2004]

Dorsal pit

Median pore. [Stachowitsch, 1992]

Dorsal plate

Spindle-shaped division of carapace in some astacidean decapods (Erymidae) intercalated in median suture; may be related to dorsal organ. [Moore and McCormick, 1969]
Spindle-shaped division of carapace intercalated with median suture in some decapods. [McLaughlin, 1980]
Spindle-shaped division of carapace intercalated with median suture. [Stachowitsch, 1992]

Dorsal process

Dorsal forked projection of basal segment of maxillule. [Stachowitsch, 1992]

Dorsal spine

Spine. [Stachowitsch, 1992]

Dorsolateral

Upper side of a structure. [Butler, T. H.]

Dorsolateral carina

Longitudinal ridge of dorsolateral region of carapace running dorsal to orbital region. [Perez Farfante and Kensley, 1997]

Dorsolateral lobule

Dorsal part of the lateral lobe of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]

Dorsolateral sulcus

Longitudinal groove sometimes present close to the dorsomedian line of the sixth abdominal somite. [Perez Farfante and Kensley, 1997]

Dorsolaterally

From upper to lower surface or margin. [Butler, T. H.]

Dorsomedian carina

Ridge extending along the middorsal line of the abdominal somites (Fig. 1). [Perez Farfante and Kensley, 1997]

Dorsomedian groove

See: Carapace grooves e [McLaughlin, 1980]
On carapace, longitudinal dorsomedian groove extending from tip of rostrum to posterior margin. [Stachowitsch, 1992]

Dorsomedian lobule

Mesial part of the medial lobe of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]

Dorsoventral axis

(Taxon-specific: Family Cyatholaimidae) An imaginary line through the surface of the body opposite the limbs to the surface bearing the limbs; the terms 'lateral' and 'medial' often are used in place of 'dorsal' and 'ventral' in descriptions of appendages. [Ferrari and Dahms, in press]

Dorsoventral muscle

One of three pairs of muscles extending in a dorsoventral direction in each trunk segment. [Stachowitsch, 1992]

Dorsoventralis posterior

Important muscle in crayfish and other decapods connecting head apodemes with internal surface of carapace just behind cervical groove. [Moore and McCormick, 1969]
Prominent muscle connecting head apodemes with inner surface of carapace posterior to cervical groove in many decapods. [McLaughlin, 1980]

Dorsoventralis posterior muscle

In cephalothorax, prominent muscle extending from head apodemes to carapace, where it inserts posterior to cervical groove. [Stachowitsch, 1992]

Dorsum

The dorsal surface of a body segment.
(pl. dorsa) [Wilson, 1989]
In carapace, more or less flattened area to each side of hinge; delimited from lateral surface by angle in valve. [Stachowitsch, 1992]

Doublure

Reflexed ventral continuation of carapace integument. [Moore and McCormick, 1969]
Reflected margin of carapace. [McLaughlin, 1980]

Duplicature

Along inner margin of valve, thickened, calcified section of inner lamella. Space between outer lamella and duplicature is termed vestibule. Medially directed surface of duplicature contacts opposite member when carapace is closed and may bear various ridges and grooves. [Stachowitsch, 1992]
That part of border of shell with calcareous peripheral part of inner lamina in contact with, or separated by vestibule from, outer lamina, generally narrow, sometimes extensive. [McLaughlin, 1980]

Dwarf male

(Taxon-specific: Order Rhabditida) In barnacle, term applied to relatively small male attached to female individual. (See also complemental male). [Stachowitsch, 1992]

Ecdysis

Act of molting the integument. [McLaughlin, 1980]
In crustaceans, the shedding of the old exoskeleton, or shell. [Bliss, 1982]
Moulting; the shedding of the old cuticle. [Ingle, 1983]
see Molting. [Butler, T. H.]
Molting of the integument. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) The process of shedding the exoskeleton during molting. [Ferrari and Dahms, in press]

Ectosoma

(Taxon-specific: Family Cyatholaimidae) That part of the body of a mesoparasite that is outside the host. [Boxshall and Halsey, 2004]

Edge

Outermost line of contact between two valves when carapace is closed (includes hinge region). Free edge refers to outermost line of contact of valves excluding hinge region. [Stachowitsch, 1992]

Efferent branchial channels

Pair of channels between ridges, venting branchial cavity and opening lateral to endostome (some Brachyura). [Poore, 2004]

Efferent channels

Channels through which water passes from gills. Openings at sides of endostome, except in Section Oxystomata in which they open at middle of endostome. [Williams, 1984]
Passageways through which water moves away from gills and out of branchial region. [Moore and McCormick, 1969]
Passageways through which water moves away from gills and out of branchial region. [McLaughlin, 1980]

Efferent respiratory channels

Channels through which water passes from the gills and which open at the dorso-external (in the Brachyrhyncha) or at the middle (in the Oxyrhyncha) of the endostome margin.
(syn. efferent branchial channels) [Ingle, 1980]
Opening through which water exits from branchial chamber under carapace. Typically applied to more restricted opening in crab-like (brachyuran) decapod; located anteriorly on each side of endostome.
(syn. efferent branchial channel) [Stachowitsch, 1992]

Egestion

Process of eliminating indigestible material, usually by way of the anus. [Butler, T. H.]

Egg

Spheroidal body produced by ovary of female, containing embryo and yolk as food supply. [Butler, T. H.]

Egg nauplius

Term referring to the naupliar larval stage when passed through as part of a longer period of embryonic development (or a long brood period) in species with yolky eggs. [Brusca and Brusca, 2002]

Egg sac

(Taxon-specific: Family Cyatholaimidae) A batch of one or more eggs contained within a sac-like membrane that remains attached to the genital opening(s); typically paired. [Boxshall and Halsey, 2004]

Egg string

(Taxon-specific: Family Cyatholaimidae) Elongate ovisac characteristic of certain parasitic copepods. [Stachowitsch, 1992]

Egg-bearing

see Ovigerous. [Butler, T. H.]

Eighth limb

See copulatory limb.
See: Copulatory limbs [Cohen, Peterson, and Maddocks, in press]

Ejaculatory duct

In male reproductive system, muscular terminal end of vas deferens. [Stachowitsch, 1992]
In male reproductive system, expanded terminal section of vas deferens. Opens to exterior on penis. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Unpaired terminal end of male reproductive system; formed by merger of vasa deferentia. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In male reproductive system, posteriormost section of vas deferens; opens to exterior via gonopore on first abdominal segment (genital somite). [Stachowitsch, 1992]
In male reproductive system, modified distal end of each vas deferens. Typically associated with penis. [Stachowitsch, 1992]

Elaphocaris

Protozoea. [Stachowitsch, 1992]

Element

(Taxon-specific: Family Cyatholaimidae) A serially repeated component or part of a segment, e.g. the dorsal formation seta, the ventral formation seta or the finishing arthrodial membrane. [Ferrari and Dahms, in press]

Elongate

Lengthened, longer than deep or wide. [Butler, T. H.]

Elytra

(Taxon-specific: Family Cyatholaimidae) Wing-like expansions of the dorsal or dorsolateral surface of postcephalic trunk somites in some siphonostomatoids. [Boxshall and Halsey, 2004]

Emarginate

Having a slight notch or indentation. [Butler, T. H.]
Having the margin concave. [Kensley and Schotte, 1989]

End sac

Proximal section of antennal gland. Typically divided into saccule and labyrinth; opens into bladder (occasionally via excretory tubule). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Expanded proximal section of each maxillary gland. Opens to exterior via coiled duct. [Stachowitsch, 1992]

Endite

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
A mesial lobe-like extension of a podomere or such an extension from the axial part of an unsegmented appendage. [Hobbs, Hobbs, and Daniel 1977]
A non-specific term to describe a branch of an appendage. [Ingle, 1983]
Inwardly (medially) directed lobe of first segments of maxillules, maxillae, and maxillipeds. Endites of maxillules may function as auxiliary mandibles. (arcuate, cone-like, digitiform, double-crested, lobe-like, subtriangular). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of precoxa, coxa, basis, or ischium. [Moore and McCormick, 1969]
Inwardly (medially) directed lobe of precoxa, coxa, basis, or ischium. [McLaughlin, 1980]
Inwardly directed projection arising from the basis of an appendage. [Holdich and Jones, 1983]
Lobe of several proximal podomeres of various appendages. [Perez Farfante and Kensley, 1997]
Lobe, usually mesial, of proximal articles of limbs, especially mouthparts. [Poore, 2004]
Medial outgrowth of the protopod. [Brusca and Brusca, 2002]
Mesial lobelike extension of podomere or of axial part of unsegmented appendage. [Hobbs and Jass, 1988]
(Taxon-specific: ) Inwardly (medially) directed, setose lobe of basal part (protopod) of trunk appendage. First endite typically well delimited, the following endites increasingly incorporated into endopod. [Stachowitsch, 1992]
One of five inwardly (medially) directed setose lobes of basal segment (protopod) of thoracic or abdominal appendage. Most distal (sixth) endite often termed endopod. Elongate endites of first thoracopod are termed flagella and may project beyond carapace margin. (lobelike, filiform). [Stachowitsch, 1992]
One of five inwardly (medially) directed, setose lobes of basal part (protopod) of trunk appendage. Most distal (sixth) endite often termed endopod, while fifth may be modified as palp (especially in male). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) In thoracic appendage (thoracopod), one of basically five inwardly (medially) directed, setose lobes of protopod. Serves in feeding. (distinct, partially fused). [Stachowitsch, 1992]
One of up to several inwardly (medially) directed, setose lobes of protopod. Termed gnathobase if considered to serve in feeding (e.g., maxillules, occasionally also maxillae and thoracopods). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of proximal part of appendage, e.g., of maxillules and represents main five-segmented branch of thoracopod (maxillipeds and pereopods). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of mouthpart (i.e., maxillule, maxilla). Basis of maxilliped also bears endite. (simple, deeply cleft). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of protopod, typically on maxillules, maxillae, and maxillipeds. (bilobed, entire).
See: Exite [Stachowitsch, 1992]
Inwardly (medially) directed lobe of proximal part of posterior mouthparts (e.g., maxillules, maxillipeds). First (proximal) endite may be termed inner plate, second termed outer plate. Shape, degree of development, and armature are of taxonomic importance, (equal, subequal, rudimentary, absent; with spines/setae). [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
A lobe on the inner (medial) margin of the protopod of an arthropod limb; enlarged anteriorly directed lobe of the basis of an isopod maxilliped. [Wetzer et al. 1997]
Inwardly (medially) directed lobe of proximal pan of posterior mouthparts (maxillules, rnaiilk. maxillipeds). If endites of first two pairs of mouthparts are paired, one may distinguish a proximal = inner and a distal = outer endite/plate/lobe. (immovable, movably articulated; rounded, cleft). [Stachowitsch, 1992]
Medially directed lobe of coxa or basis of an appendage, especially the maxilliped. [Kensley and Schotte, 1989]
Inwardly (medially) directed lobe of inner branch of biramous appendage. [Stachowitsch, 1992]
Inwardly (medially) directed lobe of first two segments of maxillules and maxillae. (bilobed, with terminal tooth). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Inwardly (medially) directed lobe of proximal part (protopod) of appendage, e.g., of maxillules or maxillae. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A non-articulating, ventral attenuation of a protopodal segment. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) An inner lobe or process on a protopodal segment of an appendage. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) Inwardly (medially) directed lobe of proximal part (protopod) of maxillule. Used to clean filtering apparatus in suspension-feeding copepod. (See also exite). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of protopod of maxillule, maxilla, and maxilliped. (See also gnathobase). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of protopod, typically in maxillule, maxilla, and thoracopod. [Stachowitsch, 1992]
Medial extension (tooth, lobe, masticatory process) of protopod, generally used in feeding.
See: Masticatory process [Cohen, Peterson, and Maddocks, in press]
One of two inwardly (medially) directed lobes of maxillule or two to four lobes of maxilla. Also refers to two lobes of first segment (coxa) of maxilliped. (See also gnathobase). [Stachowitsch, 1992]
Inwardly (medially) directed lobe of proximal section (protopod) of mouthpart (i.e., maxillule, maxilla, maxilliped). [Stachowitsch, 1992]
One of two inwardly (medially) directed, setose lobes of base (protopod) of maxillules and maxillae. (simple, bilobed, trilobed). [Stachowitsch, 1992]

Endognath

Endopod (inner and principal branch) of maxilliped. [Moore and McCormick, 1969]
Endopod of maxilliped. [McLaughlin, 1980]
Inner or principal branch of a maxilliped. [Williams, 1984]
Inner or principal branch (endopod) of maxilliped.
See: Exognath [Stachowitsch, 1992]

Endoparasite

An internal parasite. [Butler, T. H.]

Endophragm

Septum formed by cephalic and thoracic apodemes.
(syn. arthrophragm) [McLaughlin, 1980]
Wall formed by union of apposed apodemes forming part of endoskeleton of some decapods.
(syn. arthrophragm) [Moore and McCormick, 1969]
In cephalothorax, septum of endoskeleton formed at border of each somite by inward projections (endopleurites, endosternites) of exoskeleton.
(syn. arthrophragm) [Stachowitsch, 1992]

Endophragmal skeleton

An internal skeleton composed of arthrophragms arising from. [Martin, 2005]
Complex internal skeletal structure formed by fusion of apodemes in decapods providing framework for muscle attachment, generally not strongly calcified. [Moore and McCormick, 1969]
Complex internal structure formed by fusion of apodemes, providing framework for muscle attachment. [McLaughlin, 1980]
the sternites and supporting the muscles of the leg bases (Fig. 7B). [Warner, 1977]
Endoskeleton. [Stachowitsch, 1992]

Endopleurite

Lateral apodeme of endoskeleton in decapods. [Moore and McCormick, 1969]
In endoskeleton, one in a series of rigid structures projecting into body from lateral part (pleurite, epimeral fold) of exoskeleton. Serves also as site of muscle attachment (apodeme) and may be branched.
See: Endosternite [Stachowitsch, 1992]
Lateral apodeme of endoskeleton. [McLaughlin, 1980]

Endopod

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Inner branch of biramous appendage, especially one arising from protopodite of pleopod. [Butler, T. H.]
Inner of two branches of biramous limb, comprising ischium through to dactylus; in many the dominant or only branch.
(syn. endopodite) [Poore, 2004]
Inner ramus of biramous appendage. [McLaughlin, 1980]
Innermost ramus of limb arising from protopod basis; in the Eumalacostraca typically composed of five segments (ischium, merus, carpus, propodus, dactylus). [Moore and McCormick, 1969]
Medial of two rami arising from the protopod and constituting the biramous limb. [Brusca and Brusca, 2002]
Mesial ramus of a biramus appendage, especially one arising from the basis or from the protopodite of the pleopod. [Perez Farfante and Kensley, 1997]
Mesial ramus of biramus appendage, originating on basal segment (basis) (see Fig. 13). [Hobbs and Jass, 1988]
The inner branch of a biramous appendage. [Ingle, 1983]
The inner of the two branches of the primitive appendage (Fig. 2). [Warner, 1977]
The medial or interior ramus of a crustacean appendage. In the Isopoda, another name for a thoracic appendage (exclusive of the coxa and basis), although more typically applied to the inner ramus of a pleopod or a uropod. [Wilson, 1989]
The mesial branch of a bifurcate appendage, especially one arising from the protopodite of the pleopod of shrimps. [Chace and Hobbs, 1969]
The mesial ramus if a biramus appendage, having its origin on the basis. [Hobbs, Hobbs, and Daniel 1977]
(Taxon-specific: ) Lobe-like inner branch (ramus) of trunk appendage; lacks articulation with protopodal part of appendage and is more or less continuous with distal endites. Forms entire distal part of limb in certain predatory water fleas.
(syn. endopodite) [Stachowitsch, 1992]
Inner lobe at distal end of thoracopod or abdominal appendage in certain tadpole shrimp. Most distal (sixth) endite also occasionally termed endopod.
(syn. endopodite) [Stachowitsch, 1992]
Unsegmented, lobe-like inner branch of trunk appendage; often termed sixth endite.
(syn. endopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Inner branch of thoracic appendage (thoracopod). Unsegmented, lobe-like, and bearing marginal setae. Not articulated with protopod and therefore occasionally termed sixth endite. Serves in feeding. (oval, rectangular) (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch of biramous appendage. Refers to two-segmented branch of antennae, lobate branch (in larvae only) of mandibles, annulate branch of maxillules, six-segmented branch of maxillae, and five to six-segmented branch of thoracopods. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Forms palp of maxillule and represents main five-segmented branch of thoracopod (maxillipeds and pereopods).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of binamous appendage. Represents only branch or main, typically five-segmented branch (ischium, mercus, carpus, propodus, dactylus) of thoracopod.
(syn. endopodite)
See: Exopod [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Refers to three-segmented part of peduncle of antenna, palp-shaped or more elongate inner branch of mouthparts, inner branch of pleopods and uropods; considered to represent main, basically five-segmented part of pereopod. (paddle-shaped, palp-shaped, pediform).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Forms palp in mouthparts (mandibles, maxillules, maxillae, maxillipeds) and represents main five-segmented part of pereopods.
(syn. endopodite)
See: Exopod [Stachowitsch, 1992]
Inner (medial) ramus of an appendage. [Wetzer et al. 1997]
Inner branch (ramus) of biramous appendage.
(syn. endopodite) [Stachowitsch, 1992]
Inner ramus of a biramous appendage. [Kensley and Schotte, 1989]
Inner branch (ramus) of biramous appendage. Represents palp of maxillae and maxillules as well as inner branch of maxillipeds, pereopods, and pleopods. Endopod of uropod may bear statocyst.
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Refers to three-segmented, flagellum-bearing branch of antennae, appendix interna-bearing branch of pleopods, and one-segmented branch of uropods, while it is considered to represent outer branch of last three thoracopods. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Inner branch (ramus) of biramous appendage. (simple, two-, three- to four-, five-segmented) (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Setose inner branch (ramus) of thoracic appendage (thoracopod). (See also exopod). [Stachowitsch, 1992]
Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Inner branch (ramus) of thoracic appendage (thoracopod in ascothoracican, cirrus in other cirripeds). (one- to three-jointed, multiarticulate) (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A ventral extension of the proximodistal axis of a limb originating on the basis of the protopod and usually segmented. Dorsal setae are absent from endopodal segments except for the penultimate and the antepenultimate segments. An endopodal segment may bear more than one ventral seta. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Inner branch (ramus) of biramous appendage. Refers to inner, main, or only branch of antenna and maxilliped, as well as to inner branch of mandible, maxillule, and pereopod. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The inner ramus of a biramous appendage. [Boxshall and Halsey, 2004]
Inner branch of biramous appendage. Refers to four-segmented branch of antenna and mandible of three-segmented branch of maxilliped. Single branch of uniramous appendage (e.g., maxilla) may also be interpreted as representing and endopod. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
In distally biramous crustacean limb, the medial ramus.
(syn. endopodite) [Cohen, Peterson, and Maddocks, in press]
Inner branch (ramus) of biramous appendage. Typically forms palp-like structure in mouthparts (e.g., mandible, maxillules) or main component of thoracopods. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
Inner or more ventral branch (ramus) of biramous appendage (antennule, antenna, trunk limb).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Basically six-segmented in throracopods, consisting of preischium, ischium, merus, carpus, propodus and dactylus. (See also exopod, gonophysis).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Represents only branch (flagellum) of antenna, palp of anterior mouthparts, and larger, basically five-segmented ramus (ischium, merus, carpus, propodus, dactylus) of thoracopods. (See also exopod).
(syn. endopodite) [Stachowitsch, 1992]
Inner branch (ramus) of biramous appendage. Represents flagellum-bearing branch of antenna, palp-like branch of maxillules and maxillae, five-segmented main branch of thoracopods, and flattened inner branch of pleopods and uropods.
(syn. endopodite)
See: Exopod [Stachowitsch, 1992]

Endopodal lobe

(Taxon-specific: Family Cyatholaimidae) The inner lobe of the baseoendopod of the fifth leg, derived from the endopod. [Boxshall and Halsey, 2004]

Endopodite

Main branch of an appendage issuing from the basis. [Holdich and Jones, 1983]
Mesial ramus of biramous appendage. [Williams, 1984]
The inner branch of a biramous appendage. [Mauchline, 1984]

Endoskeleton

Internal hard parts of some decapods consisting mainly of endophragms. [Moore and McCormick, 1969]
(Taxon-specific: Family Pycnogonidae) Term occasionally applied to various more rigid internal structures serving as sites of muscle attachment. [Stachowitsch, 1992]
Internal skeletal structure of head and thorax (cephalothorax). When fully developed, consists of complex system of fused projections (endopleurites, endosternites).
(syn. endophrogmal skeleton, endophragmal system)
See: Exoskeleton [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In head, weakly developed internal skeleton consisting of two endosternites. [Stachowitsch, 1992]
Thin internal skeleton of body; forms complex framework supporting limbs and caudal rami. [Stachowitsch, 1992]

Endosoma

(Taxon-specific: Family Cyatholaimidae) That part of the body of a mesoparasite that is inside the host. [Boxshall and Halsey, 2004]

Endosternite

Mesodermal tendonous plate below anterior part of alimentary canal (e.g., Notostraca); also firm calcareous plate between nerve cord and alimentary canal in anterior part of thorax in some crabs. [Moore and McCormick, 1969]
Mesodermal tendonous plate below anterior part of alimentary canal; also firm calcareous plate between nerve cord and alimentary canal anteriorly in thorax of some decapods. [McLaughlin, 1980]
In endoskeleton, one in a series of rigid structures projecting into body from ventral part (sternites) of exoskeleton. Serves also as site of muscle attachment (apodeme) and may be branched. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) One head, one of two transverse skeletal elements arising from ventral surface (sternite) and forming internal skeleton (endoskeleton). Serves as site of attachment for muscles of antennae and mouthparts, one being located directly behind esophagus, the second in region of maxilla. [Stachowitsch, 1992]

Endostome

Palate-like part of buccal frame in some brachyuran decapods.
(syn. palate) [Moore and McCormick, 1969]
Part of epistome forming palate in brachyurans and usually separated from epistome proper by transverse ridge. [Williams, 1984]
Plate inside buccal cavern surrounding mouth. [Poore, 2004]
Platelike part of buccal frame in some brachyuran decapods. [McLaughlin, 1980]
The area posterior to the epistome forming the roof of the buccal cavity. [Ingle, 1983]
In crab-like (brachyuran) decapod, posterior part of epistome; forms roof of mouth (buccal frame) and may be separated from epistome by transverse ridge.
(syn. palate) [Stachowitsch, 1992]

Entire

Complete; usually referring to the margin of a structure that is smooth. [Kensley and Schotte, 1989]

Ephippium

A portion of the shed carapace that functions as an egg case in some cladoceran taxa. [Brusca and Brusca, 2002]
Semielliptical modification of cuticle in dorsal region of carapace valves forming encasement for eggs, capable of withstanding dessication after being shed (Cladocera).
(pl. ephippia) [McLaughlin, 1980]
Semielliptical part of dorsal region in each valve of cladoceran branchiopods altered to form encasement for eggs, shed as unit and constructed in manner that facilitates ultimate hatching after desiccation (especially characteristic of Daphniidae).
(pl. ephippia) [Moore and McCormick, 1969]
(Taxon-specific: ) Egg case formed by walls of brood chamber. Typically separated from rest of carapace during molting. (knobby and with two eggs, reticulated and with single egg). [Stachowitsch, 1992]

Epibenthic

Living at the surface of the substratum, or on the sea bed. [Ingle, 1992]

Epibiont

An organism attached to an external surface. [Ingle, 1983]

Epibranchial

Anterior part of branchial region of decapod (brachyuran) carapace. [Moore and McCormick, 1969]
Part of porcellanid (crab) carapace situated behind orbit and above metabranchial region. Region situated between cervical groove and linea anomurica. Often a strong spine on region, referred to as epibranchial spine.
(syn. epibranchial region) [Williams, 1984]
The region on the dorsal surface of the carapace bounded by parts of the margin of the hepatic, protogastric, metagastric and metabranchial regions and part of the antero-lateral margin of the carapace. [Ingle, 1983]

Epibranchial lobe

See: Carapace regions c [McLaughlin, 1980]

Epibranchial region

The anterior part of the branchial region on the carapace of crabs. [Chace and Hobbs, 1969]
Branchial region. [Stachowitsch, 1992]

Epibranchial space

Part of gill chamber above (external to ) gills. [Moore and McCormick, 1969]
In each branchial chamber in cephalothorax, space above (exterior to) gills, i.e., between gills and lateral wall of carapace.
See: Hypobranchial space [Stachowitsch, 1992]

Epicaridium

First of three larval stages (epicaridium, microniscus, cryptoniscus) of certain parasitic isopods. Free-living, characterized by stout, segmented body lacking last (= seventh) pair of pereopods. Swims by means of antennae and pleopods and attaches to intermediate host. [Stachowitsch, 1992]

Epidermis

Outer cellular layer of body wall; secretes cuticle. Formerly termed hypodermis. [Stachowitsch, 1992]
Outer cellular layer of body wall; secretes cuticle. [Stachowitsch, 1992]

Epigastric area

See: Carapace regions f [McLaughlin, 1980]

Epigastric lobes

A paired anterior boss on the gastric region of the carapace of crabs. [Chace and Hobbs, 1969]
Anterior extension of gastric region of decapod (brachyuran) carapace. [Moore and McCormick, 1969]
Anterior lobes or subregions of gastric regions. [Williams, 1984]

Epigastric region

Gastric region. [Stachowitsch, 1992]

Epigastric spine

A median dorsal spine posterior to rostrum, on gastric region; sometimes has the appearance of a rostrum, e.g., Pasiphaeidae. [Butler, T. H.]

Epigastric tooth

Tooth of the carapace situated above the gastric region behind the first (posteriormost) rostral tooth (Fig. 2A). [Perez Farfante and Kensley, 1997]

Epigean

Living on the surface of the earth, as opposed to spelean. [Chace and Hobbs, 1969]

Epignath

See: Epipodite [Martin, 2005]

Epimeral fold

Steep fold of endopleurites connected with branchiostegite to form branchial chamber in some decapods. [McLaughlin, 1980]
Steep fold of endopleurites in some decapods connected with branchiostegite to form branchial chamber. [Moore and McCormick, 1969]
Steep fold of certain lateral elements (endopleurites) of exoskeleton. Lies parallel to and attaches to side walls (branchiostegites) of carapace, thus forming branchial chamber enclosing gills. [Stachowitsch, 1992]

Epimeral line

A line on each branchiostegite running obliquely and then posteriorly, along which a split develops in the early stages of ecdysis. [Ingle, 1983]

Epimere

A lateral fold of a somite's integument dorsal to the limbs. Sometimes called the pleurite or tergal fold. [Wilson, 1989]
Each lateral part of integument of somite.
(syn. epimeron, pleurepimere, pleurite, pleuron, pleura, pleural lobe, tergal fold) [McLaughlin, 1980]
Lateral downfold of tergite.
(syn. epimeron, pleurepimere, pleurite, pleuron (pl., pleura), pleura (pl., pleurae), tergal fold) [Moore and McCormick, 1969]
Lateral part of wall of body somites situated between tergum and insertion of appendages. [Williams, 1984]
Poorly developed lateral part/extension of somites in pereon and pleon region. [Stachowitsch, 1992]
Pleurite.
(syn. epimeron) [Stachowitsch, 1992]
Lateral projection of segments of anterior abdomen (pleomere). (posterodistal angle: acute, rounded, quadrate, prolonged into large tooth; margins: smooth, serrate, setose).
(syn. epimeral plate) [Stachowitsch, 1992]
Lateral extension of body,either of the body wall proper or, in the pereon, more frequently of coxae of pereopods (more accurately termed coxal plate).
(syn. epimeron) [Stachowitsch, 1992]

Epimeron

See: Epimere [Martin, 2005]
Lateral projection of pereonite or pleonite. [Holdich and Jones, 1983]
See epimere. [McLaughlin, 1980]
Lateral part of a somite. [Kensley and Schotte, 1989]

Epimorphic development

Direct development thought to result from a delay in hatching of the embryo, which causes the nauplius (and any other possible larval stages) to be suppressed or absent. [Brusca and Brusca, 2002]
In which larval stages are supressed or passed within the egg prior to hatching and the juvenile hatches with adult morphology. [Ingle, 1992]

Epipelagic

Zone usually in the ocean from surface to 200m, or referring to its inhabitants. [Butler, T. H.]

Epiphyte

A plant attached to an external surface of another plant or animal which uses its host for support. [Ingle, 1983]

Epipod

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
A lateral extension from the base of an appendage (Fig. 2). [Warner, 1977]
A respiratory endite arising from the coxal segment of a pereiopod. [Ingle, 1983]
A small projection arising from the thoracic legs. [Mauchline, 1984]
Lateral branch of limb attached sometimes with gill (podobranch) to coxa, coxal endite.
(syn. epipodite) [Poore, 2004]
Lateral exite of the coxa of a thoracic appendage, sometimes branchial in function (Fig. 3C). [Perez Farfante and Kensley, 1997]
Laterally directed lobe (exite ) of the basal segment ( coxa ) of the maxilliped. [Wilson, 1989]
Laterally directed ramus (exite) of coxa; may be present or absent. [Moore and McCormick, 1969]
Respiratory process arising from coxa of a thoracic appendage; usually elongate and flat, but may be folded; has taxonomic value. [Butler, T. H.]
(Taxon-specific: ) In trunk appendage, laterally (outwardly) directed lobe projecting from base of protopod. Represents only lobe articulated with appendage and serves in respiration.
(syn. epipodite) [Stachowitsch, 1992]
Dorsally directed lobe extending from lateral (outer) margin of thoracic appendage (thoracopod) or abdominal appendage. Serves in respiration.
(syn. epipodite) [Stachowitsch, 1992]
In trunk appendage, fleshy, lobe-like projection from base of protopod. Serves, along with inner wall of carapace, in respiration. Dorsally directed part of flabellum may also represent an epipod.
(syn. epipodite) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) In thoracic appendage (thoracopod), laterally (outwardly) directed lobe of protopod; located distal to preepipod(s). Serves in respiration.
(syn. epipodite) [Stachowitsch, 1992]
Pseudepipod. [Stachowitsch, 1992]
In first pair of maxillipeds, enlarged lateral lobe of first segment (coxa). Consists of two parts, the first directed posteriorly into branchial chamber and bearing branchial lobules, the second (siphonal lobe) directed anteriorly to form part of siphon (the latter may alternately be interpreted as representing an exopod).
(syn. epipodite) [Stachowitsch, 1992]
Well-developed projection of first segment (coxa) of each maxilliped. If fully developed, consists of stalk-like proximal section (muscular peduncle) and distal expanded section. The latter may further bear small lobe basally and finger-like process (terminal spine) terminally. Projects posteriorly into branchial chamber and serves in respiration. (kidney-shaped, sickle-shaped, spoon shaped).
(syn. epipodite) [Stachowitsch, 1992]
In appendage (pereopod) of pereon, inwardly directed lobe of protopod. Serves in respiration and therefore frequently termed coxal gill or branchia.
(syn. epipodite) [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
(Figure only.) [Wetzer et al. 1997]
Lateral extension of a protopodite. [Kensley and Schotte, 1989]
Dorsal projection from outer branch (exopod) of thoracopods. First thoracic epipod extends dorsally and posteriorly under carapace and serves to renew water supply for respiration. In certain mysidaceans, epipods of thoracopods 2-7 form ramified gills (branchiae).
(syn. epipodite) [Stachowitsch, 1992]
Laterally directed branch of base of first five thoracic appendages (thoracopods); with respiratory function in thoracopods 3-5.
(syn. epipodite) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In thoracic appendage (thoracopod), laterally (outwardly) directed lobe of protopod. Serves in respiration.
(syn. epipodite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Flabellum. [Stachowitsch, 1992]
Extension (usually setose flat lobe) of lateral protopod; in ostracodes it often forms a branchial plate used to circulate water. [Cohen, Peterson, and Maddocks, in press]
Laterally directed lobe of protopod. May also refer to modified exopod (branchial plate) of appendage.
(syn. epipodite) [Stachowitsch, 1992]
One of two projections of first segment (coxa) of thoracopod. Serves in respiration.
(syn. epipodite) [Stachowitsch, 1992]
Projection of basal section (protopod) of each maxilliped. Extends posteriorly under carapace, serving in respiration and ventilation of brood pouch in female.
(syn. epipodite) [Stachowitsch, 1992]
Laterally (outwardly) directed lobe of basal segment (coxa) of thoracic appendage (thoracopod). Those of second through eighth thoracopods serve in respiration and are therefore termed gills or podobranchs.
(syn. epipodite) [Stachowitsch, 1992]

Epipodite

A lateral plate-like extension from the coxa often bearing gill filaments. [Hobbs, Hobbs, and Daniel 1977]
Branchial exite borne by the basal region of an appendage ( especially the maxilliped). [Holdich and Jones, 1983]
Laterally directed exite of protopod, usually branchial in function. [McLaughlin, 1980]
Outgrowth of first 7 thoracic coxae. [Williams, 1984]
Inwardly (medially) directed lobe of first two segments of thoracopods (maxillipeds and pereopods). Typically with respiratory function. (simple, lobate).
(syn. epipod)
See: Mastigobranch [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) An outer lobe (exite) on the outer margin of a protopodal segment (coxa) of an appendage. [Boxshall and Halsey, 2004]

Episternum

Posterolateral projection of various sterna of decapods. [Moore and McCormick, 1969]
On ventral surface of cephalothorax, one in a series of posterolateral projections of successive sternites; serves as ventral support for articulation of pereopod. [Stachowitsch, 1992]
Posterolateral projection of various sterna. [McLaughlin, 1980]

Epistome

A broad strongly calcified plate in front of, and above, the mouth. It represents the fused sternites of the third and fourth segments. [Warner, 1977]
A transverse plate situated anterior to the mouth. [Hobbs, Hobbs, and Daniel 1977]
Antennal sternum mainly represented by epistome, a plate of varying shape lying between labrum and bases of antennae. In shrimps, comparatively narrow and separated on each side from lateral portions of carapace by exhalant branchial channels. In Astacidea and Anomura, broad and in contact with carapace on each side; in Brachyura, becoming firmly united with carapace. The epistome forms the anterior part of the buccal frame. [Williams, 1984]
Front part of head above labrum, sometimes produced anteriorly into a spine. [Holdich and Jones, 1983]
Plate of varying shape between labrum and bases of antennae in brachyuran decapods, also defined as sternum of antennal somite. [Moore and McCormick, 1969]
Plate of varying shape between labrum and bases of antennae; also sternum of antennal somite. [McLaughlin, 1980]
Region of carapace between front of carapace, antennules and buccal region. [Poore, 2004]
The transverse plate anterior to the mouth area in crayfishes and crabs. [Chace and Hobbs, 1969]
The transverse plate forming the anterior border of the buccal frame, laterally fused with the carapace and (usually), anteriorly fused with the front. [Ingle, 1983]
Transverse plate (usually somewhat triangular in shape) situated ventrally and anterior to gnathal appendages of crayfishes (see Fig. 23i). [Hobbs and Jass, 1988]
Transverse plate anterior to mouth area. [Perez Farfante and Kensley, 1997]
Rostrum. [Stachowitsch, 1992]
On underside of head, pair of small plates between bases of antennules. Adjoined posteriorly by upper lip (labrum). [Stachowitsch, 1992]
Relatively large, plate-like structure in front of mouth on underside of head. May be divided into more narrow anterior part extending between antennae and broader posterior portion (endostome). Adjoined posteriorly by labrum. Also considered to be sternum of second cephalic segment (antennal somite).
See: Metapon [Stachowitsch, 1992]
On underside of head, plate-like structure in front of upper lip (labrum). (pointed, rounded). [Stachowitsch, 1992]
Relatively large, plate-like structure in front of mouth on underside of head (cephalon); adjoined posteriorly by labrum. [Stachowitsch, 1992]

Epizoism

An association in which animals live on others for substrate requirements. [Ingle, 1983]

Erichthus larva

Later larval stage of most stomatopods; similar stage in other stomatopods is termed alima. [Stachowitsch, 1992]

Esophageal connective

(Taxon-specific: ) One of two strands of nerve tissue surrounding esophagus and connecting posterior part of brain with ventral nerve cord. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two strands of nerve tissue extending around esophagus and connecting posterior part of supraesophageal ganglion with antennal ganglion (tritocerebrum). [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and connecting supraesophageal ganglion with subesophageal mass. [Stachowitsch, 1992]
Circumesophageal connective. [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and connecting brain (supraesophageal ganglion) with subesophageal ganglion. [Stachowitsch, 1992]
One of two strands o( nerve tissue surrounding foregut and connecting brain (supraesophageal ganglion) with subesophageal ganglion. [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and joining supraesophageal ganglion to subesophageal ganglion or directly to ventral nerve cord. [Stachowitsch, 1992]
Circumoral connective. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of two strands of nerve tissue surrounding esophagus and connecting brain (supraesophageal ganglion) with ventral nerve cord. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of two strands of nerve tissue extending around esophagus and connecting supraesophageal and subesophageal ganglia.
(syn. circumesophageal connective) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Circumesophageal connective. [Stachowitsch, 1992]
One of two strands of nerve tissue extending from posterior part of brain (tritocerebrum) around esophagus. [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and connecting supraesophageal ganglion to ventral nerve cord. [Stachowitsch, 1992]
One of two strands of nerve tissue surrounding esophagus and connecting brain (supraesophageal ganglion) with ventral nerve cord. [Stachowitsch, 1992]

Esophagus

Anterior part of alimentary canal between pharynx or mouth and stomach or stomodeum.
(syn. oesophagus) [Moore and McCormick, 1969]
(Taxon-specific: ) Relatively short and narrow anterior section of digestive tract. From mouth, esophagus curves forward, then upward and backward to more expanded midgut. May be highly elongated in certain predatory water fleas. [Stachowitsch, 1992]
Relatively short, narrow section of digestive tract between mouth and midgut. Directed dorsally, then posteriorly. [Stachowitsch, 1992]
Relatively short and narrow anterior section of digestive tract. From mouth, esophagus curves forward, then upward and backward to more expanded midgut. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Relatively short section of digestive tract between mouth and midgut. Directed dorsally, then posteriorly. [Stachowitsch, 1992]
Anterior section of digestive tract. [Stachowitsch, 1992]
Short, relatively narrow section of digestive tract between mouth and stomach.
(syn. oesophagus) [Stachowitsch, 1992]
Relatively short section of digestive tract between mouth and stomach. [Stachowitsch, 1992]
Relatively short, narrow, cuticle-lined section of digestive tract between mouth and cardiac stomach. [Stachowitsch, 1992]
Relatively short, cuticle-lined section of digestive tract between mouth and stomach. Esophagus and stomach together form foregut. [Stachowitsch, 1992]
Foregut. [Stachowitsch, 1992]
Relatively short section of digestive tract between mouth and stomach. May be lined internally with posteriorly directed spines. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Short, cuticle-lined section of digestive tract between mouth and stomach. Esophagus and stomach form foregut. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Section of digestive tract between mouth and midgut; partially contained within proboscis. (See also foregut). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Muscular, cuticle-lined, and relatively narrow section of digestive tract between mouth and midgut. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Narrow section fo digestive tract between mouth and stomach; cuticle-lined, muscular, and basically corresponding to foregut. [Stachowitsch, 1992]
Anterior section of foregut (stomodeum). From mouth, esophagus curves forward, then upward and backward. Surrounded laterally by posterior part of brain (tritocerebrum and esophageal connectives). May refer to entire foregut. [Stachowitsch, 1992]
Narrow, muscular section of digestive tract between mouth and midgut. Cuticle-lined and occasionally armed with ridges or modified into gastric mill. (See also foregut). [Stachowitsch, 1992]
In anaspidacean, relatively short, narrow section of digestive tract between mouth and stomach. [Stachowitsch, 1992]
Relatively short, slender section of digestive tract between mouth and stomach. [Stachowitsch, 1992]
Short section of digestive tract between mouth and stomach. [Stachowitsch, 1992]

Esthetasc

Aesthetasc. [Stachowitsch, 1992]
See aesthetasc. [McLaughlin, 1980]
Sensory seta covered by delicate cuticle projecting from most antennules and antennae.
(syn. olfactory hair, esthete) [Moore and McCormick, 1969]

Excavate

Hollowed out. [Kensley and Schotte, 1989]

Excretory duct

In antennal gland, short duct leading from bladder to excretory pore on basal segment (coxa) of antenna.
See: Excretory tubule [Stachowitsch, 1992]

Excretory organ

Antennal gland. [Stachowitsch, 1992]

Excretory pore

An opening, on the first penduncular segment of the antenna, of the excretory organ or green gland. [Ingle, 1983]
Opening of each antennal gland to exterior; located on basal segment (coxa) of antenna. May bear operculum.
(syn. nephropore) [Stachowitsch, 1992]

Excretory tubule

Narrow section of antennal gland occasionally joining second part of end sac (labyrinth) to bladder.
See: Excretory duct [Stachowitsch, 1992]

Exhalant passage

Anterior to gill chamber leading to large anterior opening, with scaphognathite for driving water outward. [McLaughlin, 1980]
Canal in front of gill chamber containing scaphognathite which functions for driving water outward, leads to large anterior opening. [Moore and McCormick, 1969]
On each side of cephalothorax, narrow chamber or canal leading from branchial chamber to exterior at anterior end. Water current driven by scaphognathite. [Stachowitsch, 1992]

Exite

Lateral outgrowth of the protopod. [Brusca and Brusca, 2002]
Laterally directed lobe arising from external margin of protopodal segment. [McLaughlin, 1980]
Laterally directed ramus of protopodal segment of limb (e.g., Notostraca). [Moore and McCormick, 1969]
Outwardly directed projection arising from the basal region of an appendage. [Holdich and Jones, 1983]
Outwardly (laterally) directed, lobe-like branch of protopod. [Stachowitsch, 1992]
Outwardly (laterally) directed lobe of basal part of maxilla. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Outwardly (laterally) directed branch of proximal part (protopod) of appendage, e.g., of maxillae. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A non-articulating, dorsal attenuation of a protopodal segment. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Any outer lobe on a protopodal segment of an appendage. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) Outwardly (laterally) directed lobe of proximal part (protopod) of maxillule. (See also endite). [Stachowitsch, 1992]
Term applied to small lobe of maxillule in anaspidacean. Also variously interpreted as representing an endopod or exopod. [Stachowitsch, 1992]
In maxillule, outwardly (laterally) directed, setose, lobe-like branch of base (protopod). (plate-like, rudimentary, absent).
See: Endite [Stachowitsch, 1992]

Exognath

Exopod (outer and secondary branch) of maxilliped. [Moore and McCormick, 1969]
Exopod of maxilliped. [McLaughlin, 1980]
Lateral or secondary branch of maxilliped. [Williams, 1984]
Outer branch (exopod) of maxilliped.
See: Endognath [Stachowitsch, 1992]

Exopod

See: Exopodite [Martin, 2005]
Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Lateral of two rami arising from the protopod and constituting the biramous limb. [Brusca and Brusca, 2002]
Lateral ramus of a biramus appendage, arising from the basis, or from the protopodite (Fig. 3C). [Perez Farfante and Kensley, 1997]
Lateral ramus of biramus appendage, originating on second segment (basis) from base (see Fig. 13). [Hobbs and Jass, 1988]
Outer branch of a biramous appendage. [Ingle, 1980]
Outer of two branches of biramous limb, comprising one or several short articles arising from basis; absent from many limbs.
(syn. exopodite) [Poore, 2004]
Outer ramus of limb arising from protopod basis; may contain variable number of segments or be much reduced or lacking. [Moore and McCormick, 1969]
The lateral branch of a bifurcate appendage arising from the basis or from the protopodite. [Chace and Hobbs, 1969]
The lateral or exterior ramus of a crustacean basis. In the Isopoda, applied to the outer ramus of a pleopod or uropod. [Wilson, 1989]
The lateral ramus of a biramous appendage, having its origin on the basis. [Hobbs, Hobbs, and Daniel 1977]
The outer of two branches of the primitive appendage (Fig. 2). [Warner, 1977]
(Taxon-specific: ) Lobe-like outer branch (ramus) of trunk appendage; lacks articulation with protopodal part of appendage. Reduced in certain predatory water fleas.
(syn. exopodite) [Stachowitsch, 1992]
Large, setose outer lobe of thoracic appendage (thoracopod) ot abdominal appendage. Extends dorsally and ventrally from narrow point of attachment; modified on last (11th) thoracopods in female to form ovisac.
(syn. exopodite, flabellum) [Stachowitsch, 1992]
Outer branch of trunk appendage; unsegmented, prolonged dorsally and ventrally, and bearing marginal setae. Dorsal extension occasionally interpreted as representing additional epipod or flabellum, ventral extension as exopod proper.
(syn. exopodite, flabellum) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Outer branch of thoracic appendage (thoracopod). Unsegmented, lobe-like, and bearing marginal setae; articulated with protopod. Serves in locomotion. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch of biramous appendage. Refers to annulate outer branch of antennae, six-segmented branch (in larvae only) of mandibles, one-segmented branch of maxillules, as well as two-segmented branches of maxillae and thoracopods. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. Represents small branch of pereopods; occasionally interpreted as representing flabellum of maxilla as well as siphonal lobe of of first maxillipeds.
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. May be present as small ramus on chelipeds and anterior pereopods. Scale-like projection (antennal scale) on antenna considered to represent exopod.
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage (endopod, exopod). Refers to antennal scale (scaphocerite) of antenna, scaphognathite of maxillula, flagelliform branch of maxillipeds, and variously developed outer branch of pereopods, pleo-pods, and uropods. (annulate, flagelliform, scale-like, spine-like).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage (e.g., pleopod, uropod).
(syn. exopodite) [Stachowitsch, 1992]
Outer (lateral) ramus of an appendage. [Wetzer et al. 1997]
Outer branch (ramus) of biramous appendage (e.g., pleopod).
(syn. exopodite) [Stachowitsch, 1992]
Outer ramus of a paired appendage. [Kensley and Schotte, 1989]
Outer branch (ramus) of biramous appendage. Represents scale-like structure (antennal scale) of antenna and flagellum-shaped branch of maxilipeds, thoracopods, and pleopods. (annulate, elongate, flattened; natatory; reduced).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. Refers to two-segmented branch of antennae, one-segmented, gill-bearing branch of pleopods, and two-segmented branch of uropods, while it is considered to represent inner branch of last three thoracopods. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Outer branch (ramus) of biramous appendage. (elongate and slender, flattened = lamellar = scale-like = plate-like).
(syn. exopodite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Setose outer branch (ramus) of thoracic appendage (thoracopod). Exopod of first two thoracopods may bear medially directed flabellum. (See also endopod). [Stachowitsch, 1992]
Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Outer branch (ramus) of thoracic appendage (thoracopod in ascothoracican, cirrus in other cirripeds). (one- to three-jointed, multiarticulate) (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A dorsal extension of the proximodistal axis of a limb originating on the basis of the protopod and usually segmented. Segments of the exopod bear a dorsal seta and often a ventral seta, but usually there is only one of each kind of seta on a segment. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Outer branch (ramus) of biramous appendage. Refers to outer branch of antenna (occasionally reduced), mandible, maxillule, and pereopod. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The outer ramus of a biramous appendage. [Boxshall and Halsey, 2004]
Out branch of biramous appendage. Refers to nine-segmented branch of antenna, seven-segmented branch of mandible, and one-segmented branch of maxilliped. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
In distally biramous crustacean limb, the lateral ramus.
(syn. exopodite) [Cohen, Peterson, and Maddocks, in press]
Outer branch (ramus) of biramous appendage. Often developed as a branchial plate. (See also endopod).
(syn. exopodite) [Stachowitsch, 1992]
Outer or more dorsal branch (ramus) of biramous appendage (antennule, antenna, trunk limb).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. In anaspidacean, representing scale-like branch (scaphocerite) of antenna (also occasionally in bathynellacean) and annulated ramus of thoracopods. (annulate, scale-shaped, spatulate, styliform).
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. Present as small lobe on maxillae, palp-like structure of maxilliped, smaller, one- to two-segmented ramus of thoracopods, and two-segmented remud of uropod.
(syn. exopodite) [Stachowitsch, 1992]
Outer branch (ramus) of biramous appendage. Represents scale (scaphocerite) of antenna, one-segmented lobe of maxilla in certain euphausiaceans, relatively small, two-segmented outer branch of thoracopods, and flattened outer branch of pleopods and uropods.
(syn. exopodite)
See: Endopod [Stachowitsch, 1992]

Exopodite

Lateral branch of the basis. [Holdich and Jones, 1983]
Lateral ramus of biramous appendage. [Williams, 1984]
Outer ramus of biramous appendage. [McLaughlin, 1980]
The outer branch of a biramous appendage. [Mauchline, 1984]
The outer of the two branches of the primitive appendage. [Warner, 1977]

Exorbital process

A process arising from the outer orbital margin. [Ingle, 1980]
On carapace of crab-like (brachyuran) decapod, tooth-like projection on margin of orbit.
(syn. external orbital tooth) [Stachowitsch, 1992]

Exoskeleton

Chitinous or calcified outer integument of crustaceans. [McLaughlin, 1980]
Chitinous or calcined outer integument of body (pleurites, sternites, tergites) and appendages.
See: Endoskeleton [Stachowitsch, 1992]
Entire horny (in part chitinous) more or less calcified outer covering of crustacean body and its appendages. [Moore and McCormick, 1969]
Outer covering of arthropods; "shell". [Hobbs and Jass, 1988]
The skeleton covering the outside of the body. [Ingle, 1983]

Explosive cells

Wandering blood cells that release a clotting agent at sites of injury or autotomy. [Brusca and Brusca, 2002]

Extended development

A long, regularly ocurring moulting sequence within a species producing morphologically discrete stages at each ecdysis, each showing some advancement over the previous stage. [Ingle, 1992]

Extensor margin

Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Outer or longer margin of a flexed appendage. [Butler, T. H.]
The outer or longer margin of a flexed appendage. [Chace and Hobbs, 1969]

Extensor muscle

The muscle which extends the leg at the MC joint (Fig. 19). [Warner, 1977]

Extensor surface

The unopposed surface of a flexed podomere of an appendage. [Hobbs, Hobbs, and Daniel 1977]
Unopposed surface (face) of flexible podomere of an appendage (in opposition to opposed, flexor surface). [Hobbs and Jass, 1988]

Externa

reproductive part of a rhizocephalan parasite positioned outside the host's body. [Brusca and Brusca, 2002]
(Taxon-specific: Order Rhabditida) Brood chamber.
(syn. reproductive sac) [Stachowitsch, 1992]

Eye

Photosensitive organ on dorsal surface of carapace; typically unpaired and positioned on ocular lobe (paired, unpaired). [Stachowitsch, 1992]
One of two photosensitive organs on carapace; positioned anterolaterally on short projections (ocular lobes). [Stachowitsch, 1992]
One of two organs of vision, each consisting of numerous ommatidia covered by cornea; typically positioned at tip of eyestalk. (sessile, stalked; club-shaped, reniform, spherical). [Stachowitsch, 1992]
One of two unstalked (sessile) organs of vision on each side of head. (contiguous, convex = globular, immense, oval, reniform; blind, oculate).
(syn. compound eye) [Stachowitsch, 1992]
Organ of vision on cephalon; when present, usually small and sessile, (sessile, stalked; pear-shaped, reniform, oval, contiguous).
(syn. compound eye) [Stachowitsch, 1992]
One of two organs of vision, each located distally on ocular peduncle. (divided, undivided, fused; plate-like, pyriform).
(syn. compound eye) [Stachowitsch, 1992]
Large, paired organ of vision on head (cephalon); each eye is positioned on eyestalk (ocular peduncle) originating on acron. (See also cornea, nauplius eye).
(syn. compound eye) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of two organs of vision located at tip of eyestalk (ocular peduncle).
(syn. compound eye) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Compund eye, nauplius eye. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Compound eye, nauplius eye. [Stachowitsch, 1992]
If present (anaspidacean), one of two organs of vision. (sessile, stalked; anteriorly/laterally directed). [Stachowitsch, 1992]
Compound eye, nauplius eye. [Stachowitsch, 1992]

Eye tubercle

Slight elevation of carapace covering compound eye. [Stachowitsch, 1992]
Protuberance on anterodorsal region of each valve; overlies ocular sinus and serves as lens for compound eye. (biconvex, concavo-convex, conical, hemispherical, tubular). [Stachowitsch, 1992]

Eyes

Compound structures borne on a small anteriorly directed lobes of the carapace. [Holdich and Jones, 1983]
Visual organ, in Crustacean either compound or naupliar (simple). [Moore and McCormick, 1969]
(Taxon-specific: ) Compound eye, nauplius eye. [Stachowitsch, 1992]
Compound eye, nauplius eye. [Stachowitsch, 1992]
Compound eye, nauplius eye. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Compound eye, nauplius eye. [Stachowitsch, 1992]
One of two sensory organs associated with anterior end of labrum on underside of head (cephalon). Located under surface of cuticle and connected to brain by optic nerve.
(syn. compound eye) [Stachowitsch, 1992]
Ocellus. [Stachowitsch, 1992]
Compound eye, nauplius eye. [Stachowitsch, 1992]

Eyespine

Anterior part of carapace, including ocular peduncles, based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]

Eyestalk

A pre-segmental appendage on either side of the median line of the carapace and bearing on its distal surface the cornea. [Ingle, 1983]
Articulating eye comprising peduncle and (usually) pigmented cornea. [Poore, 2004]
Peduncle movably articulated with head, carrying eye at its distal extremity, may be divided into 2 or 3 segments and may be retractable.
(syn. ocular peduncle) [Moore and McCormick, 1969]
Peduncle or unfaceted part of the eye supporting the cornea. [Perez Farfante and Kensley, 1997]
Peduncle or unfaceted protion of eye bearing cornea. [Butler, T. H.]
See ocular peduncle. [McLaughlin, 1980]
The peduncle or unfaceted portion of the eye supporting the cornea. [Chace and Hobbs, 1969]
Ocular peduncle. [Stachowitsch, 1992]
Ocular peduncle. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Ocular peduncle. [Stachowitsch, 1992]
In anaspidacean, one of two projections of head bearing eyes; may bear tubercle. [Stachowitsch, 1992]
Ocular peduncle. [Stachowitsch, 1992]

Falcate

Sickle-shaped or hooked. [McLaughlin, 1980]
Sickle shaped; curved and tapering to a point. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) Used for a curved or hooked element. [Boxshall and Halsey, 2004]

Family

A major subdivision of an order, suborder or infraorder in the classification of animals, usually consisting of several genera. [Bliss, 1982]

Fan seta

A specialized seta on the distal tip of the maxilliped's endite. It is made thin, hyaline cuticle (difficult to see) and is usually broad with many laterally pointed lobes. In the munnopsids, it appears at two distinct types: a medial, more heavily sclerotized seta with fewer lobes, generally found on the distomedial corner of the maxillipedal endite; and a thin lamellar form placed in a row just proximal to the distal edge of the endite. [Wilson, 1989]

Fastigial plate

Anteriormost of three plates (fastigial, ocular, postocular) composing acron at tip of head. [Stachowitsch, 1992]

Fecundity

Relative number of eggs, sperm, or young produced by a shrimp. [Butler, T. H.]

Fenestra

Type of valve sculpture: one in a series openings either in ridge (carina) or wall (murus) of reticulate pattern. [Stachowitsch, 1992]

Fertilization duct

(Taxon-specific: Family Cyatholaimidae) In female reproductive system, narrow duct connecting median seminal receptacle to end of each oviduct. [Stachowitsch, 1992]

Fifth limb

5th limb, labeled "maxilla" in many papers; controversially considered to be and labeled "1st trunk leg," "1st thoracic limb" or "maxilliped" by some podocopid specialists; use care in reading literature descriptions.
(syn. 2nd maxilla) [Cohen, Peterson, and Maddocks, in press]

Filament

Slender, basally forked projection on dorsal surface of telson. Relative position within series of spines on telson is of taxonomic importance.
(syn. forked filament) [Stachowitsch, 1992]

Filamentary appendage

Membranous process developed on body in many cirripeds (Ascothoracica, Lepadomorpha) commonly on bases of cirri; may contain branches of testes; presumed to be respiratory in function. [Moore and McCormick, 1969]
Membranous process developed on body in some cirripeds commonly at base of cirrus. [McLaughlin, 1980]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Filter chamber

Space beneath thorax (e.g., phyllocarids) enclosed by ventral body wall and rhythmically moved thoracopods which functions for food-gathering from currents sucked into it. [Moore and McCormick, 1969]
Space beneath thorax enclosed by ventral body wall and moving thoracopods used for food-gathering. [McLaughlin, 1980]

Filtering apparatus

Series of plates (median, upper lateral, lower lateral) separating larger anterior division of stomach (cardiac stomach) from smaller posterior division (pyloric stomach). Functions as sieve.
(syn. posterior cardiac plate) [Stachowitsch, 1992]

Finger

One of terminal elements of chela; movable finger is the dactylus; fixed finger is the terminal extension of propodus. [Butler, T. H.]
One of the rami of the chela; the movable finger consisting of the dactyl and the immovable finger of the opposable part of the propodus. [Hobbs, Hobbs, and Daniel 1977]
One of the terminal elements forming the pincers of a chela, the movable finger being the dactyl and the immovable finger the terminal extension of the propodus. [Chace and Hobbs, 1969]
One of two rami of chela; movable finger (dactyl) and immovabe finger of opposable part of propodus. [Hobbs and Jass, 1988]
Chela. [Stachowitsch, 1992]
One of two finger-like elements of chela. One may distinguish a movable finger (dactyl) bearing down on a fixed finger (thumb, pollex), which is an extension of expanded propodus (manus, palm). (straight, curved, agape, closely fitting; cutting edge: corneous, entire, pectinate, serrate, sharp, sinuous, tuberculate, toothed; tips: acute, bidentate, corneous, incurved, spoon-shaped, subacute). [Stachowitsch, 1992]
Dactyl. [Stachowitsch, 1992]

Fingers

Narrow scissor-like blades of pincer end of cheliped, movable finger being dactyl, and fixed finger the terminal part of propodus.
(syn. digits) [Williams, 1984]
Scissor-like blades of claw end of cheliped, one finger movable and other immovable (fixed); very exceptionally (Psalidopus) both fingers are movable. [Moore and McCormick, 1969]

Finishing arthrodial membrane

(Taxon-specific: Family Cyatholaimidae) An arthrodial membrane which completes a segment and whose formation defines the location of the segment along the proximodistal axis of a limb. The finishing arthrodial membrane usually is the distal arthrodial membrane of a segment that forms proximal to the source segment, and is the proximal arthrodial membrane of a segment that forms distal to the source segment. [Ferrari and Dahms, in press]

First antenna

See: Antennule [Martin, 2005]
See antennule. [McLaughlin, 1980]
Antennule. [Stachowitsch, 1992]
Antennule. [Stachowitsch, 1992]
Antennule. [Stachowitsch, 1992]
Antennule. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Antennule. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Antennule. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Antennule. [Stachowitsch, 1992]
1st (cephalic) pair of limbs.
(syn. antennula) [Cohen, Peterson, and Maddocks, in press]
Antennule. [Stachowitsch, 1992]
Antennule. [Stachowitsch, 1992]

First form male

Sexually functional male crayfish (Cambaridae)); at least one terminal element of first pleopod usually corneouss. [Hobbs and Jass, 1988]
The breeding form of male crayfishes in which one of the terminal projections of the first pleopod is corneous, as opposed to the second from male in which this projection is not corneous. [Chace and Hobbs, 1969]
The sexually functional male cambarid, most readily recognized by the possession of at least one corneous terminal element on the first pleopod. [Hobbs, Hobbs, and Daniel 1977]

First maxilla

See: Maxillule [Martin, 2005]
See maxillule. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Maxillule. [Stachowitsch, 1992]
Maxillule. [Stachowitsch, 1992]
Maxillule. [Stachowitsch, 1992]
Maxillule. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Maxillule. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The paired limb of the somite of the cephalon posterior to the mandible.
(syn. maxilla 1) [Ferrari and Dahms, in press]
Maxillule. [Stachowitsch, 1992]
Maxillule. [Stachowitsch, 1992]
Maxillule. [Stachowitsch, 1992]

First-stage lobster

The first of three free-swimming larval stages of a true lobster; corresponds to the mysis stage of a penaeid shrimp. [Bliss, 1982]

Fissure

Separation of shell by sulcus; occurs on carapace between antennal and postorbital spines of some crangonid shrimps. [Butler, T. H.]

Fixed finger

Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Immovable distal part of propodus of chela.
(syn. pollex, thumb) [Moore and McCormick, 1969]
Immovable distal part of propodus of chela.
(syn. pollex) [McLaughlin, 1980]
Prolongation of propodus of chelate limb.
(syn. pollex) [Poore, 2004]
see Finger. [Butler, T. H.]
Finger.
(syn. immovable finger, pollex, thumb) [Stachowitsch, 1992]

Flabellum

Thin distal exite of branchiopod gnathobase with setose margin. [Moore and McCormick, 1969]
Thin distal exite; or epipodite of thoracopod. [McLaughlin, 1980]
Exopod. [Stachowitsch, 1992]
Term applied to entire outer branch (exopod) of trunk appendage or to dorsally directed part of exopod only. Modified in 9th through 11th appendages into elongate, slender structures for attachment of eggs. [Stachowitsch, 1992]
Flattened lateral branch of maxilla. Considered to represent an exopod. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) On first two pairs of thoracic appendages (thoracopods), medially (backwardly) directed projection from base of outer branch (exopod).
(syn. epipod) [Stachowitsch, 1992]

Flagellar lobule

A slender process extending from the distomesial angle of that lateral major lobe of the first maxilliped. [Hobbs, Hobbs, and Daniel 1977]

Flagellomere

(Taxon-specific: Family Cyatholaimidae) A segment of a flagellum which is part of the ramus of antenna 1 or antenna 2 of many crustaceans. Flagellomeres are not moved by muscles and are formed distad to the first flagellomere, which is the source segment for the flagellomeres. Copepods do not have a flagellum on either antenna 1 or antenna 2. [Ferrari and Dahms, in press]

Flagellum

A long, multi-segmented sensory appendage found at the distal ends of the antennae. [Mauchline, 1984]
Antennal endopodite; thin, tapering, multiarticulate, elongate extension of antenna and antennule (distal to peduncle). [Hobbs and Jass, 1988]
Multiarticulate appendage of antennule (2 present) and antenna (1 only); also appendage of exopods of maxillipeds.
(pl. flagella) [Poore, 2004]
Multiarticulate distal portion of antennule, antenna, or exopod.
(pl. flagella) [McLaughlin, 1980]
Multiarticulate, usually whiplike terminal part of the antennule or antenna (Fig. 3B).
(pl. flagella) [Perez Farfante and Kensley, 1997]
Slender, multiarticulate distal part of antennule, antenna or exopod. [Moore and McCormick, 1969]
The distal, multiarticulate endite attached to the antennal and antennular peduncle and exopods of the maxillipeds. [Ingle, 1983]
The long, tapering distal part of either the antennula or antenna, generally made of many annuli. [Wilson, 1989]
The multiarticulate, typically filamentous part of an antennule or antenna. [Hobbs, Hobbs, and Daniel 1977]
The multiarticulate, usually whiplike terminal portion of an antennule or antenna.
(pl. flagella) [Chace and Hobbs, 1969]
The multiarticulate, usually whiplike terminal portion of antenule or antenna.
(pl. flagella) [Butler, T. H.]
The often long and multi-articled region distal to the peduncle of the antennule and antennae, and the basis of the uropod. [Holdich and Jones, 1983]
One of two multisegmented branches of antenna; each of the up to 25 segments (articles) bears a row of spine-like setae anteriorly and brush-like setae posteriorly. Number of segments is of taxonomic importance. [Stachowitsch, 1992]
Aesthetasc. [Stachowitsch, 1992]
Distal division of antennule of antenna (peduncle, flagellum). In antennule, one may distinguish a larger outer (main) and smaller inner (accessory) flagellum. Flagellum of antennule bears aesthetascs. (multiarticulate, uniarticulate). [Stachowitsch, 1992]
Distal division of antennule or antenna (peduncle, flagellum). Antennule may bear two flagella (with distal segments bearing aesthetascs). [Stachowitsch, 1992]
Distal of two divisions (peduncle, flagellum) of antennule or antenna; typically paired in the former, unpaired in the latter. Slender, consisting of numerous segments (articles). May also refer to branch of mouthpart. (straight, bent; filiform, fusiform, plate-like; cross section: circular, dorsoventrally flattened, U-shaped; hairy, smooth, spinose). [Stachowitsch, 1992]
Distal division of antennule or antenna (peduncle, flagellum). May bear sensory structures (aesthetascs on antennules, calceoli on antennules and antennae). If two flagella are present on antennule, one distinguishes a larger (primary) and smaller (accessory) flagellum. [Stachowitsch, 1992]
Distal division of antennule or antenna (peduncle, flagellum); composed of a varying number of articles. [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Distal part of antenna or antennule, usually multiarticulate, occasionally reduced to one or a few articles. [Kensley and Schotte, 1989]
Narrow distal part of antenna or antennule, usually multiarticulate, occasionally reduced to one or a few articles, without intrinsic musculature. [Wetzer et al. 1997]
In antennule, pair of elongate branches of peduncle. In antenna, elongate inner branch of peduncle consisting of three- to four-segmented basal section and multisegmented distal section. Also refers to annulate distal part of outer branch (exopod) or thoracopod. [Stachowitsch, 1992]
Distal section of antennule or antenna (peduncle, flagellum); slender, consisting of numerous segments (articles). Antennule bears three flagella (one dorsal and divided ventral flagella); antenna, one flagellum (on endopod). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Distal division (peduncle, flagellum) of antennule. Represents inner branch (endopod). May also refer to endopod of antennule. (long with many small articles, small with few large articles). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Palp. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Multiarticulate distal section of antennule. [Stachowitsch, 1992]
Distal section of antennule. One may distinguish a longer dorsal flagellum composed of 11 or 12 segments (articles) and a shorter ventral flagellum composed of 8 articles (in one case fused into a blade-like structure). Each article bears several setae. [Stachowitsch, 1992]
Distal division of antennule or antenna (peduncle, flagellum). (paired, unpaired) (See also scaphocerite). [Stachowitsch, 1992]
Distal division of antennule or antenna (peduncle, flagellum), paired in the former, unpaired in the latter. (See also aesthetasc). [Stachowitsch, 1992]
Elongate, multiarticulate distal end of antennule or antenna. Paired in the former, unpaired and representing inner branch (endopod) in the latter. [Stachowitsch, 1992]

Flange

In closing apparatus of valve, ridge-like inner margin formed by projecting outer lamella. Fits into flange groove of opposite valve. (See also list, selvage). [Stachowitsch, 1992]
Ridge along valve margin formed by projection of outer lamella as narrow brim. [McLaughlin, 1980]

Flange groove

Groove-like depression along inner margin of valve. Separates major ridge (selvage) from flange on thickened part (duplicature) of inner lamella. [Stachowitsch, 1992]

Flexor margin

Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Inner or shorter margin of flexed appendage. [Butler, T. H.]
The inner or shorter margin of a flexed appendage. [Chace and Hobbs, 1969]

Flexor muscle

A muscle which flexes the leg at the MC joint (Fig. 19). [Warner, 1977]

Flexor surface

Opposable surface (face) of flexible podomere of appendage (in opposition to non-opposed extensor surface). [Hobbs and Jass, 1988]
The opposable surface of a flexed podomere of an appendage. [Hobbs, Hobbs, and Daniel 1977]

Foliaceous

Leaf-like. [Wilson, 1989]

Food groove

(Taxon-specific: ) In filter-feeding water fleas, elongate median groove between bases of trunk appendages, passed anteriorly along food groove, and transferred to mouth. [Stachowitsch, 1992]
Elongate median groove between thoracopod bases on ventral side of thorax. Food is trapped by thoracopods, passed anteriorly along food groove, and transferred to mouth. [Stachowitsch, 1992]
Elongate median groove between bases of trunk appendages. Food is trapped by trunk appendages, passed along food groove, and transferred to mouth. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Elongate median groove between thoracopod bases on ventral side of thorax. Food is trapped by thoracopods, passed anteriorly along food groove, and transferred to mouth. [Stachowitsch, 1992]

Foregut

See: Stomodaeum [Martin, 2005]
Anterior cuticle-lined region of digestive tract comprising esophagus, cardiac stomach, and anterior half of pyloric stomach.
(syn. stomodeum, stomodaeum)
See: Hindgut, Midgut [Stachowitsch, 1992]
See stomodeum. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Esophagus. [Stachowitsch, 1992]
Anterior of three basic divisions (foregut, midgut, hind-gut) of digestive tract. Typically consists of esophagus and stomach. [Stachowitsch, 1992]
Anterior of two basic divisions (foregut, hindgut) of digestive tract. Characterized by various internal folds (lamellae), chambers, and ridges. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Anterior region of digestive tract (foregut, midgut, hindgut); consists of esophagus and stomach. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Anterior of three regions (foregut, midgut, hindgut) of digestive tract; corresponds to esophagus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Esophagus. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Anterior of three regions (foregut, midgut, hindgut) of digestive tract. Cuticle-lined, corresponding to esophagus (and occasionally including anterior part of stomach). [Stachowitsch, 1992]
Stomodeum. [Stachowitsch, 1992]
Anterior of three regions (foregut, midgut, hindgut). Of digestive tract. Cuticle-lined, corresponding to esophagus. [Stachowitsch, 1992]
Anteriormost of three divisions of digestive tract (foregut, midgut, hindgut; cuticle-lined, consists of muscular anterior portion and narrower tube-like posterior portion; extends from mouth to border of head (cephalon) and trunk. [Stachowitsch, 1992]

Forehead

Part of head anterior to mouth; bears antennules, antennae, and frontal organ. [Stachowitsch, 1992]

Forked process

Well-developed prolongation of basal part (protopod) of uropod. Flattened, extending between endopod and exopod. (with two terminal spines = bifurcate, with three terminal spines). [Stachowitsch, 1992]

Formation seta

(Taxon-specific: Family Cyatholaimidae) The first dorsal and/or first ventral seta that forms during development of a segment. The first dorsal seta of an exopodal segment often forms before the first ventral seta, and the first ventral seta of endopodal segment often forms before the first dorsal seta. [Ferrari and Dahms, in press]

Fornix

(Taxon-specific: ) Ridge in lateral part of cephalon above insertion of antennal muscles. [McLaughlin, 1980]
(Taxon-specific: ) Ridge-like extension of each side of head; may merge with rostrum to form ventrally directed, beak-like structure. (covering/not covering most of antennules; simple, forming spinous processes). [Stachowitsch, 1992]

Fossa

a ventral trough in the clypeus into which the mandible's condyle articulates. [Wilson, 1989]
Type of valve scultpture: single mesh in reticulate pattern (reticulum). Consists of central space (solum) and surrounding walls (muri). [Stachowitsch, 1992]

Four-celled sense organ

In anaspidacean, small pigmented area anterior to cervical groove on dorsal surface of head. [Stachowitsch, 1992]

Fourth limb

4th (cephalic) limb, labeled "maxilla" in many papers; use care in reading literature descriptions.
(syn. 1st maxilla, maxillula) [Cohen, Peterson, and Maddocks, in press]

Foveola

Type of valve sculpture: minute pit (one order of magnitude smaller than punctum). (elliptical, irregular, rounded, stellate). [Stachowitsch, 1992]

Free edge

Edge. [Stachowitsch, 1992]
Line of contact between closed valves except along hinge line marking distal limit of contact margin, sometimes inside free margin. [McLaughlin, 1980]

Free margin

All parts of margin except hingement. [McLaughlin, 1980]
Margin. [Stachowitsch, 1992]
The perimeter of the valves (exclusive of the hinge region) where valves are in contact. [Cohen, Peterson, and Maddocks, in press]

Frena

Tegumentary folds holding eggs (Cirripedia). [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Tegumentary folds holding eggs. [McLaughlin, 1980]

Frill

Type of valve sculpture: wide, wing-like structure. Typically double-walled and extending beyond free edge of valves. (denticulate, nodulous, reticulate, septate, spinose, striate, undulating). [Stachowitsch, 1992]

Frons

The anterior part of the cephalon bearing the clypeus. It is found between the antennule and antennae, and below the rostrum or vertex. [Wilson, 1989]

Front

Anterior median region of dorsal carapace between orbits and gastric region; or in crabs the margin between the orbits. [Poore, 2004]
Frontal portion of carapace; that portion of crab carapace lying between orbits. [Williams, 1984]
Part of crab carapace between orbits. [Moore and McCormick, 1969]
The anterior margin of the carapace between each first antero-lateral tooth. [Ingle, 1983]
The margin of that portion of the carapace of crabs lying between the orbits; often used interchangeably with frontal region. [Chace and Hobbs, 1969]
In crab-like (brachyuran) decapod, median anterior margin of carapace between orbits. (defected, deflexed, sinuous, triangular, tridentate, trilobate, truncate).
(syn. frontal margin) [Stachowitsch, 1992]

Frontal appendage

One pair of filaments arising in many Anostraca from bases of antennae but independent of them; may be ramified. [Moore and McCormick, 1969]
Frontal organ. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Paired filaments arising from bases of antennae but independent of them. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Unpaired median process projecting from head between antennae. (unbranched, branched; with two terminal branches, with three terminal branches; shorter/longer than antenna). [Stachowitsch, 1992]

Frontal arch

A thickening of the cephalic frons that provides a strengthened arch between the fossal regions of the clypeus on either side of the frons. Generally associated with enlarged and heavily sclerotized mandibles. [Wilson, 1989]

Frontal band

Glandular organ of adhesion in frontal region of various parasitic copepods serving for attachment to host fishes. [Moore and McCormick, 1969]
Glandular organ of adhesion in frontal region of various parasitic copepods used for attachment to host. [McLaughlin, 1980]

Frontal filament

(Taxon-specific: Family Cyatholaimidae) One of two slender projections extending from rostrum of free-living copepod. With sensory function. [Stachowitsch, 1992]
Frontal organ. [Stachowitsch, 1992]

Frontal heart

Cor frontale. [Stachowitsch, 1992]

Frontal lamina

Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
A sternal plate arising between the bases of the antennae and probably homologous to the epistome of their arthropods; in many isopods the frontal lamina may extend anteriorly to be visible in the dorsal aspect; in many Valvifera the upper and lower regions of this structure may be separately elevated and visible in the dorsal aspect as two distinct structure (frontal lamina 1 and frontal lamina 2). [Wetzer et al. 1997]
Plate-like structure anterior to mouth-parts, usually situated between antennae, (pentagonal, quadrate, spiniform, triangular). [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Platelike structure of the cephalon immediately anterior to, and sometimes fused with, clypeus. [Kensley and Schotte, 1989]

Frontal lobe

On dorsal surface of carapace, bell-shaped prominence marking anterior margin of head. Bears ocular lobes anteriorly and is adjoined laterally and anteriorly by pseudorostrum. [Stachowitsch, 1992]

Frontal margin

Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Separates the upper surface of the cephalon from the frontal lamina; anterior margin of cephalon. [Wetzer et al. 1997]

Frontal organs

Sensory cells on anterior surface of cephalon.
(syn. haft organ, frontal eye) [McLaughlin, 1980]
Sensory cells or setae on front surface of heads on some branchiopods, copepods, and decapods. [Moore and McCormick, 1969]
(Taxon-specific: ) General term for any of several similar sensory organs in head. The different positions of these frontal organs has led to an array of terms for the individual structures, including nuchal or neck organ and, in the older literature, dorsal and ventral frontal organs. All are innervated by brain and considered to represent reduced photosensitive organs. [Stachowitsch, 1992]
Sensory organs adjoining nauplius eye. [Stachowitsch, 1992]
In certain clam shrimp, unpaired, pyriform projection on middorsal surface of head.
(syn. frontal appendage) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) pair of sensory organs adjoining nauplius eye on anterior end of head; innervated by brain.
(syn. ventral frontal organ, paired ventral frontal organ) [Stachowitsch, 1992]
One pf several sensory structures represented by setae of anteromedian lobes (rostral plate) of cephalon. [Stachowitsch, 1992]
Unpaired sensory structure located near eye on head; innervated by supraesphageal ganglion and typically developed as tentacle- or filement-like projection. [Stachowitsch, 1992]

Frontal plate

Modified rostrum of brachyuran decapods which bears downward projection process between antennules that unites with epistome. [Moore and McCormick, 1969]
(Taxon-specific: Family Pycnogonidae) Clypeus. [Stachowitsch, 1992]
In carapace of crab-like (brachyuran) decapod, modified rostrum which bears downwardly directed process united with ventral epistome. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, plate-like structure at anterior end of head; formed by fusion of frontal margin with bases of antennules. Bears pair of suckers (lunules). [Stachowitsch, 1992]
Modified rostrum with downward projecting process united with epistome. [McLaughlin, 1980]
Somewhat extended anterior margin of carapace. (short and triangular, truncate). [Stachowitsch, 1992]

Frontal process

Pair of unique sensory structures of unknown function on the head of remipedes. [Brusca and Brusca, 2002]
The lower region of the epistomal plate or sclerite, in which some Valvifera projects outward to become visible in the dorsal aspect as a protuberance lying above the frontal lamina. [Wetzer et al. 1997]
One of two anteriorly projecting processes on underside of head (cephalon) near base of antennules; relatively small, each consisting of main shaft bearing stout spine. (club-like, "jointed," rod-like).
(syn. frontal filament, preantennular process) [Stachowitsch, 1992]

Frontal region

See: Carapace region e [Martin, 2005]
Anterior area of carapace lying between orbits and bounded posteriorly by gastric region. [Butler, T. H.]
Anterior area of the carapace lying between the orbits and bounded posteriorly by the gastric region. [Perez Farfante and Kensley, 1997]
The anterior area of the carapace lying between the orbits and bounded posteriorly by the gastric region. [Chace and Hobbs, 1969]
The region on the dorsal surface on the carapace bounded by the anterior margin of the carapace and parts of the margins of the orbital, protogastric and mesogastric regions. [Ingle, 1983]
See: Carapace regions e [McLaughlin, 1980]
Anteromedian region of carapace. May bear rostrum and is adjoined posteriorly by gastric region, laterally by orbital region. [Stachowitsch, 1992]

Frontal teeth

True frontal teeth; those teeth originating on front but exclusive of inner orbital teeth. [Williams, 1984]

Frontal tooth

Rostral tooth. [Stachowitsch, 1992]

Fronto-orbital distance

The interval between the outer orbital angles of crabs. [Chace and Hobbs, 1969]

Frontolateral horn

One of pair of tubular frontolateral extensions of cuticle of cirriped nauplii (except Ascothoracica), apparently perforate at tips and provided with mass of gland cells at base. [Moore and McCormick, 1969]
One pair of tubular frontolateral extensions of cuticle of cirriped nauplius (except Ascothoracica). [McLaughlin, 1980]

Furca

See: Caudal furca [Martin, 2005]
See caudal furca. [McLaughlin, 1980]
The prominent spine present at each posterio-external region of the telson. This term is reserved here for the brachyuran zoea since in the infra-orders a spine or seta is variably developed on this region of the telson. [Ingle, 1992]
(Taxon-specific: Order Rhabditida) Caudal furca. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Caudal ramus, sternal furca. [Stachowitsch, 1992]
Terminal (may be ventral in position) body extensions. [Cohen, Peterson, and Maddocks, in press]

Furcal claw

Caudal ramus. [Stachowitsch, 1992]
Caudal ramus. [Stachowitsch, 1992]

Furcal ramus

Branch of caudal furca. [Moore and McCormick, 1969]
See caudal ramus. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Caudal ramus. [Stachowitsch, 1992]

Furcate

Forked or branched. [Butler, T. H.]

Furcilia

Fourth larval stage in euphausiaceans, marked by movable compound eyes that project beyond edge of carapace. [Moore and McCormick, 1969]
Larval stage of euphausiids that has stalked eyes and resembles the adult in general body form. [Mauchline, 1984]
Second larval stage following the nauplius stage in euphausids, corresponding roughly to the zoea stage. [Brusca and Brusca, 2002]
Fourth of several larval stages (nauplius, metanauplius, calyptopis, furcilia). Characterized by emergence of movable eyes from under carapace and progressive development of thoracic and abdominal somites. Last substage, formerly termed cyrtopia, involves final differentiation of second antennae, mandibles (palps), first thoracopods, and telson and development of pleopods for swimming. [Stachowitsch, 1992]

Furrow

Toothed furrow. [Stachowitsch, 1992]
Type of valve sculpture: shallow groove. [Stachowitsch, 1992]

Fused zone

See zone of concrescence.
See: Zone of concrescence [Cohen, Peterson, and Maddocks, in press]

Galea

Outer distal hood-like lobe of 2nd segment of maxillule; adjacent to inner spiny lobe (lacina). [Moore and McCormick, 1969]
Outer distal hoodlike lobe of second segment of maxillule. [McLaughlin, 1980]

Gametogenesis

The production of reproductive cells. [Ingle, 1983]

Ganglion

Ventral nerve cord. [Stachowitsch, 1992]

Gastric caecae

Long coiled caecae arising from the gut wall whose function may be absorptive or osmoregulatory. [Ingle, 1983]

Gastric groove

See: Stomatopod integumental ornamentation [McLaughlin, 1980]
Longitudinal furrow on either side of median carina on stomatopod carapace. [Moore and McCormick, 1969]
Longitudinal groove in carapace, one on each side of median carina; extends from anterior end (rostrum) to posterior margin. (See also cervical groove). [Stachowitsch, 1992]

Gastric mill

A food grinding apparatus in the foregut of decapod crustaceans; in penaeid shrimps, consists of denticles (tooth-like processes) and lateral ridges in wall of anterior chamber; in crayfishes, lobsters, and crabs, consists of one dorsal and two lateral teeth at junction of anterior and posterior chambers. [Bliss, 1982]
Apparatus of varying complexity in stomodeum which serves to break up food; consists of framework of movably articulated ossicles developed as thickened and calcified part of stomodeal lining, most highly specialized in decapods. [Moore and McCormick, 1969]
Heavily sclerotized teeth of the cardiac stomach of most decapods. [Brusca and Brusca, 2002]
The structures responsible for grinding food within the stomach (Fig. 10). [Warner, 1977]
Grinding apparatus in posterior region of cardiac stomach. If fully developed, consists of muscular stomach walls bearing plates (ossicles), projecting teeth, and various pads and folds. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Apparatus in cardiac stomach (stomodeum) with framework of movably articulated ossicles developed as thickened and calcified parts of stomodeal lining used to break up food, most highly specialized in decapods; also chitinous triturating apparatus in foregut of some acrothoracicans. [McLaughlin, 1980]
In certain ostracods, term occasionally applied to lamellar respiratory process located dorsally on trunk. [Stachowitsch, 1992]

Gastric region

See: Carapace region f [Martin, 2005]
Large median area, in crab carapace, bounded behind by cervical suture, laterally by hepatic regions, and anteriorly by frontoorbital regions. Divisible into following subregions or lobes: epigastric, protogastric, mesogastric, metagastric, and urogastric. [Williams, 1984]
Median region of dorsal carapace between frontal region and cardiac region; divided from anterior in midline into mesogastric, metagastric and urogastric regions, and with protogastric and epigastric regions laterally. [Poore, 2004]
Principal dorsolateral or mesial area on carapace lying anterior to cervical groove, bounded posteriorly by cardiac region, laterally by branchial and hepatic regions, and anteriorly by frontal and orbital regions. [Butler, T. H.]
Principal median area of the carapace bounded anteriorly by the frontal and orbital regions, and posteriorly by the cardiac region, and laterally by the branchial and hepatic regions. [Perez Farfante and Kensley, 1997]
The principalmesial area on the carapace lying anterior to the cervical groove and bounded posteriorly by the cardiac region, laterally by the branchial and hepatic regions, and anteriorly by the frontal and orbital regions; in the true crabs, it comprises the unpaired mesogastric and metagastric regions, the urogastric lobe, the paired protogastric regions, and the epigastric lobes. [Chace and Hobbs, 1969]
See: Carapace regions f [McLaughlin, 1980]
Relatively large, unpaired region of carapace overlying stomach. May be variously subdivided (from anterior to posterior) into paired epigastric and protogastric as well as unpaired mesogastric, metagastric, and urogastric regions or areas. Adjoined anteriorly by frontal region, posteriorly by cardiac region. [Stachowitsch, 1992]

Gastric tooth

See: Carapace tooth b [Martin, 2005]
See: Carapace teeth b [McLaughlin, 1980]
On midline of carapace, tooth-like projection on gastric region just anterior to cervical groove. [Stachowitsch, 1992]

Gastro-orbital carina

Main lateral carina on shrimps of genus Notostomus. [Butler, T. H.]
See: Carapace carinae d [McLaughlin, 1980]

Gastrofrontal carina

Short longitudinal ridge extending posteriorly from the ventral extremity of the orbital region (Fig. 2B). [Perez Farfante and Kensley, 1997]

Gastrofrontal sulcus

Short longitudinal depression accompanying the gastrofrontal carina dorsally (Fig. 2B). [Perez Farfante and Kensley, 1997]

Gastrohepatic gland

Digestive and storage gland in shrimps; also termed heptopancreas. [Butler, T. H.]
Digestive gland associated with the midgut, within the cephalothorax. [Perez Farfante and Kensley, 1997]

Gastrolith

Discoid calcareous nodule common in stomodeum of some decapods. [Moore and McCormick, 1969]
Disc-shaped, calcareous nodule in anterior region of cardiac stomach. [Stachowitsch, 1992]
Discoid calcareous nodule, common in stomodeum. [McLaughlin, 1980]

Gastroorbital carina

See: Carapace carina d [Martin, 2005]
Short longitudinal ridge extending (often curving) anterodorsally from the cervical sulcus towards the orbital region (Fig. 2B). [Perez Farfante and Kensley, 1997]
On each side of carapace, narrow, longitudinal ridge extending posteriorly from supraorbital spine.
(syn. supraorbital Carina) [Stachowitsch, 1992]

Gastroorbital groove

See: Carapace groove d [Martin, 2005]
See: Carapace grooves f [McLaughlin, 1980]
On each side of carapace, short, longitudinal groove extending from cervical groove toward orbit. [Stachowitsch, 1992]

Geniculate

Bent; having upper part of filament forming more or less obtuse angle with lower, e.g., antennule. [McLaughlin, 1980]
Knee-like, or displaying an acute angle between two segments. As in geniculate segments 2 and 3 of the antennula. [Wilson, 1989]
Bent at an abrupt angle, as in the body of many arcturid isopods. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) Used of male antennules with a specialised articulation with restricted adduction/abduction movement, dividing the limb into proximal and distal regions; also used of armature elements with a well-defined articulating zone. [Boxshall and Halsey, 2004]

Genital appendage

One of two reduced appendages on first abdominal somite (= ninth postcephalic segment). Ovisac of female is attached to genital appendage. [Stachowitsch, 1992]

Genital atrium

(Taxon-specific: Order Monhysterida) Vagina. [Stachowitsch, 1992]

Genital complex

(Taxon-specific: Family Cyatholaimidae) Part of body formed from the fifth pedigerous and genital double-somites. [Boxshall and Halsey, 2004]

Genital cone

Conical structure situated on the ventral surface of pereonite 6 on to which the male gonopore opens. [Holdich and Jones, 1983]
In male repoductive system, cone-shaped process on ventral surface (sternite) of last thoracic segment (= last or seventh pereonite). Bears male gonopore(s). (paired, unpaired). [Stachowitsch, 1992]

Genital double-somite

(Taxon-specific: Family Cyatholaimidae) A division of the urosome formed from the genital and first abdominal somites. [Boxshall and Halsey, 2004]

Genital flap

Small cuticular flap on base (protopod) of each limb of 14th trunk segment or at each end of sternal bar of 14th trunk segment; serves to cover male gonopore or facilitate copulation. [Stachowitsch, 1992]

Genital lobe

Lobe-like protuberance on posterior end of trunk in front of caudal rami. Bears gonopores. [Stachowitsch, 1992]

Genital operculum

(Taxon-specific: Family Cyatholaimidae) The plate derived from the sixth legs that close off the genital aperture(s) or gonopore(s). [Boxshall and Halsey, 2004]

Genital papilla

Penis. [Stachowitsch, 1992]
Penis. [Stachowitsch, 1992]

Genital region

See: Urogastric lobe [Williams, 1984]
See: Carapace regions f [McLaughlin, 1980]
Urogastric region. [Stachowitsch, 1992]

Genital segment

(Taxon-specific: Family Pycnogonidae) Collective term for first and second abdominal somites. More or less fused and bearing penes in male and ovisac in female.
(syn. genital somite) [Stachowitsch, 1992]

Genital somite

(Taxon-specific: Family Cyatholaimidae) Segment of body bearing gonopores. Typically corresponds to first abdominal segment, yet also to fused last thoracic and first abdominal somites. May be enlarged in parasitic female.
(syn. genital complex) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The somite bearing the genital apertures, corresponding the seventh thoracic somite. [Boxshall and Halsey, 2004]

Genitalia

The external reproductive structures. [Perez Farfante and Kensley, 1997]

Genitoabdomen

(Taxon-specific: Family Cyatholaimidae) A posterior body region formed by fusion, or failure to separate, of the genital and abdominal somites. [Boxshall and Halsey, 2004]

Genus

A main subdivision of a family or subfamily in the classification of animals, usually consisting of more than one species.
(pl. genera) [Bliss, 1982]

Genus inquirendum

(Taxon-specific: Family Cyatholaimidae) An inadequately characterised genus. [Boxshall and Halsey, 2004]

Gill

See: Branchia [Martin, 2005]
See branchia. [McLaughlin, 1980]
Branchial lobule. [Stachowitsch, 1992]
One of several respiratory projections that may be associated with each thoracic appendage (thoracopod). According to position one may distinguish arthrobranchs, pleurobranchs, or podobranchs; according to structure, dendrobranchs, phyllobranchs, or trichobranchs. Typically contained in branchial chamber on each side of cephalothorax.
(syn. branchia)
See: Gill formula [Stachowitsch, 1992]
Accessory gill, coxal gill, sternal gill. [Stachowitsch, 1992]
Branchia. [Stachowitsch, 1992]
In certain mysidaceans, one in a series of branched respiratory structures arising dorsally from base of thoracopod. (See also epipod). [Stachowitsch, 1992]
Respiratory projections on appendages (pleopods) of first five abdominal appendages (pleomeres); located on exopod. Epipods of third through fifth thoracopods also with respiratoty function.
(syn. branchia) [Stachowitsch, 1992]
In certain ostracods, term occasionally applied to lamellar respiratory process located dorsally on trunk.
(syn. branchia) [Stachowitsch, 1992]
Respiratory structure associated with second through eighth thoracopods. Projects from basal segment (coxa) of appendages, thus representing an epipod and often being termed podobranch. Not covered by carapace. Gill forms greater part of reduced eighth (and occasionally seventh) thoracopods.
(syn. podobranch, podobranchial gill, epipod) [Stachowitsch, 1992]

Gill bailer

Leaf-like flap in a channel at the anterior opening of each branchial chamber in decapod crustaceans; by its beating, drives water forward in and out of the branchial chamber.
(syn. scaphognathite) [Bliss, 1982]
See scaphognathite. [Brusca and Brusca, 2002]
Scaphognathite. [Stachowitsch, 1992]

Gill cavity

Space on either side of cephalothorax containing gills. [Butler, T. H.]

Gill chamber

See: Branchial chamber [Martin, 2005]
See branchial chamber. [McLaughlin, 1980]
Branchial chamber. [Stachowitsch, 1992]

Gill formula

Notation indicating type and number of gills associated with each thoracopod. Full complement would include one podobranch, two arthrobranchs, and one pleurobranch per thoracopod.
(syn. branchial formula) [Stachowitsch, 1992]

Gill plate

In first pair of maxillipeds, plate-like structure on posteriorly directed part of epipod. Located in branchial chamber; bears series of branchial lobules. [Stachowitsch, 1992]

Gills

Respiratory organs composed of a series of plates (lamellae) arranged on both sides of a flattened central axis. [Ingle, 1983]

Gland cone

In each antenna, conical projection on second segment of base (peduncle). Bears opening of antennal gland apically. [Stachowitsch, 1992]

Glaucothoe

Ontogenetic stage in larval development of pagurid decapods. [Moore and McCormick, 1969]
Stage in larval development of hermit crabs, equivalent to megalopa. [McLaughlin, 1980]
Term often used to refer to the first postlarval stage in the Anomura. [Brusca and Brusca, 2002]
The postlarval stage of an anomuran crab. [Bliss, 1982]
Postlarva. [Stachowitsch, 1992]

Gnathal

Of the biting or grinding surface of the mandible. [Wilson, 1989]

Gnathal lobe

Masticator endite of mandible.
(syn. masticator process) [Moore and McCormick, 1969]
Masticatory endite of mandible.
(syn. masticatory process) [McLaughlin, 1980]

Gnathobase

Endite which through medial contact with opposite member of its pair serves for comminution of food; may also serve in food transport. [Moore and McCormick, 1969]
Paired endites used to manipulate or move food. [McLaughlin, 1980]
One of several setose projections of base (protopod) of maxillule. Extends under labrum and serves in manipulating food. Endites of maxillae and thoracopods also occasionally termed gnathobases. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Inwardly (medially) directed lobe of proximal part (protopod) of mouthpart. Represents greater part of each mandible, maxillule, and maxilla. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Basal part of mandible. Basically consists of elongated projection whose toothed tip extends over mouth. Bears palp (with endopod and exopod).
(syn. blade) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The projecting medial surface of the coxal segment of an appendage. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) The ventral extension of the mandibular coxa, including its setose endite. [Ferrari and Dahms, in press]
Projection of base (protopod) of each mandible. Extends under labrum and serves in macerating food. [Stachowitsch, 1992]
Basal part of mandible. Corresponds to coxa and consists of elongated projection who toothed tip extends over mouth. [Stachowitsch, 1992]
In anaspidacean, one of two spinose lobes (endites) of first segment (coxa) of maxilliped. [Stachowitsch, 1992]

Gnathopods

Chelate or subtotal, prehensile maxilliped (e.g., Amphipoda); also used for first two prehensile pereiopods of amphipods whether chelate or subchelate. [Moore and McCormick, 1969]
Prehensile maxilliped; also 1st 2 prehensile pereopods of amphipods, either chelate or subchelate. [McLaughlin, 1980]
Modified second and third thoracopod pairs (= first and second pereopods). Uniramous, consisting of modified, immovable coxa (coxal plate) and six free segments (basis, ischium, merus, carpus, propodus, dactylus). Last segments typically form subchela. (sexually/not sexually dimorphic, polymorphic: carpo-subchelate, chelate, subchelate). [Stachowitsch, 1992]
A loosely used term usually referring to chelate or subchelate pereopods associated with the head region and used for food handling. This term is rarely used for isopods. [Wetzer et al. 1997]
Term applied to more anterior pereopod(s) if modified as prehensile (grasping) organ. Last segments typically form subchela. [Stachowitsch, 1992]
Term applied to thoracic endopods when these are modified as mouthparts. [Stachowitsch, 1992]

Gnathothorax

Cephalothorax with all appendages of fused thoracic somites modified as maxillipeds. [McLaughlin, 1980]
Tagma resulting from fusion of gnathal somites (mandibular, two maxillary) with one or more thoracic somites, limbs of which are modified to act as mouth parts.
See: Cephalothorax [Moore and McCormick, 1969]

Gonads

Hollow reproductive organ in either sex, cavity communicating with pair of efferent ducts (pair in some parasitic isopods). [Moore and McCormick, 1969]
Organs producing gametes (ovaries in female; testes in male). [Ingle, 1983]
Reproductive organ of either sex, communicating with pair of efferent ducts. [McLaughlin, 1980]
Paired male (testes) and/or female (ovaries) reproductive system. Extends through thorax and part of abdomen and opens onto last (11th) thoracopods. In hermaphroditic tadpole shrimp, gonads consist of both ovarian and testicular tissue (ovotestis). [Stachowitsch, 1992]
Paired male (testes) or female (ovaries) reproductive system. Extends throughout trunk and opens onto 11th trunk somite via vasa deferentia (male) or oviducts (female). [Stachowitsch, 1992]
Ovary, testis. [Stachowitsch, 1992]
Ovary, testis. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Ovary, testis. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Ovary, testis. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Ovary, testis. [Stachowitsch, 1992]
Ovary, testis. [Stachowitsch, 1992]

Gonapophysis

Median process arising from base of first or second pleopods of male syncarids. [Moore and McCormick, 1969]
Median process from base of 1st or 2nd pleopods of male. [McLaughlin, 1980]

Gongylodont hinge

A crenulate hinge with a systematic increase in size of teeth and decrease in size of sockets from anterior to posterior in the right valve, left valve complementary (Family Loxoconchidae only). [Cohen, Peterson, and Maddocks, in press]

Gonochoristic

Pertaining to a unisexual individual; remaining as the same sex throughout the life cycle. [Holdich and Jones, 1983]
Sexes separate; producing distinct males and females. [McLaughlin, 1980]

Gonocoel

(Taxon-specific: Order Monhysterida) Cavity, separate from main body cavity (hemocoel), containing ovary.
(syn. circumgenital body cavity) [Stachowitsch, 1992]

Gonoduct

Common duct formed by merger of vas deferens and oviduct on each side of sixth thoracic segment (thoracomere). Opens through gonopore. [Stachowitsch, 1992]

Gonophysis

In male, median process from base of first or second pleopods. Represents modified endopods and serves in copulation. [Stachowitsch, 1992]

Gonopod

First abdominal appendage (pleopod) modified for sperm transfer in malacosatracans. [Brusca and Brusca, 2002]
Modified male pleopod serving for transmittal of spermatophores to female. [Moore and McCormick, 1969]
Pleopod in male modified for reproductive purposes. [Hobbs and Jass, 1988]
Pleopod modified for reproductive purposes. [McLaughlin, 1980]
Modified pleopod serving in reproduction. Typically refers to first or second pleopod of male.
See: Appendix masculina, Petasma [Stachowitsch, 1992]
Second pleopod of male; inner branch (endopod) may be modified into a rod-shaped structure (appendix masculina) for reproductive purposes. [Stachowitsch, 1992]
In male, term applied to pleopod (usually third or fourth) modified for copulatory purposes. [Stachowitsch, 1992]

Gonopore

External opening of the oviduct or vas deferens. [Holdich and Jones, 1983]
Outlet for genital products, generally placed constantly in different crustaceans.
(syn. sexual pore) [Moore and McCormick, 1969]
Outlet for genital products.
(syn. sexual pore) [McLaughlin, 1980]
(Taxon-specific: ) Opening of male or female reproductive system to exterior. In male, located either behind last pair of trunk appendages, on postabdomen, or terminally near caudal furca. In female, see vulva. (single, paired) (See also penis). [Stachowitsch, 1992]
Opening of male or female reproductive system to exterior on last (11th) thoracic segment. In male, gonopores open on thoracopods; in female, oviducts open into ovisacs.
(syn. genital pore) [Stachowitsch, 1992]
One of two openings of male or female reproductive system to exterior on 11th trunk somite.
(syn. genital pore) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Oviduct, penis. [Stachowitsch, 1992]
Pair of common openings of male and female reproductive systems, one located on posterior face of protopod of each appendage (thoracopod) of sixth thoracomere.
(syn. genital opening) [Stachowitsch, 1992]
Opening of reproductive system to exterior. In female, pair of pores on first segments (coxae) of third pereopods; in male, pair of pores on ventral surface (sternite) of last (fifth) pereon segment. [Stachowitsch, 1992]
Opening of male or female reproductive system to exterior. In male, pair of pores on genital cone(s) on last (seventh) pereonite; in female, pair of pores ventrally on fifth pereonite. [Stachowitsch, 1992]
One of two openings of reproductive system to exterior. In male, pore on
basal segment (coxa) of last (eighth) thoracopods; in female, pore on coxa of sixth thoracopods (third pereopods). [Stachowitsch, 1992]
In female reproductive system, opening of each oviduct to exterior. Located on ventral surface (sternite) of fifth pereon segment (pereonite).
(syn. genital pore)
See: Penis [Stachowitsch, 1992]
In female reproductive system, opening of each oviduct to exterior; located on ventral surface (sternite) of fifth pereon segment (pereonite).
See: Penis [Stachowitsch, 1992]
Opening of reproductive system to exterior. In female, pair of pores, one located at base of each thoracopod of sixth thoracic somite. For male, see penis. [Stachowitsch, 1992]
Opening of male or female reproductive system to exterior. In female, single opening on underside of sixth thoracic segment (thoracomere); in female, pore at tip of penis on each appendage (thoracopod) of eight thoracomere. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Opening of reproductive system to exterior. In male, opening at tip of papilla (genital papilla) on coxa of each eighth thoracopod; in female, opening on coxa of each sixth thoracopod. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In male reproductive system, unpaired opening on ventral surface of last thoracic somite (fourth thoracomere). In female, see vagina.
(syn. genital aperture) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In female reproductive system, opening of each oviduct to exterior; located on first thoracic somite at or near bases of first cirri. For male see penis. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Opening to reproductive system to exterior on ventral surface (sternite) of first abdominal segment (genital somite). In male, one or two openings, in female, either paired or in the form of a common atrium.
(syn. genital pore) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The external opening of the oviduct in the female and of the vas deferens in the male. [Boxshall and Halsey, 2004]
Single opening of male or female reproductive system; located on right side of ventral surface (sternite) of third thoracoabdominal somite. [Stachowitsch, 1992]
Opening of male or female reproductive system to exterior. In female, pore or larger opening (also termed uterine opening) of each oviduct on genital lobe. In male, paired or unpaired opening of vasa deferentia in front of caudal rami between or on penes. (See also vagina). [Stachowitsch, 1992]
Opening of male or female reproductive system to exterior. Two gonopores are present, one on 7th trunk segment (female), one on 14th trunk segment (male), latter borne on a genital papilla.
(syn. genital pore) [Stachowitsch, 1992]
Opening of reproductive system of exterior. In male, single or paired opening on ventral surface (sternite) of last (eighth) thoracic somite. In female, pair of pores on firs segments (coxae) of sixth thoracopods. [Stachowitsch, 1992]
Openings of reproductive system to exterior. In female, pair of pores on ventral surface (sternite) of sixth thoracic segment; in male, pair of pores on penes on last (eighth) thoracic segment. [Stachowitsch, 1992]
Opening of reproductive system to exterior. In female, opening of oviduct on coxae of sixth thoracopods; in d, openings of both vasa deferentia on last (eighth) thoracomere. [Stachowitsch, 1992]

Granulate

Having the appearance of bearing beadlike or grainlike protuberances; usually applied to the description of a surface. [Kensley and Schotte, 1989]

Granule

Type of valve sculpture: minute protuberance. Often closely spaced. [Stachowitsch, 1992]

Green glands

Excretory organs situated just behind the eyes and opening on the first peduncular segment of the antennae. [Ingle, 1983]
One of pair of complex excretory glands located on antenna in front of head of decapod (e.g., crayfish).
(syn. antennal gland) [Moore and McCormick, 1969]
See antennal glands. [McLaughlin, 1980]
Antennal gland. [Stachowitsch, 1992]

Grimothea

Postlarva. [Stachowitsch, 1992]

Groove

See: Carapace groove [Martin, 2005]
One of numerous furrows extending along carapace. According to position and according to group, one may distinguish antennal, branchiocardiac, buccal, cervical, dorsomedian. gastroorbital, hepatic, inferior, intercervical, intestinal, marginal, parabranchial, postcer-vical, seller, submedian, and urogastric grooves. [Stachowitsch, 1992]
Cervical groove, gastric groove. [Stachowitsch, 1992]

Growth line

One in a series of concentric lines on outer surface of each side (valve) of carapace; each growth line marks a successive molt. Number of lines is of taxonomic importance. (distinct, indistinct; widely spaced, crowded). [Stachowitsch, 1992]

Guide setule

One in a series of fine setules on molar process of each mandible. [Stachowitsch, 1992]

Gymnoplean

(Taxon-specific: Family Cyatholaimidae) Used ot the body plan in which the prosome-urosome boundary lies posterior to the fifth pedigerous somite. [Boxshall and Halsey, 2004]

Gymnopleans

(Taxon-specific: Family Cyatholaimidae) Copepods on which the major body articulation of the adult, is between the sixth and the seventh thoracic somites; there is also a significant difference in size between these two somites (see also podoplean and thaumatopsylloid). [Ferrari and Dahms, in press]

Gynandromorph

Abnormal individual exhibiting secondary characters of both sexes; particularly well known in insects; occurs also in Crustacea, birds, mammals. [Hobbs and Jass, 1988]

Habitus

Appearance of the whole animal. [Wilson, 1989]

Haemocoel

Body cavity; an expanded part of the blood system. [Ingle, 1983]
circulatory system which fill all gaps between tissues and organs. [Warner, 1977]
Composed of the blood-filled spaces mainly on the venous side of the. [Martin, 2005]

Haft organ

Pear- to wedge-shaped appendage of some branchiopods (e.g., Limnadopsis) attached to mid-dorsal surface of head at narrower end.
(syn. frontal organ, affixing organ) [Moore and McCormick, 1969]
See frontal organ. [McLaughlin, 1980]

Hair

Seta. [Stachowitsch, 1992]

Hand

Propodus and dactyl of cheliped.
(syn. chela) [Williams, 1984]
Sometimes used as name for chela. [Butler, T. H.]
(Taxon-specific: Family Pycnogonidae) Long, forked terminal outgrowth of basal segment of antenna in males of certain anostracans. [Stachowitsch, 1992]
Manus. [Stachowitsch, 1992]

Haplocerate

(Taxon-specific: Family Cyatholaimidae) Used of weakly modified male antennules, with only slightly swollen middle segments and with a variable number of segments distal to the geniculation. [Boxshall and Halsey, 2004]

Hard crab

Any crab that has not recently molted and is very hard, due to compounds of calcium and other minerals in the shell.
(syn. hard-shelled crab) [Bliss, 1982]

Head

See: Cephalon [Martin, 2005]
(Taxon-specific: ) Anterior of two divisions (tagmata) of body (head, trunk); Consists of five somites bearing antennules, antennae, mandibles, maxillules, and (reduced) maxillae. Bears compound and naupliar eyes and may be covered by a head shield. Not enclosed by carapace. (Clearly delimited/not clearly delimited; helmeted, rounded, with/without rostrum).
(syn. cephalon) [Stachowitsch, 1992]
Anterior of three divisions (tagmata) of body (head, thorax, abdomen). Consists of five somites bearing in part poorly developed antennules, antennae, mandibles, maxillules, and maxillae. Covered, along with thorax, by carapace; border between head and thorax indicated by cervical groove. [Stachowitsch, 1992]
Anterior of two divisions (tagmata) of body (head, trunk). Consists of five somites bearing antennules, antennae, mandibles, maxillules, and maxillae. Bears ventral rostrum, compound and nauplius eyes, and is typically entirely enclosed by carapace. (entirely/not entirely enclosed by carapace; with/without frontal appendage).
(syn. cephalon) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Anterior of three divisions (tagmata) of bosy (head, thorax, abdomen). Consists of five somites bearing antennules, antennae, mandibles, maxillules, and maxillae. Also bears pair of compound eyes laterally and nauplius eye middorsally; superfically subdivided dorsally by transverse mandibular groove.
(syn. cephalon) [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Anterior of three basic divisions (tagmata) of body (head, thorax, abdomen). Consists of five somites with five pairs of appendages (antennules, antennae, mandibles, maxillules, maxillae); fused with first thoracic somite (bearing maxillipeds), this entire complex also being termed head. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Anterior of three basic divisions (tagmata) of body (head, thorax, abdomen). Fused with anterior thoracic segments (thoracomeres) to form cephalothorax; covered by carapace. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Cephalon. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Cephalon. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Anterior of typically two basic divisions (tagmata) of body (head, thorax; in ascothoracican: head, thorax, abdomen). If fully consists of five fused segments (somites) bearing antennules, antennae, mandibles, maxillules, and maxillae. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Anterior of two major regions (head, thorax) of body; unsegmented and not clearly delimited from thorax. Bears five pairs of appendages (cephalic appendages), including antennules, antennae, mandibles, maxillules, and maxillae as well as eye. Entirely enclosed in carapace.
(syn. cephalon) [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Anterior of three major divisions (tagmata) of body (head, thorax, abdomen). Consists of basically five somites (bearing antennules, antennae, mandibles, maxillules, and maxillae), although in anaspidacean and stygocaridacean first thoracic somite (bearing maxillipeds) is fused to head. (See also cervical groove, rostrum).
(syn. cephalon) [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]
Cephalon. [Stachowitsch, 1992]

Head apodeme

Fused endopleurite and endosternite forming place for muscle attachment at anterior end of skeleton in Astacidea. [Moore and McCormick, 1969]
Fused endopleurite and endosternite forming place for muscle attachment at anterior end of skeleton. [McLaughlin, 1980]
Apodeme. [Stachowitsch, 1992]

Head pore

(Taxon-specific: ) One of several minute pores in middorsal line of head shield. [Stachowitsch, 1992]

Head shield

See cephalic shield. [Brusca and Brusca, 2002]
(Taxon-specific: ) Variously developed, unpaired, shield-like structure covering head. [Stachowitsch, 1992]
Cephalic shield. [Stachowitsch, 1992]
Cephalic shield. [Stachowitsch, 1992]

Heart

(Taxon-specific: ) In circulatory system, typically short, muscular pumping organ located anterior to brood chamber in trunk. Blood enters heart through single pair of ostia and is pumped anteriorly into a sinus, although certain predatory water fleas have been described as bearing anterior bulbous arterious and short anterior aorta. (elongate, oval, subovate). [Stachowitsch, 1992]
In circulatory system, elongate, muscular pumping organ extending through 11 thoracic segments above digestive tract. Blood enters heart through 11 pair of ostia and is pumped anteriorly. [Stachowitsch, 1992]
In circulatory system, muscular pumping organ extending from head (from maxillule-bearing somite) into third trunk somite. Blood enters heart posteriorly and through typically four pairs of ostia. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) In circulatory system, elongate, muscular pumping organ extending through entire body above digestive tract. Blood from pericardial sinus enters heart through ostia and is pumped anteriorly. [Stachowitsch, 1992]
In circulatory system, muscular pumping organ extending through thorax; bears pair of ostia in each somite. [Stachowitsch, 1992]
Muscular pumping organ of circulatory system. Relatively short, located dorsally in more anterior pereon segments (pereonites). Bears one pair of ostia and gives rise to anterior and posterior aortas as well as series of lateral arteries. [Stachowitsch, 1992]
Elongate, muscular pumping organ of circulatory system. Located within pericardial sinus above digestive tract; typically extends through entire pereon. Bears two pairs of ostia (in pereonites 2 and 3) and gives rise to single anterior lorta, pair of posterior aortas, and up to several pairs of lateral arteries. [Stachowitsch, 1992]
In circulatory system, relatively short, muscular pumping organ located dorsally in posterior region of cephalothorax. Receives blood from pericardium through three pairs of ostia and pumps ii anteriorly, posteriorly, and ventrally via numerous blood vessels (aortas, arteries). [Stachowitsch, 1992]
Elongate, muscular pumping organ of circulatory system; located within pericardial sinus above digestive tract and extending through most of pereon (first to sixth segments). Bears three pairs of ostia and gives rise to anterior and posterior aortas as well as series of lateral arteries. [Stachowitsch, 1992]
Muscular pumping organ of circulatory system; relatively short, located above hindgut in abdomen (pleon). Bears one to two pairs of ostia and gives rise to anterior aorta and series of lateral arteries. [Stachowitsch, 1992]
In circulatory system, muscular pumping organ above digestive tract in thorax. Bears two or three pairs of ostia and gives rise to series of aortas and arteries. [Stachowitsch, 1992]
Main longitudinal vessel of circulatory system. Located middorsally above digestive tract and gonads and extending through most of thorax and abdomen. Bears 13 pairs of ostia and gives rise to series of paired, segmentally arranged lateral arteries to anterior and posterior aortas. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In circulatory system, elongate, tubular pumping organ extending above digestive tract and gonads from posterior region of head to fourth pleomere. Bears 11 ostia and gives rise to numerous arteries as well as anterior and posterior aortas. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In circulatory system, muscular pumping organ located dorsally in last thoracic somite (fourth thoracomere). Receives blood through pair of ostia at posterior end and pumps it anteriorly via aorta, ventrally and posteriorly through additional openings. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Rostral sinus. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) In circulatory system of certain copepods, relatively short, muscular pumping organ located dorsally in anterior region of thorax. Recieves blood from pericardium through three ostia and pumps it anteriorly via aorta. [Stachowitsch, 1992]
In circulatory system of certain ostracods, relatively short, muscular pumping organ located anterodorsally behind eye. Receives blood from pericardium through pair of posterodorsal ostia and pumps it through anteroventral aortic valve and aorta as well as through posteroventral hepatic valves. [Stachowitsch, 1992]
Main longitudinal vessel of circulatory system; located middorsally above digestive tract. Muscular portion restricted to head (cephalon) region. [Stachowitsch, 1992]
Muscular pumping organ of circulatory system. In anaspidacean, elongate, extending dorsal to digestive tract from first thoracic to fourth abdominal somite. Bears pair of ostia at level of third thoracic somite (thoracomere) and gives rise to aortas and arteries. In bathynellacaens, relatively short, located in fourth thoracomere. [Stachowitsch, 1992]
Muscular pumping organ of circulatory system. Short, located dorsally in first thoracic segment (thoracomere). Bears pair of ostia and gives rise to anterior and posterior aortas. [Stachowitsch, 1992]
In circulatory system, relatively short, dorsoventrally flattened pumping organ; located within pericardial sinus in posterodorsal region of cephalo-thorax. Bears two pairs of ostia and gives rise to numerous anterior, posterior, and lateral blood vessels (aortas, arteries). [Stachowitsch, 1992]

Helmet

(Taxon-specific: ) Helmet-shaped elongation of anterior margin of head in certain individuals of a population. Appearance of helmeted individuals and shape of helmet is governed by environmental and genetic factors. (See also cyclomorph). [Stachowitsch, 1992]

Hemiamphidont hinge

An amphidont hinge in which the posterior element is crenulate and the others are smooth. [Cohen, Peterson, and Maddocks, in press]

Hemipenes

Podocopan term for paired male copulatory appendages. [Cohen, Peterson, and Maddocks, in press]

Hemiplumose

A modified form of the plumose seta in which setules are found in a row on only one side. [Wilson, 1989]

Hemocoel

Lacunar system extending throughout much of body, filled by blood. [Moore and McCormick, 1969]
Lacunar system extending throughout much of body, filled with blood. [McLaughlin, 1980]
The extensive spaces of an arthropod's body through which hemolymph circulates. [Bliss, 1982]
(Taxon-specific: Family Pycnogonidae) Body cavity through which blood circulates; separated from pericardial sinus by pericardial septum.
(syn. hemocoele) [Stachowitsch, 1992]

Hemocyanin

Copper-containing respiratory pigment in blood of malacostracans. [Moore and McCormick, 1969]
Copper-containing respiratory pigment in blood. [McLaughlin, 1980]

Hemoglobin

Oxygen-carrying protein colored substance of red plasma in blood of some crustaceans. [McLaughlin, 1980]
Oxygen-carrying protein coloring substance of red plasma in blood, found in some crustaceans (e.g., Ostracoda), may be colored or colorless in conchostracans, present also in blood of anostracans, cladocerans, notostracans, some harpacticid and parasitic copepods, branchiurans, and some parasite cirripeds. [Moore and McCormick, 1969]

Hemolymph

The circulating and tissue-bathing fluid of arthropods; composed of cells and plasma; often loosely termed as blood. [Bliss, 1982]

Hepatic area

In crayfishes, paired cephalolateral regions of the carapace between the orbit and cervical groove. [Hobbs, Hobbs, and Daniel 1977]
Paired cephalolateral region to either side of carapace between orbit and cervical groove (in crayfishes) (see Fig. 14). [Hobbs and Jass, 1988]

Hepatic artery

Artery. [Stachowitsch, 1992]

Hepatic caeca

Pouch-like diverticula generally connected with mesenteron, serving functions of liver. [Moore and McCormick, 1969]
See hepatic cecum. [McLaughlin, 1980]

Hepatic carina

Carina located above hepatic region, generally in line with antennal and suprabranchial carinae. [Butler, T. H.]
Longitudianlly or obliquely disposed ridge of variable length lying ventral to the hepatic region, sometimes extending almost to the anterior margin of the carapace. [Perez Farfante and Kensley, 1997]

Hepatic cecum

Pouchlike diverticulum generally connected with mesenteron, with liver function; also see hepatopancreas. [McLaughlin, 1980]
(Taxon-specific: ) Digestive cecum. [Stachowitsch, 1992]
One of up to four pairs of relatively short, lateral digestive ceca opening into digestive tract at stomach/midgut border.
(syn. digestive caecum) [Stachowitsch, 1992]
One of typically two large digestive glands occupying greater part of cephalothorax, each opening into junction of pyloric stomach and intestine. (paired, unpaired).
(syn. hepatopancreas, digestive gland) [Stachowitsch, 1992]
Midgut cecum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Digestive cecum. [Stachowitsch, 1992]
Hepatic gland. [Stachowitsch, 1992]

Hepatic gland

One of two large, branching digestive organs arising ventrally at border of pyloric stomach and midgut. Extends through most of thorax.
(syn. digestive cecum, hepatic cecum, hepato-pancreas) [Stachowitsch, 1992]

Hepatic groove

See: Carapace groove e [Martin, 2005]
See: Carapace grooves g [McLaughlin, 1980]
On each side of carapace, short, longitudinal groove connecting cervical with postcervical and branchiocardiac groove: more or less continuous with antennal groove. [Stachowitsch, 1992]

Hepatic lobe

One of three pairs of lobes on the cephalolateral margin of the carapace of aeglids delimited anteriorly and posteriorly by emarginations. [Hobbs, Hobbs, and Daniel 1977]

Hepatic region

See: Carapace region g [Martin, 2005]
Paired anterolateral areas of the carapace bounded anteriorly by the antennal region, posteriorly by the branchial region, and mesially by the gastric region. [Perez Farfante and Kensley, 1997]
Paired anterolateral areas on carapace bounded posteriorly by branchial region, mesially by gastric region, and anteriorly by antennal region. [Butler, T. H.]
Paired anterolateral areas on the carapace bounded posteriorly by the branchial region, mesially by the gstric region, and anteriorly by the orbital or (in the shrimps) antennal region. [Chace and Hobbs, 1969]
Paired regions of dorsal carapace between orbits and branchial regions, defined laterally in crabs by anterolateral margin, sometimes bearing hepatic spine(s), and sometimes (prawns and lobsters) with a curved hepatic groove or ridge ventrally. [Poore, 2004]
Small (paired)subtriangular, anterolateral region, wedged between branchial and gastric regions, and either margin of carapace or margin of orbit in Brachyura. [Williams, 1984]
The region on the dorsal surface of the carapace bounded by part of the antero lateral margin of the carapace and part of the margin of the orbital, protogastic and epibranchial regions. [Ingle, 1983]
See: Carapace regions g [McLaughlin, 1980]
One of two lateral regions of carapace more or less corresponding to underlying hepatic ceca. Adjoining regions include antennal, branchial, cardiac, and pterygostomial regions. [Stachowitsch, 1992]

Hepatic spine

See: Carapace spine c [Martin, 2005]
A lateral spine situated near the anterior margin of the hepatic region on the carapace of certain shrimps; it probably represents the branchiostegal spine displaced posteriorly from the anterior margin of the carapace. [Chace and Hobbs, 1969]
A spine located near the anterior margin of the hepatic area of the carapace of certain shrimps. [Hobbs, Hobbs, and Daniel 1977]
Lateral spine on carapace near anterior margin of hepatic region. [Butler, T. H.]
Lateral spine situated near the anterior margin of the hepatic region of the carapace (Fig. 2A). [Perez Farfante and Kensley, 1997]
Spine on hepatic region in shrimps (Fig. 2). [Williams, 1984]
Spine situated near anterior margin of hepatic area of carapace of certain shrimps, or on hepatic area of cambarids (see Fig. 14). [Hobbs and Jass, 1988]
See: Carapace spines c [McLaughlin, 1980]
In shrimp-like (natantian) decapod, anteriorly directed, spine-like projection on hepatic region on each side of carapace. [Stachowitsch, 1992]

Hepatic sulcus

Groove ventral to the hepatic region extending posteriorly, sometimes from near the anterior margin of the carapace. [Perez Farfante and Kensley, 1997]

Hepatic valve

One of two posteroventral openings in heart through which blood is pumped to digestive tract. (See also aortic valve). [Stachowitsch, 1992]

Hepatopancreas

Comprising a number of caeca lying alongside the hindgut which are involved in producing digestive enzymes and in absorbing the products of digestion . [Holdich and Jones, 1983]
considerable proportion of the space within the body cavity (Fig. 7). [Warner, 1977]
Digestive gland consisting of ramified tubules spread through cephalothorax performing functions of both liver and pancreas. [Moore and McCormick, 1969]
Digestive gland consisting of tubules ramifying through cephalothorax, with both liver and pancreas functions. [McLaughlin, 1980]
either side of the mid-gut as a much branched diverticulum and occupies a. [Martin, 2005]
Hepatic cecum. [Stachowitsch, 1992]
Digestive cecum. [Stachowitsch, 1992]

Hermaphrodite

A shrimp capable of functioning both as a male and a female during its life. [Butler, T. H.]
Organism with both male and female reproductive organs. [McLaughlin, 1980]

Hermaphroditic

Pocessing male and female organs - either simultaneously or sequentially. [Holdich and Jones, 1983]

Heterochelate

Chelae of left and right chelipeds differing in shape amd size. [McLaughlin, 1980]
Chelae of left and right chelipeds differing in shape and size. [Moore and McCormick, 1969]

Heteromorph

Adult female, inferred by carapace structure, in dimorphic genera. [McLaughlin, 1980]

Hindgut

[Martin, 2005]
See proctodeum. [McLaughlin, 1980]
(Taxon-specific: ) Short posteriormost section of digestive tract between midgut and anus; may be associated with single ventral cecum.
(syn. rectum) [Stachowitsch, 1992]
Short posteriormost section of digestive tract between midgut and anus.
(syn. rectum) [Stachowitsch, 1992]
Short posteriormost section of digestive tract between midgut and anus. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Short posteriormost section of digestive tract between midgut and anus. [Stachowitsch, 1992]
Elongate section of digestive tract between midgut and anus. Extends through most of pereon and abdomen and may be coiled in the former. [Stachowitsch, 1992]
Posteriormost cuticle-lined region of digestive tract (foregut, midgut, hindgut). Opens via rectum and anus to exterior.
(syn. proctodeum, proctodaeum) [Stachowitsch, 1992]
Posterior of three basic divisions (foregut, midgut, hindgut) of digestive tract. Cuticle-lined and opening to exterior via anus.
(syn. proctodeum, rectum) [Stachowitsch, 1992]
Posterior of two basic divisions (foregut, hindgut) of digestive tract; elongate, typically extending through part of pereon and entire abdomen (pleon). Opens posteriorly via anus at base of lelson. [Stachowitsch, 1992]
Relatively short, cuticle-lined section of digestive tract between midgut and anus. Restricted to last (sixth) abdominal somite (pleomere). [Stachowitsch, 1992]
Posterior section of digestive tract; follows midgut at level of fifth abdominal somite (pleomere). Opens to exterior via anus on telson. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Posterior region of digestive tract (foregut, midgut, hindgut); extends through one or more abdominal segments and opens to exterior via anus. If present, rectal cecum extends above hindgut. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Posterior of three regions (foregut, midgut, hindgut) of digestive tract; extends through abdomen and opens to exterior via anus.
(syn. rectum) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Posteriormost, relatively narrow, cuticle-lined section of digestive tract between midgut and anus. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Posterior of three regions (foregut, midgut, hindgut) of digestive tract. Relatively short, extending only through last two abdominal somites; opens to exterior via anus. Cuticle-lined and equipped with muscles.
(syn. proctodeum) [Stachowitsch, 1992]
Proctodeum. [Stachowitsch, 1992]
Posterior of three regions (foregut, midgut, hindgut) of digestive tract. Relatively short, cuticle-lined, and opening to exterior via anus. [Stachowitsch, 1992]
Short posteriormost division of digestive tract (foregut, midgut, hindgut) located in anal segment. Opens to exterior via anus. [Stachowitsch, 1992]
In anaspidacean, relatively short section of digestive tract between midgut and anus; restricted to last (sixth) abdominal somite (pleomere). [Stachowitsch, 1992]
Posteriormost section of digestive tract between midgut and anus; may give rise to short blind diverticulum. [Stachowitsch, 1992]

Hindgut gland

Relatively small, unpaired gland opening into end of digestive tract.
(syn. rectal gland) [Stachowitsch, 1992]

Hinge

Complementary interlocking articulatory structures on inner dorsal margin of valves.
See: Adont hinge, Merodont hinge, Lophodont hinge, Pentodont hinge, Holomerodont hinge, Antimerodont hinge, Entomodont hinge, Gongylodont hinge, Amphidont hinge, Holamphidont hinge, Hemiamphidont hinge, Schizodont hinge [Cohen, Peterson, and Maddocks, in press]
In carapace, structures along dorsal margin serving in articulation of two valves. If fully developed, consists of a series of teeth and ridges that fit into sockets and grooves of opposite valve; one may distinguish anterior, anteriomedian, posteromedian, and posterior hinge elements. (adont, amphidont, archidont, desmodont, entomodont, heterodont, lobodont, merodont, schizodont, taxodont). [Stachowitsch, 1992]

Hinge joint

(Taxon-specific: Family Cyatholaimidae) In male, modified joint in midregion of geniculate type of antennule to fold down on basal half, antennule serves as grasping organ during copulation. [Stachowitsch, 1992]

Hinge line

Mid-dorsal line of junction of two valves composing carapace, permitting movement between them (e.g., Conchostraca, Ostracoda, Phyllocarida). [Moore and McCormick, 1969]
Middorsal line of junction of two valves of carapace, permitting movement between them. [McLaughlin, 1980]
Longitudinal middorsal line of carapace. Considered either to mark connection of two valves of carapace or to represent thinner and most flexible region of continuous shield. (straight, in an arc). [Stachowitsch, 1992]

Hinge margin

In valve, dorsal margin adjoining hinge (as opposed to free = anterior, ventral, and posterior margins). [Stachowitsch, 1992]

Hinge nodes

Localized thickened parts of right valve hinge of phyllocarids, somewhat elongate in line of hinge and serving to strengthen it. [Moore and McCormick, 1969]
(Taxon-specific: Class Adenophorea) Localized thickened parts of right valve hinge. [McLaughlin, 1980]

Hinge selvage

In dorsal margin (hinge area) of valve; ridge-like elevation corresponding and occasionally continuous with selvage of anterior, ventral, and posterior margins). [Stachowitsch, 1992]

Hingement

Collective term for structure comprising articulation of valves. [McLaughlin, 1980]
Hinge. [Stachowitsch, 1992]

Hirsute

Bearing hairs (elongate hairs in the case of most isopods). [Kensley and Schotte, 1989]

Holamphidont hinge

An amphidont hinge in which all elements are smooth. [Cohen, Peterson, and Maddocks, in press]

Holomerodont hinge

A merodont hinge in which all elements are crenulate and negative on one valve, positive on the other. [Cohen, Peterson, and Maddocks, in press]

Holotype

The single specimen used as the basis of the original published description of a species and later designated as the type specimen. [AHD]

Horn

(Taxon-specific: Family Cyatholaimidae) In parasitic copepod, one of two to four horn-like projections of head. Used in attachment to host. (branched, unbranched). [Stachowitsch, 1992]

Host

Shrimp parasitized by an organism of another species. [Butler, T. H.]

Hyaline lamella

(Taxon-specific: Family Cyatholaimidae) Thin, membrane-like crest along certain segments of appendage (e.g., of antennule, pereopod). (broad, narrow, notched, smooth, toothed, triangular). [Stachowitsch, 1992]

Hypobranchial space

Area of gill chamber below gills. [McLaughlin, 1980]
Part of gill chamber below gills. [Moore and McCormick, 1969]
In each branchial chamber in cephalothorax, space below gills.
See: Epibranchial space [Stachowitsch, 1992]

Hypodermis

Epidermis. [Stachowitsch, 1992]

Hypopharynx

See: Metastoma [Martin, 2005]
See metastoma. [McLaughlin, 1980]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]

Hypostoma

See: Metastoma [Martin, 2005]
See metastoma. [McLaughlin, 1980]

Hypostome

See: Metastoma [Martin, 2005]
See metastoma. [McLaughlin, 1980]
Labium.
(syn. hypostoma) [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]

IM

The junction between the basi-ischium and the merus. It is called IM rather than BM because the junction is with the basi-ischium (Figs. 2, 12). [Warner, 1977]

Imbricate plates

[Martin, 2005]

Immersed

Sunken into, as with one structure into another. [Kensley and Schotte, 1989]

Immovable finger

Finger. [Stachowitsch, 1992]

Incisor

Cutting process of the mandible, usually dentate, sometimes modified for piercing. [Kensley and Schotte, 1989]

Incisor process

Biting portion of gnathal lobe of mandible.
(syn. pars incisiva) [Moore and McCormick, 1969]
Biting portion of gnathal lobe of mandible.
(syn. pars incisiva) [McLaughlin, 1980]
Cutting process on mandible; widely separated from molar or grinding process in some shrimps, e.g., Pandalidae, in close proximity in others, e.g., Oplophoridae. [Butler, T. H.]
Cutting process, often toothed or cusped, of the mandible. [Perez Farfante and Kensley, 1997]
Cutting surface (lobe) of mandible (as opposed to molar or grinding lobe) (see Fig. 23h). [Hobbs and Jass, 1988]
The cutting (as opposed to the molar or grinding) lobe of the mandible. [Hobbs, Hobbs, and Daniel 1977]
The distal biting part of the mandible that typically bears one or more cusps. On its medial side, it bears the spine row. [Wilson, 1989]
The fixed distal 'cutting blade' of the mandible. [Holdich and Jones, 1983]
Food-gripping process (vs. grinding = molar process) at end of each mandible) Extends into atrium oris under labrum. Variously armed with spines, setae, and denticles. [Stachowitsch, 1992]
Distal gripping process (vs. grinding = molar process) of each mandible.
(syn. pars incisiva) [Stachowitsch, 1992]
Distal gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]
Food-gripping process (vs. grinding = molar process) of each mandible. May be fused with molar process.
(syn. pars incisiva) [Stachowitsch, 1992]
Gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]
Distal, often toothed gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Grasping, piercing or slicing structure arising apically on body of mandible. [Wetzer et al. 1997]
Distal gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]
Well-developed food-gripping (vs. grinding = molar process) of each mandible; bears single row of teeth and lies over labrum.
(syn. pars incisiva) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Gripping process (vs. grinding = molar process) of each mandible. (simple, with teeth). [Stachowitsch, 1992]
Cutting process (vs. grinding = molar process) at tip of each mandible; incisor processes of left and right mandibles are generally asymmetrical, i.e., number (three or four) and shape of large denticles differ. [Stachowitsch, 1992]
Distal gripping process (vs. proximal grinding = molar process) of each mandible. [Stachowitsch, 1992]
Distal gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]
Gripping process (vs. grinding = molar process) of each mandible. [Stachowitsch, 1992]

Incisur

Terminal process of mandible, cutting blade, often toothed (more properly, incisor process).
(syn. incisor process) [Poore, 2004]
An anterior indentation (ranging from slight to deep and even slit-like) of the valves of the carapace; it acts like an oar-lock for the rowing antennae of many swimming Myodocopa.
(syn. incisure, rostral incisur) [Cohen, Peterson, and Maddocks, in press]

Indirect development

See Anamorphic development. [Ingle, 1992]

Induarte

Heavily sclerotized or calcified, and often rough. [Wilson, 1989]

Indurate

Hardened, usually by calcium carbonate or sclerotized protein. [Kensley and Schotte, 1989]

Inferior abdominal artery

Subneural artery. [Stachowitsch, 1992]

Inferior antennal sinus

postantennal sinus. [Stachowitsch, 1992]

Inferior groove

See: Carapace groove f [Martin, 2005]
See: Carapace grooves h [McLaughlin, 1980]
On each side of carapace, transverse groove extending from junction of hepatic and cervical grooves toward lateral margin; more or less continuous with cervical groove. [Stachowitsch, 1992]

Infra-gastro-orbital carina

Short lateral carina ventral to gastro-orbital carina on carapace of shrimps of genus Notostomus. [Butler, T. H.]

Inframedian lateral

See: Latus (inframedian) b [Martin, 2005]

Inframedian latus

See latus. [McLaughlin, 1980]
Valve of some cirriped shells located below upper latus. [Moore and McCormick, 1969]

Infraorbital spine

See: Carapace spine d [Martin, 2005]
See: Carapace spines d [McLaughlin, 1980]

Infraorder

A major subdivision of a suborder in the classification of animals, usually consisting of several superfamilies and families. [Bliss, 1982]

Inner lamella

Inner layer of epidermis and cuticle of the dorsal body fold forming the valve, entirely uncalcified or calcified only around the free margin. [Cohen, Peterson, and Maddocks, in press]
Relatively thin, lamella-like structure joined to outer wall (outer lamella) of valve. Secreted by epidermis; covers body except dorsally in hinge region. Junction with outer lamella along valve margin may be thickened to form duplicature. (membranous, calcareous). [Stachowitsch, 1992]

Inner lamina

In cirripeds, innershell layer of compartmental plate separated from outer lamina by parietal tubes. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Inner shell layer of compartmental plates separated from outer lamina by longitudinal tubes. [McLaughlin, 1980]

Inner lobe

Labium. [Stachowitsch, 1992]

Inner margin

The inner or proximal edge of the calcified inner carapace lamella, forming an abrupt line or shelf in dead or fossil valves of Podocopida. [Cohen, Peterson, and Maddocks, in press]

Inner plate

Endite. [Stachowitsch, 1992]

Inquilism

An association in which one species regularly shelters near, or within the body of another species for protection. [Ingle, 1983]

Insemination

The act of placing or introducing sperm onto or into the thelycum or seminal receptacles of the female. [Perez Farfante and Kensley, 1997]

Instar

A discreet stage in a growth series, delimited by successive molting. [Wilson, 1989]

Integument

Outer covering of exoskeleton. [Perez Farfante and Kensley, 1997]
Outer covering, e.g., the exoskeleton. [Kensley and Schotte, 1989]

Inter-antennular septum

A median, ventrally directed, cuticular outgrowth that separates the two cavities into which each antennule is retracted.
See: Orbito-antennulary pits [Ingle, 1980]
Plate in some malacostracans that separates one antennular cavity from other.
(syn. proepistome) [Moore and McCormick, 1969]
Plate separating antennular cavities in some malacostracans.
(syn. preopistome) [McLaughlin, 1980]
The plate which separates the two antennular cavities from each other, formed by the union of a slender anterior process of the epistome and the front. [Ingle, 1983]
On anterior margin of carapace, median, ventrally directed, cuticular outgrowth extending from front to proepis-tome; separates left and right antennules as well as cavities into which each antennule may be retracted. [Stachowitsch, 1992]

Interantennular

Between antennae. [Wilson, 1989]

Intercalary spine

A spine on the dorsal margin of the orbit lying between the postorbital spine and the supraorbital eave (Majidae). [Ingle, 1983]

Intercalated stages

A type of delayed development in which extra stages appear between those normally ocurring in a preponderance of developmental sequences. [Ingle, 1992]

Intercervical groove

See: Carapace grooves i [McLaughlin, 1980]
On each side of carapace, oblique groove connecting postcervical and cervical grooves. [Stachowitsch, 1992]

Intercoxal plate

(Taxon-specific: Family Cyatholaimidae) On underside of thorax, fold of sternite uniting basal segments (coxae) of each pereopod pair. Permits synchronous strokes during rapid swimming.
(syn. median coupler plate) [Stachowitsch, 1992]

Intercoxal sclerite

(Taxon-specific: Family Cyatholaimidae) A flat chitinous plate, connecting the coxae of a pair of swimming legs.
See: Intercoxal plate [Boxshall and Halsey, 2004]

Interior spine

Spine. [Stachowitsch, 1992]

Interlaminate figure

In Cirripedia (Balanomorpha), simple or arborescent lines Seen running between epicuticle of outer lamina through longitudinal septa into inner lamina, when paries is sectioned parallel to base. [Moore and McCormick, 1969]
Simple or arborescent lines extending between epicuticle of outer lamina through longitudinal septa into inner lamina in sections parallel to base in some balanomorph Cirripedia. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: when plate of unstalked form is sectioned parallel to base, line running from outer to inner lamina through longitudinal septum. (simple, arborescent). [Stachowitsch, 1992]

Intermediate carina

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Intermediate denticle

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Intermediate tooth

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Interna

Interal, ramifying nutrient-absorbing part of a rhizocephalan. [Brusca and Brusca, 2002]
(Taxon-specific: Order Rhabditida) In female rhizocephalan, root-like section of body extending into host. (See also exerna). [Stachowitsch, 1992]

Interpleurite

Endopleurite, endosternite. [Stachowitsch, 1992]

Interpodal bar

(Taxon-specific: Family Cyatholaimidae) A ventral exoskeletal structure uniting the contralateral pair of thoracic limbs; an interpodal bar may unite thoracic limb pairs 2-6 of most copepods. [Ferrari and Dahms, in press]

Intersex

see Transitional. [Butler, T. H.]

Interstitial

Relating to interstices; living in the interstices of sand grains, gravel, or rubble. [Kensley and Schotte, 1989]

Intertidal zone

Portion of sea bottom between high and low tide lines. [Butler, T. H.]

Intestinal groove

See: Carapace grooves j [McLaughlin, 1980]
On posterior part of carapace, short, transverse groove across dorsomedian surface; interrupted by tubercle. [Stachowitsch, 1992]

Intestinal region

See: Carapace region h [Martin, 2005]
Most posterior median region of the dorsal carapace, sometimes with intestinal spine(s). [Poore, 2004]
The most posterior of the mesial areas on the carapace of crabs, bounded anteriorly by the cardiac region and laterally by the branchial regions. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by the posterior margin of the carapace and parts of the margins of the cardiac and metabranchial regions. [Ingle, 1983]
See: Carapace regions h [McLaughlin, 1980]
Unpaired region at posterior end of carapace. Adjoined anteriorly by cardiac region.
(syn. posterior cardiac lobe) [Stachowitsch, 1992]

Intestine

Elongate slender posterior part of alimentary canal, in some crustaceans partly corresponding to mesenteron and invariably to part of proctodeum. [Moore and McCormick, 1969]
(Taxon-specific: ) Midgut. [Stachowitsch, 1992]
Elongate section of digestive tract extending through abdomen from pyloric stomach to rectum. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Posterior section of midgut; opens into hindgut at border of thorax and abdomen. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Midgut. [Stachowitsch, 1992]
More narrow posterior section of midgut (stomach, intestine); opens into hindgut. [Stachowitsch, 1992]

Intramedian latus

(Taxon-specific: Order Rhabditida) Barnacle plate: paired plates (latera) in stalked form, one below each upper latus. [Stachowitsch, 1992]

Intraparies

Secondary lateral margin of carina in some cirripeds (Lepadomorpha). [Moore and McCormick, 1969]
Secondary lateral margin of carina in some lepadomorph cirripeds.
(pl. intraparietes) [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in certain stalked forms, secondary lateral margins of carina. [Stachowitsch, 1992]

Intromittent organ

(Taxon-specific: Order Rhabditida) Penis. [Stachowitsch, 1992]

Inverted

Pertaining to chela of first pereiopod of shrimps of genus Beteaus, where movable finger or dactylus is ventral in position. [Butler, T. H.]

Ischial spine

Spine projecting from ischium or third segment of thoracic appendage. [Perez Farfante and Kensley, 1997]

Ischiobasis

Segment of appendage (thoracopod) formed by fusion of basis and ischium.
(syn. basi-ischium) [Stachowitsch, 1992]

Ischiocerite

Third segment of antennal peduncle. [Moore and McCormick, 1969]
Thrid segment of antennal peduncle. [McLaughlin, 1980]
In antenna, term applied to first of three segments (ischiocerite, merocerite, carpocerite) of inner branch (endopod). Alternate interpretation: third segment of peduncle. [Stachowitsch, 1992]

Ischiomerus

Fused ischium and merus (maxilliped 3 of Gnathophyllidae). [Poore, 2004]
Segment of appendage (thoracopod) formed by fusion of ischium and merus. [Stachowitsch, 1992]
Merus. [Stachowitsch, 1992]

Ischiopod

? See Ischium. [Martin, 2005]
Ischium.
(syn. ischiopodite) [Stachowitsch, 1992]

Ischiopodite

See ischium. [McLaughlin, 1980]
The third segment from the base of a segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
Third segment from base of a segmented appendage. [Hobbs and Jass, 1988]

Ischium

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Article 3 of pereopod (not always present in tanaids). [Holdich and Jones, 1983]
Fifth article from distal end of leg; usually first large article of maxilliped.
(syn. ischiopodite) [Williams, 1984]
Fifth segment of a pereiopod counted from the distal end. [Ingle, 1983]
See ischiopodite. [Hobbs, Hobbs, and Daniel 1977]
See ischiopodite. [Hobbs and Jass, 1988]
The third segment from the proximal end of a typically 7-segmented appendage.
(pl. Ischia) [Chace and Hobbs, 1969]
The third segment of a thoracic appendage.
See: Pereopod [Wilson, 1989]
Third article of limb (first article of endopod). [Poore, 2004]
Third limb segment distal from body articulating with basis and comprising first segment of endopod.
(syn. ischiopod(ite)) [Moore and McCormick, 1969]
Third podomere from the proximal end of a tyically 7-segmented appendage (Fig. 3C).
(pl. Ischia) [Perez Farfante and Kensley, 1997]
Third segment from the proximal end of a typically 7-segmented appendage.
(pl. ischia) [Butler, T. H.]
Third segment of pereopod or 1st segment of endopod articulating with basis.
(syn. ischiopod) [McLaughlin, 1980]
First of five segments (ischium, merus, carpus, propodus, dactylus) of endopod of thoracopod (maxillipeds and pereopods).
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Third of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod. Relatively short; may be fused
with basis.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Third segment of appendage (thoracopod), positioned between basis (last segment of protopod) and merus and thus representing first segment of endopod. May be fused with basis to form ischiobasis or with merus to form ischiomerus.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Third of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod; represents second movable (free) segment.
(syn. ischipopd, ischiopodite) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Article 3 of pereopod. [Kensley and Schotte, 1989]
Third segment of pereopod; located between basis and merus.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Second of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Merus. [Stachowitsch, 1992]
Second of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) or thoracopod.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
First of basically five segments (ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Frequently interpreted as being fused to second segment (basis) of protopod in maxilliped, to merus in the other thoracopods (pereopods).
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]
Third segment of thoracopod (first segment of endopod); positioned between basis and merus.
(syn. ischiopod, ischiopodite) [Stachowitsch, 1992]

Isometric growth

Growth of one part of the body relative to another part in which there is no change in relationships of proportions or shape. [Ingle, 1983]

Isopod

Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
(Figure only.) [Kensley and Schotte, 1989]

Isopoda

Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
(Figure only.) [Kensley and Schotte, 1989]

Joint

Articulation (most commonly applicable to movable connection of individual segment of appendage with neighbors or body but relates also to movable connection of body parts); loosely and undesirably employed as synonym of segment. [Moore and McCormick, 1969]
Article, segment. [Stachowitsch, 1992]
Article, segment. [Stachowitsch, 1992]
Article, segment. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Article. [Stachowitsch, 1992]
Article, segment. [Stachowitsch, 1992]
Segment. [Stachowitsch, 1992]

Jugal region

See: Carapace region i [Martin, 2005]
See: Carapace regions i [McLaughlin, 1980]
Pterygostomial region. [Stachowitsch, 1992]

Juvenile

A young shrimp, lobster or crab that has completed its larval and postlarval stages but its not yet a sexually mature adult. [Bliss, 1982]

Keel

See: Carina [Martin, 2005]
Ridge-like elevation of posterior hinge line; produced into series of serrations by continued growth lines. [Stachowitsch, 1992]
In certain mysidaceans, one of several elevated ridges on carapace. According to position one may distinguish dorsal, midlateral, and lower lateral keels. [Stachowitsch, 1992]
Posterior extension of carapace.
(syn. caudal process) [Cohen, Peterson, and Maddocks, in press]

Keeled

see Carinate. [Butler, T. H.]

Kentrogon

In Cirripedia (Rhizocephala), dedifferentiated cells of female or hermaphrodite cyprid larva, at time they are being extruded through cyprid first antenna into host crustacean; or of male cyprid, being extruded into mantle cavity of female. [Moore and McCormick, 1969]
Infective larval stage of kentrogonid rhizocephalans that develops beneath the cyprid exoskeleton. [Brusca and Brusca, 2002]
(Taxon-specific: Order Rhabditida) In Rhizocephalan, dedifferentiated stage following cyprid larva. Injected into host through stylet. [Stachowitsch, 1992]
(Taxon-specific: Suborder Enoplina) Undifferentiated cells following cyprid. [McLaughlin, 1980]

Knee

Point of most pronounced flexure of endopod. [Moore and McCormick, 1969]
In thoracopod, main bend of inner branch (endopod). Basically located between third and fourth segments (merus and carpus). [Stachowitsch, 1992]
Joint between segments of appendage at which limb forms an angle (e.g., between protopodite and endopodite of first thoracopod or between coax and basis of antenna). [Stachowitsch, 1992]
In thoracopod, main bend of inner branch (endopod). In anaspidacean, located between fourth and fifth segments (carpus and propodus). [Stachowitsch, 1992]

Knob

Type of valve sculpture: Prominent protuberance. Larger than node and differentiated from surrounding area by distinct angulation. [Stachowitsch, 1992]

Labial spine

(Taxon-specific: Order Monhysterida) One of two hollow spines in proboscis; each is located at tip of swelling and projects into anterior end of buccal cavity. Associated with gland. [Stachowitsch, 1992]

Labium

See: Metastoma [Martin, 2005]
Flat, non-segmented, bilobed structure situated posterior to the oral opening.
(syn. paragnath, lower lip) [Holdich and Jones, 1983]
Paired, laminar mouth parts immediately posterior to the mandibles. [Mauchline, 1984]
See metastoma. [McLaughlin, 1980]
(Taxon-specific: ) Unpaired, median lip-like structure posterior to mouth. (with/without median keel).
(syn. lower lip, paragnath) [Stachowitsch, 1992]
Lobe-like structure posterior to mouth. Divided into two lobes. (See also labrum).
(syn. lower lip) [Stachowitsch, 1992]
Lobe-like structure posterior to mouth. Divided into two main lobes (para-gnaths) which may bear hairs, spines, or comb-like rows of short setae, (with/without palp).
(syn. lower lip, hypopharynx) [Stachowitsch, 1992]
Lip-like structure posterior to mouth on underside of head; symmetrically bilobed, each lobe being termed paragnath. (paragnath: oval, distally attenuated, sinuous).
(syn. metastome, hypostoma, hypostome, hypopharynx, paragnath) [Stachowitsch, 1992]
Lobe-like structure posterior to mouth. Typically divided into two lobes (paragnaths), each of which may be further subdivided into a large section (outer lobe), a median inner lobe, and a posterolateral extension (mandibular lobe).
(syn. lower lip) [Stachowitsch, 1992]
Lobe-like structure posterior to mouth. Typically divided into two lobes (paragnaths).
(syn. lower lip, hpopharynx, posterior lip) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Lower lip; usually consisting of a pair of lobes posterior to the mouth. [Kensley and Schotte, 1989]
The posterior border of the buccal field; the "lower lip" (see paragnath). [Wetzer et al. 1997]
Lobe-like structure posterior to mouth. Divided into two well-developed lobes (paragnaths).
(syn. lower lip) [Stachowitsch, 1992]
Lip-like structure posterior to mouth and mandibles on underside of head (cephalon); bulbous and bilobed, each fringed lobe being termed paragnath.
(syn. lower lip) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Lobe-like structure posterior to mouth; divided into two lobes (paragnaths).
(syn. lower lip) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Lower lip, paragnath. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Lip-like structure posterior to mouth on underside of head; bilobed, each lobe being termed paragnath. May be drawn out, along with upper lip (labrum), into cone-like structure (mouth cone).
(syn. lower lip) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The lower lip; a median lobe derived from the fusion of the paragnaths, forming the posterior wall of the oral cone in siphonostomatoids. [Boxshall and Halsey, 2004]
Lip-like structure posterior to mouth on underside of head. May be bilobed, each lobe being termed paragnath.
(syn. lower lip, hypostome) [Stachowitsch, 1992]
Paragnath. [Stachowitsch, 1992]
Lobe-like structure posterior to mouth; relatively elongate, with terminal spines or setae. (See also labium).
(syn. lower lip) [Stachowitsch, 1992]
Lobe-like structure posterior to mouth; divided into two lobes (paragnaths).
(syn. lower lip) [Stachowitsch, 1992]

Labral ganglion

Large ganglion adjoining posterior end (tritocerebrum) of brain and innervating labrum.
(syn. ganglion labrii) [Stachowitsch, 1992]

Labrum

A bulbous structure lying next to the epistome and bordering the anterior margin of the oral opening.
(syn. upper lip) [Holdich and Jones, 1983]
An unpaired, flat segment of the cephalon that articulates with the clypeus, and anteriorly covers the mandibles. [Wilson, 1989]
Unpaired outgrowth arising just in front of mouth and more or less covering it.
(syn. upper lip) [Moore and McCormick, 1969]
Unpaired outgrowth arising just in front of mouth and often more or less covering it.
(syn. upper lip) [McLaughlin, 1980]
Upper lip or unpaired structure arising anterior to the mouth and often covering it. [Perez Farfante and Kensley, 1997]
(Taxon-specific: ) Relatively large, unpaired lobe covering mouth. Distal ends of mandibles extend under labrum. (ventral edge: smooth, toothed).
(syn. upper lip) [Stachowitsch, 1992]
Large, unpaired lobe covering mouth and extending over end of mandibles.
(syn. upper lip) [Stachowitsch, 1992]
Relatively large, unpaired lobe covering mouth; free (posterior) margin bears prominent spine. Tips (molar processes) of mandibles extend into preoral cavity (atrium oris) under labrum.
(syn. upper lip) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Large, bulbous, unpaired lobe covering mouth and extending over end of mandibles (with/without knob-like protuberance).
(syn. upper lip) [Stachowitsch, 1992]
Large, bulbous, unpaired lobe covering mouth and extending over end (molar and incisor processes) of mandibles and to a lesser extend over maxillules. Preoral cavity formed under labrum is termed atrium oris. Anterior end of labrum may be associated with "eyes." (narrowly or broadly rounded anteriorly and posteriorly, somewhat pointed anteriorly and posteriorly; oval, obovate).
(syn. upper lip) [Stachowitsch, 1992]
Unpaired, lobe-like structure anterior to mouth; adjoins bases of antennules and antennae. (See also labium).
(syn. upper lip) [Stachowitsch, 1992]
Unpaired, lobe-like structure an-erior to mouth. Adjoined anteriorly by clypeus.
(syn. upper lip) [Stachowitsch, 1992]
Relatively large, unpaired, fleshy lobe in front of and partially covering mouth; adjoined anteriorly by epistome.
(syn. upper lip) [Stachowitsch, 1992]
Unpaired, lobe-like structure anterior to and partially covering mouth, (rounded, medially incised = apically notched = bilobed; lobes: symmetrical/ asymmetrical).
(syn. upper lip) [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Flaplike structure posterior to and borne upon the frontal lamina or clypeus, usually free but occasionally fused to the head; the "upper lip" (see clypeus). [Wetzer et al. 1997]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Unpaired projection anterior to mouth, attached to the clypeus; upper lip. [Kensley and Schotte, 1989]
Unpaired, lobe-like structure anterior to and partially covering mouth.
(syn. upper lip, frontal lip) [Stachowitsch, 1992]
Unpaired, helmet-shaped structure anterior to mouth; extends posteriorly, covering mouth and part of mandibles. (bilobate, entire, with/without anterior spiniform projection).
(syn. upper lip) [Stachowitsch, 1992]
Relatively small, unpaired fleshy lobe in front of mouth; adjoined anteriorly and laterally by epistome.
(syn. upper lip) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Unpaired lobe-like structure anterior to and partially covering mouth.
(syn. upper lip) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Lip-like structure in front of mouth; either consists of fleshy, papilla-shaped elevation or is reduced, along with paragnaths, to serrate flap enclosed in proboscis.
(syn. upper lip) [Stachowitsch, 1992]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Unpaired lobe covering mouth; typically bear pair of palps. Forms part of oral pyramid in ascothoracican. (bullate, not bullate; cutting edge: straight, concave, with median notch; with/without setae or spines).
(syn. upper lip) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A lobe-like flap originating near the anterior margin of the head, between the bases of the antenna 1, and extending posteriorly across the ventral surface of the body to the mouth area. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The upper lip; a posteroventrally-directed, muscular, median lobe forming the anterior wall of the oral cone. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) Unpaired, lip-like structure in front of mouth. May cover basal part (gnathobase) of mandible or be drawn out, along with lower lip (labium), into cone-like structure (mouth cone).
(syn. upper lip) [Stachowitsch, 1992]
Large, bulbous, unpaired lobe covering mouth. Contains large gland and labral ganglion and extends over gnathobases of mandibles. (distal = posterior end: gradually expanded, abruptly expanded).
(syn. upper lip) [Stachowitsch, 1992]
Unpaired, lip-like structure in front of mouth. May contain salivary glands or glands which produce a luminescent secretion.
(syn. upper lip) [Stachowitsch, 1992]
Relatively large, fleshy lobe anterior to mouth; divided by transverse furrow into subtriangular anterior part and bulbous posterior part, the latter with a fossa and dense array of ribbon setae on posterior margin. Projecting posterior margin forms atrium oris below and extending somewhat behind true mouth. [Stachowitsch, 1992]
Unpaired structure anterior to mouth. (See also paragnath).
(syn. upper lip) [Stachowitsch, 1992]
Unpaired, lobe-like structure anterior to and partially covering mouth.
(syn. upper lip) [Stachowitsch, 1992]

Labyrinth

In antennal gland, more distal of two divisions (saccule, labyrinth) of end sac. Characterized by complexly folded walls and opening either directly or indirectly (via excretory tubule) into bladder. [Stachowitsch, 1992]

Lacertus

(Taxon-specific: Family Cyatholaimidae) The proximal segment (representing the syncoxa) of the maxilla of some siphonostomatoids. [Boxshall and Halsey, 2004]

Lacinia mobilis

An enlarged, nearly articulated spine of the mandible's spine row that is adjacent to the incisor process. It is found only on the left mandible. On the right mandible, it is replaced by a large spine similar in shape to the more posterior members of the spine row. [Wilson, 1989]
Articulated accessory process of the mandible between the molar and incisor process typical of peracarids. [Brusca and Brusca, 2002]
Small, generally toothed process articulated with incisor process of mandible. [Moore and McCormick, 1969]
The articulated 'cutting ' blade of the mandible. Exhibits varying degrees of development in the Tanaidacea. [Holdich and Jones, 1983]
Small, articulated process between setal row and incisor process on mandible. Fully developed only on left mandible. [Stachowitsch, 1992]
Small, articulated process between setal row and incisor process on mandibles. May be present only on left mandible, (present/absent on right mandible). [Stachowitsch, 1992]
Small, generally toothed, process articulated with incisor process of mandible. [McLaughlin, 1980]
Small, articulated accessory process between setal row and incisor process on each mandible. Differs in shape on left and right mandibles. (serrate, smooth). [Stachowitsch, 1992]
Small, usually toothed, process articulating at base of incisor in left or both mandibles. [Kensley and Schotte, 1989]
Small, usually toothed, process articulating at base of incisor of left or both mandibles; present in most isopod groups. [Wetzer et al. 1997]
Toothed, movably articulated process between setal row and incisor process on left (and occasionally also on right) mandible. [Stachowitsch, 1992]
Articulated process between pars centralis (setal row) and incisor process on left mandible; frequently absent on right mandible. [Stachowitsch, 1992]
Movable, toothed process between molar and incisor processes at tip of each mandible. Laciniae mobili of left and right are asymmetrical, i.e., of different shape and/or denticle number. (margin: concave and sickle-like, with three or six denticles). [Stachowitsch, 1992]
Articulated process between lifting spines and incisor process on each mandible. [Stachowitsch, 1992]

Lacinia(e)

Inner distal spiny lobe of 2nd segment of maxillule, adjacent to outer hood-like lobe (galea). [Moore and McCormick, 1969]
Inner distal spiny lobe of second segment of maxillule. [McLaughlin, 1980]

Lacuna

In circulatory system, large, longitudinal space between digestive tract and ventral nerve cord in which blood collects before entering gills. (See also sinus). [Stachowitsch, 1992]

Lamella

A broad, flattened appendage. [Wilson, 1989]
Thin flat plate or scale.
(pl. lamellae) [Butler, T. H.]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, outer and inner walls of paries and radius. Separated by longitudinal septa forming longitudinal tubes.
(syn. lamina) [Stachowitsch, 1992]
Inner lamella, outer lamella. [Stachowitsch, 1992]

Lamellar

In the shape or structure of a thin plate or lamella. [Kensley and Schotte, 1989]

Lamina

Blade or expanded part of scale or appendage segment.
(pl. laminae) [Butler, T. H.]

Lamina dentata

Serrate platelike structure in the mandible of anthurideans, formed by the fusion of spines of the spine-row. [Kensley and Schotte, 1989]
Serrate platelike structure on the mandible of anthurideans, presumed to have been formed by the fusion of spines of the spine-row. [Wetzer et al. 1997]

Lanceolate

Lance shaped; narrow and tapering to a point. [Kensley and Schotte, 1989]

Lappet

Down-hanging lateral part of carapace. [Moore and McCormick, 1969]
Membranous structure, often leaf-like, attached to the distal end of the first segment of the first antenna. [Mauchline, 1984]
Ventrally projecting subdivisions of pleura. [McLaughlin, 1980]
One of two (anterior and posterior) lobe-like extensions of pleura. [Stachowitsch, 1992]

Larva

General term for early stages of shrimps after hatching from the egg, morphologically quite different from adult.
(pl. larvae) [Butler, T. H.]
(Taxon-specific: Order Monhysterida) One of up to nine stages of development after hatching from egg. On may distinguish larvae that swim by means of antennae and mandibles and those that swim with thoracopods. [Stachowitsch, 1992]

Larvologist

One who studies the larval phases of animals. [Ingle, 1992]

Lash

Flexible distal portion of exopod on third maxilliped of shrimps of family Crangonidae. [Butler, T. H.]

Lasiopod

In Cirripedia (Lepadomorpha), appendage where rami of cirrus have setae arranged in groups along lesser curvature; like brushes (cf. ctenopod; acanthopod). [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Appendage (cirrus) with setae in transverse row at each articulation. [McLaughlin, 1980]

Latera

See: Latus [Martin, 2005]
See latus. [McLaughlin, 1980]

Lateral

Located away from midline; pertaining to the side. [Butler, T. H.]
Plate of cirriped shell between carinolateral and rostrum.
(syn. latus) [Moore and McCormick, 1969]
Referring to or toward side. [Hobbs and Jass, 1988]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Lateral plate. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of pair of compartmental plates typically located between carino- and rostrolaterals, with radius on carinal side and ala on rostral side, sometimes between carina and rostrolateral or compound rostrum; homologous with lepadomorph median latus. [McLaughlin, 1980]

Lateral artery

One of up to several pairs of blood vessels originating from sides of heart. Terminal pair often termed posterior aortas. [Stachowitsch, 1992]
Artery. [Stachowitsch, 1992]
Artery. [Stachowitsch, 1992]
Artery. [Stachowitsch, 1992]

Lateral bar

In Cirripedia (Acrothoracica), pair of chitinous thickenings (best developed in Cryptophialidae) running from chitinous apertural thickenings medially down each side of mantle sac. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) In acrothoracican, pair of chitinous thickenings reinforcing each side of mantle; extends from aperture halfway down body. [Stachowitsch, 1992]
(Taxon-specific: Suborder Leptolaimina) Pair of external chitinous thickenings extending from apertural thickenings medially down each side of mantle sac. [McLaughlin, 1980]

Lateral carina

See: Carapace carina e [Martin, 2005]
See: Carapace carinae e, Stomatopod integumental ornamentation [McLaughlin, 1980]
Narrow, longitudinal ridge extending along each side (lateral margin) of carapace. [Stachowitsch, 1992]

Lateral cecum

One of up to five pairs of digestive glands opening ventrolaterally into digestive tract at border between pyloric stomach and midgut. (See also dorsal cecum).
(syn. lateral diverticulum, digestive cecum) [Stachowitsch, 1992]

Lateral cups

Paired element of nauplius eye of nonmalacostracan crustaceans. [McLaughlin, 1980]

Lateral denticle

Small spine that may extend from the ventral edge of the carapace or be located on the outside of the carapace some distance above the edge.
See: Stomatopod integumental ornamentation [Mauchline, 1984]

Lateral depressor pit

In cirripeds, small hollow near basitergal angle of scutum for attachment of lateral depressor muscle. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Small depression near basitergal angle of scutum for attachment of lateral depressor muscle. [McLaughlin, 1980]

Lateral eye

Paired compound eyes of most Myodocopida. [Cohen, Peterson, and Maddocks, in press]

Lateral gastrocardiac markings

Insertions of attractor epimeralis muscle in brachyuran decapods lacking branchiocardiac groove. [McLaughlin, 1980]
Insertions of attractor epimeralis muscle in most Brachyura, in which the branchiocardiac groove has disappeared. [Moore and McCormick, 1969]
In crab-like (brachyuran) decapod, marking on each side of carapace formed by insertion of attractor epimeralis muscle (if normal point of insertion—branchiocardiac groove—is absent). [Stachowitsch, 1992]

Lateral lobe

One of the paired lateral parts, often folded, of the petasma. [Perez Farfante and Kensley, 1997]
Extension of each anterolateral margin of head; may accommodate eyes. (angular, rounded; prolonged).
(syn. anterior head lobe) [Stachowitsch, 1992]
Lobe. [Stachowitsch, 1992]
Lobe. [Stachowitsch, 1992]

Lateral margin

Differentiated edge of carapace in some advanced macrurans and many brachyurans. [Moore and McCormick, 1969]
In crab-like (brachyuran) decapod, outer edge of body formed by sharp bend in carapace. [Stachowitsch, 1992]

Lateral midgut diverticulum

(Taxon-specific: Family Cyatholaimidae) One of up to several pairs of lateral extensions of midgut. (bifurcate, multilobed, simple). [Stachowitsch, 1992]

Lateral muscle

Prominent longitudinal muscle band, one along each side of body. [Stachowitsch, 1992]

Lateral plate

One of the paired, adjacent flaps sometimes present of sternite XIV in females (Fig. 4A). [Perez Farfante and Kensley, 1997]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: in unstalked form, paired lateral plates, one located either between each rostrolateral and carinolateral or between carina and rostrolateral or rostrum. Consists of median paries with radius on one (carinal) side, ala on other (rostral) side. [Stachowitsch, 1992]

Lateral process

Pleurite. [Stachowitsch, 1992]

Lateral ramus

Outer branch (not necessarily equivalent to the exopod) (Fig. 1). [Perez Farfante and Kensley, 1997]

Lateral scutal depressor

Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Lateral spine

Posteriorly directed, spine-shaped projection on each side of abdominal somites (9th-19th postcephalic segments). Also interpreted as representing pleura. [Stachowitsch, 1992]

Lateral tooth

See: Carapace tooth c [Martin, 2005]
See: Carapace teeth c, Stomatopod integumental ornamentation [McLaughlin, 1980]
On carapace, one in a series of tooth-like projections along each side. According to position relative to cervical groove, one may distinguish anterolateral, mediolateral, and posterolateral teeth.
See: Anterolateral tooth [Stachowitsch, 1992]

Lateral wall

The subvertical portion of the carapace of crablike decapods extending ventrally from the later margin. [Chace and Hobbs, 1969]

Lattice organs

Fine cuticular cephalic chemosensory structure unique to thecostracans. [Brusca and Brusca, 2002]

Latus

Any of lepadomorph capitular plates except paired scuta and terga and unpaired rostrum, carina, subrostrum, and subcarina. Smaller plates in basal whorls below paired latera referred to as lower latera; sometimes all or some absent. Types of paired plates:
(a) carinal. Plate on each side of carina.
(b) inframedian. Plate below upper latus.
(c) median. Plate between rostral and carina latera in forms with paired latera in one whorl.
(d) rostral. plate on each side of rostrum or below scutum.
(e) upper. plate in upper whorl between scutum and tergum or carina.
(pl. latera) [McLaughlin, 1980]
In cirripeds (Lepadomorpha), any of paired plates forming part of shell, not including carina or rostrum or opercular plates (scutum, tergum). Includes following different types:
a) carinal. Plate located on either side of carina, with radii on either side and alae on rostral side; corresponds to carinolateral in Balanomorpha.
b) inframedian. Plate beneath median latera in some cirripeds (e.g., Arcoscalpellum).
c) lower. Plate in some cirripeds (e.g., Zeugmatolepas) near basis. (syn. imbricate plate(s))
d) median. One of series of plates between carina and rostrum which maybe disposed in whorls (e.g., Scillaelepas).
e) rostral. Plate located on either side of rostrum, with radii on both rostral and carinal sides; corresponds to rostrolateral in Balanomorpha.
f) upper. Plate between carinal and rostral latera just below opercular valves (e.g., scalpellids).
(syn. lateral) [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate: in stalked form, any plate on capitulum except scuta, terga, rostrum, subrostrum, carina, and subcarina. According to position one may distinguish carinal, inframedian, median, rostral, and upper paired latera. [Stachowitsch, 1992]

Lecithotrophic

(Taxon-specific: Family Cyatholaimidae) Feeding on yolk. [Boxshall and Halsey, 2004]

Leg

General term applied to appendage (thoracopod) of thorax or abdomen. Also termed phyllopod dur to flattened construction. [Stachowitsch, 1992]
Swimming leg, walking leg. [Stachowitsch, 1992]
Preferred term for any appendage after cephalic appendages, i.e., for thoracopod or poreopod. [Stachowitsch, 1992]

Levator muscle

A muscle which moves the limb upwards by rotating it about the CB joint. [Martin, 2005]

Lifting spine

In mandible, row of spine-like projections between molar process and lacinia mobilis. [Stachowitsch, 1992]

Ligament

connective tissue spanning from top of head to umbonal region of carapace. Joins body to carapace (along with adductor muscles).
(syn. attachment ligament) [Stachowitsch, 1992]

Light organ

Photophore. [Stachowitsch, 1992]

Limadiiformes

Carapace with recurvature of posterior margin near dorsal line. [McLaughlin, 1980]
Conchostracan carapaces exhibiting recurvature of posterior margin near dorsal line, characteristic of several of the Limnadioidea; pseudorecurvature observed in some leaiids. [Moore and McCormick, 1969]

Limb

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
(Taxon-specific: Family Cyatholaimidae) The paired appendage of the five cephalic and seven thoracic somites. A limb has three axes, anterioposterior, proximodistal, and dorsoventral (the latter often called mediolateral). A limb develops in steps and may be composed of up to three protopodal segments (praecoxa, coxa and basis), and usually an endopod and an exopod both of which may be segmented (see also appendage and swimming leg). [Ferrari and Dahms, in press]
One of a pair of appendages of each trunk segment. Each trunk limb is ventrolaterally directed and biramous, consisting of protopod with three-segmented exopod and four-segmented endopod. All limbs are homonomous, with the first being somewhat more slender and the posteriormost ones somewhat smaller. Bears different types of setae.
(syn. trunk limb, trunk appendage) [Stachowitsch, 1992]

Line of concrescence

The proximal edge of the zone of concrescence. [Cohen, Peterson, and Maddocks, in press]

Linea

Linear marking on carapace. [Moore and McCormick, 1969]
Linear marking on carapace.
(pl. lineae) [McLaughlin, 1980]

Linea anomurica

Longitudinal lateral groove defining upper margin of branchiostegite in Anomura. [Poore, 2004]
On carapace of certain decapods, longitudinal groove or uncalcifled line. [Stachowitsch, 1992]

Linea anomurica, L. homolica, L. thalassinica

A groove running from behind and forward on either side of the carapace (in Homoloidea, a superfamily of the Section Dromiacea). [Ingle, 1983]
Longitudinal groove or uncalcified line on carapace of many anomuran decapods. [Moore and McCormick, 1969]
Longitudinal groove or uncalcified line on carapace of many anomuran decapods. [McLaughlin, 1980]
Longitudinal groove or uncalcified line on carapace which may form a hinge; such lines found in various groups, from which come the names. [Williams, 1984]

Linea branchiostegalis

Longitudinal groove or uncalcified line extending backwards from front margin of carapace slightly above branchiostegal spine and reaching to or beyond hepatic spine (e.g., palaemonid carideans). [Moore and McCormick, 1969]
Longitudinal groove or uncalcified line extending posteriorly from anterior margin of carapace, slightly above branchiostegal spine, to or slightly beyond hepatic spine in some caridean decapods. [McLaughlin, 1980]
In shrimp-like (natantian) decapod, longitudinal groove or uncalcified line extending from anterior margin of carapace (slightly above branchiostegal spine) to or slightly beyond hepatic spine. [Stachowitsch, 1992]

Linea dromica

Feature on carapace of dromiid crabs comparable to thalassinica.
(syn. linea dromiidica) [Moore and McCormick, 1969]
Longitudinal groove or uncalcified line on dromioidean decapods comparable with linea thalassinica.
(syn. linea dromiidica) [McLaughlin, 1980]
On each side of carapace in certain decapods, longitudinal groove or uncalcified line— comparable to linea thalassinica—extending from anterior to posterior margin.
(syn. linea dromiidica) [Stachowitsch, 1992]

Linea dromiidica

See: Linea dromica [Martin, 2005]
See linea dromica. [McLaughlin, 1980]

Linea homolica

Feature similar to linea thalassinica and possibly equivalent to it. [Moore and McCormick, 1969]
Longitudinal groove or uncalcified line on homoloidean decapods comparable with or equivalent to linea thalassinica. [McLaughlin, 1980]
On each side of carapace in certain decapods, longitudinal groove or uncalcified line—comparable to linea thalassinica—extending from anterior to posterior margin. [Stachowitsch, 1992]

Linea lateralis

Longitudinal groove or uncalcified line extending backward from front margin of carapace below orbit, in some forms to rear extremity of carapace (e.g., some penaeids). [Moore and McCormick, 1969]
Longitudinal groove ot uncalcified line extending posteriorly from frontal margin of carapace below orbit sometimes to posterior extremity of carapace in some penaeoideans. [McLaughlin, 1980]
In shrimp-like (natantian) decapod, longitudinal groove or uncalcified line extending from frontal margin of carapace (below orbit) as far as posterior extremity of carapace. [Stachowitsch, 1992]

Linea thalassinica

Longitudinal groove or uncalcified line on dorsal part of carapace extending from anterior margin below antennal spine across entire length of carapace to its posterior edge (most thalassinoid decapods). [Moore and McCormick, 1969]
Longitudinal groove or uncalcified line on dorsal part of carapace extending from anterior margin below antennal spine to posterior margin in most thalassinoideans. [McLaughlin, 1980]
Longitudinal lateral groove defining upper margin of branchiostegite in Thalassinidea. [Poore, 2004]
On each side of carapace in certain decapods, longitudinal groove or uncalcified line extending from anterior region below antennal spine to posterior margin. [Stachowitsch, 1992]

Linguiform

Tongue shaped. [Kensley and Schotte, 1989]

List

In closing apparatus of valve, less prominent, ridge-like elevation along inner margin; located on thickened part (duplicature) of inner lamella, above major ridge (selvage). See also flange, selvage groove). [Stachowitsch, 1992]
Ridge on proximal side of selvage on contact margin. [McLaughlin, 1980]

Liver

Cecum. [Stachowitsch, 1992]

Lobe

One of four (two anteromedian and two anterolateral = lateral) extension of anterior (antennulary) part of head (cephalon). Anteromedian lobes occasionally termed rostral plate. Configuration of lobes is of taxonomic importance. [Stachowitsch, 1992]
Type of valve sculpture: rounded, major protuberance. According to position one may distinguish, e.g., anterior, median, and posterior lobes (designated L1, L2, and L3). Typically separated by grooves (sulci). Also refers to lobes of appendages. [Stachowitsch, 1992]

Locking folds, dorsal

Paired projections of the male's first pleopod's dorsal cuticle. They form a seat for the medial edge of the second pleopods, allowing both pairs of pleopods to function together during mating or as an operculum. [Wilson, 1989]

Longitudinal canal

See longitudinal tube. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Longitudinal tube. [Stachowitsch, 1992]

Longitudinal septum

In cirripeds (Balanomorpha), wall of tubes disposed normal to inner and outer laminae of compartment plate separating them.
(syn. parietal septum) [Moore and McCormick, 1969]
Partition disposed normal to inner and outer laminae of compartmental plate in some balanomorph cirripeds, resulting in longitudinal tubes.
(pl. longitudinal septa) (syn. parietal tubes) [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell feature: in unstalked form, one in a series of longitudinal walls between inner and outer lamellae of compartmental plate. Septa are arranged perpendicular to lamellae and form canals (longitudinal tubes). (primary, secondary).
(syn. parietal septum) [Stachowitsch, 1992]

Longitudinal suture

Fine longitudinal line extending posteriorly just above the base of the antennal spine. [Perez Farfante and Kensley, 1997]

Longitudinal tube

Canal formed in compartmental plate of some balanomorph cirripeds between longitudinal septa and inner and outer lamina.
(syn. longitudinal canal, parietal tube, parietal pore) [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, one in a series of canals between inner and outer lamellae of compartmental plate. Formed by series of longitudinal septa between the lamellae.
(syn. longitudinal canal, parietal tube, parietal pore) [Stachowitsch, 1992]

Lophodont hinge

A merodont hinge in which all elements are smooth. [Cohen, Peterson, and Maddocks, in press]

Lower lateral

Valve in shell of some cirripeds.
See: Latus (lower) c [Moore and McCormick, 1969]

Lower latus

(Taxon-specific: Order Rhabditida) Barnacle plate: in stalked form, general term for one of a number of smaller plates forming a series (whorl) below each upper latus. [Stachowitsch, 1992]

Lower lip

See: Metastoma [Martin, 2005]
See metastoma. [McLaughlin, 1980]
(Taxon-specific: ) Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Labium. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Refers to either 1) paragnaths of labium surrounding mouth posteriorly or 2) lip-like lower margin (bearing labial spines and associated glands) of proboscis. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]

Lower submedian spine

Lateral spine of carapace, between submedian and hepatic spines of Mesocrangon muntinella. [Butler, T. H.]

Lumen

The hollow canal extending the length of the setal shaft interior. [Watling, 1989]

Luminescent organs

Areas producing light on the shrimp body; internal as part of gastro-hepatic gland (organ of Pesta), or as dermal photophore.
(syn. luminous) [Butler, T. H.]
Photophore. [Stachowitsch, 1992]
Photophore. [Stachowitsch, 1992]

Lunule

Attachment disc at base of antennule in some parasitic copepods. [McLaughlin, 1980]
(Taxon-specific: Family Cyatholaimidae) A sucker-like structure located ventrally on the frontal plates on the anterior margin of the flattened cephalothorax of some caligiform copepods. [Boxshall and Halsey, 2004]
In parasitic copepod, one of two anteroventral sucker-like structures on anterior margin (frontal plate) of head. (crescent-shaped, round). [Stachowitsch, 1992]

MC

The junction between the merus and the carpus (Fig. 12). [Warner, 1977]

Majid seta

Anteriormost, usually prominent, submarginal seta on carapace postereio-lateral margin of oxyrhynch zoeae. Identified as a pappose type in species studied. [Ingle, 1992]

Major claw

Enlarged chela in decapods. [Brusca and Brusca, 2002]

Male-cell receptacle

In Cirripedia (Rhizocephala), pocket or pair of pockets within mantle cavity of female into which dedifferentiated cells of male cyprid migrate and differentiate into "testes.". [Moore and McCormick, 1969]
(Taxon-specific: Suborder Enoplina) Pocket or pair of pockets within mantle cavity of female receiving cells of male cyprid, later differentiated into "testes". [McLaughlin, 1980]

Manca

In isopods and certain other Peracarida, one of the first three stages or instars of the postmarsupial life cycle, wherein the seventh pereopod is absent or rudimentary. In some janiorideans (e.g. Lipomera) this condition is retained in the adult; for these taxa, the manca stage can not be identified by an absence of the last pereopod. [Wilson, 1989]
Prejuvenile hatching stage lacking the last pair of thoracopods in peracarids. [Brusca and Brusca, 2002]
Young of some Peracarida (e.g., Isopoda, Tanaidacea, Cumacea) in which last thoracopod is lacking. [Moore and McCormick, 1969]
Young of some Peracarida lacking last thoracopod at time of release from marsupium. [McLaughlin, 1980]
First larval stage after release from brood pouch (marsupium). Resembles adult, yet lacks last (fifth) pair of pereopods. [Stachowitsch, 1992]
Larval stage at which tanaidaceans are released from brood pouch (marsupium). Consists of several substages. [Stachowitsch, 1992]
First free-living larval stage after release from brood pouch (marsupium). Resembles adult, yet characterized by lack of last (= seventh) pair of pereopods. [Stachowitsch, 1992]
Young of most peracarids (including isopods), lacking last (eighth) thoracic appendages at time of release from broodpouch. [Wetzer et al. 1997]
Young of some peracaridean crustaceans (including isopods), lacking last thoracic appendage at time of release from broodpouch. [Kensley and Schotte, 1989]
In certain thermosbaenaceans, stage at which larva is released from brood pouch. Lacks last two pairs (seventh and eighth) of thoracopods and pleopods. [Stachowitsch, 1992]

Manca stage

A post-embryonic stage in development; manca II leaves the marsupium. [Holdich and Jones, 1983]
(Taxon-specific: Class Secernentea) Postlarval stage at which leptostracans hatch. Well developed, differing from adult in having rudimentary fourth pleopod pair.
(syn. mancoid stage) [Stachowitsch, 1992]

Mancoid stage

Postlarval leptostracan that differs from adult in having rudimentary 4th pleopod. [Moore and McCormick, 1969]
(Taxon-specific: Class Adenophorea) Postlarval stage with rudimentary 4th pleopod. [McLaughlin, 1980]

Mandible

Most anterodorsally situated of gnathal appendages; one, of a pair, of heavily calcified jaws; the "teeth." [Hobbs and Jass, 1988]
On of the heavily calcified jaws lying anterior to (beneath, in ventral view) the other mouth parts but visible in certain crabs. [Chace and Hobbs, 1969]
One of 3rd pair of cephalic appendages, used to masticate food. [McLaughlin, 1980]
One of a pair of heavily calcified jaws situated anterodorsal to other gnathal appendages. [Hobbs, Hobbs, and Daniel 1977]
One of the heavy calcified jaws lying anterior to (beneath in ventral view) other mouth parts. [Butler, T. H.]
One of the heavy calcified jaws lying anterior to (beneath, in ventral view) to other mouth parts. [Perez Farfante and Kensley, 1997]
One of third pair of cephalic appendages used to masticate food. [Moore and McCormick, 1969]
The third cephalic appendage, and first mouthpart appendage of isopods. It generally has a lateral three-articled palp and is made up of the following functional regions: incisor process, spine row, molar process, dorsal condyle, and posterior articulation. [Wilson, 1989]
Third limb of cephalon, comprising a thick body with mesial molar process, terminal incisor process and mandibular palp, usually of 3 articles. [Poore, 2004]
(Taxon-specific: ) Third paired appendage of head; relatively small and simple (i.e., without palp). Typically with simple ridged or toothed distal end which extends under labrum. [Stachowitsch, 1992]
Third paired appendage of head; located between small antennae and maxillules and extending under labrum. Relatively large, simple (without palp), and with toothed or spinous distal end. [Stachowitsch, 1992]
Third paired appendage of head; located between large antennae and maxillules. Simple (i.e., without palp), massive, with ridged or toothed terminal molar processes extending into preoral cavity (atrium oris) under labrum. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Third paired appendage of head; located between antennae and maxillules and extending under labrum. Relatively large, with undivided distal end. (without palp, with vestigial palp). [Stachowitsch, 1992]
Third paired appendage of head (cephalon); located between antennae and maxilules and extends into atrium oris under labrum. Bears terminal molar and incisor processes. [Stachowitsch, 1992]
Third paired appendage of head (cephalon); located between antennae and maxillules. Represents first pair of mouthparts and, if fully developed, consists (proximally to distally) of molar process, spine row, lacinia mobilis, and incisor process. (base: pointed, truncate). [Stachowitsch, 1992]
Third paired appendage of head; located between antennae and maxillules. Represents first pair of mouthparts and, if fully developed, consists (proximally to distally) of molar process, spine row, lacinia mobilis, incisor process, as well as a palp. Mouthparts may be absent in male. (monocondylic, dicondylic). [Stachowitsch, 1992]
Anteriormost paired mouthpart on underside of head; borne by third cephalic segment (mandibular somite). If fully developed, bears terminal molar and incisor processes as well as palp. [Stachowitsch, 1992]
Third paired appendage of head (cephalon); located between antennae and maxillules. Represents first pair of mouthparts and, if fully developed, consists (proximally to distally) of molar process, spine row, lacinia mobilis, incisor process, and palp. (with/without palp). [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
First pair of mouthparts, functioning as jaws, often sclerotized. [Kensley and Schotte, 1989]
H & I [Wetzer et al. 1997]
Third pair of head appendages; first (anteriormost) pair of mouthparts functioning as jaws and typically sclerotized. [Wetzer et al. 1997]
Third paired appendage of head (cephalon); located between antennae and maxillules. Represents first pair of mouthparts and, if fully developed, consists (proximally to distally) of molar process, spine row, lacinia mobilis, incisor process, and palp, (biting/chewing, piercing/sucking = styliform). [Stachowitsch, 1992]
Third paired appendage of head. Located between antennules and maxillules. Represents first pair of mouthparts. If fully developed, consists (proximally to distally) of molar process, pars centralis (spine row), lacinia mobilis, incisor process, and palp. Left and right mandibles differ considerably. [Stachowitsch, 1992]
Anteriormost paired mouthpart on underside of head (cephalon); borne on third cephalic somite. Well developed, bearing molar and incisor processes. (with/without palp). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Third paired appendage of head (cephalon); located between antennae and maxillules. Represents first pair of mouthparts and, if fully developed, consists of basal incisor and molar processes as well as distal palp. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Paired, serrate mouthpart closely associated with mouth on underside of head. Typically enclosed, along with mouth and surrounding labrum and paragnaths, in proboscis. Lacks palp. [Stachowitsch, 1992]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) First pair of mouthparts on head. Consists largely of gnathobase and, in acrothoracican, bears palps. Typically closely associated with labrum. (with/without palp; serrate, suctorial). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The paired limb of the somite of the cephalon posterior to antenna 2. The mandible bears a coxal gnathobase during the copepodid phase of development; it may (the fourth to sixth naupliar stages of calanoid copepods) or may not (all other copepods) bear a coxal gnathobase during naupliar phase of development. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The third cephalic appendage. [Boxshall and Halsey, 2004]
Third paired appendage of cephalon; located between antennae and maxilllules. Biramous, consisting of protopod, four-segmented endopod, and seven-segmented exopod. Projection (gnathobase) of protopod extends under labrum. Serves in locomotion and feeding. [Stachowitsch, 1992]
3rd limb (3rd head limb). [Cohen, Peterson, and Maddocks, in press]
Anterior-most paired mouthpart on underside of head. Basically a biramous, limb-like appendage consisting of proximal gnathobase and distal palp (the latter with endopod and exopod). (biramous, uniramous; falcate, stylet-like = styliform). [Stachowitsch, 1992]
Third paired appendage of head. Mandibles flank mouth and are basically biramous, consisting of proximal gnathobase and distal palp. [Stachowitsch, 1992]
Anterior-most paired, asymmetrical mouthpart on underside of head (cephalon); lacks palp. Each mandible bears three masticatory processes (incisor process, lacinia mobilis, molar process) which lie in cavity (atrium oris) between labrum and mouth. [Stachowitsch, 1992]
Third paired appendage of head; located between antennae and maxillules. Represents first pair of mouthparts. If fully developed, consists of molar and incisor processes as well as palp. (with/without palp) (See also penicilla). [Stachowitsch, 1992]
Third paired appendage of cephalon; located between antennae and maxillules. Represents first pair of mouthparts. Consists (proximally to distally) of molar process, lifting spines, lacinia mobilis, incisor process, and palp. [Stachowitsch, 1992]
Third paired appendage of head (cephalon); located between antennae and maxillules. Represents first pair of mouthparts and typically consists of basal molar and incisor processes as well as a distal palp. (with/without palp). [Stachowitsch, 1992]

Mandible body

Inflated base (coxa) of mandible providing for attachment of mandibular muscles.
(syn. body of mandible, corpus mandibulae) [Moore and McCormick, 1969]
Inflated base of mandible for attachment of mandibular muscles.
(syn. corpus mandibulae) [McLaughlin, 1980]

Mandibles

Most anterior part of anterior mouthparts situated on either side of oral opening. [Holdich and Jones, 1983]
Paired mouthparts used to macerate food. Consists of a fairly hard, chitinised region with spines and, often, opposed grinding surfaces. A segmented palp is often present and used to manipulate food. [Mauchline, 1984]
Paired, jaw-like cutting, grinding or crushing appendages at the mouth of a decapod and other crustaceans. [Bliss, 1982]
The appendages of the 4th head segment. They form a pair of jaws which bite from side to side across the mouth. [Warner, 1977]
The first (most anterior) pair of mouthparts. [Brusca and Brusca, 2002]
The first pair of mouthparts (or third pair of appendages). [Ingle, 1983]

Mandibular artery

Artery. [Stachowitsch, 1992]

Mandibular foramen

Relatively large opening in body of mandible for passage of transverse adductor muscle. [Moore and McCormick, 1969]
Relatively large opening in mandibular body for passage of transverse adductor muscle. [McLaughlin, 1980]

Mandibular groove

Transverse groove located between cervical groove and dorsal organ in anterior region of carapace. [Stachowitsch, 1992]
Transverse groove located between cervical groove and dorsal organ in anterior region of carapace. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Transverse groove across dorsal surface of head; superficially divides head into anterior and posterior regions. [Stachowitsch, 1992]
Cervical groove. [Stachowitsch, 1992]

Mandibular lobe

In lower lip (labium), posterolateral extension of each paragnath.
(syn. mandibular process) [Stachowitsch, 1992]

Mandibular palp

A small, inwardly curved, segmented, flattened endite on the dorsal face of the mandible. [Ingle, 1983]
Distal articulated part of mandible that functions as aid in feeding or cleaning. [Moore and McCormick, 1969]
Distal articulated part of mandible used in feeding or cleaning. [McLaughlin, 1980]
One-to-three-segmented endopod attached laterally to the masticatory part of the mandible. [Perez Farfante and Kensley, 1997]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Mandibular stylet

(Taxon-specific: Family Cyatholaimidae) The gnathobase of siphonostomatoids, modified as a slender process. [Boxshall and Halsey, 2004]

Mantle

Fleshy structure of cirripeds strengthened by five calcified plates (carina, terga, scuta). [Moore and McCormick, 1969]
(Taxon-specific: ) Large, gelatinous envelope enclosing body in certain water fleas. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In barnacle, soft outer part of body typically covered by a series of plates. In other cirripeds, outer cover of body. Often referred to as carapace. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Membranous covering of body, often strengthened by calcareous plates in thoracic Cirripedia.
See: Carapace [McLaughlin, 1980]

Mantle cavity

Space in cirripeds occupied by body, opening by posteroventral aperture. [Moore and McCormick, 1969]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) In barnacle, space between main, appendage-bearing part of soft body and outer wall (mantle). Eggs may be stored in mantle cavity. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Space occupied by body, with aperture. [McLaughlin, 1980]

Manus

Another term for chela. [Butler, T. H.]
Broad proximal part of cheliped propodus (i.e., this propodus minus fixed finger).
(syn. palm) [Moore and McCormick, 1969]
Broad proximal part of propodal cheliped.
(syn. palm) [McLaughlin, 1980]
In pincer (chela), broad proximal part of next to last segment (propodus); movable finger (dactylus) closes on distal extension (fixed finger) of propodus.
(syn. palm, hand) [Stachowitsch, 1992]

Margin

Entire margin of carapace (or valve) when viewed from the side. Free margin refers to margin of carapace not held together by hinge (i.e., anteriorly, ventrally, posteriorly), while contact margin is restricted to that part of free margin of each valve that touches each other when carapace is closed. (See also edge).
(syn. border) [Stachowitsch, 1992]

Marginal carina

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Marginal groove

See: Carapace groove g [Martin, 2005]
See: Carapace grooves k [McLaughlin, 1980]
On each side of carapace, groove close to and parallel with margin; according to position one may distinguish lateromarginal and posteromarginal grooves.
(syn. lateromarginal groove, posteromarginal groove) [Stachowitsch, 1992]

Mariculture

Large-scale cultivation of marine organisms under controlled conditions, for use as food or for other economic purposes; also utilization of the marine habitat for cultivation of aquatic organisms. [Bliss, 1982]

Marsupium

A ventral pereonal enclosure on females for developing embryos. It is composed of oostegites projecting medially from the coxae of the anterior pereopods (Pereopoda I-VI in the munnopsids). [Wilson, 1989]
Brood pouch. [Moore and McCormick, 1969]
Brood pouch. [McLaughlin, 1980]
Chamber on ventral surface of female formed by overlapping oostegites in which the eggs, embryos and mancas are brooded. [Holdich and Jones, 1983]
Ventral brood pouch formed from inwardly directed plates of the leg coxae (called oostegites) in most peracarids. [Brusca and Brusca, 2002]
Brood chamber. [Stachowitsch, 1992]
In female, chamber formed on ventral surface of pereon by oostegites.
See: Ovisac [Stachowitsch, 1992]
Brood pouch. [Stachowitsch, 1992]
Brood pouch. [Stachowitsch, 1992]
Structure in which eggs and embryos are retained and brooded by female the broodpouch. Isopod marsupia are typically formed by overlapping medial plates (oostegites) arising from certain pereonal coxae in females; in a few groups the oostegites have been reduced or lost in lieu of internal brooding. [Wetzer et al. 1997]
Structure in which eggs are retained by female, the broodpouch. [Kensley and Schotte, 1989]
In female, chamber formed on ventral surface of thorax on two to seven pairs of oostegites. Serves to brood eggs and embryos.
(syn. brood pouch) [Stachowitsch, 1992]
Brood pouch. [Stachowitsch, 1992]

Masticatory process

See: Gnathal lobe [Martin, 2005]
See gnathal lobe. [McLaughlin, 1980]
See endite.
(syn. maxilla)
See: Endite [Cohen, Peterson, and Maddocks, in press]

Mastigobranch

Slender respiratory at base of epipod.
(syn. mastigobranchia) [McLaughlin, 1980]
Slender respiratory process at base of epipod(ite).
(syn. mastigobranchia (pl., mastigobranchiae)) [Moore and McCormick, 1969]
In basal segment (coxa) of thoracic appendage (thoracopod), that part of epipodite which is not modified as gill (podobranch). Projects between gills and serves as both supporting and respiratory structure. [Stachowitsch, 1992]

Mastigopus

Postlarva. [Stachowitsch, 1992]

Mastigopus stage

Larval stage in development of some decapods equivalent to adult of Leucifer. [McLaughlin, 1980]
Larval stage in ontogeny of some decapods equivalent to permanent adult form of Leucifer (penaeid). [Moore and McCormick, 1969]

Maxilla

Appendage next behind maxillule serving functions in feeding and respiration.
(syn. second maxilla) [Moore and McCormick, 1969]
One of a pair of two sets gnathal appendages situated immediately posteroventral to mandibles. [Hobbs and Jass, 1988]
One of a pair of two sets of appendages lying immediately posterior to the mandible. [Hobbs, Hobbs, and Daniel 1977]
One of two paired appendages in mouth region, posterior to (above in ventral view) mandible.
(pl. maxillae) [Butler, T. H.]
Paired appendage of 5th cephalic somite, used in feeding, often also in respiration.
(pl. maxillae) (syn. 2nd maxilla) [McLaughlin, 1980]
Paired mouthpart appendages of the fourth and fifth cephalic somites.
(pl. maxillae) [Perez Farfante and Kensley, 1997]
Paired mouthparts used to filter food particles from the water. They are located immediately posterior to the mandibles and labia, and are usually laminar in form. [Mauchline, 1984]
The third paired mouthpart and fifth cephalic appendage. In the Janiroidea, it consists of a basal segment bearing three setose lobes. [Wilson, 1989]
Third limb of cephalon, small, complex and membranous.
(syn. maxilla 2) [Poore, 2004]
(Taxon-specific: ) Fifth and last paired appendage of head. Typically absent, yet if present, then reduced to tiny lobe. Associated with opening of maxillary gland. (absent, rudimentary).
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head; located between maxillules and first thoracopods. Associated with opening of maxillary gland. (with well-developed lobe, reduced, absent).
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head; located between maxillules and first trunk appendages. If present, tiny, setose, and lobe-like. Associated with opening of maxillary gland. (vestigial, absent).
(syn. second maxilla) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Fifth paired appendage of head; located between maxillules and first thoracopods. relatively small, reduced to simple lobe.
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head (cephalon); located between maxillules and first thoracopods. Consists of protopod with five to six endites and large pseudepipod, six-segmented endopod, and two-segmented exopod.Basically biramous, although occasionally referred to as tri-, multi-, or polyramous due to numerous endites and pseudepipod.
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head (cephalon); located between maxillules and first maxillipeds. Represents third pair of mouthparts and consists of base (protopod) with two endites as well as lateral flabellum (exopod).
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head; located between maxillules and maxillipeds. Represents third pair of mouthparts and, if fully developed, consists of protopod bearing two endites. May be reduced to simple lobe. Mouthparts may be absent in male. [Stachowitsch, 1992]
Third paired mouthpart on underside of head; borne on fifth cephalic segment (maxillar somite) and located between maxillule and first maxilliped. Typically consists of protopod, two endites, palp, and scaphognathite.
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head (cephalon); located between maxillules and maxillipeds. Represents third pair of mouthparts. Relatively small, consisting of base and two endites.
(syn. second maxilla) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
(1 and 2). Two sets of paired mouthpart appendages immediately posterior to mandible. [Kensley and Schotte, 1989]
C & E [Wetzer et al. 1997]
Fifth pair of head appendages, functioning as mouthparts, immediately posterior to maxillules (=second maxillae).
(pl. maxillae) [Wetzer et al. 1997]
Fifth paired appendage of head (cephalon); located between maxillules and maxillipeds. Represents third pair of mouthparts. Relatively small, consisting of base and two or three endites.
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head; located between maxillules and maxilipeds. Represents third pair of mouthparts and consists of base bearing two to three endites, two-segmented endopod (palp), and exopod.
(syn. second maxilla) [Stachowitsch, 1992]
Third paired mouthpart on underside of head (cephalon); borne on fifth cephalic somite and located posterior and external to maxillules. Conists of four segments, the first being cylindrical, the others flattened; segments one and two with endites (that of second is bilobed). Bears opening of maxillary gland.
(syn. second maxilla) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Fifth paired appendage of head (cephalon); located between maxillules and first pair of thoracopods. Represents third pair of mouthparts and, if fully developed, consists of proximal section with four endites as well as distal branches (endopod and exopod). Maxillary glands open at base of maxillae.
(syn. second maxilla) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Paired appendage on underside of head between maxillules (suction discs) and first thoracopods. Uniramous, consisting of several spinose segments and terminal claw. Bears basal plate and opening of maxillary gland basally.
(syn. second maxilla) [Stachowitsch, 1992]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Third paired mouthpart on head. Consists largely of gnathobase; associated with openings of maxillary glands. (fused, not fused) (See also oral pyramid).
(syn. second maxilla) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The fifth and last pair of cephalic appendages. [Boxshall and Halsey, 2004]
Fifth paired appendage of cephalon; located between maxillules and maxillipeds. Uniramous, consisting of protopod (with endites) and four-segmented shaft. Serves in locomotion and feeding.
(syn. second maxilla) [Stachowitsch, 1992]
Third paired mouthpart on underside of head; located between maxillules and maxillipeds. Uniramous, either setose and serving in suspension feeding, with terminal hooks/spines and serving as a raptorial organ, or arm-like and modified for attachment to host. Bears opening of maxillary gland basally. The term second maxilla is often preferentially applied.
(syn. second maxilla) [Stachowitsch, 1992]
Third paired mouthpart on underside of head (cephalon) posterior to maxillules. Uniramous, consisting of six or seven segments, and with main point of flexure between third and fourth segments. First two or three segments bear endites, the last bears terminal claw; all segments bear setae along inner margin. (prehensile, subchelate).
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head; located between maxillules and maxillipeds or between maxillules and first thoracopods. Represents third pair of mouthparts and bears two to four endites.
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of cephalon; located between maxillules and maxillipeds. Represents third pair of mouthparts and consists of protopod bearing three endites, palp (endopod), and small lobe (exopod).
(syn. second maxilla) [Stachowitsch, 1992]
Fifth paired appendage of head (cephalon); located between maxillules and first thoracopods. Represents third pair of mouthparts and, if fully developed, consists of three-segmented base (protopod) with two endites as well as distal endopod (palp) and exopod. (foliaceous).
(syn. second maxilla) [Stachowitsch, 1992]

Maxillae

Second maxilla; mouthparts immediately posterior to maxillules
sessile eyes - eyes set directly on the head. [Brusca and Brusca, 2002]
The appendages of the 5th and 6th head segments are the first and second pairs of maxillae respectively (Fig. 3). Both pairs are included in the mouthparts and the 2nd maxillae bear the scaphognathites. [Warner, 1977]
The third pair of mouthparts (or fifth pair of appendages). [Ingle, 1983]
Third pair of mouthparts (maxillae 2). [Holdich and Jones, 1983]

Maxillary gland

Excretory organ in maxillary somite with duct opening on maxilla.
(syn. shell gland) [McLaughlin, 1980]
Excretory organ located in maxillary segment, having its duct opening on maxilla.
(syn. shell gland) [Moore and McCormick, 1969]
Nephridial excretory organs exiting via a pore at the base of the maxillae. [Brusca and Brusca, 2002]
(Taxon-specific: ) One of two excretory organs located in head and opening ventrally at level of maxillae. Forms several loops.
(syn. shell gland) [Stachowitsch, 1992]
One of two excretory organs located in head and opening ventrally on maxillae. Highly elongated, forming loops visible through carapace on each side of median keel.
(syn. shell gland) [Stachowitsch, 1992]
One of two excretory glands located in head (and extending into carapace); opens ventrally at level of maxillae. Forms several loops.
(syn. shell gland) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two excretory glands located in head and opening ventrally at level of reduced maxillae. [Stachowitsch, 1992]
One of two simple excretory organs in head (cephalon); each opens via pore on posterior surface of base of maxilla. [Stachowitsch, 1992]
Pair of excretory glands located in head, one opening to exterior at base of each maxilla. [Stachowitsch, 1992]
Pair of excretory organs in head, one opening to exterior at base of each maxilla. [Stachowitsch, 1992]
Pair of excretory organs in head (cephalon), one opening at base of each maxilla.
See: Antennal gland [Stachowitsch, 1992]
In certain mysidaceans, one of two excretory glands in head, each opening to exterior at base of maxilla. (See also antennal gland). [Stachowitsch, 1992]
Pair of excretory organs in head (cephalon), each opening to exterior via pore on basal segment of maxilla. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Pair of excretory glands located in head under carapace adductor muscle, one opening to exterior at base of each maxilla. (See also antennal gland). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two relatively large excretory organs located in head, each opens at base of maxilla and consists of end sac and duct. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of two excretory organs located in head and opening via ducts at level of maxillae. [Stachowitsch, 1992]
Excretory gland, one opening at base of each maxilla. (See also antennal gland). [Stachowitsch, 1992]
Pair of excretory organs, one located in each posterolateral corner of head (cephalon); open to exterior at base of each maxilla. [Stachowitsch, 1992]
One of two excretory glands located in posterior region of head. Consists of convoluted tubules opening on maxillae. In bathynellacean, loop of tubule extends posteriorly to level of fourth thoracic somite. (See also uropodal gland). [Stachowitsch, 1992]

Maxillary hook

On ventral surface of head in parasitic copepod, one of two posteriorly directed, hook-like processes posterior to antennae. [Stachowitsch, 1992]

Maxilliped

Anterior thoracic limb (one, two, or three) modified to act as mouth part, its body segment usually fused to cephalon. [Moore and McCormick, 1969]
One of a pair of three sets of appendages lying immediately posterior to the maxilla. [Hobbs, Hobbs, and Daniel 1977]
One of a pair of three thoracic appendiges, arising posterior to the primary mouthparts. The two anterior pairs are often modified for feeding, while the third pair (Fig.1) is often pediform, resembling the pereopods. [Perez Farfante and Kensley, 1997]
One of pair of three sets of gnathal appendages lying immediately posterior to second pair of maxillae. (see Fig. 14). [Hobbs and Jass, 1988]
One of the pair of three sets of cephalothoracic appendages arising posterior to the primary mouth parts. The most prominent set, the third or outer maxillipeds, are, in the shrimps, slender elongate appendages resembling the pereiopods and, in the crabs, broadened and flattened structures that close to form a more or less complete operculum over the other mouth parts. [Chace and Hobbs, 1969]
One of three paired appendages posterior to the maxillae; most prominent pair, the third or outer maxillipeds elongate in shrimps, resembling pereiopods; in penaeidean shrimps, second maxillipeds also prominent. [Butler, T. H.]
One of three pairs of complex thoracic mouthparts; maxilliped 1 is membraneous like the maxilla, maxilliped 2 a little more robust, and maxilliped 3 is much larger and may be more or less opercular over the other mouthparts in crabs or pereopod-like in shrimps and prawns. [Poore, 2004]
Paired appendage on the posterior and ventral edge of the cephalon. Actually it is the first thoracic appendage, but its body somite is fused into the cephalon, and it is modified for feeding. It consists of the following functional parts: coxa, basis bearing a flattened and setose endite, palp with five segments (ischium, merus, carpus, propodus, dactylus), and epipod attached laterally to the coxa. [Wilson, 1989]
The second pair of maxillae of euphausiids are often referred to as maxillipeds. They are thoracic in origin and there may be 1-3 pairs, depending on the type of crustacean. They handle the food. [Mauchline, 1984]
One of first three pairs of thoracopods serving as mouthparts and belonging to three thoracic somites fused to head. Basically consists of basal section (coxa, basis) bearing five-segmented palp (endopod: ischium, merus, carpus, propodus, dactylus) as well as an exopod. (See also epipod, retinaculum).
(syn. maxillipede) [Stachowitsch, 1992]
Fourth and largest pair of mouthparts. Represents modified pair of appendages (thoracopods) of first thoracic segment (which is fused to head). Basically consists of proximal section (coxa, basis) bearing segmented palp. Coxa bears well-developed epipod; basis bears endite. Variously fused to one another basally.
(syn. maxillipede) [Stachowitsch, 1992]
One of three pairs of mouthparts posterior to maxillae on underside of head. Maxillipeds represent highly modified and anteriorly displaced first three pairs of thoracic appendages (thoracopods); basically consist of protopod (bearing endite and epipodite), endopod, and exopod. Posterior pair(s) increasingly resemble fourth through eighth thoracopods (pereopods) and may bear gills (podobranchs).
(syn. maxillipede)
See: Crista dentata [Stachowitsch, 1992]
Fourth and largest pair of mouthparts. Represents highly modified pair of appendages (thoracopods) of first thoracic segment (which is fused to head). Basically consists of basal section (coxa, basis) bearing a five-segmented (ischium, merus, carpus, propodus, dactylus) palp. Basis and ischium typically with endites. Maxilliped pair variously fused, (with/without palp; maxilliped pair: with fused coxae, with fused coxae and endites, reduced to single unpaired plate).
(syn. maxillipede) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
First paired appendage of the thorax; usually incorporated into the mouthparts. [Kensley and Schotte, 1989]
Fourth and largest pair of mouthparts. Represents highly modified pair of appendages (thoracopods) of first thoracic segment (which is fused to head). Basically consists of basal section (coxa, basis) bearing five-segmented (ischium, merus, carpus, propodus, dactylus) palp. Segments may bear variously developed endites. Maxillipeds may be coupled to one another by retinacula.
(syn. maxillipede) [Stachowitsch, 1992]
F & G [Wetzer et al. 1997]
Modified first pair of thoracopods, functioning as mouthparts.
(pl. maxillipeds) [Wetzer et al. 1997]
Two pairs (rarely one, three, or four) of mouthparts posterior to maxillae. Represents modified endopod of thoracopod.
(syn. maxillipede) [Stachowitsch, 1992]
Term occasionally applied to first five appendages (thoracopods) of thorax.
(syn. maxillipede) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Maxilla. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of up to three anterior pairs of thoracic appendages (cirri) modified as mouthparts. First maxillipeds of acrothoracican may also be termed mouth cirri.
(syn. maxillipede) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The first pair of thoracic appendages located on the last somite of cephalosome. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) The paired limb of the first thoracic somite of copepods. [Ferrari and Dahms, in press]
Sixth paired appendage of body. Typically biramous, consisting of protopod (with endites) bearing three-segmented endopod and one-segmented exopod. Serves in feeding. (biramous, unirmous; with exopod, without exopod).
(syn. maxillipede) [Stachowitsch, 1992]
Fourth and generally largest paired mouthpart on underside of head. Uniramous, located posterior to and often closely adjoining maxillae. Represents modified appendage (thoracopod) of first thoracic somite (thoracomere); second thoracopod may also be modified as maxilliped. (lamellate, prehensile, raptorial, setose, subchelate).
(syn. maxillipede) [Stachowitsch, 1992]
Paired appendage posterior to maxillae on underside of head (cephalon). Uniramous, consisting of seven or eight segments, and with main point of flexure between third and fourth segments. First one to three segments with endites, last with terminal claw, all with setae along inner margin. (prehensile, subchelate).
(syn. maxillipede) [Stachowitsch, 1992]
In anaspidacean and stygocaridacean, pair of mouthparts posterior to maxillae. Represents modified first pair of thoracopods.
(syn. maxillipede) [Stachowitsch, 1992]
Fourth and largest pair of mouthparts. Represents modified pair of appendages (thoracopods) of first thoracic segment (which is fused to cephalon). If fully developed, consists of protopod bearing two endites and an epipod as well as distal endopod and exopod. (Sexually dimorphic, not sexually dimorphic).
(syn. maxillipede) [Stachowitsch, 1992]

Maxillipedal somite

According to interpretation dividing body into cephalon, maxillipedal segment, and thoracoabdomen, one-segment tagma bearing maxillipeds. May also be considered as belonging to cephalon or thorax. [Stachowitsch, 1992]

Maxillipeds

Appendages of the fused first three thoracomeres that have been incorporated into the head as additional mouthparts. [Brusca and Brusca, 2002]
Fourth to sixth pair of mouthparts (or sixth to eighth pairs of appendages). [Ingle, 1983]
Most posterior pair of mouthparts, derived from first pair of thoracic appendages. [Holdich and Jones, 1983]
Paired appendages modified for feeding on 1st, up to 3rd, thoracic somites, usually fused to cephalon. [McLaughlin, 1980]
There are three pairs of maxillipeds borne on the first three segments of the thorax; all three pairs are included in the mouthparts. Maxillipeds are biramous and bear epipods (Fig. 3). [Warner, 1977]

Maxillopodan eye

A compound eye unique to the "maxillopodan" taxa containing three optical cups, each with tapetal cells. [Brusca and Brusca, 2002]

Maxillula

The second mouthpart and fifth cephalic appendage. In the Janiroidea, it consists of two setose lobes: a large outer lobe armed with robust, tooth-like setae; and a smaller inner lobe with only one setae.
(pl. maxillulae) (syn. maxillule, first maxilla) [Wilson, 1989]
See Fourth and Fifth limbs.
(syn. maxilla)
See: Fourth limb, Fifth limb [Cohen, Peterson, and Maddocks, in press]

Maxillule

Cephalic appendages next behind mandible, serving as mouth part.
(syn. first maxilla, maxillula. In cirripeds, also termed inner maxilla) [Moore and McCormick, 1969]
First maxilla; mouthparts immediately posterior to mandibles. [Brusca and Brusca, 2002]
One of a pair of the 4th cephalic appendages, usually serving as a mouthpart.
(syn. 1st maxilla) [McLaughlin, 1980]
Second limb of cephalon, small and membranous.
(syn. maxilla 1) [Poore, 2004]
Second pair of mouthparts (maxillae I). [Holdich and Jones, 1983]
Second pair of mouthparts (or fourth pair of appendages). [Ingle, 1983]
(Taxon-specific: ) Fourth paired appendage of head. Consists of very small, simple, setae-bearing lobe. (absent, minute).
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head; relatively small, located between mandibles and maxillae. Uniramous, simple, typically with spines along medial (inner) margin. (See also paragnath). [Stachowitsch, 1992]
Fourth paired appendage of head; located between mandibles and maxillae. Relatively small, simple, setose lobe with small anterior accessory lobe.
(syn. first maxilla) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Fourth paired appendage of head; located between mandibles and maxillae. Relatively small, uniramous, and typically bearing series of spines or setae along medial margin.
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Biramous, consisting of protopod (with large endite), annulate endopod, and one-segmented exopod.
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Represents second pair of mouthparts and consists of base (protopod) with two endites as well as distal palp (endopod).
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head. Located between mandibles and maxillae; represents second pair of mouth-parts. If fully developed, consists of protopod bearing two endites as well as a palp (endo-pod). Mouthparts may be absent in male.
(syn. first maxilla) [Stachowitsch, 1992]
Second paired mouth-part on underside of head; borne on second cephalic segment (maxillular somite) and located between mandibles and maxillae. If fully developed, consists of protopod (with two endites), endopodal palp, and exile.
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Represents second pair of mouthparts and, if fully developed, consists of base with two endites as well as distal palp.
(syn. first maxilla) [Stachowitsch, 1992]
B & D [Wetzer et al. 1997]
Fourth pair of head appendages, functioning as mouthparts, immediately posterior to mandibles (= first maxillae).
(pl. maxillules) [Wetzer et al. 1997]
Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Represents second pair of mouthparts and typically consists of base with two differently developed endites.
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head; located between mandibles and maxillae. Represents second pair of mouthparts. Consists of base bearing one or occasionally two endites, rarely also with endopod palp.
(syn. first maxilla) [Stachowitsch, 1992]
Second paired mouthpart on underside of head (cephalon); borne on fourth cephalic somite and located between mandibles and maxillae. Consists of two segments (coxa and basis, each with endite) and small endopod (palp).
(syn. first maxilla) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Represents second pair of mouthparts and, if fully developed, consists of proximal section with two endites as well as distal palp.
(syn. first maxilla) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Second paired mouthpart on underside of head (between mandibles and maxillae). Typically developed as prominent pair of suction discs, yet also as uniramous appendage with distal claws.
(syn. first maxilla) [Stachowitsch, 1992]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Second paired mouth-part on head; located between mandibles and maxillae. Consists largely of gnathobase. (with/without notch) (See also oral pyramid).
(syn. first maxilla) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The fourth cephalic appendage. [Boxshall and Halsey, 2004]
Fourth paired appendage of cephalon; located between mandibles and maxillae. Uniramous, consisting of elongate protopod (with endites) and four-segmented shaft. Serves in locomotion and feeding.
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head; located posterior to mouth. Consists basically of proximal protopod with endites (masticatory processes) and variously developed distal branches (endopod, exopod). Serves, along with madibles, as masticatory appendage or is modified for locomotion.
(syn. first maxilla, maxilla) [Stachowitsch, 1992]
Second paired mouthpart on underside of head; located between mandibles and maxillae. If fully developed, consists of proximal protopod with endites and exites as well as distal biramous palp with inner branch (endopod) and outer branch (exopod). The term first maxilla is often preferentially applied. (biramous, uniramous; setose, spinose, subchelate; prehensile).
(syn. first maxilla) [Stachowitsch, 1992]
Second paired mouthpart on underside of head (cephalon) between mandibles and maxillae. Uniramous, consisting of seven segments, and with main point of flexure between fourth and fifth segments. First four segments with endites, seventh with terminal talon, all with setae along inner margin. (prehensile, subchelate). [Stachowitsch, 1992]
Fourth paired appendage of head; located between mandibles and maxillae. Represents second pair of mouthparts. Bears two endites and, in anaspidacean, a small lobe (exite, also variously interpreted as endopod or exopod).
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of cephalon; located between mandibles and maxillae. Represents second pair of mouthparts. Consists of two-segmented protopod bearing two endites and small palp (endopod).
(syn. first maxilla) [Stachowitsch, 1992]
Fourth paired appendage of head (cephalon); located between mandibles and maxillae. Represents second pair of mouthparts and, if fully developed, consists of three-segmented base with two endites and one exile as well as distal endopod (palp). (foliaceous).
(syn. first maxilla) [Stachowitsch, 1992]

Median

On or near the plane dividing the shrimp into two mirror image parts. [Butler, T. H.]
At, near, or directed toward the middle or midline. [Kensley and Schotte, 1989]

Median articulated spine

Projection of telson in eocarids, seemingly not homologous with skeletal structure of any extant crustacean. [Moore and McCormick, 1969]

Median carina

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Median dorsal plate

Elongate plate separating carapace valves posterodorsally (Phyllocarida Rhinocarina). [Moore and McCormick, 1969]
Elongate plate separating carapace valves posterodorsally in some phyllocarids. [McLaughlin, 1980]

Median element

Hinge. [Stachowitsch, 1992]

Median eye

See nauplius eye. [McLaughlin, 1980]
Sessile unpaired eye of nauplius larva which persists in some adults.
(syn. naupliar eye) [Moore and McCormick, 1969]
Term sometimes used to refer to a naupliar eye; see naupliar eye. [Brusca and Brusca, 2002]
(Taxon-specific: ) Nauplius eye. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Naplius eye. [Stachowitsch, 1992]

Median keel

Elevated, longitudinal keel along midline of carapace; extends anteriorly to transverse cervical groove. [Stachowitsch, 1992]

Median lateral

See: Latus (median) d [Martin, 2005]

Median latus

See latus. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate: in stalked form paired latera in one series (whorl), plate on each side of capitulum between rostral and carinal latera. [Stachowitsch, 1992]

Median lobe

One of the paired dorsal parts, often folded, of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]
The middle lobe of the frontal region of the carapace. [Ingle, 1980]

Median pore

Dorsal pit in carapace; located along midline between cervical groove and anterior bifurcation of median carina.
(syn. dorsal pit) [Stachowitsch, 1992]

Median protuberance

Conspicuous elevation, sometimes platelike, arising from the posteromedian part of the penultimate (XIII) thoracic sternite (Fig. 4A). [Perez Farfante and Kensley, 1997]

Median sulcus

Dorsomedian groove on the carapace (Fig. 2B). [Perez Farfante and Kensley, 1997]

Medulla terminalis X-organ

X-organ. [Stachowitsch, 1992]

Megalopa

A larva with setose pleopods, used for swimming, on some or all abdominal segments. [Ingle, 1983]
First postlarval stage in development of many Eucarida. [McLaughlin, 1980]
First postlarval stage in ontogeny of crabs, not developed in macruran decapods or other crustaceans.
(syn. megalops stage) [Moore and McCormick, 1969]
Term often used to refer to the first postlarval stage in the Amphionidacea, Caridea, and Brachyura. [Brusca and Brusca, 2002]
Terminal larval stage in Brachyura and Anomura. [Poore, 2004]
The postlarval stage of a brachyuran crab. [Bliss, 1982]
Postlarva. [Stachowitsch, 1992]

Membranous

Pertaining to the very soft, fragile integument of some shrimps. [Butler, T. H.]

Mereopod

See merus. [McLaughlin, 1980]

Merocerite

In antenna, term applied to second of three segments (ischiocerite, merocerite, carpocerite) of outer branch (endopod); alternate interpretation: fourth segment of peduncle. [Stachowitsch, 1992]

Merodont hinge

Three-element hinge, with anterior and posterior teeth (or sockets) separated by median bar (or groove). [Cohen, Peterson, and Maddocks, in press]

Meropodite

See: Merus [Martin, 2005]

Merus

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
Article 4 of pereopod (article 3 of cheliped). [Holdich and Jones, 1983]
Fourth article from distal end of leg; sometimes called arm of cheliped.
(syn. meropodite) [Williams, 1984]
Fourth article of limb. [Poore, 2004]
Fourth limb segment distally from body, its proximal extremity articulating with ischium; usually forms first long segment of cheliped and pereiopod.
(syn. meropod(ite)) [Moore and McCormick, 1969]
Fourth segment (distally from body), articulating proximally with ischium and distally with carpus.
(syn. meropod) [McLaughlin, 1980]
Fourth segment from proximal end of a typically 7-segmented appendage.
(pl. meri) [Butler, T. H.]
Fourth segment from proximal end of segmented appendage. [Hobbs and Jass, 1988]
Fourth segment of a pereiopod or maxilliped, counted from the distal end. [Ingle, 1983]
Fouth segment from the proximal end of a typically 7-segmented appendage. (Fig. 3C).
(pl. meri) [Perez Farfante and Kensley, 1997]
The 4th podomere from the tip of the endopod of a limb (Figs. 1, 2). [Warner, 1977]
The fourth segment from the proximal end of a segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
The fourth segment from the proximal end of a typically 7-segmented appendage.
(pl. meri) [Chace and Hobbs, 1969]
The fourth segment of a thoracic appendage.
(pl. meri) (syn. meropodite)
See: Pereopod [Wilson, 1989]
Second of five segments (ischium, merus, carpus, propodus, dactylus) of endopod of thoracopod (maxillipeds and pereopods).
(syn. meropod, meropodite) [Stachowitsch, 1992]
Fourth of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Fourth segment of appendage (thoracopod); positioned between ischium and carpus. May be fused to ischium to form ischiomerus.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Fourth of basically seven segments (coxa, basis, ischium, merus, carpus propodus, dactylus) of thoracopod; represents third movable (free) segment.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Article 4 of pereopod. [Kensley and Schotte, 1989]
Fourth segment of pereopod; located between ischium and carpus.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Third of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Fourth segment of thoracic appendage (thoracopod). Considered to represent fused ischium and merus (ischiomerus), yet also interpreted as being separate from and following ischium. [Stachowitsch, 1992]
Third of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Second of basically five segments (ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Frequently interpreted as being fused to ischium.
(syn. meropod, meropodite) [Stachowitsch, 1992]
Fourth segment of thoracopod (second segment of five-segmented endopod); positioned between ischium and carpus.
(syn. meropod, meropodite) [Stachowitsch, 1992]

Mesenteron

Mid-portion of alimentary tract of endodermal origin with surface commonly increased by pouch-like extensions which serve as digestive glands and aid absorption of partly digested food.
(syn. midgut) [Moore and McCormick, 1969]
Midportion of alimentary tract, of endodermal origin, with surface commonly increased by pouchlike extensions serving as digestive glands.
(syn. midgut) [McLaughlin, 1980]
Midgut. [Stachowitsch, 1992]

Mesial

Referring to inner margins or surfaces, closer to midline than sides. [Butler, T. H.]
Referring to or toward middle. [Hobbs and Jass, 1988]
Near or toward the middle or midline. [Kensley and Schotte, 1989]

Mesial process

Terminal process located mesially on modified first pleopod (gonopod) of male cambarid crayfishes (Figs. 23, 32, 63). [Hobbs and Jass, 1988]

Mesial ramus

Inner branch (not necessarily equivalent to the endopod) (Fig. 1). [Perez Farfante and Kensley, 1997]

Mesial ridge

Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]

Mesial tubercle

Strong conical to low, rounded protberance on mesial surface of optic calathus. [Perez Farfante and Kensley, 1997]

Mesobranchial lobe

Intermediate part of branchial region of decapod (brachyuran) carapace.
(syn. mesobranchial area) [Moore and McCormick, 1969]
See: Carapace regions c [McLaughlin, 1980]

Mesobranchial region

The intermediate portion of the branchial region on the carapace of crabs. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by a part of the postero-lateral margin of the carapace and parts of the margins of the epibranchial, urogastric and metabranchial regions. [Ingle, 1983]
Branchial region. [Stachowitsch, 1992]

Mesocerebrum

Ganglion of antennular somite.
(syn. deuterocerebrum) [McLaughlin, 1980]
Ganglion of antenular somite.
(syn. deuterocerebrum) [Moore and McCormick, 1969]

Mesogastric lobe

Medial division of gastric region of decapod (brachyuran) carapace, generally pentagonal in outline with long narrow forward prolongation. [Moore and McCormick, 1969]
Median lobe or subregion of gastric region; pentagonal in form, and with long, narrow, anterior prolongation. [Williams, 1984]
See: Carapace regions f [McLaughlin, 1980]

Mesogastric region

The central portion of the gastric region on the carapace of crabs. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by parts of the margins of the frontal, protogastric, and metagastric regions. [Ingle, 1983]
Gastric region. [Stachowitsch, 1992]

Mesoparasite

(Taxon-specific: Family Cyatholaimidae) A parasitic copepod that lives partly embedded in its host, usually with the anterior end forming an anchor process. [Boxshall and Halsey, 2004]

Mesopelagic

Zone in the open ocean 200-1000m below the surface, or pertaining to it inhabitants. [Butler, T. H.]

Mesoplankton

Planktonic organisms of intermediate size, 0.2-20 mm. [Ingle, 1992]

Mesosome

Collective term for all free thoracic somites behind head (not common usage). [McLaughlin, 1980]
Collective term for all free thoracic somites behind head. [Moore and McCormick, 1969]
Pereon. [Stachowitsch, 1992]

Mesosternum

Median plate arising from sternum in many brachyurans. [Moore and McCormick, 1969]
Median plate of sternum in some brachyruan decapods. [McLaughlin, 1980]
On underside of cephalothorax in crab-like (brachyuran) decapod, median plate of sternum; may give rise to inwardly directed endosternite. [Stachowitsch, 1992]

Metabranchial

That region of porcellanid (crab) carapace situated below linea anomurica and, therefore, not completely united with main part of carapace.
(syn. metabranchial region) [Williams, 1984]
The region on the dorsal surface of the carapace bounded by part of the postero-lateral margin of the carapace and parts of the margins of the epibranchial, cardiac and intestinal regions. [Ingle, 1983]

Metabranchial lobe

Posterior part of branchial region of decapod (brachyuran) carapace. [Moore and McCormick, 1969]
See: Carapace regions c [McLaughlin, 1980]

Metabranchial region

The posterior portion of the branchial region on the carapace of crabs. [Chace and Hobbs, 1969]
Branchial region. [Stachowitsch, 1992]

Metacerebrum

Ganglion of antennal somite.
(syn. tritocerebrum) [Moore and McCormick, 1969]
Ganglion of antennal somite.
(syn. tritocerebrum) [McLaughlin, 1980]

Metagastric lobe

Posterior division of gastric region of decapod (brachyuran) carapace; may be ill defined or undifferentiated. [Moore and McCormick, 1969]
Posterolateral lobe or subregion of gastric region; often not defined. [Williams, 1984]
See: Carapace regions f [McLaughlin, 1980]

Metagastric region

The posteromesial portion of the gastric region on the carapace of crabs. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by parts of the mesogastric, protogastric, epibranchial and urogastric regions. [Ingle, 1983]
Gastric region. [Stachowitsch, 1992]

Metamorphic

In which noticeable morphological changes occur during larval development. [Ingle, 1992]

Metamorphic development

Type of extreme "mixed" development seen among the Eucarida; it includes dramatic transitions in body form from one life history stage to another, similar to holometabolous development in insects. [Brusca and Brusca, 2002]

Metamorphosed

Tranformed; changed in appearance, structure, or function. [Kensley and Schotte, 1989]

Metamorphosis

Period of abrupt transformation from one distinctive stage in the life history to another, especially from larva to adult. [Butler, T. H.]

Metanauplius

A stage of development between the nauplius and calyptopis in euphausiids. A vestigial abdomen is present. [Mauchline, 1984]
Developmental stage following the nauplius larval stage and bearing the same three appendages but having additional body segments. [Brusca and Brusca, 2002]
Postnaupliar larva with generally same body and body shape as nauplius, but with additional appenages. [McLaughlin, 1980]
Postnaupliar larva with same general body and limb morphology as nauplius, but having additional limbs. [Moore and McCormick, 1969]
(Taxon-specific: ) Larval stage at which certain predatory water fleas hatch; otherwise, metanuaplius is typically passed while still within egg. [Stachowitsch, 1992]
Later larval stage between nauplius and adult. Earlier metanauplii bear only first three pairs of appendages (as in nauplii), yet exhibit further segmentation of trunk. Most tadpole shrimp hatch as metanauplii. [Stachowitsch, 1992]
Late larval stage; carapace typically first produced by metanauplius. (see also nauplius). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Later larval stage between nauplius and adult. Characterized by gradual increase in number of segments and appendages. [Stachowitsch, 1992]
Larval stage at which cephalocarids hatch. Includes a number of substages characterized by a gradual increase in number of segments and appendages. [Stachowitsch, 1992]
Second of basically five larval stages (nauplius, metanauplius, protozoea, zoea, postlarva). Resembles nauplius, but bears additional appendages. Typically still contained within egg; if free-swimming, with antennal locomotion. [Stachowitsch, 1992]
One of several substages in in development between nauplius and adult. Characterized by gradual increase in number of segments and appendages. [Stachowitsch, 1992]
Nauplius. [Stachowitsch, 1992]
Second of several larval stages (nauplius, metanauplius, calyptopis, furcilia). Characterized by development of labrum and rudiments of maxillules, maxillae, and first thoracopods.
See: Cyrtopia [Stachowitsch, 1992]

Metapon

Entire preoral area on underside of head; includes interannular septum, epistome, endostome, and part of mandibular somite. [Stachowitsch, 1992]
Entire preoral area, including part of mandibular somite. [McLaughlin, 1980]

Metasoma

See: Metasome [Martin, 2005]
See metasome. [McLaughlin, 1980]

Metasome

In copepods, part of prosome consisting of free thoracic somites in front of major articulation; in amphipods first three abdominal somites bearing unmodified pleopods. [Moore and McCormick, 1969]
Part of prosome, consisting of free thoracic somites anterior to major articulation (Copepoda); or first three abdominal somites (Amphipoda, not general usage).
(syn. metasoma) [McLaughlin, 1980]
Thoracic segments of a copepod posterior to those segments fused with the cephalasome. [Brusca and Brusca, 2002]
Labium. [Stachowitsch, 1992]
Pleon. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The posterior part of the prosome comprising the free pedigerous somites. [Boxshall and Halsey, 2004]
One of three divisions (tagmata) of body (ceohalosome, metasome, urosome). Consists of free thoracic somites (thoracomeres) anterior to flexure point of body. Region comprising cephalosome and metasome ma be termed prosome. [Stachowitsch, 1992]

Metastoma

Lower lip behind mandibles, usually cleft into pair of lobes termed paragnatha.
(syn. hypostoma, hypostome, hypopharynx, labium, lower lip, paragntha) [Moore and McCormick, 1969]
Lower lip posterior to mandibles, usually cleft into pair of lobes (paragnaths).
(syn. hypostoma, hypostome, hypopharynx, labium) [McLaughlin, 1980]

Metazoea

Last stage of zoea larva in Brachyura. [Moore and McCormick, 1969]
Last zoeal substage of larval brachyurans. [McLaughlin, 1980]
In crab-like (brachyuran) decapod, last zoeal substage before metamorphosis to postlarva. [Stachowitsch, 1992]

Metopon

Entire preoral area in decapods, including parts of mandibular somite. [Moore and McCormick, 1969]

Micronicus

See epicaridum. [McLaughlin, 1980]
Second of three larval stages (epicaridium, microniscus, cryptoniscus) in certain parasitic isopods. Parasitic on intermediate host. Characterized by loss of natatory function of antennae and pleopods as well as by development of last (= seventh) pereopod pair. [Stachowitsch, 1992]

Midgut

See: Mesenteron [Martin, 2005]
See mesenteron. [McLaughlin, 1980]
(Taxon-specific: ) Elongate section of digestive tract between esophagus and hindgut. Occasionally one may distinguish between a more expanded stomach region anteriorly and a more narrow posterior intestinal region. May bear pairof digestive ceca anteriorly. (straight, coiled = convoluted). [Stachowitsch, 1992]
Elongate section of digestive tract between esophagus and hindgut. Extends through thorax and most of abdomen and bears two ceca anteriorly. [Stachowitsch, 1992]
Elongate, somewhat exapanded section of digestive tract between esophagus and hindgut in trunk. Bears pair of digestive ceca anteriorly. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Elongate section of digestive tract between esophagus and hindgut. Extends through thorax, and most of abdomen and bears pair of midgut diverticula anteriorly. [Stachowitsch, 1992]
Greater part of digestive tract; extends posteriorly from esophagus through thorax and most of abdomen.
(syn. mesenteron) [Stachowitsch, 1992]
Relatively short section of digestive tract between stomach and hindgut. Wall of midgut distinguished from that of stomach by larger (syncytial) cell structure. [Stachowitsch, 1992]
Elongate section of digestive tract between stomach and rectum. Digestive diverticula open into digestive tract at border of stomach and midgut. [Stachowitsch, 1992]
Region of digestive tract between foregut and hindgut. Either restricted to posterior section of pyloric stomach or corresponding to greater part of intestine. Not lined by cuticle.
(syn. mesenteron) [Stachowitsch, 1992]
Elongate section of digestive tract between foregut (esophagus and stomach) and hindgut. Gives rise to various ceca anteriorly (at stomach/ midgut border) and posteriorly. [Stachowitsch, 1992]
Poorly defined section of digestive tract between foregut and hindgut. Term either applied to relatively short section of digestive tract near origin of midgut ceca or considered to be represented by midgut ceca themselves. [Stachowitsch, 1992]
Elongate section of digestive tract between stomach and hindgut. Extends through most of thorax and abdomen. [Stachowitsch, 1992]
Narrow section of digestive tract between posterior division of stomach (pyloric stomach) and hindgut; extends through posterior somites of thorax and through abdomen. Give rise anteriorly to pair of digestive glands. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Elongate section of digestive tract between foregut and hindgut. May bear one to several pairs of midgut ceca anteriorly and pair of rectal ceca posteriorly. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Region of digestive tract in thorax between foregut (esophagus) and hindgut. One may distinguish an anterior crop and posterior intestine. Gives rise anteriorly to pair of highly branched ceca. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Elongate, somewhat extended (in barnacle, U-shaped) section of digestive tract between esophagus and hindgut; bears digestive ceca. Expanded region of midgut may be termed stomach. [Stachowitsch, 1992]
Region of digestive tract between foregut (stomodeum) and hindgut (protocdeum). Extends throughout most of thoracoabdomen and lacks diverticula; with folded, relatively thick walls anteriorly, thinner walls posteriorly. [Stachowitsch, 1992]
Region of digestive tract between foregut and hindgut. Extends through most of body and may be divided into expanded anterior stomach and more tube-like posterior section. [Stachowitsch, 1992]
Region of digestive tract between foregut and hindgut. Extends through most of body and may be divided into expanded stomach and narrower intestine. Bears ceca. [Stachowitsch, 1992]
Elongate section of digestive tract between foregut and hindgut; extends through trunk and bears pair of lateral diverticula in each segment. [Stachowitsch, 1992]
Elongate section of digestive tract between stomach and hindgut. Extends through thorax and abdomen, giving rise anteriorly to series of ceca and posteriorly (at level of first and fifth pleomeres) to additional dorsal ceca. [Stachowitsch, 1992]
Elongate section of digestive tract between stomach and anus. Extends through most of body. Digestive ceca open into digestive tract at border of stomach and midgut. [Stachowitsch, 1992]
Elongate section of digestive tract between stomach and hindgut. Gives rise to pair of small dorsal ceca and pair of large ventral hepatic glands. [Stachowitsch, 1992]

Midgut cecum

One of several tubular outpocketings of digestive tract. According to position, one may distinguish 1) two pairs of posteriorly directed lateral ceca (two dorsal and two ventral) arising at stomach/midgut border and extending through most of body, 2) single or paired, anteriorly directed ceca arising mid-dorsally at stomach/midgut border, and 3) single or paired, anteriorly directed ceca arising from posterior end of midgut. In certain amphipods may also refer to large, unpaired pouch into which esophagus opens.
(syn. cecum) [Stachowitsch, 1992]
One of up to three pairs of elongate outpocketings of digestive tract. Originates in anterior region of pereon at border of foregut and hindgut and extends through most of pereon.
(syn. digestive cecum, hepatic cecum) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of up to several pairs of variously developed digestive organs extending either anteriorly or posteriorly from anterior end of midgut. Relatively short, anteriorly directed pair of dorsal ceca are termed dorsal ceca. (sac-like, trilobed) (See also rectal cecum).
(syn. digestive gland, diverticulum) [Stachowitsch, 1992]
Dorsal cecum. hepatic gland. [Stachowitsch, 1992]

Midgut diverticulum

(Taxon-specific: ) Digestive cecum. [Stachowitsch, 1992]
Cecum. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two short outpocketings of midgut. Located in head and opening into digestive tract posterior to esophagus/midgut border.
(syn. cecum) [Stachowitsch, 1992]

Midgut glands

Paired glandular or storage organs of decapod crustaceans; digestive juices from midgut glands flow via tubules into the caudal (midgut) portion of the posterior chamber. Often called "fat," "liver," or tomally.
(syn. hepatopancreas or digestive glands) [Bliss, 1982]

Milne-Edwards openings

The main inhalant respiratory openings; one on either side between the base of the cheliped and the lower edge of the branchiostegite. [Warner, 1977]

Molar

Grinding, and sometimes piercing, structure of the mandible. [Kensley and Schotte, 1989]

Molar process

(syn. incisor process) [Butler, T. H.]
A medial process of the mandible. In the plesiomorphic condition, it has a broad, distal, triturating surface with circumgnathal denticles, a posterior row of broad, setulate setae, and sensory pores on the distal surface. [Wilson, 1989]
Grinding portion of gnathal lobe of mandible.
(syn. pars molaris) [McLaughlin, 1980]
Grinding portion of gnathal lobe of mandible.
(syn. pars molaris) [Moore and McCormick, 1969]
Inwardly directed process of mandible usually bearing spines or a flat grinding surface. [Holdich and Jones, 1983]
Terminal end of each mandible; extends into preoral cavity (atrium oris) under upper lip (labrum). [Stachowitsch, 1992]
Grinding process (vs. gripping = incisor process) at end of each mandible. Bears numerous small teeth and extends into atrium oris under labrum. [Stachowitsch, 1992]
Proximal grinding process (vs. gripping = incisor process) of each mandible. (columnar = cylindrical = truncate, styliform).
(syn. pars molaris) [Stachowitsch, 1992]
Proximal grinding process (vs. gripping = incisor process) of each mandible. [Stachowitsch, 1992]
Grinding process (vs. gripping = incisor process) of each mandible. May be fused with incisor process.
(syn. pars molaris) [Stachowitsch, 1992]
Proximal grinding process (vs. gripping = incisor process) of each mandible. (laminar, ridged, rounded, setulose, smoothly truncated, absent). [Stachowitsch, 1992]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Grinding, or piercing or slicing structure, arising mid-basally on body of mandible; pars molaris. [Wetzer et al. 1997]
Proximal grinding process (vs. gripping = incisor process) of mandible. (immovable, movably articulated; blade-like, blunt-pointed, broad and truncate, pointed with apical setae, spiniform, truncate with teeth). [Stachowitsch, 1992]
Proximal grinding process (vs. gripping = incisor process) of each mandible. [Stachowitsch, 1992]
Well-developed grinding process (vs. gripping = incisor process) of each mandible. Armed with two rows of teeth and extends beneath labrum into mouth.
(syn. pars molaris) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Grinding process (vs. gripping = incisor process) of each mandible. [Stachowitsch, 1992]
Grinding process (vs. cutting = incisor process) at tip of each mandible; located on pedestal and composed of broad, flat basin containing dense rows of spines [Stachowitsch, 1992]
Proximal grinding process (vs. distal gripping = incisor process) of each mandible. [Stachowitsch, 1992]
Proximal grinding process (vs. gripping = incisor process) of each mandible. Bears series of fine setae (guide setules). [Stachowitsch, 1992]
Grinding process (vs. gripping = incisor process) of each mandible. [Stachowitsch, 1992]

Molt

With reference to crustaceans, a clearly defined series of activities that precede, include and follows shedding of the shell (ecdysis). Among these activities are limb regeneration, decalcification of the old shell, laying down of the new shell, and hardening of the new shell. [Bliss, 1982]
(Taxon-specific: Family Cyatholaimidae) The transition from one developmental stage to the next. [Ferrari and Dahms, in press]

Molting

Periodic shedding of shell to permit an increase in size and/or change of form. [Butler, T. H.]

Morphology

Study of the form of a shrimp considered as a whole or in its gross aspects. [Butler, T. H.]

Moult to puberty

The moult to sexual maturity and consequently to the reproductive phase. [Martin, 2005]

Mouth

(Taxon-specific: ) Anterior opening of digestive tract under labrum; opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head; located under labrum and opening into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract; located under labrum and associated with large preoral cavity (atrium oris). Opens into esophagus. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Anterior opening of digestive tract on underside of head; located under labrum and opening into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract; located under labrum and associated with large preoral cavity (atrium oris). [Stachowitsch, 1992]
Anterior opening of digestive tract. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium); opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium); opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head; bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium), and flanked by mandibles, maxillules, and maxillae (and to various degrees by maxillipeds). Leads into cardiac stomach via esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium); opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head (cephalon). Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium). [Stachowitsch, 1992]
Anterior opening of digestive tract. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium). Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head (cephalon); bordered anteriorly by labrum, posteriorly by labrum and mouthparts. Opens directly into stomach. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Anterior opening of digestive tract on underside of head. Bordered anteriorly by labrum, posteriorly by labium (paragnaths); opens into esophagus. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Anterior opening of digestive tract on underside of cephalothorax; typically enclosed, along with surrounding labrum, mandibles, and paragnaths, in proboscis. Opens into esophagus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Anterior opening of digestive tract. Closely associated with labrum and mouthparts (trophy). Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract. Located under labrum; opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium), and flanked by mandibles (and to a lesser extent by other mouthparts: maxillules, maxillae, maxillipeds). Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium), and flanked by mandibles. Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head (cephalon); located in cavity (atrium oris) formed by projecting posterior margin of labrum and by paragnaths. Perioral area highly setose due to setae of labrum and paragnaths. Opens into foregut. [Stachowitsch, 1992]
Anterior opening of digestive tract. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (paragraphs). Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract. Located on underside of cephalon and bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium). Opens into esophagus. [Stachowitsch, 1992]
Anterior opening of digestive tract on underside of head. Bordered anteriorly by upper lip (labrum), posteriorly by lower lip (labium); opens into esophagus. [Stachowitsch, 1992]

Mouth cirri

(Taxon-specific: Order Rhabditida) Cirrus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) First pair of cirri considerably modified. [McLaughlin, 1980]

Mouth cone

(Taxon-specific: Order Rhabditida) Cone. [Stachowitsch, 1992]
In parasitic copepod, cone- or tube-shaped structure around mouth. Formed by extension of upper lip (labrum) and lower lip (labium); open basally to accommodate mandibles.
(syn. mouth tube siphon) [Stachowitsch, 1992]

Mouthparts

A collective term for the appendages around the mouth which are concerned with feeding: mandibles, maxillae and maxillipeds. [Warner, 1977]
All cephalothoracic limbs involved with feeding: mandibles through to third maxillipeds. [Poore, 2004]
Appendages associated with the buccal frame. [Ingle, 1983]
Mandibles, maxillae, and maxillipeds; used for obtaining, handling, and processing food. [Butler, T. H.]
Appendage closely associated with mouth. Includes paired mandibles, maxillules, maxillae, and maxillipeds as well as unpaired labrum and labium. [Stachowitsch, 1992]

Movable finger

Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Dactyl of chela. [McLaughlin, 1980]
Dactylus of chela. [Moore and McCormick, 1969]
Distalmost podomere of segmented appendage.
(syn. dactyl) [Hobbs and Jass, 1988]
Finger. [Stachowitsch, 1992]

Movable spine

Spine set in socket; depressible, by movement towards basal structure such as carapace or segment of appendage. [Butler, T. H.]

Mucoid

Like mucus or related to mucus. [Bliss, 1982]

Mucous gland

Gland located in proximal part (protopod) of each limb; empties through duct opening near endites. [Stachowitsch, 1992]

Mucro

Spine on inferoposteal angle of carapace in some Cladocera.
(pl. mucrones) [Moore and McCormick, 1969]
Spine on inferoposteal angle of carapace in some cladocera.
(pl. mucrones) [McLaughlin, 1980]
(Taxon-specific: ) Sharp point at lower posterior end of carapace. (in immature forms: with minute dorsal notches, with minute ventral notches). [Stachowitsch, 1992]

Multiarticulate

Composed of many articles. [Kensley and Schotte, 1989]

Multiseriate

(Taxon-specific: Family Cyatholaimidae) Used of egg sacs containing two or more rows of eggs. [Boxshall and Halsey, 2004]

Mural plate

(Taxon-specific: Order Rhabditida) Compartmental plate. [Stachowitsch, 1992]

Murus

Type of valve sculpture: one element in a meshwork of walls forming a reticulate patterm. A single mesh in reticulum-consisting of central space (solum) and surrounding muri- is termed fossa. (caperate, excavate, foveolate, papillate, perforate, undercut). [Stachowitsch, 1992]

Muscle pit

(Taxon-specific: Order Rhabditida) Adductor muscle pit. [Stachowitsch, 1992]

Mysis

Zoea.
(syn. mysis stage, schizopod larva) [Stachowitsch, 1992]

Mysis Larva

Advanced zoeal stage of some malacostracans. [Brusca and Brusca, 2002]

Mysis stage

Larval stage in penaeoidean development equivalent to zoeal stage of Nephropoidea.
(syn. schizopod larva) [McLaughlin, 1980]
Post-cypris larval stage in ontogeny of most crustaceans, characterized by presence of biramous limbs on all thoracic somites.
(syn. schizopod larva) [Moore and McCormick, 1969]
The third in a series of free-swimming larval stages of penaeid shrimps. [Bliss, 1982]

Myxal surface

(Taxon-specific: Family Cyatholaimidae) The medial surface of the corpus of the maxilliped of siphonostomatoids, sometimes produced into a short (myxal) process. [Boxshall and Halsey, 2004]

Natapod

A natatory pereopod of a munniopsid janiroidean, the fifth through seventh pereopods. [Wilson, 1989]

Natasome

The often posteriorly streamlined body section of a munnopsid janiroidean consisting of the following body segments: heavily muscularized pereonites 5-7, and the pleotelson. [Wilson, 1989]

Natasomite

A pereonite of the natasome. [Wilson, 1989]

Natatory

Adapted for swimming. [Ingle, 1983]
Adapted for swimming. [Kensley and Schotte, 1989]

Natatory lobe

(Taxon-specific: Order Monhysterida) On last pair of thoracic appendages (fourth thoracopods), lobe-like projection of protopod. Serves in swimming. [Stachowitsch, 1992]

Naupliar eye

Relatively simple, median eye, typically consisting of 3 photoreceptor units (up to 7 in taxa where it persists in the adult) and first appearing in the nauplius larval stage. Thought to be a primitive (defining) feature of the Crustacea; it is secondarily reduced or lost in many taxa. [Brusca and Brusca, 2002]
Unpaired median eye found in naupliar larval stages and commonly in more mature stages as well.
(syn. median eye) [Moore and McCormick, 1969]
Unpaired median eye, common in nauplii and many adult crustaceans; structure simple, consisting of 1 to few light-sensitive cells.
(syn. median eye) [McLaughlin, 1980]
(Taxon-specific: ) Small median photosensitive organ located ventrally on head between mouth and compound eye.
(syn. median eye, ocelus) [Stachowitsch, 1992]
Small median photosensitive organ located in front of compound eyes on sloping anterior of carapace; consists of four cups.
(syn. median eye) [Stachowitsch, 1992]
Small median photosensitive organ located ventrally on rostrum of head. (See also compound eye).
(syn. median eye) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Unpaired median photosensitive organ located somewhat posteriorly to antennules on anterior part of head; relatively small, consisting of three (two lateral, one ventral) cups. (see also compound eye). [Stachowitsch, 1992]
Ocellus. [Stachowitsch, 1992]
Single medial anterior eye, normally composed of 3 eye cups, has reflecting tapetal layer.
(syn. medial eye) [Cohen, Peterson, and Maddocks, in press]

Naupliar shield

(Taxon-specific: Family Cyatholaimidae) The expanse of the exoskeleton of an unspecified number of somites, uninterrupted by arthrodial membranes, and covering the dorsal and lateral part of the naupliar body. [Ferrari and Dahms, in press]

Nauplioid

First larval stage after hatching from egg membrane. With naupliar appendages only (antennae, antennules, mandibles). [Stachowitsch, 1992]

Nauplius

Characteristic crustacean larval stage bearing median simple (naupliar) eye and 3 pairs of setose, functional appendages destined to become the antennules, antennae and mandibles. [Brusca and Brusca, 2002]
Early larval stage having only antennules, antennae, and mandibles. [Moore and McCormick, 1969]
Early larval stage with only 3 pairs of appendages, antennules, antennae, and mandibles.
(pl. nauplii) [McLaughlin, 1980]
Free-swimming, microscopal larval stage, after hatching from egg, chracteristic of penaeidean shrimps.
(pl. nauplii) [Butler, T. H.]
The larval stage that hatches from the egg of euphausiids. The first antennae are used as swimming appendages. [Mauchline, 1984]
The minute, egg-shaped or pear-shaped, earliest larval form, into which many crustaceans, including penaeid shrimps, hatch from the egg. Higher shrimps, as well as lobsters and crabs, pass through the naupliar stage within the egg and hatch at a later stage of development. [Bliss, 1982]
Early larval stage characterized by presence of only three pairs of appendages (antennules, antennae, mandibles) and unsegmented trunk. Certain tadpole shrimp hatch as nauplii. (See also metanauplius). [Stachowitsch, 1992]
Early larval stage; basically characterized by three pairs of appendages (antennules, antennae, mandibles), although antennules are typically reduced. Some nauplii bear broad dorsal shield. (See also metanauplius). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Early larval stage characterized by presence of only three pairs of appendages (antennules, antennae, mandibles) and an unsegmented trunk. [Stachowitsch, 1992]
First of basically five larval stages (nauplius, metanauplius, protozoea, zoea, postlarva). Characterized by three pairs of appendages (antennules, antennae, and mandibles). Hatching from egg may take place at nauplius stage (certain shrimp-like decapods) or later. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Early larval stage; characterized by frontolateral horns, nauplius eye, and three pairs of appendages (antennules, antennae, and mandibles). (See also cypris larva). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A developmental stage whose somites do not articulate, with only three transformed limbs, and with an arthrite on the coxa of antenna 2. A naupliar arthrite may not be present on nauplii which do not feed. Nauplii are designated by Roman numerals. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The first larval phase, typically with three functional pairs of appendages (antennules, antennae and mandibles). [Boxshall and Halsey, 2004]
Early larval stage after hatching from egg. Bears three simple appendages (antennules, antennae, mandibles) and is covered by carapace. [Stachowitsch, 1992]
First (earlier) of two basic stages in larval development (nauplius, copepodid). Characterized by presence of only three pairs of appendages (antennules, antennae, mandibles) and excretion by means of antennal glands. Typically involves five to six substages, the first two being referred to an orthonauplii, the remaining as metanauplii. [Stachowitsch, 1992]
First of several larval stages (nauplius, metanauplius, calyptopis, furcilia). Characterized by three pairs of appendages (antennules, antennae, mandibles).
See: Cyrtopia [Stachowitsch, 1992]

Nauplius eye

Minute, unpaired light-sensitive organ on ocular plate between eyestalks (ocular peduncles). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) On dorsal midline of carapace, one to three simple photosensitive structures. (See also compound eye).
(syn. median eye, ocellus) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Unpaired median photosensitive organ in larvae (nauplius, cypris). May be retained under plates of adult barnacle. [Stachowitsch, 1992]
On dorsal surface of body near base of antennules, median unpaired photosensitive structure consisting of three ocelli. (See also compound eye). [Stachowitsch, 1992]
On dorsal surface of cephalic shield, median photosensitive structure consisting of three ocelli. [Stachowitsch, 1992]
Small median photosensitive organ located between eyestalks (ocular peduncles) under rostrum.
See: Compound eye [Stachowitsch, 1992]

Nauplius larva

(See nauplius). [Brusca and Brusca, 2002]
Larval stage at which most mystocacarids hatch. Characterized by presence of only three appendage pairs (antennules, antennae, mandibles). (See also metanauplius). [Stachowitsch, 1992]

Neck

(Taxon-specific: Family Cyatholaimidae) A narrow part of the body separating the head from the trunk in highly metamorphic parasites, typically formed by a pedigerous somite. [Boxshall and Halsey, 2004]
In parasitic copepod, relatively narrow region of body between head and trunk; composed of several thoracic somites (thoracomeres). [Stachowitsch, 1992]

Neck organ

See: Nuchal organ [Martin, 2005]
See nuchal organ. [McLaughlin, 1980]
(Taxon-specific: ) Nuchal organ. [Stachowitsch, 1992]

Nephropore

Elevated opening of antennal gland on ventral surface of coxa of antenna. [McLaughlin, 1980]
Elevated outlet of antennal gland, located on coxa of antenna. [Moore and McCormick, 1969]
Excretory pore. [Stachowitsch, 1992]

Neutrum

Sexually neutral juvenile. Depending on sex of accompanying adults, neutrum develops into male or female. [Stachowitsch, 1992]

Neutrum stage

Term used by some workers to define early post-marsupial stages. [Holdich and Jones, 1983]

Nisto

Postlarval stage of some palinurans.
(syn. pseudibacus, puerulus) [McLaughlin, 1980]
Postlarva. [Stachowitsch, 1992]

Node

Type of valve sculpture: protuberance of intermediate size (between tubercle and knob). Node associate with attachment of different internal muscles is termed muscle scar node, subcentral tubercle, or submedian tubercle. [Stachowitsch, 1992]

Non-annulate seta, robust

These are often both mechano- and chemoreceptive; they usually occur in places where mechanical stress is high, such as along adjoining surfaces of chelae or on biting edges of amphipod and isopod mouthparts. [Watling, 1989]

Non-annulate seta, small, non-robust

This may be a heterogenous assemblage with several basic homologies represented and consequently will need re-evaluation; they are usually very small sensory setae found at numerous sites on the body surface. [Watling, 1989]

Normal pore canals

Numerous perforations through valve with chemosensory and tactile sensilla, which communicate with nerve cells in the underlying epidermis; may be simple (open) or covered with sieve plates. [Cohen, Peterson, and Maddocks, in press]

Notum

Posterior part of dorsal carapace in shrimplike decapods (limited usage). [McLaughlin, 1980]
Posterior part of dorsal region of macruran decapod carapace. [Moore and McCormick, 1969]
Term occasionally applied to posterior part of dorsal region of carapace in shrimp-like (natantian) decapod or to dorsal plate of carapace in crab-like (brachyuran) decapod. [Stachowitsch, 1992]

Nuchal organ

Sense organ on upper side of head in many branchiopods.
(syn. neck organ) [Moore and McCormick, 1969]
Sense organ on upper side of cephalon.
(syn. neck organ) [McLaughlin, 1980]
(Taxon-specific: ) Frontal organ. [Stachowitsch, 1992]
Dorsal organ. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Unpaired median sensory organ located on dorsal surface of head; visible beneath cuticle.
(syn. neck organ) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Organ associated with specialised areas of modified integument, possibly with osmoregulatory function, typical of fresh and brackish water taxa. [Boxshall and Halsey, 2004]

Obliquely erect

Directed obliquely, more or less at 45 degrees to basal surface. [Butler, T. H.]

Obsolescent

Vestigial. [AHD]

Obsolete

Only faintly apparent or absent. [Butler, T. H.]
Becoming vestigial, and losing original function. [Kensley and Schotte, 1989]

Obtuse

Blunt at tip. [Butler, T. H.]

Occipital notch

Angulated indentation at rear of cephalon. [McLaughlin, 1980]
Angulated indentation at rear of head in some conchostracans. [Moore and McCormick, 1969]
Notch-like depression in dorsal posterior region of head. May be preceded by occipital point. (shallow and inconspicuous, acute and pronounced, deeply cleft). [Stachowitsch, 1992]

Occipital point

One dorsal posterior region of head, protuberance in front of occipital notch. [Stachowitsch, 1992]

Occludent margin

In cirripeds, margin of scutum and tergum forming aperture and occluding with comparable margins of opposed scutum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: margin of scutum or tergum facing aperture. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Margin of scutum and tergum bordering orifice. [McLaughlin, 1980]

Occludent teeth

In cirripeds, small projections on occludent scutal margin formed by extensions of external growth ridges that interdigitate with similar teeth on margin of opposed scutum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: one in a series of small projections along margin of scutum facing aperture (occludent margin). Formed by extensions of growth ridges; fits into corresponding structures of opposed scutum when aperture is closed. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Small projections on occludent scutal margin, formed by extensions of external growth ridges, interdigitating with teeth on margin of opposed scutum. [McLaughlin, 1980]

Ocellus

Little eye, distinct from main organ of vision. [Williams, 1984]
Simnple single eye or eye spot; common in some branchiopods and copepods.
See: Naupliar eye [McLaughlin, 1980]
Unpaired median eye, common in some branchiopods (e.g., Notostraca) and copepods (e.g., Cyclopoida) but otherwise uncommon. [Moore and McCormick, 1969]
(Taxon-specific: ) Nauplius eye. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Nauplius eye. [Stachowitsch, 1992]
One of four photosensitive organs located dorsally on anterior (annteulary) part of cephalon (head). (with/without lens). [Stachowitsch, 1992]
One of three simple photosensitive structures forming nauplius eye. (closely adjoining, widely separated). [Stachowitsch, 1992]

Ocular acicle

Acicle. [Stachowitsch, 1992]

Ocular bulla

Knob on inner surface of carapace connecting lower and upper orbital margins with basal segment of antenna, serving for protection of eye. [Moore and McCormick, 1969]
Knob on inner surface of carapace connecting lower and upper orbital margins with basal segment of antenna, serving to protect eye. [McLaughlin, 1980]

Ocular lobe

On anterior section of carapace, small, unpaired median projection of frontal lobe; typically bears eyes.
(syn. eye lobe) [Stachowitsch, 1992]
Pair of relatively short, immovable projections, one located anterolaterally on each side of carapace; bears eyes. [Stachowitsch, 1992]
One of two small, articulated lobes on head of certain eyeless amphipods. Function unknown.
(syn. eye lobe) [Stachowitsch, 1992]

Ocular papilla

Anterior projection on eyestalk of some mysidaceans. [Moore and McCormick, 1969]
Anterior projection on eyestalk. [McLaughlin, 1980]

Ocular peduncle

See: Eyestalk [Martin, 2005]
Eyestalk. [Williams, 1984]
Peduncle movably articulated with cephalon, with compound eye at distal end, sometimes with two or three segments, sometimes retractable.
(syn. eyestalk) [McLaughlin, 1980]
One of two eye-bearing, movable projections of head; typically consists of two segments (proximal basiophthalmite and distal cornea-bearing podophthalmite). Segment of head (ophthalmic segment) bearing ocular peduncles is termed acron and is not considered to be true somite. (retractile, nonretractile; two-segmented, three-segmented; club-shaped, conical, dilated, elongate, oval, triangular; pubescent, setiferous).
(syn. eyestalk) [Stachowitsch, 1992]
One of two eye-bearing movable projections of head. Consists of single segment and may bear papilla on inner or dorsal surface.
(syn. eyestalk) [Stachowitsch, 1992]
One of two eye-bearing, movable projections of medial (ocular) plate of acron. (cylindrical, dilated, subtriangular).
(syn. eyestalk) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Movable, eye- or visual pigment-bearing projection on each side of head (cephalon). (simple, denticulate = serrate, flat and crescentic, scimitar-like; with/without ocular scale).
(syn. eyestalk) [Stachowitsch, 1992]
One of two compound eye-bearing, movable projections of head. Consists of two indistinctly separated segments and bears photophore.
(syn. eyestalk) [Stachowitsch, 1992]

Ocular plate

Median cephalic plate bearing the eyestalks laterally (Fig. 3A). [Perez Farfante and Kensley, 1997]
Second of three plates (fastigial, ocular, postocular composing acron at tip of head; bears eyestalks (ocular peduncles). [Stachowitsch, 1992]

Ocular scale

Articulating plate attached mesially on eyestalks (some Anomura, Stomatopoda). [Poore, 2004]
Scale-like structure located on basal segment of eyestalk (Fig. 3A). [Perez Farfante and Kensley, 1997]
One of two small, dorsally directed projections of last plate (postocular plate) of acron. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Scale- or spine-shaped structure projecting from base of each eye-stalk (ocular peduncle); tip may cover ocular peduncle dorsally.
(syn. basal scale) [Stachowitsch, 1992]

Ocular sinus

Cavity in anterodorsal margin of each valve; contains compound eye and is overlaid by eye tubercle. [Stachowitsch, 1992]

Ocular spine or projection

Spine of lobe on carapace above eyes (some Palinura or Caridea). [Poore, 2004]

Ocular stylet

Spiniform process arising from ocular plate in the genus Sicyonia (Fig. 3A).

Oesophagus

See: Esophagus [Martin, 2005]

Oil sac

Elongate, sac-like structure containing oil droplets; located dorsally along narrower section of midgut. Considered to serve in buoyancy and as a food reserve.
(syn. oil gland) [Stachowitsch, 1992]

Olfactory hair

See aesthetasc. [McLaughlin, 1980]
Sensory seta covered by delicate cuticle projecting from most antennules and antennae.
(syn. aesthetasc, esthetasc, aesthete, esthete) [Moore and McCormick, 1969]

Olfactory seta

(Taxon-specific: ) Aesthetasc. [Stachowitsch, 1992]

Ommatidia

Individual visual components of the compound eye. [Kensley and Schotte, 1989]

Ommatidium

Cylindrical or prismoidal visual constituent of compound eye covered by transparent cuticle (cornea). [Moore and McCormick, 1969]
Cylindrical or prismoidal visual constituent of compound eye covered by transparent cuticle (cornea).
(pl. ommatidia) [McLaughlin, 1980]
One of numerous elongate, closely adjoining units forming eye; covered by cornea. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of up to 75 elongate, closely adjoining units forming each compound eye; lacks directly overlying true cornea. [Stachowitsch, 1992]

Ontogenic

The course of growth and development of an individual to maturity. [Ingle, 1992]

Oostegite

Medially directed lamellar structure arising from coxa of pereopod in the female, forming part of the broodpouch or marsupium. [Kensley and Schotte, 1989]

Oostegites

Flattened plates arising from inner proximal margin of coxa of certain pereopods. [Holdich and Jones, 1983]
Inner medially directed lamella arising from coxa of pereipod in females participating in formation of mid-ventral marsupium. [Moore and McCormick, 1969]
Inwardly directed plates of the leg coxae that form a brood pouch or marsupium. [Brusca and Brusca, 2002]
Lamellar lobes of cuticle extending medially from the coxa of an adult female isopod. They may be Seen in two forms: developing oostegites are small fat lobes that do not cross the ventral midline; oostegites of the brooding female are broad, long lamellae that overlap on the ventral midline, forming a marsupium for the developing embryos. [Wilson, 1989]
Unique, thinly flattened thoracic coxal endites that form a ventral brood pouch in all peracarids except thermosbaenaceans. [Brusca and Brusca, 2002]
In female, one in a series of flattened plates projecting from basal segments (coxae) of last maxilliped pair and first three pereopod pairs. Overlap to form brood chamber. (See also rudimentary oostegite).
(syn. brood plate) [Stachowitsch, 1992]
In female, one in a series of flattened plates projecting from basal segments (coxae) of second through fifth pereo-pods. Overlap to form marsupium or ovisac. [Stachowitsch, 1992]
Inner, medially directed lamella arising from coxa of pereopod in female, part of midventral marsupium. [McLaughlin, 1980]
In female, one in a series of flattened plates projecting from basal segments (coxae) of second through fifth pereopod pairs. Overlapping or interlocking to form brood chamber (marsupium). (pentagonal, rectangular, subrectangular).
(syn. brood plate) [Stachowitsch, 1992]
On female, one in a series of flattened plates typically projecting from basal segments (coxae) of second through fifth or sixth pereopods. Overlap to form brood chamber (marsupium).
(syn. brood plate) [Stachowitsch, 1992]
Thin ventromedial plates, born on coxae of some pereopods in female peracarids forming the marsupium, or broodpouch. [Wetzer et al. 1997]
In female, one of two, three, or seven pairs of flattened plates projecting from bases of thoracopods. Overlap to form brood chamber (marsupium).
(syn. brood plate) [Stachowitsch, 1992]

Oostegopod

appendage of genital somite in some branchiopods modified as brood pouch. [Moore and McCormick, 1969]

Open petasma

The lateral lobes are quite flexible, partially or entirely extended laterally, with the ventral costae not or barely turned ventrally.
See: Petasma [Perez Farfante and Kensley, 1997]

Open thelycum

One in which the seminal vesicles are absent.
See: Thelycum [Perez Farfante and Kensley, 1997]

Opener muscle

The muscle which moves the dactylus up relative to the propodus (Figs. 12, 13). [Warner, 1977]

Opercula

The visible opening of the female genital ducts on the third sternite. [Ingle, 1983]

Opercular membrane

Thin, flexible membrane attaching opercular valves to sheath, periodically shed during ecdysis, in balanomorph Cirripedia; represented by membranous hinge in verrucomorph Cirripedia. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell feature: in unstalked form, thin, flexible membrane attaching opercular valves (scuta, terga) to sheath. [Stachowitsch, 1992]

Opercular valve

Movable plate in orifice of cirriped shell, one of pairs of scuta and terga joined to sheath by opercular membrane. Moore and McCormick, 1969]. [Martin, 2005]
One of 2 or 4 movable plates occluding aperture in sessile barnacles. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell feature: in unstalked barnacle, calcareous plate forming part of closing apparatus (operculum). Consists of symmetrical forms of both scuta and terga, in asymmetrical forms of single (movable) scutum and single (movable) tergum. Attached to inner wall (sheath) of shell by opercular membrane. [Stachowitsch, 1992]

Operculiform

In the form of a cover or lid. [Kensley and Schotte, 1989]

Operculum

(female pleopod[s] II). — A plate over the branchial chamber of the abdomen of female janiroideans, consisting of the fused second pleopods. The first pleopods are absent in female Janiroidea. In males, pleopods I and II lock together to form an operculum somewhat similar to that Seen in the females. [Wilson, 1989]
In cirripeds, terga, scuta and associated membranes (Balanomorpha). or tergum and scutum of one side (Verrucomorpha), forming apparatus guarding aperture. [Moore and McCormick, 1969]
Scuta and terga (balanomorph) or movable scutum and tergum (verrucomorph) and associated membrane, forming apparatus occluding aperture. [McLaughlin, 1980]
In crab-like (brachyuran) decapod, small, lid-like structure serving to close opening (excretory pore) of antennal gland. [Stachowitsch, 1992]
Protective cover on ventral surface of abdomen (pleon); usually derived from anterior pleopod pair(s) or uropods.
See: Valve [Stachowitsch, 1992]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) In unstalked barnacle, movable, lid-like structure used to close aperture. Consists of symmetrical forms of articulated scutum and tergum closing against opposite scutum and tergum, in asymmetrical forms of movable scutum closing against movable tergum. [Stachowitsch, 1992]

Ophthalmic artery

Anterior aorta. [Stachowitsch, 1992]

Ophthalmic scale

Scale-like projection on proximal segment of eye-stalk (ocular peduncle). (unarmed, acuminate, serrate, with spines).
See: Ocular acicle [Stachowitsch, 1992]

Ophthalmic somite

See: Acron [Martin, 2005]
See acron. [McLaughlin, 1980]
Acron. [Stachowitsch, 1992]
Acron. [Stachowitsch, 1992]
Acron. [Stachowitsch, 1992]

Optic artery

Artery. [Stachowitsch, 1992]

Optic calathus

Terminal article of the eyestalk supporting, often embracing the cornea of the eye (Fig. 3A). [Perez Farfante and Kensley, 1997]

Optic lobe

Ganglion of brain for nervation of eye. [Moore and McCormick, 1969]
Ganglion of brain or nervous system for innervation of eye. [McLaughlin, 1980]

Optic nerve

Nerves that innervate the eyes and connect them to the protocerebrum. [Brusca and Brusca, 2002]
(Taxon-specific: ) Large nerve leading from supraesophageal ganglion to each (fused) compound eye. [Stachowitsch, 1992]

Optic vesicle

(Taxon-specific: ) Protuberance of outer wall of head whose cavity encloses compound eye. Optic vesicle does not communicate with exterior via pore. (touching/not touching margin of head). [Stachowitsch, 1992]
Compound eye. [Stachowitsch, 1992]

Oral appendages

Maxilliped-like appendages of first the thoracomere in cirripedes. [Brusca and Brusca, 2002]

Oral cone

Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: oral cone, posterior view; and oral cone, lefft lateral view. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Oral pyramid. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The conical or tubular mouth of siphonostomatoid copepods, formed by the anterior labrum and posterior labium. [Boxshall and Halsey, 2004]

Oral opening

Mouth. [Holdich and Jones, 1983]
(Taxon-specific: Family Cyatholaimidae) The mouth. [Boxshall and Halsey, 2004]

Oral pyramid

(Taxon-specific: Order Rhabditida) Cone-like projection, especially well developed in ascothoracican, formed by close association of mouthparts (labrum, mandibles, maxillules, maxillae).
(syn. mouth cone, oral cone) [Stachowitsch, 1992]

Orbit

Cavity in carapace containing eye. [Williams, 1984]
Circular opening in front part of some decapod carapaces enclosing eyestalk. [Moore and McCormick, 1969]
Circular to rectangular opening in anterior face of carapace supporting ocular peduncle in some decapods. [McLaughlin, 1980]
One of a pair of excavations on the anterior margin of the carapace in which the eye is situated. [Hobbs, Hobbs, and Daniel 1977]
One pair of excavations on anterior margin of carapace bodering eye (or remnant). [Hobbs and Jass, 1988]
The eye socket or excavation in the anterior margin of the carapace in which the eye is lodged. [Chace and Hobbs, 1969]
The eye socket. [Butler, T. H.]
The region of the carapace nearest to the eyes. [Ingle, 1983]
The socket at the front of the carapace in which the eye is situated and into which it can be folded. [Warner, 1977]
On anterior margin of carapace, one of two openings enclosing eyestalks (ocular peduncles). (circular, tubular). [Stachowitsch, 1992]

Orbital border

Anterior margin of the orbital region and the free margin below the eye anterior to the subhepatic region. [Ingle, 1983]

Orbital carina

See: Carapace carina f [Martin, 2005]
See: Carapace carinae f [McLaughlin, 1980]
On carapace, narrow ridge on margin of each orbit. [Stachowitsch, 1992]

Orbital fissure

See: Orbital hiatus [Martin, 2005]

Orbital hiatus

Gap in orbital margin of carapace at its lower (inner) angle. [M&M]. [Martin, 2005]
Gap or slit in orbital margin of carapace. [McLaughlin, 1980]

Orbital margin

Anterior border of the carapace, often continuing to the eye. [Perez Farfante and Kensley, 1997]

Orbital region

See: Carapace region j [Martin, 2005]
Narrow space bordering upper margin of orbit; not always distinguishable. [Williams, 1984]
One of two relatively narrow regions along anterior margin of carapace; corresponds to to point of projection of eyestalks. Adjoining regions include frontal, antennal or hepatic, and gastric regions. [Stachowitsch, 1992]
Paired areas on carapce adjacent to orbits. [Butler, T. H.]
Paired areas on the carapace just posterior to the eyes. [Perez Farfante and Kensley, 1997]
The paired areas on the carapace adjacent to the orbits. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by the part of the margin of the front and parts of margins of the frontal, protogastric and hepatic regions. [Ingle, 1983]
See: Carapace regions j [McLaughlin, 1980]
One of two relatively narrow regions along anterior margin of carapace; corresponds to to point of projection of eyestalks. Adjoining regions include frontal, antennal or hepatic, and gastric regions. [Stachowitsch, 1992]

Orbital spine

Spine projecting from the ventral extremity of the orbital margin (Fig. 2A). [Perez Farfante and Kensley, 1997]

Orbital tooth

See: Carapace tooth d [Martin, 2005]
See: Carapace teeth d [McLaughlin, 1980]
Exorbital process. [Stachowitsch, 1992]

Orbital-antennal sulcus

Longitudinal or oblique depression between the orbital margin and the hepatic spine (Fig. 2A). [Ingle, 1983]

Orbito-antennulary pits

Cavities below each orbital region into which the eyes and distal segments of the antennules can be retracted in the Dromioidea. [Ingle, 1983]
Cavities into which the antennules are folded. [Ingle, 1980]
On anterior margin of carapace, one of two cavities into which eyestalk and antennule may be retracted.
See: Antennular fossette [Stachowitsch, 1992]

Orbitorostral groove

Paired grooves between median ridge extending to rostrum and ridges above eyes (Alpheidae). [Poore, 2004]

Order

A major subdivision of a class in the classification of animals, usually consisting of several suborders and sometimes of infraorders. [Bliss, 1982]

Organ of Bellonci

Vesicular structure surrounded by sensory cells located directly under dorsal ingument of eyestalk. Often connected to exterior by sensory pore. Frequently found at base or in ocular papilla. Presumably with neurosecretory and sensory functions. [Stachowitsch, 1992]

Organs of pesta

Luminescent modified areas of the gastrohepatic glands, found within the cephalothorax of some species Sergestes s.1. [Perez Farfante and Kensley, 1997]
One of several processes on the gastrohepatic gland, modified to produce light; found on species of genus Sergestes. [Butler, T. H.]

Orifice

Opening in sessile barnacle wall occupied by operculum.
See: Aperture [McLaughlin, 1980]
Opening in upper part of cirriped shell containing opercular valves. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Aperture. [Stachowitsch, 1992]

Ornament

Valve sculpture. [Stachowitsch, 1992]

Ornamentation

(Taxon-specific: Family Cyatholaimidae) The spinulation, denticulation and markings on the surface of the body or appendages, of epicuticular origin.
See: Ornament [Boxshall and Halsey, 2004]

Orthonauplius

Nauplius. [Stachowitsch, 1992]

Ossicles

Small, hard plates and projections of the internal gastric skeleton of decapod crustaceans; serve in part for attachment of muscles that move the foregut. [Bliss, 1982]
One in a complex of rigid, plate-like structures associated with wall of cardiac stomach and, to a lesser extent, with pyloric stomach. Serves as site of attachment of muscles operating gastric mill or gives rise to tooth-like projections. [Stachowitsch, 1992]

Ostia

Three pairs of small openings in the heart of a decapod crustaceans; through the ostia, blood enters the heart from the pericardium. [Bliss, 1982]

Ostium

Opening in wall of heart through which blood is drawn from the pericardial sinus. [Holdich and Jones, 1983]
Valve of heart. [Moore and McCormick, 1969]
Valved opening in heart for retum of blood.
(pl. ostia) [McLaughlin, 1980]
(Taxon-specific: ) One of two lateral openings in heart. Blood enters heart through ostia and is pumped anteriorly. [Stachowitsch, 1992]
One of 11 pairs of segmentally arranged openings of heart in thorax; blood enters through ostia. [Stachowitsch, 1992]
One of typically four pairs of lateral openings in heart (one pair on head region, three in first three trunk somites). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of 14 to 18 pairs of segmentally arranged openings of heart; blood from precardial sinus enters heart through ostia. [Stachowitsch, 1992]
One of two openings of heart in each thoracic segment (thoracomere). [Stachowitsch, 1992]
Pair of muscular openings in posterior region of heart. Blood in pericardial sinus enters heart through ostia. [Stachowitsch, 1992]
One of typically two pairs of muscular openings in anterior region of heart. Blood from pericardial sinus enters heart through ostia. [Stachowitsch, 1992]
One of typically three pairs of muscular openings in heart. Blood from pericardial sinus enters heart through ostia. According to position one may distinguish dorsal, lateral, and ventral pairs of ostia. [Stachowitsch, 1992]
One of basically three pairs of muscular openings in heart at level of second, third, and fourth segments of pereon. Blood in pericardial sinus enters heart through ostia.
(syn. brood plate) [Stachowitsch, 1992]
One of one or two pairs of muscular openings of heart. Blood from pericardial sinus enters heart through ostia. [Stachowitsch, 1992]
Muscular opening in heart, either two pairs at level of third and fourth thoracomeres or three pairs at level of second through fourth thoracomeres. Blood from pericardial sinus enters heart via ostia. [Stachowitsch, 1992]
One of 13 pairs of openings of longitudinal heart (six pairs in thorax, seven in abdomen). Each ostium is equipped with a valve and serves to return blood into heart. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of 11 muscular openings in heart (three pairs of lateral ostia followed by three unpaired dorsal and one pair of lateral ostia). Blood in pericardium enters heart through ostia. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Opening at each posterolateral angle of heart. Blood enters heart through ostia and is pumped anteriorly through aorta, ventrally and posteriorly through additional openings. [Stachowitsch, 1992]
One of three openings (two lateral, one posteroventral) in heart. Blood from pericardium enters heart through ostia and is pumped anteriorly via aorta. [Stachowitsch, 1992]
One of two posterodorsal openings in heart. Blood from pericardium enters heart through ostia and is pumped through anteroventral aortic valve and aorta as well as posteroventrally through hepatic valves. [Stachowitsch, 1992]
Pair of muscular openings in heart of anaspidacean. Located at level of third thoracic somite (thoracomere). [Stachowitsch, 1992]
One of two muscular openings of heart. Blood from carapace sinus enters heart via ostia. [Stachowitsch, 1992]
One of two pairs of muscular openings in heart. Blood from pericardial sinus enters heart through ostia. [Stachowitsch, 1992]

Outer lamella

Relatively think outer wall of valve. Consists of a mineralized layer between two thinner, chitinous layers. (See also inner lamella). [Stachowitsch, 1992]
The outer layer of epidermis and cuticle of the dorsal body fold forming the valve; may be calcified or uncalcified. [Cohen, Peterson, and Maddocks, in press]

Outer lobe

Labium. [Stachowitsch, 1992]

Outer plate

Endite. [Stachowitsch, 1992]

Ovary

Female reproductive organ, producing ova. [Butler, T. H.]
In free-living copepod unpaired, parasitic copepod paired, expanded section of female reproductive system in which eggs are produced. Located dorsally, above midgut, near border of head and thorax. Opens to exterior on first abdominal segment (genital somite) via oviduct. (paired, unpaired). [Stachowitsch, 1992]
The organ which produces the female gametes or ova. [Ingle, 1983]
(Taxon-specific: ) Paired section of female reproductive system in which eggs are produced; typically extends through anterior part of trunk, one alond each side of midgut. Opens dorsally via oviduct into brood chamber. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Paired section of female reproductive system in which eggs are produced; extends anteriorly from fourth or fifth abdominal somite to eighth or seventh thoracic somite. Opens to exterior via oviduct originating near first or second abdominal somite (= genital somite). [Stachowitsch, 1992]
One of two sections of female reproductive system in which eggs are produced. Located in posterior end of head (cephalon) and opens exterior via highly elongated oviduct and short common gonoduct. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Paired, tube-like, located on each side in person. Each ovary opens to exterior on third pereopods via oviduct. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Paired, tube-like, extending through most of pereon. Each ovary opens to exterior via oviduct. [Stachowitsch, 1992]
Paired, expanded section of female reproductive system typically located in posterodorsal region of cephalothorax. Connected by bridge, each ovary opening to exterior on basal segment (coxa) of third pereopod via oviduct. [Stachowitsch, 1992]
Paired section of female reproductive system in which eggs are produced. Elongate, cylindrical, extending between heart and digestive tract in pereon. Each ovary opens to exterior on fifth pereon segment (pereonite) via oviduct and gonopore. [Stachowitsch, 1992]
Paired section of female reproductive system in which eggs are produced. Located dorsolateral to digestive tract in pereon, each ovary opening to exterior on ventral surface (sternite) of fifth pereon segment (pereonite) via oviduct. [Stachowitsch, 1992]
Paired section of female reproductive system in which eggs are produced. Located dorsolateral to digestive tract in thorax. May be connected by bridge. Each ovary opens on base of sixth thoracopod via oviduct. [Stachowitsch, 1992]
Paired section of female reproductive system in which eggs are produced. Elongate, extending along thorax and abdomen between heart and digestive glands. Fused posteriorly in telson and opening to exterior on sixth thoracic somite (thoracomere) via pair of oviducts, unpaired seminal receptacle, and gonopore. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In female reproductive system, pair of relatively slender, tubular organs in which eggs are produced; located between digestive tract and heart and extending through most of body. Each ovary opens at base of sixth thoracopods via oviduct. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Large, unpaired section of female reproductive system in which eggs are produced. Occupies greater part of thorax and opens to exterior via pair of short oviducts. Described as being located within separate body cavity (gonocoel). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Paired section of female reproductive system located in peduncle (stalked barnacle) or anteriorly in basis and mantle wall (unstalked barnacle). Each ovary opens to exterior via oviduct. [Stachowitsch, 1992]
Unpaired section of female reproductive system in which eggs are produced. Considered to consist of ovary proper and nutritive section ("yolk gland"). Extends throughout thoracoabdomen and opens to exterior via oviduct. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Typically paired, located in posterior region of trunk, and opening to exterior via oviducts. (paired, unpaired). [Stachowitsch, 1992]
Unpaired section of female reproductive system in which eggs are produced; located dorsally in posterior region of head (cephalon) and opening to exterior on seventh trunk segment via oviducts. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Paired, in anaspidacean, extending from anterior or posterior half of thorax to end of abdomen. Each ovary opens to exterior via oviduct. Restricted to abdomen in bathynellacean. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Paired, elongate, extending through most of thorax. Each ovary opens to exterior on sixth thoracic segment via oviduct. [Stachowitsch, 1992]
Section of female reproductive system in which eggs are produced. Paired (connected anteriorly), located between heart and digestive] tract, and extending through most of digestive tract. Each ovary opens to exterior at base of sixth thoracopod via oviduct. [Stachowitsch, 1992]

Ovate

Egg shaped or oval. [Kensley and Schotte, 1989]

Oviducal diverticulum

In female reproductive system, relatively large outpocketing of each oviduct near its point of origin at ovary. [Stachowitsch, 1992]

Oviduct

In females passageway from ovary to uterus and leading to genital aperture. [Moore and McCormick, 1969]
Passageway from ovary to genital aperture. [McLaughlin, 1980]
The duct connecting the posterior lobe of the ovary to the spermatheca. [Ingle, 1983]
Tube carrying ova from ovary to the exterior. [Holdich and Jones, 1983]
(Taxon-specific: ) Short and narrow section of female reproductive system between posterior part of each ovary and dorsal brood pouch. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Section of female reproductive system between eeach ovary and single ovisac. Originates from ovary near first or second abdominal somite (= genital somite). Distal portion of oviduct (extending into ovisac) occasionally referred to as uterus, terminal end as vagina. [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopore. Highly elongated, extending posteriorly to 18th postcephalic segment and soubling back to 6th thoracomere. Eggs accumulate at point of flexure. Terminal section merges with vas deferens to form common duct (gonoduct). [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on first segments (coxae) of third pereopods. [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on sixth thoracic segment (= fifth pereonite). [Stachowitsch, 1992]
Narrow section of female reproductive system extending from each dorsal ovary to gonopore on basal segment (coxa) of sixth thoracopod(= third pereopod). May be modified terminally to form seminal receptacle and vagina. [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on ventral surface of fifth pereon segment (pereonite). [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on ventral surface (sternite) of fifth pereon segment (pereonite). [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on bases (coxae) of sixth thoracopods. [Stachowitsch, 1992]
Section of female reproductive system between each ovary and unpaired seminal receptacle. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Relatively short, slender section of female reproductive system between each ovary and gonopore. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two short ducts leading from ovary to gonopore (vagina) on last thoracic somite (fourth thoracomere). Considered to function alternately. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Section of female reproductive system between each ovary and gonopores at bases of first pair of cirri. [Stachowitsch, 1992]
Section of female reproductive system leading from ovary to gonopore/atrium on first abdominal segment (genital somite). Paired, originating at anterior end of ovary and giving rise to oviducal diverticula. Secretes material forming ovisacs. [Stachowitsch, 1992]
Section of female reproductive system leading from ovary to gonopore; may be developed distally into uterus. Seminal receptacle frequently opens into oviduct via canal (spiral canal). (paired, unpaired). [Stachowitsch, 1992]
Paired section of female reproductive system between ovary and female gonopore; extends dorsally above gut from head or trunk border to seventh trunk segment. [Stachowitsch, 1992]
Section of female reproductive system between each ovary and gonopores on sixth thoracopods. [Stachowitsch, 1992]
Relatively short, slender section of female reproductive system between each ovary and gonopores on sixth thoracic segment. [Stachowitsch, 1992]
Slender section of female reproductive system between each ovary and corresponding female gonopore on coxae of sixth thoracopods. [Stachowitsch, 1992]

Ovigerous

Bearing developing embryos in the marsupium. [Wilson, 1989]
Bearing eggs attached to the pleopods. [Ingle, 1983]
Bearing or carrying eggs. [Bliss, 1982]
Pertaining to the condition of, or a female, carrying external fertilized eggs. [Butler, T. H.]

Ovigerous frena

In Cirripedia (certain Lepadomorpha), fleshy ridge or flap on interior mantle surface, adhering to and holding egg masses (ovigerous lamellae) in place. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Fleshy ridge or flap on inner surface of mantle adhering to and holding egg masses in place in some lepadomorph Cirripedia.
(pl. Ovigerous frenae) [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) In certain stalked barnacles, one in a series of fleshy ridges to which egg masses (ovigerous lamellae) are attached. [Stachowitsch, 1992]

Ovigerous lamella

In Cirripedia, eggs adhering in one or more lamellae, within mantle cavity and in certain Lepadomorpha, held in position by ovigerous frenae. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Adherent egg masses forming one or more lamellae within mantle cavity, in some lepadomorph Cirripedia, held in place by ovigerous frena. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) In certain stalked barnacles, one in a series of egg masses within mantle cavity. (See also ovigerous frena). [Stachowitsch, 1992]

Ovigerous spines

(Taxon-specific: Family Cyatholaimidae) The long spinous processes on the ventral surface of the genital double-somite of female monstrillids, used for carrying eggs. [Boxshall and Halsey, 2004]

Ovisac

In female, brood chamber for eggs on each appendage of last (11th) thoracic segments; chamber formed by exopod, with epipod serving as lid. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) In female, unpaired, sac-like structure projecting from ventral surface of first and second abdominal somites (= genital somite). Contains cement glands and serves as brood chamber for eggs. (cylindrical, subglobular).
(syn. egg sac) [Stachowitsch, 1992]
Sac-like structure attached to rudimentary appendage ("genital appendage") of ninth postcephalic segment (= first abdominal segment). Serves as brood chamber for egg. (single, paired). [Stachowitsch, 1992]
In female of certain tanaidaceans, term applied to brood chamber
formed by single pair of oostegites of fifth pereopod pair.
See: Marsupium [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Region of mantle cavity in which eggs are brooded. (See also brood chamber). [Stachowitsch, 1992]
In female, sac-like structure projecting from ventral surface of first abdominal segment (genital somite). Secreted by oviduct; serves as brood chamber for extruded, fertilized eggs. (single, paired).
(syn. egg sac) [Stachowitsch, 1992]
In certain female euphausiaceans, sac-like structure associated with posterior thoracopods and serving to brood eggs. (single, double, fused). [Stachowitsch, 1992]

Ovotestis

Gonad. [Stachowitsch, 1992]

Ovum

Mature, but unfertilized egg.
(pl. ova) [Butler, T. H.]

PD

The junction between the propodus and the dactylus (Fig. 12). [Warner, 1977]

Paired receptacles

Invaginated into the cephalothoracic cavity, opening through well protected slits usually on anterior border of sternite XIV, or on anterior part of XIII.
See: Seminal receptacles [Perez Farfante and Kensley, 1997]

Palate

See: Endostome [Martin, 2005]
Roof of buccal cavity in crabs. [Williams, 1984]
See endostome. [McLaughlin, 1980]
Endostome. [Stachowitsch, 1992]

Palm

See: Manus [Martin, 2005]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Body of propodus of chelate limb (excluding fixed finger). [Poore, 2004]
Expanded portion of propodus of chela situated proximal to "fingers" (Fig. 14). [Hobbs and Jass, 1988]
Portion of a chela proximal to the fingers. [Butler, T. H.]
Portion of the chela proximal to the propodal finger (Fig. 3C). [Perez Farfante and Kensley, 1997]
Proximal part of propodus of chela. [Williams, 1984]
See manus. [McLaughlin, 1980]
The broadened portion of the propodus of a chela proximal to the fingers. [Hobbs, Hobbs, and Daniel 1977]
The portion of a chela proximal to the fingers. [Chace and Hobbs, 1969]
Manus. [Stachowitsch, 1992]
In subchela of first two pairs of pereopods (gnathopods), posterior margin of propodus against which dactylus bears down. [Stachowitsch, 1992]
Cutting edge of the propodus, often defined proximally by a spine, in a subchelate appendage. [Kensley and Schotte, 1989]

Palp

A lateral appendage of the mandible or the maxilliped. [Wilson, 1989]
Reduced distal portion of limb, usually only one of its rami, but may compromise both rami plus basis; usually consists of distal 2 or 3 segments following merus. [Moore and McCormick, 1969]
Relatively slender 2- or 3-segmented appendage of mandible. [Hobbs and Jass, 1988]
Segemented, sensory structure attached to mandible; its presence or absence, and number of segments, of taxonomic value. [Butler, T. H.]
Structure found on the outer margin of the mandible, maxillule, maxilla and maxilliped, sometimes reduced or absent. Articulated on mandible and maxilliped. [Holdich and Jones, 1983]
The comparatively slender 2- or 3-segmented part of the mandible. [Hobbs, Hobbs, and Daniel 1977]
The two or three distal segments of the third maxilliped of crabs distal to the merus. [Chace and Hobbs, 1969]
Usually one ramus (endopod), sometimes both, and basis, reduced distally to 1 to 3 segments, associated with mouthparts; also nonsegmented setose structure attached to mandible and to lateral margin of labrum in thoracic Cirripedia. [McLaughlin, 1980]
Elongate process of fifth endite on trunk appendage.
(syn. tactile process) [Stachowitsch, 1992]
Posteriorly directed distal part of maxillule. Elongate and typically bearing filaments extending into branchial chamber. [Stachowitsch, 1992]
Distal projection of mouthpart (i.e., of mandible, maxillule). If fully developed, consists of three segments in the former, two in the latter. Also refers to distal section (endopod) of maxilliped or to terminal process on each lobe (paragnath) of lower lip (labium). [Stachowitsch, 1992]
Branch-like projection of mouthpart (mandible, maxillule, maxilla, or first maxilliped); consists of distal portion of mouthpart and is typically endopodal in nature. (one-, two-, three-segmented/jointed; club-shaped, flattened, recurved). [Stachowitsch, 1992]
Distal projection of mouthpart (mandible, maxillule, maxilla, maxilliped). Represents endopod and, if fully developed, consists of five segments (ischium, merus, carpus, propodus, dactylus). (one- to five-segmented/articulate). [Stachowitsch, 1992]
Articulated ramus consisting of one to three articles in mandible, of up to five articles in the maxilliped. [Kensley and Schotte, 1989]
Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Articulated ramus consisting of one to three articles on the mandible, and up to five articles on the maxilliped. (Palps do not occur on the maxillules or maxillae of isopods.). [Wetzer et al. 1997]
Distal projection of mandible or maxilliped. Represents endopod and basically consists of three segments in mandible, five segments in maxilliped. [Stachowitsch, 1992]
Distal projection of mouthpart (mandible, maxilla, rarely maxillule). Three-segmented and well-developed in mandibles, two-segmented in maxillae. Represents endopod in posterior mouthparts. [Stachowitsch, 1992]
Relatively slender, typically three-segmented branch of mandible. Occasionally also refers to small endopod of maxillule. (one-, two-, three-segmented). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Branch-like projection of mouthpart (mandible, maxillule, maxilla). May represent various parts of appendage (e.g, endopod, exite). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Slender medial projection of each antennule. Consists of two to three segments and may be tipped by setae. Formerly termed flagellum (along with thin epipods-flabella-of first two thoracopods). (uniramous, biramous). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of two projections from lateral margins of labrum; in acrothoracican, one of two projections from each mandible. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The basis plus rami of a limb. The palp may be reduced to a poorly-sclerotized extension of the exoskeleton bearing a crown of small setae corresponding to the terminal setae of one or both rami. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The part of the mandible or maxillule distal to the segment bearing the gnathobase or arthrite respectively. [Boxshall and Halsey, 2004]
Biramous, more distal part of fully developed mandible (gnathobase, palp) or maxillule (protopod, palp). Consists of inner branch (endopod) and outer branch (exopod). [Stachowitsch, 1992]
Distal part of manible. Basically biramous (with endopod and exopod), although basis and endopod form its principal component. [Stachowitsch, 1992]
Term used for a podocopan arm-like jointed portion (endopod or endopod plus basis) of limb, either directed forward and used for food manipulation, or directed backward and used for clasping. [Cohen, Peterson, and Maddocks, in press]
In anaspidacean and bathynellacean, distal projection of mandibles. (one- to three-segmented; prehensile, not prehensile). [Stachowitsch, 1992]
Distal projection of mouthpart. Considered to represent inner branch (endopod) in mandible, maxillule, and maxilla, outer branch (exopod) in maxilliped. [Stachowitsch, 1992]
Distal projection of mouthpart (mandible, maxillule, maxilla). Generally considered to be endopodal in nature. (unsegmented, two-/three-segmented). [Stachowitsch, 1992]

Palp foramen

Small circular opening in body of mandible communicating with mandibular palp. [Moore and McCormick, 1969]
Small opening in mandibular body communicating with mandibular palp. [McLaughlin, 1980]

Palpus

Oval setose mandibular endopod of cirripeds, attached directly to mandible (Acrothoracica) or to lateral margin of labrum (Thoracica). [Moore and McCormick, 1969]

Papilla

Tube- or finger-shaped projection from inner surface of each ocular peduncle.
(syn. ocular papilla) [Stachowitsch, 1992]
Type of valve sculpture: small, step-sided projection (one order of magnitude smaller tan tubercle or spine). [Stachowitsch, 1992]

Papillate

A small cylindrical protuberance that is slightly expanded distally and that has a convex, polished, dorsal surface. [Ingle, 1980]

Pappose seta

Shaft thin with long, flexible, sparsely to densely arranged setules, irregularly distributed along shaft; annulus probably absent; pore absent or present. [Ingle, 1992]

Parabranchial groove

See: Carapace grooves l [McLaughlin, 1980]
On each side of carapace, groove below, behind, and almost parallel with branchiocardiac and postcervical grooves; joins latter in lower part. [Stachowitsch, 1992]

Paracopulatory organ

Specialized endopod of pleopod in some Isopoda serving accessory function in copulation. [Moore and McCormick, 1969]
Specialized enpopod of pleopod in some isopods; used in copulation. [McLaughlin, 1980]

Paraesophageal ganglion

Swelling of each circumesophageal connective between supraesophageal and subesophageal ganglia. [Stachowitsch, 1992]

Paragnath

See: Labium, Metastoma [Martin, 2005]
A pair of ventral projections of the cephalic cuticle just posterior and medial to the mandibles. Each projection has two lobes, a broad lamellar outer lobe with hair-like setae on the inner margins and a thick inner lobe covered with many hair-like setae.
(syn. paragnathae or lower lips) [Wilson, 1989]
See metastoma. [McLaughlin, 1980]
(Taxon-specific: ) Labium. [Stachowitsch, 1992]
One of a pair of lobe-like structures between mandibles and maxillules posterior to mouth. Considered to represent either true lower lip or additional lobe of each maxillule. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) On underside of head, structure posterior to mouth between mandibles and maxillules; considered to represent or at least function as lower lip. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
In isopods, the labium is usually produced and cleft into a large bilobed structure, and hence more commonly referred to as the paragnath (=hypostome, mesastome, hypopharynx). [Wetzer et al. 1997]
One two lobes of labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of two lobe-like structures forming lower lip (labium) posterior to mouth. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two lobes of lower lip (labium); either papilla-shaped elevations posterior to mouth or reduced, along with labrum, to serrate flap enclosed in proboscis. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A pair of articulating lobes often bearing setae and located posterior to the mandible and anterior to maxilla 1. Homologies of the paragnath have not been determined, but it may be the praecoxa of the mandible or it may be that section of the praecoxa of maxilla 1 bearing a second lobe. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) A small paired lobe located on ventral surface of cephalosome, between the bases of mandibles and maxillules. [Boxshall and Halsey, 2004]
Labium. [Stachowitsch, 1992]
One of two lobes of lower lip (labium). [Stachowitsch, 1992]
One of a pair of lobes flanking opening (atrium oris) to mouth; margin of each paragnath bear dense cover of ribbon setae. [Stachowitsch, 1992]
One of two lobe-like structures forming lower lip (labium) posterior to mouth. [Stachowitsch, 1992]
Labium. [Stachowitsch, 1992]
One of two lobe-like structures forming lower lip (labium) posterior to mouth. [Stachowitsch, 1992]

Parapenaeid spine

Spine projecting from the distomesial margin of the first antennular segment. [Perez Farfante and Kensley, 1997]

Parasite

An organism, deriving its sustenance from a shrimp, the host. [Butler, T. H.]

Paries

Median triangular part of cirriped compartment plate, with lower edge attached to basis and adjoined laterally by margins of carinal tectum. [Moore and McCormick, 1969]
Median triangular part of each compartmental plate in sessile barnacles.
(pl. parietes) [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, median triangular part of each compartmental plate. Bears alae and/or radii laterally. [Stachowitsch, 1992]

Parietal canal

(Taxon-specific: Order Rhabditida) Longitudinal tube. [Stachowitsch, 1992]

Parietal plate

One of different kinds of shell elements forming calcareous wall surrounding body of cirripeds. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Plate. [Stachowitsch, 1992]

Parietal pore

See longitudinal tube. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Longitudinal tube. [Stachowitsch, 1992]

Parietal septum

In cirripeds, same as longitudinal septum. [Moore and McCormick, 1969]
See longitudinal septum. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Longitudinal septum. [Stachowitsch, 1992]

Parietal tube

One of myriad pore-like canals in longitudinal septum of balanomorph cirripeds, disposed normal to inner and outer laminae of compartment plate and separating them.
(syn. parietal pore, longitudinal pore, longitudinal tube) [Moore and McCormick, 1969]
See longitudinal tube. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Longitudinal tube. [Stachowitsch, 1992]

Pars ampullaris

Bottle-shaped diverticulum on entrance of caeca into pyloric chamber of stomach in syncarids. [Moore and McCormick, 1969]
Bottle-shaped diverticulum at entrance of ceca into pyloric chamber of stomach. [McLaughlin, 1980]
Ampulla. [Stachowitsch, 1992]
In digestive tract of anaspidacean, diverticulum at junction of posterior (pyloric) stomach and ceca. [Stachowitsch, 1992]

Pars centralis

In mandible, central part between lacinia mobilis and molar process. Typically with spine row or with cutting or grinding structures. [Stachowitsch, 1992]

Pars incisiva

See: Incisor process [Martin, 2005]
See incisor process. [McLaughlin, 1980]
Incisor process. [Stachowitsch, 1992]
Incisor process. [Stachowitsch, 1992]

Pars molaris

See: Molar process [Martin, 2005]
See molar process. [McLaughlin, 1980]
Molar process. [Stachowitsch, 1992]
Molar process. [Stachowitsch, 1992]

Parva

Postlarva.
(syn. parva stage) [Stachowitsch, 1992]

Parva stage

First postlarval stage in development of caridean decapods. [McLaughlin, 1980]
First postlarval stage in ontogeny of Caridea. [Moore and McCormick, 1969]

Pattern

(Taxon-specific: Family Cyatholaimidae) The order in which somites are added to the body relative to other somites, or that elements of segments are added to a limb relative to other elements; also the process of adding in a fixed order during development. [Ferrari and Dahms, in press]

Paucisetose

Having few setae. [Wilson, 1989]

Pecten

(Taxon-specific: ) One of up to three (proximal, middle, distal) series of small teeth along each caudal ramus. (teeth: equal, not equal). [Stachowitsch, 1992]

Pectinate

Having teeth like a comb. [Kensley and Schotte, 1989]

Pedestal seta

A spine-like seta that is raised above the dorsal surface of the body by a pedestal-like out-pocketing of the cuticle. [Wilson, 1989]

Pedicle

(Taxon-specific: Order Rhabditida) Protopod. [Stachowitsch, 1992]

Pedigerous

Bearing footlike appendages. [McLaughlin, 1980]
(Taxon-specific: Family Cyatholaimidae) With reference to the swimming legs; used of somites bearing swimming legs. [Boxshall and Halsey, 2004]

Peduncle

A stalk-like structure. [AHD]
Basal portion of certain appendages; also fleshy part of body in some cirripeds (Lepadomorpha), between capitulum and attachment to substrate with or without armor of chitinous or calcareous beads, scales, or filaments. [Moore and McCormick, 1969]
Basil articles of antennules and antennae. [Holdich and Jones, 1983]
Proximal segments of biramous limb, especially of antennule, antenna, pleopods and uropod.
(syn. protopod, sympod) [Poore, 2004]
Stalk in lepadomorph cirripeds, supporting capitulum, attached to substrate by opposite end, commonly armed with calcareous scales. [McLaughlin, 1980]
Stalklike structure supporting another structure or organ; in shrimps, main reference to part of antennule or antenna; sometimes another term for eyestalk. [Butler, T. H.]
The three proximal segments of the antennule. The five segments of the antenna of which the second and third are fused (referred to as the second + third segments). [Ingle, 1983]
(Taxon-specific: ) Basal part of each antenna. Relatively long, bearing two- to four-segmented dorsal and ventral branches (rami). [Stachowitsch, 1992]
Proximal division of antennule or antenna (peduncle, flagellum). If fully developed, consists of three segments in the former, five in the latter. May also refer to proximal part of pleopod or uropod. [Stachowitsch, 1992]
Proximal division of antennule or antenna (peduncle, flagellum). If fully developed, consists of four segments in the former, two in the latter (the second bearing an antennal scale). Proximal peduncular segment is large. [Stachowitsch, 1992]
Proximal of two divisions (peduncle, flagellum) of antennule or antenna. In antennule, typically consists of three segments (also termed protopod) and bears stylocerite. In antenna, typically consists of two-segmented protopod and two- or three-segmented endopod and bears scaphocerite.
See: Ocular peduncle [Stachowitsch, 1992]
Proximal division of antennule or antenna (peduncle, flagellum), although also applied to base of other appendages (e.g., maxilliped, pleopod, uropod). Typically consists in antennule of three segments, in antenna of five; second peduncular segment of latter bears opening of antennal gland. [Stachowitsch, 1992]
Enlarged proximal, or basalmost region of an isopod antennule, antenna, pleopod, or uropod; contains intrinsic musculature. [Wetzer et al. 1997]
Proximal division of antennule or antenna (peduncle, flagellum). Typically consists of three segments in antennule, five segments in antenna. [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Stalk or proximal part of an appendage, as in antennae. [Kensley and Schotte, 1989]
Three-segmented proximal division of antennule or antenna. Bears pair of flagella in former, flagellum and anntennal scale in latter. [Stachowitsch, 1992]
Proximal portion of antennule or antenna (two-segmented in the former, three-segmented in latter); bears flagella. (See also ocular peduncle). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Proximal of two divisions (peduncle, flagellum) of antennule or antenna. (three-/four-segmented; fourth segment: with/without process, with tuft of bristles). [Stachowitsch, 1992]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) In stalked barnacle, one of two external division of body (capitulum, peduncle). Attached to substratum by cement glands; contains ovaries. (naked, armed with scales).
(syn. stalk) [Stachowitsch, 1992]
Proximal part of antennule. Consists of two segments (articles), the proximal one bearing pad with numerous aesthetascs, the distal one being bifurcate and bearing two (dorsal and ventral) flagella. May also refer to base of antenna. [Stachowitsch, 1992]
Proximal divison of antennule or antenna (peduncle, flagellum). First segment of peduncle in antennule of anaspidacean and bathynellacean bears statocyst. (two-, three-, four-segmented). [Stachowitsch, 1992]
Proximal division of antennule or antenna (peduncle, flagellum). Consists of three segments in the former; not as clearly delimited in the latter, interpreted as consisting of five segments. [Stachowitsch, 1992]
Proximal division of antennule or antenna. Consists in the former of three segments, the first bearing antennular lappet; in the latter, consists of a single, superficially divided segment which bears opening of antennal gland. [Stachowitsch, 1992]

Peeler crab

As used in the fishery for blue crabs, a crab about to shed its shell; recognizable by the red line along the edge of the swimming paddles (fifth pair of thoracic legs). [Bliss, 1982]

Peg

(Taxon-specific: Order Monhysterida) On last pair of thoracic appendages (fourth thoracopods) of male, peg-like process of protopod. Fits into socket of third thoracopods in a peg-and-socket arrangement and serves to hold both thoracopods together during copulation. (acute, bent, conical, cylindrical, finger-like, spherical, two-jointed). [Stachowitsch, 1992]

Pelagic

Zone above the sea bottom; or living free from the bottom. [Butler, T. H.]

Penaeid shrimps

Primitive shrimps, members of the family Penaeidae; constitute the backbone of the shrimp fishing industry in North and South America and in many parts of Asia. [Bliss, 1982]

Penes

Paired (occasionally fused) submedian processes from vas deferens on sternum of male pereonite VII or pleonite 1. (Singular = penis). [Wetzer et al. 1997]

Penial rami

Paired submedian process on sternite 7 of male. [Kensley and Schotte, 1989]

Penicilla

Dentate setae on mandible.
(pl. penicillae) [McLaughlin, 1980]
In stygocaridacean, one in a series of dentate setae on mandible. [Stachowitsch, 1992]

Penicillus

Tuft of fine hairs resembling small brush. [Moore and McCormick, 1969]
Tufts of fine hair resembling small brush.
(pl. penicilli) [McLaughlin, 1980]

Penile papillae

Male cuticle projections on the posterior and medial margin of the seventh pereonite of janiroidean isopods. They contain the opening of the vasa diferentia.
(syn. penes) [Wilson, 1989]

Penis

A papilla on the coxa of the fifth pereiopod or sternite of the male denoting the opening of the genital duct. [Ingle, 1983]
Male copulatory organ. [May be exceptionally long in some cirripeds.]. [Moore and McCormick, 1969]
Male copulatory organ; probosciform in hermaphroditic thoracic Cirripedia and greatly distensible.
(pl. penes) [McLaughlin, 1980]
(Taxon-specific: ) Typically unpaired male copulatory structure at end of postabdomen. (single, paired). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two eversible male copulatory structures associated with fused first and second abdominal somites (= genital somite). Basically bipartite, consisting of exapnded basal part and apical segment of copulatory part. Vas deferens opens at tip of each penis. (proceeding ventrally close to each other, proceeding ventrolaterally to laterally and widely separated from each other; basal part: rigid, soft and flexible; apical part: with/without spines, serrate-denticulate). [Stachowitsch, 1992]
Tubular male copulatory structure associated with first segment (coxa) of last pair of pereopods; consists of extensible terminal part of vas deferens and may be variously enclosed in cuticular sheath. Functions in conjunction with modified anterior pleopod pairs. (single, paired).
(syn. sexual tube) [Stachowitsch, 1992]
Pair of relatively small male copulatory structures on ventral surface (sternite) of last (seventh) pereon segment (pereonite), one associated with each vas deferens.
(syn. penis papilla) [Stachowitsch, 1992]
In male, paired ventral copulatory papillae (occasionally a single cone) on ventral surface (sternite) of last (seventh) pereon segment (pereonite); transfers sperm to gonopods. [Stachowitsch, 1992]
Pair of male copulatory organs located on ventral surface (sternite) of last (eighth) thoracic somite.
(syn. genital papilla) [Stachowitsch, 1992]
Elongate male copulatory structure on precoxa of each appendage (thoracopod) of eighth thoracic somite (thoracomere). Sperm ducts and ducts of accessory glands open at tips of penes.
(syn. genital papilla) [Stachowitsch, 1992]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Male copulatory organ. In barnacle, located between bases of sixth (= last) pair of thoracic appendages (cirri); in ascothoracican, extends from first abdominal segment. (smooth, annulated; armed, unarmed; with/without basidorsal point).
(syn. intromittent organ) [Stachowitsch, 1992]
Complex, sclerotized copulatory structure in front of caudal rami on posterior end of trunk. Typically bears opening of vas deferens. (paired, unpaired). [Stachowitsch, 1992]
Paired, movable male copulatory organs located on ventral surface (sternite) of last (eighth) thoracic somite. [Stachowitsch, 1992]

Pentodont hinge

A five element hinge, in which the anterior and posterior region of the median element are differentiated, either crenulate or smooth (Family Pectocytheridae only). [Cohen, Peterson, and Maddocks, in press]

Penultimate

Second from last, as a segment of appendage. [Butler, T. H.]

Peraeopod

See: Pereiopod [Martin, 2005]
See pereopod. [McLaughlin, 1980]

Pereion

Anterior portion of trunk, usually provided with locomotory appendages; differs from thorax in excluding somite of maxillipeds.
(syn. pereon) [Moore and McCormick, 1969]
See pereon. [McLaughlin, 1980]

Pereionite

A segment of the pereon. [Wilson, 1989]
See pereonite. [McLaughlin, 1980]
Thoracic somite.
(syn. pereonite) [Moore and McCormick, 1969]

Pereiopod

Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
A thoracic appendage used for movement, feeding, and defense. [Mauchline, 1984]
Locomotory thoracopod.
(syn. peraeopod, pereopod, ambulatory leg, walking leg) [Moore and McCormick, 1969]
One of five pairs of appendages (legs) supporting cephalothorax; walking and chelate legs.
(syn. pereopod) [Hobbs and Jass, 1988]
One of five pairs of posterior appendages or legs attached to the cephalothorax. [Butler, T. H.]
One of the five posterior paired appendages or legs attached to the cephalothorax. [Chace and Hobbs, 1969]
The chelipeds and four pairs of walking legs posterior to the chelipeds (or ninth to thirteenth pairs of appendages). [Ingle, 1983]
Thoracic appendage used in locomotion; syn., ambulatory leg, walking leg.
(syn. peraeopod or pereopod) [McLaughlin, 1980]

Pereomere

See pereonite. [Brusca and Brusca, 2002]
Term occasionally applied to thoracic segments (thoracomeres) not fused with head. i.e., somites of pereon.
(syn. peraeomere) [Stachowitsch, 1992]

Pereon

Anterior portion of trunk with thoracopods, exclusive of maxillipedal somites and appendages.
(syn. paraeon, pereion) [McLaughlin, 1980]
Term referring to the free (unfused) thoracomeres posterior to the maxilliped-bearing thoracomeres in malacostracans. [Brusca and Brusca, 2002]
That portion of the thorax not fused to the head (when such fusion occurs). [Brusca and Brusca, 2002]
Thoracic division of body, comprising six free pereonites (thoracomeres) and bearing uniramous appendages. [Holdich and Jones, 1983]
Thoracic segments 2-8 bearing the locomotory appendages, or pereopods. (Thoracic segment 1 is part of the cephalon and bears the maxilliped.). [Wilson, 1989]
Division (tagma) of body between head (cephalon) and abdomen (pleon) or, more accurately, between cephalothorax and abdomen. Consists of five somites (pereonites), each bearing appendages (pereopods). Morphologically not equivalent to thorax (with a total of eight somites) because first three somites are fused to cephalon (i.e., cephalothorax). [Stachowitsch, 1992]
Division (tagma) of body between head and abdomen (pleon). Morphologically not equivalent to thorax (with a total of eight somites) because first thoracomere (bearing maxillipeds) is fused to head, the second being covered by and fused to carapace; accordingly, pereon can be considered to consist of seven or six segments (pereonites).
(syn. peraeon, pereion) [Stachowitsch, 1992]
Division (tagma) of body between head (cephalon) and abdomen (pleon) or more accurately between cephalothorax and abdomen. Consists of four to seven segments (pereonites), each bearing appendages (pereopods). Morphologically not equivalent to "thorax" because first (and occasionally second) thoracic segment (bearing maxilliped) is fused to cephalon.
(syn. peraeon, pereion, mesosome) [Stachowitsch, 1992]
Middle or thoracic region of the body, consisting of seven segments or pereonites, first fused with cephalon in isopods. [Kensley and Schotte, 1989]
Second and largest division (tagma) of body between head (cephalon) and abdomen (pleon) or more accurately between cephalothorax and pleon. Typically consists of seven segments (pereonites); morphologically not equivalent to thorax because first (and occasionally second) thoracic segment (bearing maxillipeds) is fused to cephalon.
(syn. peraeon, pereion) [Stachowitsch, 1992]
Those thoracic segments not fused to the cephalon. [Wetzer et al. 1997]
Term occasionally applied to that part of thorax not fused with head, i.e., second (or third) through eighth thoracomeres.
(syn. peraeon) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Region of body comprising three free thoracic somites (the first thoracomere being fused to head). [Stachowitsch, 1992]
In one interpretation of main body regions, division between cephalon (head + first thoracic somite) and abdomen. Accordingly, pereon consists of seven somites (pereonites), their appendages being termed pereopods.
(syn. pereaon, pereion) [Stachowitsch, 1992]

Pereonal segment

Pereonite. [Stachowitsch, 1992]

Pereonite

A segment of the pereon.
(syn. pereomere) [Brusca and Brusca, 2002]
Somite belonging to the pereon. [Holdich and Jones, 1983]
Somite of pereon.
(syn. paraeonite, pereionite) [McLaughlin, 1980]
One of five segments (somites) of pereon (i.e., all thoracomeres except first three which are fused to cephalon). [Stachowitsch, 1992]
One of seven segments (somites) of pereon (i.e., all thoracomeres except first, which is fused to head). [Stachowitsch, 1992]
One of up to seven segments (somites) of pereon (i.e., all thoracomeres except first and occasionally second, which are fused to cephalon). [Stachowitsch, 1992]
A segment of the pereon (=pereomere). [Wetzer et al. 1997]
One of typically seven segments of pereon (i.e., all thoracomeres except first ind occasionally second, which are fused to cephalon). Appendages of pereonites are termed pereopods.
(syn. pereiomere) [Stachowitsch, 1992]
Segment of the pereon. [Kensley and Schotte, 1989]
One of seven segments (somites) of pereon (i.e., all thoracomeres except first, which is fused to cephalon). [Stachowitsch, 1992]

Pereopod

See: Pereiopod [Martin, 2005]
An appendage of the pereon. [Brusca and Brusca, 2002]
Non-maxilliped thoracic limbs; five pairs in Decapoda (thoracopods 4-8) and three pairs in Stomatopoda (thoracopods 6-8); includes one pair of chelipeds and four pairs of walking legs in Brachyura. Each pereopod comprises the seven articles coxa, basis and endopodal articles ischium to dactyus, plus sometimes an exopod (attached to the basis). [Poore, 2004]
One of the five posterior paired appendages or legs of the cephalothorax (Fig.1, 3C). [Perez Farfante and Kensley, 1997]
One of the seven pereonal appendages. Consists of the following segments: coxa, basis, ischium, merus, carpus, propodus, dactylus. The coxa of adult female bears oostegites. The distal five podomeres are homologous with the endopod of the more primitive biramous thoracic limb of other Crustacea. [Wilson, 1989]
Thoracic appendage used in locomotion.
(syn. paraeopod, pereiopod, ambulatory leg, walking leg) [McLaughlin, 1980]
Uniramous appendage of the pereon (walking leg) usually of seven articles. [Holdich and Jones, 1983]
One of five pairs of appendages of pereon. Basically biramous, consisting of basal section (coxa, basis) bearinf five-segmented endopod (ischium, merus, carpus, propodus, dactylus) as well as smaller exopod. Number of pereopods bearing exopods is of taxonomic importance. (with/without exopod).
(syn. peraeopod, pereiopod) [Stachowitsch, 1992]
One of seven pairs of appendages (thoracopods 2-8) of pereon. First pair developed as chelipeds (leading to alternate nomenclature in which only six pairs of pereopods are recognized). (uniramous, biramous = with/without exopod; with/without ischium).
(syn. peraeopod, pereiopod) [Stachowitsch, 1992]
One of two appendages on each side of last five thoracic somites (appendage pairs of first three being modified as maxillipeds). Basically biramous, consisting of protopod, endopod, and exopod; exopod is often reduced, resulting in seven-segmented limb (coxa, basis, ischium, merus, carpus, propodus, dactylus). (ambulatory, natatory; biramous, uniramous; achelate, chelate, subchelate; equal, subequal, unequal; elongate, filiform, flagelliform, flattened, paddle-shaped, slender, stout; denticulate, granulate, hairy, pubescent, smooth, spinose, spinulose, tuberculate, unarmed).
(syn. pereiopod, peraeopod) [Stachowitsch, 1992]
One of up to seven pairs of appendages of pereon. Uniramous, consisting of modified (immovable) coxa (coxal plate) and six free segments (basis, ischium, merus, carpus, propodus, dactylus). Anterior two pairs may be differentiated as gnathopods. (simple, che-late, subchelate; ambulatory, raptorial).
(syn. peraeopod, pereiopod, walking leg) [Stachowitsch, 1992]
One of up to seven pairs of appendages of pereon. Uniramous, consisting of coxa, basis, ischium, merus, carpus, propodus, and dactylus. Anterior one or two pairs may be differentiated as gnathopods.
(syn. peraeopod, pereiopod) [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Paired appendage of the pereon, consisting of seven articles when unmodified. [Kensley and Schotte, 1989]
The paired legs of each pereonite. [Wetzer et al. 1997]
Term occasionally applied to appendage of thoracic somites not fused with head, i.e., thoracic appendages not modified as mouthparts (maxillipeds).
(syn. peraeopod, pereiopod) [Stachowitsch, 1992]
One of four pairs of appendages used in locomotion. Pereopods represent appendages (thoracopods) of thorax segments (thoracomeres) two through five, those of first being modified as maxillipeds, those of sixth often as copulatory limbs. Biramous, consisting of proximal protopod with distal inner branch (endopod) and outer branch (exopod). The term leg is often preferentially applied to all appendages following cephalic appendages.
(syn. pereiopod, peraeopod) [Stachowitsch, 1992]
In anaspidacean and stygocaridacean, term occasionally applied to appendage of thoracic somite not fused with head, i.e., all appendages except those of first thoracomere, which is fused to head and bears maxilipeds.
(syn. paraeopod, pereiopod) [Stachowitsch, 1992]
One of up to seven pairs of typically biramous appendages of pereon. Represents thoracopods 2-8 (i.e., excluding first thoracopods = maxillipeds).
(syn. peraeopod, pereiopod) [Stachowitsch, 1992]
Thoracopod. [Stachowitsch, 1992]

Pericardial cavity

Special cavity or sinus containing heart. [Butler, T. H.]

Pericardial membrane

Muscular membrane which separates heart from rest of body cavity. [Holdich and Jones, 1983]

Pericardial septum

(Taxon-specific: Family Pycnogonidae) In circulatory system, ventral wall of pericardial sinus; separates pericardial sinus from underlying hemocoel. Perforated by series of holes to permit flow of blood from hemocoel to sinus. [Stachowitsch, 1992]

Pericardial sinus

Space, bounded ventrally by a pericardial membrane, within which the heart lies. [Holdich and Jones, 1983]
(Taxon-specific: Family Pycnogonidae) In circulatory system, elongate cavity surrounding heart. Blood collects within sinus and enters heart through ostia; separated from underlying hemocoel by pericardial septum. [Stachowitsch, 1992]
Cavity surrounding heart. Blood collected in pericardial sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Blood collected in pericardial sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Blood, coming from gills, collects in pericardial sinus and enters heart via ostia.
(syn. pericardial sac, pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Elongate, often extending beyond heart as far posteriorly as telson. Blood collected in pericardia! sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Blood collected in pericardial sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Blood collected in pericardial sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]
Cavity surrounding heart. Blood collected in pericar-dial sinus enters heart via ostia.
(syn. pericardium) [Stachowitsch, 1992]

Pericardium

Blood sinus surrounding heart and communicating with it by pair of ostia in each somite except terminal one, may run entire length of trunk above gut. [Moore and McCormick, 1969]
Blood sinus surrounding heart and communicating with it by paired ostia. [McLaughlin, 1980]
The blood-filled area surrounding the heart of a decapod crustacean.
(syn. pericardial sinus) [Bliss, 1982]
Elongate cavity surrounding heart. Blood, coming from gills, collects in pericardium and enters heart via ostia.
(syn. pericardial cavity) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Elongate cavity surrounding heart. Blood collected in pericardium enters heart through ostia.
(syn. pericardial sinus) [Stachowitsch, 1992]
Cavity surrounding heart; delimited ventrally from digestive tract by septum (pericardial floor). Blood in pericardium enters heart via ostia.
(syn. pericardial chamber, pericardial sac) [Stachowitsch, 1992]
In circulatory system, cavity surrounding heart. Divided into anterior and posterior sections (the former enclosing heart). Blood in pericardium enters heart through ostia. [Stachowitsch, 1992]

Peritrophic membrane

Chitinous sheath secreted around feces (e.g., some Ostracoda). [Moore and McCormick, 1969]
Chitinous sheath secreted around feces. [McLaughlin, 1980]
Chitinous membrane, secreted in anterior region of midgut and surrounding feces; considered to protect midgut lining from damage during passage of undigestible material. [Stachowitsch, 1992]

Peritrophic membrane gland

Pair of small glands, one extending along each side of posterior (pyloric) stomach; opens into midgut and secretes membrane (peritrophic membrane) surrounding food material coming from digestive glands. [Stachowitsch, 1992]

Petasma

A complex genital structure attached to the mesial margins of the protopodites of the first pair of pleopods in male penaeidean shrimps. [Chace and Hobbs, 1969]
Abdominal appendage modified as gonapophysis in males of some eucarids, syncarids, and stomatopods. [Moore and McCormick, 1969]
Abdominal structure developed from male pleopods, used in copulation. [McLaughlin, 1980]
Anterior abdominal pleopod modified for sperm transfer in the Dendrobranchiata. [Brusca and Brusca, 2002]
Complex genital structure attached to the inner margins of protopodites of the first pair of pleopods on male penaeidean shrimps. [Butler, T. H.]
Copulatory organ of male penaeid shrimps that is formed from the first abdominal appendages (pleopods); used by the male to thrust the spermatophore against the thelycum of the female. [Bliss, 1982]
Endopodite of first pleopods in male Penaeidae; a complicated membranous plate bearing coupling hooks mesially which interlock with those on member of opposite side; may terminate distally in various complex-shaped lobes. [Williams, 1984]
Male genital structure comprising the enlarged and coupled endopods of pleopods 1 (Dendrobranchiata); usually composed of complex lobes and lobules. [Poore, 2004]
The male genital structure consisting of the much enlarged and coupled endopods of the first pair of pleopods. The presence or absence of a petasma, or in juveniles, the position of the first endopods (situated more distally in females than in males), is the easiest means of distinguishing between the sexes in penaeidean shrimps (Fig. 1, 4B).
(pl. petasmata) [Perez Farfante and Kensley, 1997]
The modified endopodite of the first pair of pleopods of male euphausiids. [Mauchline, 1984]
In reproductive system of male in shrimp-like (natantian) decapod, expanded structure formed by modified inner branches (endopods) of first pair of pleopods; may bear series of distal lobes (e.g., distolateral, distoventral, distomedian lobes) and other processes. Functions in transferring spermatophores into thelycum of female. [Stachowitsch, 1992]
In male reproductive system, copulatory structure on each appendage (pleopod) of first abdominal somite (pleomere). Located on inner branch (endopod) and pleuropod; consists of hook-shaped and tubular processes. [Stachowitsch, 1992]
In male, copulatory structure formed by first two pleopods. [Stachowitsch, 1992]
In male, one of first two pairs of pleopods modified as copulatory structure. Inner branch (endopod) basically consists of four lobes (auxiliary = additional, internal, median, setiferous lobes), each bearing a variety of projections (blades, heel, processes, setae, spines). Serves to transfer spermatophores into thelycum of female. [Stachowitsch, 1992]

Pharynx

Part of alimentary tract next to mouth and adjoining esophagus. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Esophagus. [Stachowitsch, 1992]

Pheromone

A chemical messenger secreted by an organism, that often elicits a specific response from another individual. [Ingle, 1983]

Phoresis

Association of one species of animal with another for the purpose of transport. [Ingle, 1983]

Phoront

Encysted stage of a ciliophoran protozoan. [Ingle, 1983]

Photophore

Light-producing organ of euphausiids. Those on the thorax and abdomen have lenticular lenses that can direct the blue-green light emissions. [Mauchline, 1984]
Luminescent integumental organ, sometimes with lens. [Poore, 2004]
Luminescent organ of the integument [Perez Farfante and Kensley, 1997]
Luminous organ generally located on eyestalk, limbs or abdomen of various crustaceans. [Moore and McCormick, 1969]
Luminous organ. [McLaughlin, 1980]
Specialized organ in some shrimps, capable of producing light, with or without lens. [Butler, T. H.]
Luminous organ; typically consisting of lens and reflector and variously distributed in and on body. [Stachowitsch, 1992]
In certain mysidaceans, bioluminescent gland emptying into reservoir which in turn opens near base of exopod of maxilla.
(syn. luminescent organ) [Stachowitsch, 1992]
One of numerous light-producing organs. Located at upper end of eyestalks (ocular peduncles), in coxae of second and eighth (often also third through sixth) thoracopods, and in middle of ventral surface (sternite) of first four abdominal somites.
(syn. light organ, luminescent organ) [Stachowitsch, 1992]

Phyllobranch

A type of decapod gill bearing a double series of platelike or leaflike branches from the axis. [Brusca and Brusca, 2002]
Gill with leaflike filaments.
(syn. phyllobranchia) [McLaughlin, 1980]
Type of gill whose axis bears series of broad and flattened, leaf-like branches.
(syn. phyllobranchia)
See: Dendrobranch, Trichobranch [Stachowitsch, 1992]

Phyllobranchia

A gill in which the lamellae are expanded as thin leaves. [Ingle, 1983]
Gill with leaf-like filaments. [McLaughlin, 1980]. [Moore and McCormick, 1969]
See phyllobranch. [McLaughlin, 1980]

Phyllobranchiate

(noun) A decapod bearing phyllobranch gills, or (adjective) the condition of having trichobranch gills. [Brusca and Brusca, 2002]

Phyllobranchiate gill

A gill in which the branches are platelike, usually occurring in paired series along the gill axis. [Perez Farfante and Kensley, 1997]
Gill with plate-like or leaf-like branches arranged in paired series along main axis. [Poore, 2004]

Phyllopod

Leg. [Stachowitsch, 1992]
Trunk appendage. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Thoracopod. [Stachowitsch, 1992]

Phyllopodia

Broad "leafy" limbs formed from enlarged exites or epipods arising from the base of a limb. [Brusca and Brusca, 2002]

Phyllopodial

(Taxon-specific: Family Cyatholaimidae) Used of non-prehensile maxillipeds with broad, flattened segments. [Boxshall and Halsey, 2004]

Phyllopodium

Leaf-like thoracic appendages of some crustaceans (e.g., Branchiopoda) including maxillulae and maxillae of Decapoda. [Moore and McCormick, 1969]
Leaflike thoracic appendages.
(syn. phyllopodia) [McLaughlin, 1980]

Phyllosoma

Early schizopod larval stage in ontogeny of palinurid and scyllarid lobsters. [Moore and McCormick, 1969]
Larval stage in development of palinuroidean decapods. [McLaughlin, 1980]
Pelagic larva of Palinura, develops eventually into peurulus stage before settlement. [Poore, 2004]
Term given to the larval (zoeal) stages of panulirid decapods. [Ingle, 1992]
The free-swimming larval stage of a spiny, or rock, lobster; corresponds in some ways to the protozoel stage and in other ways to the mysis stage of a penaid shrimp. [Bliss, 1982]
Zoea. [Stachowitsch, 1992]

Phylotypic stage

(Taxon-specific: Family Cyatholaimidae) The stage of development, relative to other stages, that has diverged least during the evolutionary history of a monophyletic group of organisms. The phylotypic stage of copepods is the first copepodid. [Ferrari and Dahms, in press]

Phylum

A major primary subdivision of the animal kingdom, consisting of one or more related classes. [Bliss, 1982]

Pilose

Covered with short hairs or setae. [Kensley and Schotte, 1989]

Pincer

Chela. [Stachowitsch, 1992]

Pinnate seta

see Plumose seta. [Butler, T. H.]

Pit

Type of valve sculpture: relatively large, more or less circular depression. May also be applied as general term for fossae, puncta, etc. [Stachowitsch, 1992]

Plankton

Animal and plant life, largely microscopic, found floating and drifting in large numbers in the ocean and in bodies of fresh water. [Bliss, 1982]
Organisms unable to maintain their position or distribution independent of the water movement or air masses. [Ingle, 1992]

Plate

(Taxon-specific: Order Rhabditida) In barnacle, one of a number of calcareous elements on outer surface of body. Produced by mantle and with characteristic structure, shape, and sculpture. One generally distinguished five primary plates (single carina and paired scuta and terga) and numerous secondary plates, including single rostrum, subrostrum, subcarina, as well as various lateral plates (lateralia, latera). (See also compartmental plate, operculum, parietal plate, scale). [Stachowitsch, 1992]

Plectrum

Process at the base of the antenna that is rubbed against a "file" on the head to produce sound in most palinuran decapods. [Brusca and Brusca, 2002]

Pleomere

See: Abdominal somite [Martin, 2005]
See abdominal somite. [McLaughlin, 1980]
One of six segments (somites) of abdomen (pleon). Last (sixth) or last two (fifth and sixth) pleomeres fused to telson to form pleotelson. First five pleomeres typically bear pleopods; last pleomere bears uropods.
(syn. pleonite) [Stachowitsch, 1992]
One of six segments (somites) of abdomen (pleon); each bears pair of appendages (pleopods). Last pleomere bears uropods and is followed by telson.
(syn. pleonite, abdominal somite) [Stachowitsch, 1992]
One of six segments (somites) of abdomen (pleon). Each pleomere bears appendages (pleopods). If abdomen is subdivided into anterior pleosome and posterior urosome, then posterior three somites may be termed urosomites. [Stachowitsch, 1992]
Pleonite. [Stachowitsch, 1992]
One of six segments (somites) of abdomen. Each pleomere may bear pair of appendages, those of first five being termed pleopods, those of sixth termed uropods. [Stachowitsch, 1992]
One of six segments (somites) of abdomen; each bears pair of appendages (pleopods). Last (sixth) somite bears uropods and is followed by telson. (See also pleotelson). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One in a series of seven segments (somites) of abdomen, the first four bearing well-developed appendages (pleopods), the fifth and sixth with reduced appendages. Bears telson posteriorly.
(syn. abdominal somite) [Stachowitsch, 1992]
One of five segments (somites) of abdomen. First pleomere termed genital somite, last pleomere termed anal somite. Lacks appendages. (See also urosomal segment).
(syn. abdominal somite) [Stachowitsch, 1992]
One of basically six segments (somites) of abdomen. Anterior five may bear pleopods, with last (sixth) pleomere bearing uropods, In bathynellacean. Last pleomere is fused with telson to form pleotelson. (anaspidacean: body flexed/not flexed at first pleomere). [Stachowitsch, 1992]
One of six segments (somites) of abdomen. Last pleomere may be fused to telson to form pleotelson. First two pleomeres bear pleopods, with last pleomere bearing uropods.
(syn. pleonite) [Stachowitsch, 1992]
One of six segments (somites) of abdomen. Each pleomere bears pair of appendages, those of first five being termed pleopods, those of sixth being termed uropods. Last pleomere bears posterior telson. (smooth, with dorsal spine, with dorsal keel). [Stachowitsch, 1992]

Pleon

A term that refers to the abdomen in malacostracans. [Brusca and Brusca, 2002]
Abdomen of crustacean. [Moore and McCormick, 1969]
Abdominal body division, usually comprising five somites and often bearing biramous pleopods. [Holdich and Jones, 1983]
See abdomen; also first 3 abdominal somites of amphipods. [McLaughlin, 1980]
Posterior division (tagma) of body (either cephalon, pereon, pleon or cephalothorax, pleon). Narrow, consisting of six somites (pleonites) bearing posterior telson.
(syn. abdomen) [Stachowitsch, 1992]
Posterior of three divisions (tagmata) of body (either head, thorax, pleon, or head, pereon, pleon). Consists basically of six somites (pleomeres) bearing posterior telson.
(syn. abdomen)
See: Pleotelson [Stachowitsch, 1992]
Abdomen. [Stachowitsch, 1992]
Posterior division (tagma) of body (cephalon, pereon, pleon) consisting basically of six somites (pleomeres). May be further subdivided into anterior pleosome and posterior urosome. Reduced or absent in certain amphipods.
(syn. abdomen) [Stachowitsch, 1992]
Abdomen. [Wetzer et al. 1997]
Posterior division (tagma) of body (cephalon, pereon, pleon) consisting basically of six segments (pleonites).
(syn. abdomen)
See: Pleotelson [Stachowitsch, 1992]
Posterior or abdominal region of the body, primitively consisting of six segments or pleonites, and bearing paired pleopod and uropod appendages. [Kensley and Schotte, 1989]
Abdomen. [Stachowitsch, 1992]
Abdomen. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Abdomen. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Abdomen. [Stachowitsch, 1992]
Abdomen. [Stachowitsch, 1992]
Abdomen. [Stachowitsch, 1992]
Abdomen. [Stachowitsch, 1992]

Pleonite

See: Abdominal somite [Martin, 2005]
A segment of the pleotelson. [Wilson, 1989]
See abdominal somite. [McLaughlin, 1980]
Segments of the abdomen.
(syn. pleomeres) [Brusca and Brusca, 2002]
Somite of pleon. [Holdich and Jones, 1983]
One of six segments (somites) of abdomen (pleon). Cylindrical, anterior pleonites occasionally bearing appendages (pleopods). Posterior pleonite bears uropods and may be fused to telson to form pleotelson. [Stachowitsch, 1992]
A segment of the pleon (=pleomere). [Wetzer et al. 1997]
One of basically six segments of pleon. Appendages of pleonite are termed pleopods; often considerably narrower than pereonites. Last (= sixth) pleonite typically fused to telson to form pleotelson.
(syn. pleomere) [Stachowitsch, 1992]
Segment of the pleon. [Kensley and Schotte, 1989]
Pleomere. [Stachowitsch, 1992]

Pleopod

An appendage attached to an abdominal segment. [Ingle, 1983]
An appendage of any one of the first five abdominal segments. [Warner, 1977]
Biramous, often natatory, appendage of pleon. [Holdich and Jones, 1983]
Distinctive, usually biramous, abdominal appendages in malacostracans. [Brusca and Brusca, 2002]
Limb of any of first five abdominal somites in Eumalacostraca (six in Phyllocarida), in many crustaceans adapted for swimming.
(syn. swimmeret) [Moore and McCormick, 1969]
One of five pairs of appendages borne on the first five abdominal segments. [Hobbs, Hobbs, and Daniel 1977]
One of five pairs of appendages on first five abdominal segments ('swimmerets," or modified into male gonopod. [Hobbs and Jass, 1988]
One of paired limbs on abdominal somites 1-5, usually biramous. [Poore, 2004]
One of the biramous paired appendages typically arising ventrally from each of the anterior five abdominal somites. In the shrimps, they are primarily swimming organs (Fig. 1). [Perez Farfante and Kensley, 1997]
One of the five paired, biramous, ventral limbs of the pleotelson. In unmodified form, it consists of a basal segment - the protopod - and two distal rami called the endopod and the exopod. The rami may be biarticulate. Female Asellota lack the first pleopods. In male Asellota, the first pleopods are present only as uniramous structures (fused into a single elongate plate in the superfamily Janiroidea). The rami of the male second pleopod are modified as copulatory structures. Pleopods III-V have very thin cuticle and function as gills (branchiae). [Wilson, 1989]
One of the paired appendages typically arising from each of first five abdominal somites; primarily used for swimming in shrimps. [Butler, T. H.]
One of the paired appendages typically arising from each of the first five abdominal somites. In the shrimps, they are primarily swimming organs; in the true crabs, they are modified for attachment of the eggs in females and as sexual appendages (two anterior pairs) or absent (three posterior pairs) in males. [Chace and Hobbs, 1969]
Paired abdominal appendages used for swimming (hence often called swimmerets) by shrimps; used for attachment of eggs by female shrimps, lobsters and crabs. [Bliss, 1982]
Paired appendage of any first 5 abdominal somites (rarely 6) in Malacostraca, adapted for swimming.
(syn. swimmeret) [McLaughlin, 1980]
Swimming appendage of the abdomen. [Mauchline, 1984]
One of a variable number of paired appendages of abdomen (pleon); typically present only in male. Conists of two-segmented basal part (peduncle) bearing two-segmented endopods and one-segmented exopods. Number of pleopods in male is of taxonomix importance. [Stachowitsch, 1992]
Paired appendage of first five somites (pleomeres) of abdomen (pleon). Consists basically of two-segmented protopod (coxa, basis) bearing one-segmented endopod and one- to two-segmented exopod. Typically absent in female. (uniramous, biramous; slender and elongate, flattened and short; simple, setose).
See: Uropod [Stachowitsch, 1992]
One of two appendages of each abdominal somite (pleomere); typically consists of base (protopod) and two branches (endopod, exopod). Serves in swimming or variously modified as copulatory structures (e.g., gonopod, petasma) in male, egg-brooding structures in female. (biramous, uniramous; symmetrical, asymmetrical).
(syn. swimmeret)
See: Uropod [Stachowitsch, 1992]
Paired appendage of each somite of anterior subdivision (pleosome) of abdomen (pleon). Basically biramous, consisting of basal segment (peduncle) and two branches (rami). Each pair may be coupled basally by hooks for swimming. First two uropod pairs represent modified pleopods. [Stachowitsch, 1992]
One of two appendages of each of the first five abdominal somites (those of sixth somite being termed uropods). Biramous, flattened, and typically consisting of basal segment and two branches (rami). Usually with respiratory function. Second pair in male modified as gonopods. [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Paired appendage of the pleon, five pairs being present in the primitive condition. [Kensley and Schotte, 1989]
The biramous, paired, lamellar appendages of each pleonite. [Wetzer et al. 1997]
One of two appendages of abdominal somite (pleomere). Basically biramous, consisting of two-segmented protopod bearing multisegmented inner branch (endopod) and outer branch (exopod). Appendges of last pleomere termed uropods. [Stachowitsch, 1992]
One of two appendages of each abdominal somite (pleomere). Biramous, flattened, and consisting of basal protopod and lamellar endopod and exopod, the former bearing an appendix interna, the latter gills. Appendages of last (sixth) pleomere are termed uropods. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of six pairs of appendages of abdomen, the first four pairs being well developed, the last two pairs being reduced. Basically biramous, consisting of protopod with inner branch (endopod) and out branch (exopod). (biramous, uniramous) (See also appendix interna).
(syn. abdominal appendage) [Stachowitsch, 1992]
One of two appendages of abdominal somite (pleomere). Full complement present only in anaspidacean, with stygocaridacean and bathynellacean bearing at most two anterior pairs of pleopods. First and second pairs modified for copulation in male. (uniramous, biramous). [Stachowitsch, 1992]
One of two pairs of appendages on first two somites (pleomeres) of abdomen. Small, uniramous, and consisting of single segment. [Stachowitsch, 1992]
One of two appendages of each of the first five abdominal somites (those of sixth somite being termed uropods). Biramous, consisting of two-segmented base as well as one-segmented endopod and exopod. First (and to a lesser extent second) pair of pleopods in male modified to form petasma.
See: Appendix interna [Stachowitsch, 1992]

Pleopodal artery

Artery. [Stachowitsch, 1992]

Pleopodal cavity

The deeply concave ventral surface of the pleotelson that encloses the pleopods dorsally and laterally. Because the more posterior pleopods function as gills, the pleopodal family is sometimes called the branchial cavity. [Wilson, 1989]

Pleosome

Anterior of two subdivisions (pleosome, urosome) of abdomen (pleon). Consists of three somites (pleomeres), each bearing pair of appendages (pleopods). [Stachowitsch, 1992]

Pleotelson

Pleonite 6 (sometimes 5 and 6) fused to telson. [Holdich and Jones, 1983]
Structure formed by fusion of one or more abdominal somites with telson, as in most isopods. [Moore and McCormick, 1969]
Structure formed by fusion of one or more abdominal somites with telson. [Butler, T. H.]
The abdominal part of the body, consisting of a short segment (pleonite 1) and a long and broad segment. The large segment is made of the fused more posterior pleonites and the telson, a terminal segment bearing the anus. Primitively, there are six pleonites: the anterior five bear ventral pleopods, and the sixth bears the uropods. In Janiroidea, only the first pleonite is expressed as a free segment. [Wilson, 1989]
Structure formed by fusion of last (sixth) abdominal somite (pleonite) with telson. [Stachowitsch, 1992]
Terminal segment of body formed by fusion of telson with last (sixth) or fifth and sixth abdominal somites (pleomeres). [Stachowitsch, 1992]
In all isopods the sixth pleonite is fused to the telson to form a pleotelson. In anthurideans the line of fusion is often visible as a deep dorsal groove or fold. [Wetzer et al. 1997]
Structure resulting from the fusion of the telson and one or more pleonal segments. [Kensley and Schotte, 1989]
Terminal structure of body formed by fusion of one or more abdominal segments (pleonites) with telson. [Stachowitsch, 1992]
Telson. [Stachowitsch, 1992]
In certain thermosbaenaceans, terminal segment of body formed by fusion of telson with last (sixth) abdominal somite (pleomere). [Stachowitsch, 1992]

Plesiomorphic

(Taxon-specific: Family Cyatholaimidae) Referring to the ancestral state of a character. [Boxshall and Halsey, 2004]

Pleura

See: Epimere [Martin, 2005]
See epimere.
(pl. pleurae) [Wilson, 1989]
Pleurite. [Stachowitsch, 1992]
On each side of abdominal segment (pleomere) in certiain mysidaceans, ventral extension of tergite. In female, pleura of first pleomere may be enlarged to support posterior part of brood chamber (marsupium). May be divided into anterior and posterior lappets. [Stachowitsch, 1992]

Pleural lobe

See: Epimere [Martin, 2005]
See epimere. [McLaughlin, 1980]
Ventral expansion of the abdominal tergite. [Brusca and Brusca, 2002]
Lateral part of integument (as opposed to sternite = ventral surface and tergite = dorsal surface); in first seven trunk somites (thoracomeres) developed as ventrolaterally directed lobes, in last (eighth) thoracomere small or reduced. (acute, rounded).
(syn. pleuron) [Stachowitsch, 1992]
Pleurite. [Stachowitsch, 1992]

Pleural suture

Line of separation of carapace in molting. [McLaughlin, 1980]
line of splitting apart of carapace in molting, corresponding to linea dromica, and present in all brachyurans. [Moore and McCormick, 1969]
Suture. [Stachowitsch, 1992]

Pleurepimere

See: Epimere [Martin, 2005]
See epimere. [McLaughlin, 1980]

Pleurite

See: Epimere [Martin, 2005]
See epimere. [McLaughlin, 1980]
Lateral part of integument of somite (as opposed to sternite = ventral surface and tergite = dorsal surface). Most clearly visible in abdomen of shrimp-like (natantian) decapod, where they may form prominent lateral extensions (those of second pleomere occasionally being largest and overlapping preceding and following pleurites). The multiplicity of terms stems from differing early interpretations of cephalothorax region, i.e., lateral side of primary somites and lateral side of overlying carapace.
(syn. epimere, epimeron, pleura, pleural lobe, pleurepimere, pleuron, tergal fold) [Stachowitsch, 1992]
Lateral extension of body segment (somite).
(syn. pleuron, lateral process) [Stachowitsch, 1992]
Lateral extension of each adult trunk segment; gut diverticula extend into each pleurite. (posterolateral corner: rounded, pointed).
(syn. pleural lobe) [Stachowitsch, 1992]
Lateral part of integument of somite; forms prominent, ventrally directed extensions in each abdominal somite (pleomere).
(syn. pleuron, epimere)
See: Sternite, Tergite [Stachowitsch, 1992]

Pleurobranch

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
A decapod gill arising from the lateral body wall or surface of the thoracic pleura; "side gills." [Brusca and Brusca, 2002]
A gill situated on the body wall dorsal to the articulation of an appendage. [Hobbs, Hobbs, and Daniel 1977]
Gill attached to body wall inside branchial cavity dorsal to coxae of pereopods, usually 1 pair per somite and pointing down between arthrobranchs. [Poore, 2004]
Gill attached to the later wall of thorax, just above origin of basal segment of appendage. [Butler, T. H.]
Gill of decapods attached directly to body wall.
(syn. pleurobranchia) [Moore and McCormick, 1969]
Gill attached directly to body wall.
(syn. pleurobranchia) [McLaughlin, 1980]
Type of gill attached directly to body wall above base of thoracopods 2-8 (i.e., if full complement is present, above all thoracopods except first maxilliped).
(syn. pleurobranchia)
See: Arthrobranch, Podobranch [Stachowitsch, 1992]

Pleurobranchia

Gill attached to the body wall (pleural membrane), dorsal to the articulation of the appendage (Fig. 3C).
(pl. pleurobranchiae) [Perez Farfante and Kensley, 1997]
See pleurobranch. [McLaughlin, 1980]

Pleurobranchiae

A gill attached directly to the body wall. [Ingle, 1983]
Gills attached to lateral wall of body dorsal to articulation of appendage. [Williams, 1984]

Pleuron

See: Epimere [Martin, 2005]
Lateral overhanging plate of abdominal segments. [Hobbs and Jass, 1988]
Lateral part of body wall, especially of abdomen, produced ventrally.
(pl. pleura) [Poore, 2004]
One of the lateral flaps on each of the anterior five abdominal somites (Fig. 1).
(pl. pleura) [Perez Farfante and Kensley, 1997]
One of the paired lateral flaps on each side of the first five abdominal somites in shrimps and crayfishes.
(pl. pleura) [Chace and Hobbs, 1969]
One of the paired lateral flaps on each side of the first five abdominal somites.
(pl. pleura) [Butler, T. H.]
See epimere.
(pl. pleura) [McLaughlin, 1980]
Pleurite. [Stachowitsch, 1992]
Pleurite. [Stachowitsch, 1992]

Pleuropod

See: Precoxa [Martin, 2005]
See precoxa. [McLaughlin, 1980]

Plicate

Pleated or folded. [Kensley and Schotte, 1989]

Plication

Type of valve sculpture: ridge or series of ridge-like folds involving entire valve wall. [Stachowitsch, 1992]

Plumodenticulate seta

Shaft usually quite thin, but always gradually tapering distally and often with setules confined to pre-annular region and denticles to post-annular; setules often long and thin, but sometimes short and broad, sometimes apposed to or interspersed with denticles; may grade into cuspidate setae. [Ingle, 1992]

Plumose natatory seta

Shaft thin and very long; setules long, alternating on shaft and without setulettes; pore absent; annulus prominent, located medially where post-annular part of shaft is often bent. [Ingle, 1992]

Plumose seta

A feather-like seta that has two dense rows of thin, long setules beginning at the base of the seta and continuing to the tip. [Wilson, 1989]
seta, with distolateral processes, resembling a feather.
(pl. setae) [Butler, T. H.]
Shaft thin, ampulla sometimes prominent; setules long, dense, to sparse and alternating on shaft and sometimes in discernible groups, often with setulettes; pore absent; annulus inconspicuous or absent; denticles absent. [Ingle, 1992]

Podobranch

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
A decapod gill attached to the coxa of an appendage; "foot gills." [Brusca and Brusca, 2002]
A gill borne on the coxa of an appendage. [Hobbs, Hobbs, and Daniel 1977]
Gill arising from an epipod. [Butler, T. H.]
Gill arising from coxa of thoracopod.
(syn. podobranchia) [McLaughlin, 1980]
Gill attached to coxa of pereopod or its epipod. [Poore, 2004]
Gill placed on epipods of thoracopods.
(syn. podobranchia) [Moore and McCormick, 1969]
Type of gill attached to first segment (coxa) or on epipod of coxa of thoracopods 2-7 (i.e., if full complement is present, on all thoracopods except first maxilliped and last pereopod).
(syn. podobranchia)
See: Arthrobranch, Pleurobranch [Stachowitsch, 1992]
Gill. [Stachowitsch, 1992]

Podobranchia

Gill born on basal segment (coxa) of a thoracic appendage.
(pl. podobranchiae) [Perez Farfante and Kensley, 1997]
See podobranch. [Butler, T. H.]

Podobranchiae

A gill arising from an epipod. [Ingle, 1983]
Gills attached to coxa of appendage. [Williams, 1984]

Podomere

A segment of a crustacean appendage. [Wilson, 1989]
A segment of an appendage joined to the body or to adjacent podomeres by joints and capable of independent movement. [Warner, 1977]
Any one of the segments of an appendage, such as a segment of a pereiopod or maxilliped. [Chace and Hobbs, 1969]
Any one of the segments of an appendage, such as a segment of a pereopod or maxilliped. [Perez Farfante and Kensley, 1997]
Individual segment of limb; not.
(syn. joint) [Moore and McCormick, 1969]
See segment. [McLaughlin, 1980]
Single segment of any appendage. [Hobbs and Jass, 1988]
Term used by some authors for segment of an appendage, such as merus of a pereiopod. [Butler, T. H.]
Segment. [Stachowitsch, 1992]
Segment of jointed crustacean limb separated from other segments by articulated joint or inflexible suture.
(syn. article) [Cohen, Peterson, and Maddocks, in press]
Segment. [Stachowitsch, 1992]

Podopericardial channel

One in a series of channels through which blood flows from ventral sinus to gills and appendages. [Stachowitsch, 1992]

Podophthalmite

One of two segments of eyestalk (when segmented), bearing cornea. [McLaughlin, 1980]
One of two segments of eyestalk, articulating with basophthalmite proximally and bearing corneal surface of eye distally. [Moore and McCormick, 1969]
Distal of typically two segments (basiophthalmite, podophthalmite) of eyestalk (ocular peduncle); bears cornea. [Stachowitsch, 1992]

Podoplean

(Taxon-specific: Family Cyatholaimidae) Used of the body plan in which the prosome-urosome boundary lies posterior to the fourth pedigerous somite. [Boxshall and Halsey, 2004]

Podopleans

(Taxon-specific: Family Cyatholaimidae) Copepods on which the major body articulation of the adult is between the fifth and the sixth thoraic somites; often there is a significant difference in size between these two somites (see also thaumatopsylloid and gymnoplean). [Ferrari and Dahms, in press]

Poison gland

(Taxon-specific: Order Monhysterida) Gland located at base of preoral sting; opens at tip of sting via duct. [Stachowitsch, 1992]

Pollex

See: Fixed finger [Martin, 2005]
See fixed finger. [Butler, T. H.]
Finger. [Stachowitsch, 1992]

Ponticulus

Type of valve sculpture: ridge (carina) modified in being perforated by a series of openings (fenestrae). (disconnected). [Stachowitsch, 1992]

Pore

One of numerous cuticular openings on carapace and body; presumably with sensory function. [Stachowitsch, 1992]
Minute pore in outer surface of valve. Serves as opening of pore canal. (celate, funnel, intramural, rimmed). [Stachowitsch, 1992]

Pore canal

Minute tubular passageway extending through shell. [McLaughlin, 1980]
One of variously developed, minute canals extending through valve; opens via pore. (false, normal, radial, sieve type). [Stachowitsch, 1992]

Post-formation seta

(Taxon-specific: Family Cyatholaimidae) One or more setae added to a segment after the initial dorsal and/or ventral formation setae have been added. Examples of post-formation setae can be found on the endopod of the maxilliped of calanoids and polyarthrans, and the proximal exopodal segment of platycopiids. [Ferrari and Dahms, in press]

Post-mandibular appendages

(Taxon-specific: Family Cyatholaimidae) The cephalic limbs maxilla 1, maxilla 2 plus the thoracic limbs maxilliped, swimming legs 1-4, limbs 5-6, and the caudal ramus. Except for the caudal ramus, these appendages are added in strict anterioposterior order during post-embryonic development. [Ferrari and Dahms, in press]

Postabdomen

See: Telson [Martin, 2005]
(Taxon-specific: ) Recurved (turned ventrally and forward) posteriormost region of trunk. Bears pair of abdominal setae proximally and caudal rami distally (telson indistinguishable), as well as series of spines (anal spines) and denticles. (cylindrical, quadrangular, subquadrate, bilobed/not bilobed, with/without spines; with marginal, with lateral, with marginal and lateral denticles).
(syn. abreptor, pygidium) [Stachowitsch, 1992]
(Taxon-specific: ) Terminal part of body. [McLaughlin, 1980]

Postannular plate

A median sclerite (plate) immediately caudal to the annulus ventralis. [Hobbs, Hobbs, and Daniel 1977]
Medially situated sclerite (plate) immediately posterior to annulus ventralis. [Hobbs and Jass, 1988]

Postantennal process

(Taxon-specific: Family Cyatholaimidae) A paired, ventral sclerite modified to form a spinoform, tapering process located on the ventral surface of the cephalothorax in some siphonostomatoids (e.g. Caligidae) and poecilostome cyclopoids (e.g. Taeniachanthide). [Boxshall and Halsey, 2004]

Postantennal sinus

On each side of head, typically excavate margin below or behind lateral lobe, adjacent to origin of antennae.
(syn. inferior antennal sinus) [Stachowitsch, 1992]

Postantennal spine

Spine located on anterolateral area of carapace on the posterior part of the antennal region. [Perez Farfante and Kensley, 1997]

Postcephalic groove

See: Carapace groove h [Martin, 2005]
See: Carapace grooves m [McLaughlin, 1980]
On carapace, groove posterior to and parallel with cervical groove; bisects cardiac region. [Stachowitsch, 1992]

Postcervical groove

See: Carapace groove i [Martin, 2005]
See: Carapace grooves n [McLaughlin, 1980]

Postcervical notch

Strong indentation of carapace at level of postcervical groove (e.g., scyllarid palinurans).
(syn. postcervical incision) [Moore and McCormick, 1969]
Strong indentation of carapace at level of postcervical groove. [McLaughlin, 1980]

Postcervical spine

Spine located immediately posterior to cervical carina. [Perez Farfante and Kensley, 1997]

Postcervical sulcus

Ancillary sulcus, posterior to and converging with, main cervical sulcus on carapace of genus Bentheogennema. [Butler, T. H.]
Subvertical carapace groove located posterior to cervical sulcus. [Perez Farfante and Kensley, 1997]

Posteriad

(Taxon-specific: Family Cyatholaimidae) Towards the posterior end of the body. [Ferrari and Dahms, in press]

Posterior

of, or pertaining to the rear end. [Butler, T. H.]
Toward caudal or "hint" end. [Hobbs and Jass, 1988]

Posterior aorta

Aorta. [Stachowitsch, 1992]
Aorta. [Stachowitsch, 1992]
Dorsal aorta. [Stachowitsch, 1992]
Aorta. [Stachowitsch, 1992]
Major blood vessel arising from posterior end of heart. Extends to end of abdomen and gives rise to series to segmental arteries.
(syn. abdominal aorta) [Stachowitsch, 1992]
Aorta.
(syn. posterior dorsal aorta) [Stachowitsch, 1992]
Major blood vessel arising from posterior end of heart. Extends to posterior end of abdomen and gives rise to series of segmental arteries supplying appendages (pleopods) and photophores. (single, paired). [Stachowitsch, 1992]

Posterior cardiac lobe

[Martin, 2005]
See: Carapace regions h [Butler, T. H.]
Intestinal region. [Stachowitsch, 1992]

Posterior cardiac plate

Filtering apparatus. [Stachowitsch, 1992]

Posterior carina

See: Carapace carina g [Martin, 2005]
See: Carapace regions h [McLaughlin, 1980]
On carapace, narrow, transverse ridge in front of marginal groove. [Stachowitsch, 1992]

Posterior chamber

Made up of the terminal portion of the foregut and the anterior portion of the midgut; often called the pyloric stomach. [Bliss, 1982]

Posterior element

Hinge. [Stachowitsch, 1992]

Posterior gastric pit

One of two small depressions near mid-line of dorsal exterior of decapod carapace marking insertion point of stomach muscle. [Moore and McCormick, 1969]
On carapace, one of two small depressions along midline marking insertion of stomach muscle. [Stachowitsch, 1992]
One of two small depressions dorsally near midline on exterior of carapace marking out point of insertion of stomach muscle. [McLaughlin, 1980]

Posterior lappet

Lappet. [Stachowitsch, 1992]

Posterior lateral artery

Artery. [Stachowitsch, 1992]

Posterior process

Posterior part of an elongate median protuberance projecting caudally onto the last (XIV) thoracic sternite (Fig. 4A). [Perez Farfante and Kensley, 1997]

Posterior protuberance

Conspicuous elevation arising from the posteromedian part of the last (XIV) thoracic sternite (Fig. 4A). [Perez Farfante and Kensley, 1997]

Posterior spine

Spine. [Stachowitsch, 1992]

Posterior tooth

See: Carapace tooth e [Martin, 2005]
See: Carapace teeth e [Butler, T. H.]
On midline of carapace, tooth-like projection between marginal groove and posterior margin.
(syn. posteromedian tooth) [Stachowitsch, 1992]

Posterolateral region

In crab-like (brachyuran) decapod, relatively small region along each posterolateral margin of carapace.
See: Anterolateral region [Stachowitsch, 1992]

Posteroventral

On rear lower side of structure. [Butler, T. H.]

Postesophageal ganglion

Cephalothoracic ganglion. [Stachowitsch, 1992]

Posthepatic carina

An oblique carina along posterior margin of hepatic sulcus, on carapace of genus Notostomus. [Butler, T. H.]
Ridge posterior to hepatic carina, extending onto lower branchiostegite (Fig. 2A). [Perez Farfante and Kensley, 1997]

Postlarva

Final larval or "preadult" stage; juvenile stage that resembles a miniature adult but is not sexually mature. [Brusca and Brusca, 2002]
Last of basically five larval stages (nauplius, metanauplius, protozoea, zoea, postlarva). Characterized by initial appearance of adult characters and, in shrimp-like (natantian) decopod, by pleopodal locomotion. According to group, this stage may be termed glaucothoe, grimothea, mastigopus, megalopa, nisto, parva, or pseudibaccus. [Stachowitsch, 1992]

Postlarval stage

Developmental stage reached after completion of megalopal or equivalent metamorphosis; marked by initial appearance of adult characters. [McLaughlin, 1980]
Ontogenetic stage reached after completion of all nauplius-to-zoea or megalopa metamorphoses, marked by initial appearance of adult characters. [Moore and McCormick, 1969]

Postmaxillary spine

(Taxon-specific: Order Monhysterida) On underside of head, pair(s) of prominent, hook-shaped spines between or posterior to base of maxillae. [Stachowitsch, 1992]

Postnauplioid

Second larval stage; characterized by all body segments and appendages of adult. Leaves brood pouch shortly before or after hatching to the juvenile stage. (See also nauplioid). [Stachowitsch, 1992]

Postocular plate

Posteriormost of three plates (fastigial, ocular, postcular) composing acron at tip of head. [Stachowitsch, 1992]

Postocular sulcus

A small groove situated near the dorsal extremity of the orbital margin. [Perez Farfante and Kensley, 1997]

Postoral ganglion

Concentration of nerve tissue posterior to mouth; consists of fused ganglia of eight somites (mandibles to fifth thoracomeres). Joined to supraesophageal ganglion by pair of long circumoral connectives and continues posteriorly as ventral nerve cord.
(syn. subesophageal ganglion) [Stachowitsch, 1992]

Postorbital carapace length

Distance from orbit to mid-caudodorsal (posterior) margin of carapace. [Hobbs and Jass, 1988]
The distance from the orbit to the mid-caudodorsal margin of the carapace. [Hobbs, Hobbs, and Daniel 1977]

Postorbital carina

See: Carapace carina h [Martin, 2005]
See: Carapace carinae h [McLaughlin, 1980]
On each side of carapace, narrow ridge slightly posterior and parallel to margin of orbit. [Stachowitsch, 1992]

Postorbital groove

Groove on carapace behind orbit and more or less parallel to margin of orbit (Fig. 2). [Williams, 1984]
On each side of carapace, groove close to and parallel with margin of orbit. [Stachowitsch, 1992]

Postorbital spine

See: Carapace spine e [Martin, 2005]
Spine situated near the orbital margin posterior to the antennal spine (Fig. 2A). [Perez Farfante and Kensley, 1997]
The hindmost spine or tooth on the orbital margin in the Oxyrhyncha. [Ingle, 1983]
See: Carapace spines e [McLaughlin, 1980]
In shrimp-like (natantian) decapod, anteriorly directed, spine-like projection somewhat behind orbit on each side of carapace. [Stachowitsch, 1992]

Postostral carina

In shrimp-like (natantian) decapod, narrow, longitudinal ridge along dorsal midline of carapace; originates behind rostrum and typically extends almost to posterior end of carapace. Usually with teeth. [Stachowitsch, 1992]

Postrostral carina

See: Carapace carina f [Martin, 2005]
Dorsomedian ridge extending posteriorly from the base of the rostrum, sometimes nearly reaching the posterior margin of the carapace (Fig. 2A). [Perez Farfante and Kensley, 1997]
See: Carapace carinae i [McLaughlin, 1980]

Postrostral spine

See: Carapace spines f [McLaughlin, 1980]
In shrimp-like (natantian) decapod, anteriorly directed, spine-like projection on carapace directly behind rostrum. [Stachowitsch, 1992]

Postsegmental region

See telson. [McLaughlin, 1980]
Telson. [Moore and McCormick, 1969]

Praecoxa

See: Precoxa [Martin, 2005]
Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
(Taxon-specific: Family Cyatholaimidae) The proximal segment of the protopod; it is proximal to the coxa and bears up to three ventral setose endites (see coxa and basis). [Ferrari and Dahms, in press]

Praniza

Juvenile, immature stage of gnathiideans. [Kensley and Schotte, 1989]
Juvenile, immature stage of gnathiideans. [Wetzer et al. 1997]
Parasitic larval stage of certain isopods. Characterized by highly expanded posterior region of pereon. [Stachowitsch, 1992]

Pre-anal carina

A rigid keel protruding from the ventral midline of the sixth abdominal somite between the insertions of the uropods in certain shrimps. [Chace and Hobbs, 1969]

Pre-epipod

Laterally directed lobe of coxa or from coxal position. [McLaughlin, 1980]
Secondary ramus of coxa directed outward (e.g., Chirocephalus).
(syn. pre-epipodite) [Moore and McCormick, 1969]
(Taxon-specific: ) On trunk appendage, laterally (outwardly) directed lobe projecting from base of protopod (proximal to epipod). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) In thoracic appendage, laterally (outwardly) directed lobe projecting from base of protopod. (single, paired; serrated, unadorned) (See also epipod).
(syn. preepipodite, proepipodite) [Stachowitsch, 1992]

Pre-pubertal

Sexually immature crabs. [Ingle, 1980]

Preanal ridge

A raised, transverse ridge on the ventral surface of the pleotelson situated between the pleopodal (or branchial) cavity and the anus. In some munnopsids, this ridge becomes very large. [Wilson, 1989]

Preanal spine

Spine. [Stachowitsch, 1992]

Preannular plate

A broad plate situated immediately anterior to the annulus ventralis in certain cambarids. [Hobbs, Hobbs, and Daniel 1977]

Precocious

Ocurring particularly early in development. [Ingle, 1992]

Precoxa

See: Praecoxa [Martin, 2005]
Limb segment proximal to coxa, present only in certain subclasses.
(syn. pleuropod) [Moore and McCormick, 1969]
Segment of protopod proximal to coxa, rarely present.
(syn. pleuropod) [Butler, T. H.]
In certain tanaidaceans, apparent segment of pereopod proximal to coxa. According to this interpretation, basal part (protopod) of pereopod consists of three segments (precoxa, coxa, basis). [Stachowitsch, 1992]
Segment of appendage occasionally distinguished proximal to coxa. [Stachowitsch, 1992]
First segment of thoracic appendage (thoracopod). Also interpreted as being fused to and therefore also termed coxa. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In thoracopod, ring-like proximal segment of protopod.
(syn. precoxal ring) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The proximal segment of the three-segmented protopod of a postmandibular appendage. [Boxshall and Halsey, 2004]
Protopod. [Stachowitsch, 1992]

Pregastric tooth

See: Carapace tooth f [Martin, 2005]
See: Carapace teeth f [McLaughlin, 1980]
On midline of carapace, tooth-like projection between gastric tooth and rostrum. (broadly rounded, bilobed and incised). [Stachowitsch, 1992]

Prehensile

Adapted for grasping or seizing. [Butler, T. H.]
Adapted for holding or clinging. [Kensley and Schotte, 1989]
Appendages (usually pereopods) adapted for holding or clinging, the dactyl is as long or longer than the propodus, strongly developed and recurved. [Wetzer et al. 1997]

Prehensile antenna

Antenna [Stachowitsch, 1992]

Preischium

Segment of endopod between protopod and ischium, rarely present. [McLaughlin, 1980]
In inner branch (endopod) of thoracopod, segment between basis and ischium. [Stachowitsch, 1992]
First of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Located between basis and ischium and may be variously fused with basis. [Stachowitsch, 1992]

Prelateral lobe

On each lateral margin of telson, lobe-like projection anterior to lateral tooth. [Stachowitsch, 1992]
Proximalmost lateromarginal lobe of telson. [McLaughlin, 1980]

Preoral sting

(Taxon-specific: Order Monhysterida) On underside of cephalothorax, unpaired projection anterior to proboscis. Distal half of anteriorly directed preoral sting can be retracted into basal socket. Needle-like tip nears opening of poison gland. Used to puncture host.
(syn. preoral spine) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Retractile piercing mechanism with poison gland. [McLaughlin, 1980]

Preorbital spine

A spine on the anterior part of the supraorbital eave in the Majidae. [Ingle, 1983]

Preparatory female

An adult female that has developing oostegites and is in the instar just before the brooding condition. [Wilson, 1989]

Presegmental region

See: Acron [Martin, 2005]
See acron. [McLaughlin, 1980]

Preungal process

Structure at base of dactyl of 4th pereopod in many pagurids; function unknown but presumed sensory. [McLaughlin, 1980]

Prezoea

A free larva stage invested with the embryonic cuticle. [Ingle, 1983]
Just-hatched larva still covered by embryonic cuticle. [Moore and McCormick, 1969]
Just-hatched post-nupliar larva still covered by embryonic cuticle. [McLaughlin, 1980]

Primary denticle

Primary denticle disposed normal to suture edges of compartment plate.
See: Denticule [Moore and McCormick, 1969]

Primary flagellum

Flagellum. [Stachowitsch, 1992]

Primary larva

Early larval stage of a pentastomid bearing two pairs of double-clawed legs and one or more piercing stylets. [Brusca and Brusca, 2002]

Primary plate

(Taxon-specific: Order Rhabditida) One of five principal plates on outer surface of body. Includes single carina as well as paired scuta and terga (and occasionally single rostrum). (See also secondary plate). [Stachowitsch, 1992]

Primordial plate

(Taxon-specific: Order Rhabditida) One of typically five more rigid, plate-like elements under shell of cypris larva.
(syn. primordial valve) [Stachowitsch, 1992]

Primordial valve

Chitinous plate in Cirripedia (Lepadomorpha and Verrucomorpha) having a distinctive honeycomb appearance, developing at incipient umbones of terga, scuta and carina, during metamorphosis. [Moore and McCormick, 1969]
One of 5 chitinous plates (scuta, terga, and carina) in cyprid larvae of lepadomorphs and verrucomorphs, site of calcification during metamorphosis, sometimes visible at umbones of these plates in adults. [McLaughlin, 1980]

Proboscate seta

Shaft somewhat stout and naked except for scattered and small denticles, usually adpressed against shaft which narrows abruptly post-annularly and terminates in an often slightly curved tubular 'snout' with apical pore; annulus often conspicuous. [Ingle, 1992]

Proboscis

(Taxon-specific: Order Monhysterida) On underside of cephalothorax, unpaired median projection posterior to preoral sting. Retractile, enclosing mouth and surrounding labrum, mandibles, and paragnaths. Supported distally by series of chitinous bars. Used to feed on host tissues; lies in groove when at rest. [Stachowitsch, 1992]

Processus masculinus

In antenna of male in most mysidaceans, setose lobe projecting (along with two flagella) from last (third) peduncular segment. [Stachowitsch, 1992]

Processus uncifer

Mesial, well separated lobule, usually having a terminal hook, in the petasma of sergestids. [Perez Farfante and Kensley, 1997]

Processus ventralis

Ventromesial lobule located on the distal half of pars media of the petasma of sergestids. [Perez Farfante and Kensley, 1997]

Procoxa

Extra segment occasionally preceding coxa in protopod of appendage. [Stachowitsch, 1992]

Proctodaeum

See: Proctodeum [Martin, 2005]
See proctodeum. [McLaughlin, 1980]

Proctodeum

Posterior part of alimentary canal lined with cuticle of ectodermal origin that is continuous with anus.
(syn. hindgut, proctodaeum) [Moore and McCormick, 1969]
Posterior part of alimentary canal lined with cuticle of ectodermal origin.
(syn. hindgut, proctodaeum) [McLaughlin, 1980]
Hindgut.
(syn. proctodaeum) [Stachowitsch, 1992]
Hindgut. [Stachowitsch, 1992]
Posterior cuticle-lined regon of digestive tract; extends through last three to four segments and opens to exterior via anus. (See also stomodeum).
(syn. hindgut) [Stachowitsch, 1992]
Hindgut. [Stachowitsch, 1992]

Produced

Extended or lengthened. [Kensley and Schotte, 1989]

Proecdysis

The period of preparation for ecdysis. [Bliss, 1982]

Proepistome

See: Inter-antennular septum [Martin, 2005]
See interantennular septum. [McLaughlin, 1980]

Promotor muscle

The muscle which moves the leg forwards by rotating it about the TC joint. [Warner, 1977]

Propodal prolongation

The distal portion of the propodus opposing the dactylus. [Ingle, 1980]

Propodus

Schematic drawing of a thoracic leg. [Holthuis, 1993]
(Figure only.) [Holthuis, 1993]
Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Endopod of Mxp 3, lateral; and endopod of Mxp 3, including basal 2 articles, distal articles omitted, central. Based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
A second segment of a pereiopod or maxilliped, counted from the distal end. [Ingle, 1983]
Article 6 of pereopod (article 5 of cheliped). [Holdich and Jones, 1983]
Penultimate segment (sixth from base) of segmented appendage. [Hobbs and Jass, 1988]
Penultimate segment of pereopod. [McLaughlin, 1980]
Second article from distal end of leg. Propodus of cheliped consists of palm and narrower fixed finger.
(syn. propodite) [Williams, 1984]
Segment of appendage immediately proximal to the dactyl. [Mauchline, 1984]
Sixth article of limb (palm of chela with fixed finger attached). [Poore, 2004]
Sixth or penultimate segment of a typically 7-segmented appendage (Fig. 3C).
(pl. propodi) [Perez Farfante and Kensley, 1997]
Sixth or penultimate segment of a typically 7-segmented appendage.
(pl. propodi) [Butler, T. H.]
The 2nd podomere from the tip of the endopod of a limb (Figs. 1, 2). [Warner, 1977]
The sixth or penultimate segment of a segmented appendage. [Hobbs, Hobbs, and Daniel 1977]
The sixth or penultimate segment of a typically 7-segmented appendage.
(pl. propodi) [Chace and Hobbs, 1969]
The sixth segment of a thoracic appendage.
(pl. propodi)
See: Pereopod [Wilson, 1989]
Fourth of five segments (ischium, merus, carpus, propodus, dactylus) of endopod of thoracopod (maxillipeds and pereopods). [Stachowitsch, 1992]
Sixth of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod. In second pair of thoracopods (cheliped or first pereopod) forms chela or subchela together with dactylus. [Stachowitsch, 1992]
Sixth segment of appendage, between carpus and dactylus. May serve as proximal element of subchela or be divided into proximal manus and distal (fixed) finger of chela. [Stachowitsch, 1992]
Sixth of basically seven segments (coxa, basis, ischium, merus, carpus, propodus, dactylus) of thoracopod; represents fifth movable (free) segment. In gnathopod, may be greatly enlarged to form subchela or chela together with dactylus.
See: Palm [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Article 6 of pereopod. [Kensley and Schotte, 1989]
Sixth or next to last segment of thoracopod; located between carpus and dactylus. [Stachowitsch, 1992]
Fifth of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. May form a multisegmented unti together with carpus (carpopropodus). (simple, multiarticulate) (See also subchela). [Stachowitsch, 1992]
Sixth segment of thoracic appendage (thoracopod); located between carpus and dactyl. In first five thoracopods, forms subchela together with dactyl (especially well developed in second thoracopod as raptorial claw). Bears tuft of setae for cleaning body on fifth thoracopod. (inner margin: smooth, pectinate, denticulate, grooved). [Stachowitsch, 1992]
Fifth of basically six segments (preischium, ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. Main bend (knee) of thoracopod typically located between carpus and propodus. [Stachowitsch, 1992]
Fourth of basically five segments (ischium, merus, carpus, propodus, dactylus) of inner branch (endopod) of thoracopod. [Stachowitsch, 1992]
Sixth segment of thoracopod (fourth and next to last segment of five-segmented endopod); positioned between carpus and dactylus. [Stachowitsch, 1992]

Prosartema

Long, thin, ciliated lobe arising dorsally from proximomesial border of first antennular segment and extending anteriorly; found in Penaeidae.
(syn. dorsal eye brush) [Williams, 1984]
Process arising from mesial margin of first article of antennule (Dendrobranchiata). [Poore, 2004]
Scale implanted on inner margin of basal segment of antennular peduncle in Penaeidae. [Moore and McCormick, 1969]
Scale implanted on inner margin of basal segment of antennular peduncle. [McLaughlin, 1980]
Variable in shape, thin, sometimes scalelike process arising from the mesial base of the first antennular segment, and extending distally (Fig. 3B). [Perez Farfante and Kensley, 1997]
In shrimp-like (natantian) decapod, long, lobe- or scale-like projection from inner (medial) margin of first antennular segment.
(syn. dorsal eye brush) [Stachowitsch, 1992]

Prosoma

See: Prosome [Martin, 2005]
See prosome. [McLaughlin, 1980]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Prosome

Anterior region of body, commonly limited behind by major articulation. In cirripeds large sac-like body in position of "head" in front of (and rostral from) thoracic limbs, supporting trophi and commonly first cirri. [Moore and McCormick, 1969]
Anterior region of body, commonly limited posteriorly by major articulation. In cirripeds, large saclike body in position of "head" in front of, and rostral to, thoracic appendages, supporting trophi and usually 1st cirri.
(syn. prosoma) [McLaughlin, 1980]
Collective term for the combined cephalasome and metasome in copepods. [Brusca and Brusca, 2002]
(Taxon-specific: Family Cyatholaimidae) The anterior tagma of the body, up to the major articulation; comprising the cephalosome and either four (podoplean tagmosis) or five (gymnoplean tagmosis) free pedigerous somites. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) The part of the adult copepod body anterior to the major body articulation. [Ferrari and Dahms, in press]
In one interpretation of body segmentation, anterior of two divisions (tagmata) of body (prosome, urosome); consists of region anterior to flexure point of body (or anterior to genital complex in forms without body articulation) and comprises cephalosome (head and fused thoracic segments) and metasome (thoracic segments anterior to flexure point). [Stachowitsch, 1992]

Prosomite

(Taxon-specific: Family Cyatholaimidae) Component somite of prosome. [Boxshall and Halsey, 2004]

Protandrous

Hermaphrodites that function as males before females. [Butler, T. H.]
Hermaphroditic condition with male elements maturing and being released before maturation of female elements. [McLaughlin, 1980]
Used of hermaphroditism when the functional male precedes the female stage. [Holdich and Jones, 1983]
In hermaphroditic forms, becoming a functional male producing spermatozoa before becoming a functional female producing eggs. [Kensley and Schotte, 1989]
In sequential hermaphroditic forms, becoming a functional male (producing spermatozoa) before become a functional female (producing eggs). [Wetzer et al. 1997]

Protocephalon

See: Acron [Martin, 2005]
Anteriormost part of the body bearing eyes. [Perez Farfante and Kensley, 1997]
See acron. [McLaughlin, 1980]
Term applied to anteriormost region of head (cephalon), especially when this is free of carapace. Consists of eyes and eyestalks, antennules, antennae, and labrum (i.e., of acron and first cephalic somite). [Stachowitsch, 1992]
Anteriormost region of head (cephalon); consists of eyes and first two head segments (antennular and antennal somites) and is movably articulated with rest of head. [Stachowitsch, 1992]

Protocerebrum

Ganglion of first (preantennulary) somite. [Moore and McCormick, 1969]
Ganglion of preantennulary region. [McLaughlin, 1980]
One of two anterior dorsal supraesophageal ganglia in the crustacean brain; receives the optic nerves. [Brusca and Brusca, 2002]
(Taxon-specific: ) Supraesophageal ganglion. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Brain. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]

Protogastric lobe

Anterolateral division of gastric region of decapod (brachyuran) carapace. [Moore and McCormick, 1969]
Anterolateral lobe of subregion of gastric region. [Williams, 1984]
See: Carapace regions f [McLaughlin, 1980]

Protogastric region

A paired anterolateral area on the gastric region of the carapace of crabs. [Chace and Hobbs, 1969]
The region on the dorsal surface of the carapace bounded by parts of the margins of the frontal, orbital, hepatic, epibranchial, metagastric and mesogastric regions. [Ingle, 1983]
Gastric region. [Stachowitsch, 1992]

Protogynous

Hermaphrodites that function as females before males. [Butler, T. H.]
Hermaphroditic condition with female elements maturing and being released before maturation of male elements. [McLaughlin, 1980]
Used of hermaphroditism when the functional female precedes the male stage. [Holdich and Jones, 1983]
In hermaphroditic forms, becoming a functional female producing eggs before becoming a functional male producing spermatozoa. [Kensley and Schotte, 1989]
In sequential hermaphroditic forms, becoming a functional female (producing eggs) before become a functional male (producing spermatozoa). [Wetzer et al. 1997]

Protopod

Peduncle of an appendage; in unmodified form, consisting of one coxal and one basal article.
(syn. protopodite) [Williams, 1984]
Proximal portion of limb, consisting of precoxa, coxa, and basis, fused together in some forms; its distal edge generally bearing endopod(ite) and exopod(ite).
(syn. coxite, sympod(ite)) [Moore and McCormick, 1969]
The basal article of a crustacean appendage.
(syn. sympod) [Brusca and Brusca, 2002]
The basal segment of the pleopods and the uropods. It consists of the fused coxa and basis of the crustacean limb. [Wilson, 1989]
(Taxon-specific: ) Poorly delimited proximal part of trunk appendage; bears on or two distinguishable endites along inner margin and epipod on outer margin, as well as distal endopod and exopod.
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of thoracic appendage (thoracopod) or abdominal appendage. Bears series of five endites on inner margin, epipod on outer margin, distal endopod (sixth endite) and exopod (flabellum).
(syn. protopodite) [Stachowitsch, 1992]
Proximal, poorly delimited part of trunk appendage; bears series of endites along inner margin, epipod on outer margin, as well as distal endopod ( = sixth endite) and exopod (flabellum). Also applied to proximal part of antenna.
(syn. protopodite) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Proximal part of each thoracic appendage (thoracopod). Unsegmented, bearing five endites medially, one or more preepipods and epipod laterally, and distal endopod and exopod.
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of appendage. Generally specified only when referring to biramous appendage (e.g., antennae, maxillules, maxilae, thoracopods). Consists basically of two segments (coxa, basis) and may bear endites and epipod (pseudepipod).
(syn. protopodite) [Stachowitsch, 1992]
Term occasionally applied to proximal part of certain appendages (e.g., maxillules, maxillae). (See also peduncle).
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of certain appendages. Typically specified only when referring to maxillules and maxillae, yet basically applicable to proximal section (coxa, basis) of other appendages.
(syn. protopodite)
See: Peduncle [Stachowitsch, 1992]
Proximal part of biramous appendage. Typically two-segmented (coxa, basis) and bearing variously developed inner (endopod) and outer (exopod) branches.
(syn. protopodite, sympod, sympodite) [Stachowitsch, 1992]
Proximal part of appendage, basically comprising coxa and basis. Only
rarely applied in amphipods (e.g., maxillules) due to modification of coxae as coxal plates. [Stachowitsch, 1992]
Proximal part of appendage. Consists basically of two segments (coxa, basis). May bear lateral lobes (endites, exites) and distal branches (endopod, exopod).
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of biramous fifth through eighth thoracopods or pleopods, three segments in the former, one (two) segment(s) in the latter. Bears endopod and exopod distally. May also refer to basal part (peduncle) of antennule or antenna.
(syn. protopodite) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Proximal part of appendage, e.g., of maxillae or pleopods.
(syn. protopodite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Proximal part of thoracic appendage (thoracopod); typically three-segmented, consisting of precoxa, coxa, and basis. Protopod of last (fourth) thoracopod may bear natatory lobe.
(syn. protopodite) [Stachowitsch, 1992]
Lepas anatifera: cirrus V; cirrus I, and extended cirral fan. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Two-segmented proximal part of thoracic appendage (thoracopods in ascothoracican, cirri in other cirripeds). Bears distal endopod and exopod.
(syn. pedicle) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The basal part of a limb that carries the rami. [Boxshall and Halsey, 2004]
Proximal part of appendage. Generally specified only when referring to antennae, mandibles, maxillules, maxillae, and maxillipeds. Considered to consist of several indistinct (fused) segments (e.g., precoxa, coxa, basis). Bears gnathobase in mandibles and endites in maxillules, maxillae, and maxillipeds.
(syn. protopodite) [Stachowitsch, 1992]
Basal podomere(s) of crustacean limb, often divided into 2 (sometimes 3) segments: the coxa attaching the limb to the body and the more distal basis.
(syn. protopodite) [Cohen, Peterson, and Maddocks, in press]
Proximal part of appendage. Typically two-segmented (coxa, basis) and bearing variously developed inner branch (endopod) and out branch (exopod). May bear endites and exites. Generally specified only when referring to legs (i.e., biramous appendages).
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of appendage; typically two-segmented (coxa, basis) and bearing variously developed inner branch (endopod) and outer branch (exopod). May bear endites.
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of biramous appendage. One-segmented, bearing endopod and exopod. [Stachowitsch, 1992]
Proximal part of appendage. Consists basically of two segments (coxa, basis). May bear lateral lobes (endites, epipods) and distal branches (endopod, exopod).
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of most appendages (with exception of antennules, antennae, mandibles, and pleopods). Conists basically of two segments (coxa, basis). May bear lateral lobes (endites; in maxillipeds also epipods) as well as distal branches (endopod, exopod). (See also peduncle).
(syn. protopodite) [Stachowitsch, 1992]
Proximal part of biramous appendage. Typically specified only when referring to thoracopod, where protopod consists of two segments (coxa, basis), although occasionally also applied to three-segmented (precoxa, coxa, basis) base of maxillules and maxillae or to two-segmented base of pleopods.
(syn. protopodite) [Stachowitsch, 1992]

Protopodite

Fused proximal segments (coxa and basis) of an appendage such as pleopod, usually with endopod and exopod. [Butler, T. H.]
Proximal part of appendage, consisting of coxa and basis or less frequently of precoxa, coxa, and basis, sometimes fused.
(syn. sympod) [McLaughlin, 1980]
The fused proximal segments (coxa and basis) of an appendage, such as pleopod, usually bearing and endopod and an exopod. [Chace and Hobbs, 1969]
Proximal part of an appendage, consisting of the coxa and basis. [Kensley and Schotte, 1989]

Protozea

Larval stage that, when present, is morphologically intermediate between metanaupliar and zoeal stages. [Brusca and Brusca, 2002]

Protozoea

Free-swimming larval stage, after nauplius, characteristic of penaeidean and some caridean shrimps. [Butler, T. H.]
Larval stage in ontogeny of some decapods preceding zoea stage. [Moore and McCormick, 1969]
The second in a series of free-swimming larval stages of a penaeid shrimp. [Bliss, 1982]
Third of basically five larval stages (nauplius, metanauplius, protozoea, zoea, postlarva). Applied to shrimp-like (natantian) decapod and characterized by antennal locomotion. May be subdivided into several substages. Protozoea of certain forms termed elaphocaris. [Stachowitsch, 1992]
First two or three postnaupliar substages in development of Penaeiodea and Euphausiacea. [McLaughlin, 1980]

Proventriculus

Elaborated anterior part of alimentary canal in some crustaceans (e.g., Isopoda) adapted for pressing juices from food and straining out solid particles. [Moore and McCormick, 1969]
Eleborated anterior part of alimentary canal in some crustaceans. [McLaughlin, 1980]

Proximal

Direction towards center of body; opposite of distal. [Moore and McCormick, 1969]
Part of structure nearest midline of body or base of attachment; opposed to distal. [McLaughlin, 1980]
Toward or near a point of attachment. [Butler, T. H.]
Toward the body; that portion of appendage nearest body. [Hobbs and Jass, 1988]
Situated near the base or point of attachment. [Wetzer et al. 1997]
Situated near the point of attachment. [Kensley and Schotte, 1989]

Proximodistal axis

(Taxon-specific: Family Cyatholaimidae) An imaginary line through the insertion of a limb on its somite, and the tip of the limb; on biramous limbs, the proximodistal axis is duplicated through each ramus. [Ferrari and Dahms, in press]

Pseudepipod

Lateral lobe arising from distal part of basis or proximal part of exopod. [McLaughlin, 1980]
Lateral ramus arising from proximal portion of exopod or from basis just proximal to exopod.
(syn. pseudepipodite) [Moore and McCormick, 1969]
Laterally directed lobe of proximal part (protopod) of maxillae and thoracopods. Relatively large, flattened, setose, and giving appendages a triramous or, with endites, a mutli- or polyramous appearance. Represents and epipod, but is termed pseudepipod due to distal point of origin on protopod.
(syn. pseudepipodite) [Stachowitsch, 1992]

Pseudibacus

Postlarval stage of some palinurians.
(syn. nisto, puerulus) [McLaughlin, 1980]
Postlarva. [Stachowitsch, 1992]

Pseudobranchial lobe

In male of certain mysidaceans, posteriorly directed projection from basis of endopod of pleopods. (bifid, curved, rod-like, spirally coiled). [Stachowitsch, 1992]

Pseudochaeta

Minute cuticular projection of body or limb. Lacks basal articulation, lumen, or innervation and therefore has only a mechanical function. [Stachowitsch, 1992]

Pseudoperculum

(Taxon-specific: Family Cyatholaimidae) Dorsal outgrowth of posterior margin of penultimate urosomal somite. [Boxshall and Halsey, 2004]

Pseudorostral lobe

One of two anterior projections of carapace. May be separated, yet typically closely adjoining to form pseuorostrum. [Stachowitsch, 1992]

Pseudorostrum

Anterior portion of gnathothorax in Cumacea, formed by pair of anterolateral parts of cephalic shield grown forward so as to meet medially in front of true rostrum. [Moore and McCormick, 1969]
Anterior part of carapace formed by pair of forward projecting plates. [McLaughlin, 1980]
Anterior projection of carapace formed by two adjoining pseudorostral lobes. (horizontal, upturned, reflexed; acute, blunt; simple, with long setae). [Stachowitsch, 1992]
In certain crab-like (brachyuran) decapods, anterior extension of carapace formed by fusion of two projecting teeth of frontal margin [Stachowitsch, 1992]

Pseudotrachea

Aerial gas exchange organs found in terrestrial isopods. [Brusca and Brusca, 2002]
Air sacs used for gas exchange in most terrestrial oniscidean isopods. [Brusca and Brusca, 2002]
Respiratory structure developed in pleopods of some Isopoda for air-breathing; they consist of small ramified tubules inside limb opening outward in slit-like apertures and filled with air. [Moore and McCormick, 1969]
Respiratory structure developed in pleopods of some terrestrial isopods for air-breathing. [McLaughlin, 1980]
In certain terrestrial isopods, modification of outer branch (exopod) of pleopod for respiratory purposes. [Stachowitsch, 1992]

Pseudozoea

A modified zoeal stage exhibited by some stomatopods. [Brusca and Brusca, 2002]
Early larval stage of certain stomatopods; characterized by biramous antennules, two uniramous thoracopods, and five pairs of pleopods. (See also antizoea, erichthus larva). [Stachowitsch, 1992]

Pterygostome

Ptergostomial region. [Stachowitsch, 1992]

Pterygostomial region

Anteroventral region of carapace (anterior part of branchiostegite of Caridea) or ventral region of carapace (of Brachyura); bearing pterygostomial spine at anteroventral angle (in Caridea and Dendrobranchiata). [Poore, 2004]
See: Carapace regions k [McLaughlin, 1980]
On ventral side of carapace, one of two anterolateral regions flanking buccal cavity. [Stachowitsch, 1992]

Pterygostomial spine

See: Carapace spines g [McLaughlin, 1980]
In shrimp-like (natantian) decapod, anteriorly directed, spine-like projection located below branchiostegal spine on anterolateral corner or carapace. [Stachowitsch, 1992]

Pterygostomian carina

Ridge running posterior to pterygostomian spine on antero-ventral part of carapace. [Perez Farfante and Kensley, 1997]

Pterygostomian region

See: Carapace region k [Martin, 2005]
Anteroventral area of the carapace. [Perez Farfante and Kensley, 1997]
Paired anteroventral are of carapace ventral to antennal region. [Hobbs and Jass, 1988]
The paired anterolateral area on the lateroventral surface of the carapace of crabs on each side of the mouth area. [Chace and Hobbs, 1969]
The paired anteroventral area of the carapace lateral to the mouth area. [Hobbs, Hobbs, and Daniel 1977]
The region on the ventral surface of the carapace bounded by the margin of the subhepatic region, the lateral margin of the buccal cavity and the branchiostegite margin. [Ingle, 1983]
Triangular space on ventral surface of carapace, on either side of buccal cavity in Brachyura. Region at anterolateral corner of carapace in shrimps. [Williams, 1984]

Pterygostomian spine

See: Carapace spine g [Martin, 2005]
A spine borne on the anteroventral margin of the carapace, ventral to the branchiostegal spine (in shrimps). [Hobbs, Hobbs, and Daniel 1977]
Marginal spine arising from the anteroventral angle or border of the carapace. [Perez Farfante and Kensley, 1997]
Spine (in shrimps) located on anteroventral margin of carapace and ventral to branchiostegal spine. [Hobbs and Jass, 1988]
Spine at anterolateral (anteroventral) corner or border of carapace in shrimps (Fig. 2). [Williams, 1984]
Spine located at anterolateral region of carapace. [Butler, T. H.]

Pubescence

A covering of down or short hairs. [AHD]
Covering of short, fine setae, easily rubbed off. [Butler, T. H.]
Dense hair covering the appendages or/and the carapace. [Ingle, 1983]

Puerulus

See pseudibacus. [McLaughlin, 1980]
The postlarval stage of a spiny, or rock, lobster. [Bliss, 1982]
Zoea. [Stachowitsch, 1992]

Punctation

Small depression (pit). [Hobbs and Jass, 1988]

Punctum

Small pitlike depression(s) in valve surface.
(pl. puncta) [McLaughlin, 1980]
Type of valve sculpture: Small, circular, pit-like depression (one order of magnitude larger than foveola). [Stachowitsch, 1992]

Pustula

Small protuberance(s) on valve surface with pore at summit.
(pl. pustulae) [McLaughlin, 1980]
Type of valve sculpture: small protuberance with pore at summit. [Stachowitsch, 1992]

Pygidium

(Taxon-specific: ) Postabdomen. [Stachowitsch, 1992]

Pylopod

First pereopod of the Gnathiidea, modified to form part of the mouthparts. [Kensley and Schotte, 1989]
Modified appendage of first pereon segment (pereonite) in certain isopods; functions as maxilliped. [Stachowitsch, 1992]
Second pair of maxillipeds in gnathiids (appendages of the second thoracomere). [Wetzer et al. 1997]

Pyloric stomach

Posterior region of the decapod foregut. [Brusca and Brusca, 2002]
Posterior and smaller division of stomach; separated from large anterior cardiac stomach by cardiopyloric valve. Characterized by highly folded, setose walls (filtering apparatus), plates, and valve-like structures. Opens into intestine; pair of ducts from hepatic cecum enter posterior end of pyloric stomach. [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Posterior and smaller division of stomach. Separated from large anterior cardiac stomach by filtering apparatus; opens into midgut via ampulla. Contains complex of plates (ossicles). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Stomach. [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Stomach. [Stachowitsch, 1992]
Posterior and smaller division of stomach; separated from larger anterior cardiac stomach by cardiopyloric valve. Opens into midgut. [Stachowitsch, 1992]

Quadrangular

Having a truncate distal margin at approximately right angles to the lateral sides. [Wilson, 1989]

Radial lirae

See carapace costae. [McLaughlin, 1980]

Radial pore canals

Modified normal pores located at free margins of valves, housing nerve filaments that lead from tactile sensilla to nerve cells in the underlying epidermis. [Cohen, Peterson, and Maddocks, in press]

Radius

In cirripeds (Balanomorpha) lateral part of compartment plate adjoining paries, marked off from it by change in direction of growth lines and by depressed exterior surface; overlaps ala of adjoining compartment plate. [Moore and McCormick, 1969]
Lateral part of compartmental plate when marked off from paries by change in direction of growth lines; overlaps ala of adjoining compartmental plate.
(pl. radii) [McLaughlin, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, lateral part of compartmental plate. Delimited from median part (paries) by altered growth lines; overlaps sides (alae) of adjoining compartmental plates. [Stachowitsch, 1992]

Ramus

A branch of an appendage, e.g. the exopood or endopod.
(pl. rami) [Perez Farfante and Kensley, 1997]
A branch of an appendage.
(pl. rami) [Wilson, 1989]
Branch of appendage or other structure (e.g., flagellum). [McLaughlin, 1980]
Branch of limb or other appendage (e.g., caudal furca). [Moore and McCormick, 1969]
Branch of limb; endopod is inner branch and exopod is outer branch.
(pl. rami) [Poore, 2004]
(Taxon-specific: ) Branch of appendage. Refers either to dorsal and ventral branches of antennae or to inner (endopod) and outer (exopod) branches of trunk appendage. [Stachowitsch, 1992]
Term applied to either branch (flagellum) of antenna. [Stachowitsch, 1992]
Branch of an appendage, typically referring to inner (endopod) and outer (exopod) branches of biramous appendage. [Stachowitsch, 1992]
Branch of appendage. Typically refers to inner (endopod) and outer (exopod) branches of biramous appendage (e.g., pleopods, uropods). (one-articulate, multiarticulate). [Stachowitsch, 1992]
Branch of an appendage. [Kensley and Schotte, 1989]
Branch of appendage; typically refers to inner (endopod) and outer (exopod) branches of biramous appendage (e.g., pleopods, uropods). [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Branch of appendage; typically refers to inner (endopod) and outer (exopod) branches of biramous appendage. (lamellar = plate-like, flagelliform). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Branch of appendage, typically referring to inner (endopod) and outer (exopod) branches of thoracic appendage (thoracopods in ascothoracican, cirri in other cirripeds). (See also caudal ramus). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A branch of an appendage; the exopod or endopod. [Boxshall and Halsey, 2004]
(Taxon-specific: Family Cyatholaimidae) A group of serially repeated segment elements along a proximodistal axis and originating on the basis; the exopod and the endopod are rami.
(pl. rami) [Ferrari and Dahms, in press]
Branch of an appendage, typically referring to inner branch (endopod) or outer branch (exopod) of biramous appendage (e.g., antenna, mandible, maxillule, pereopod). [Stachowitsch, 1992]
Branch of an appendage, typically referring to inner (endopod) and outer (exopod) branch of trunk appendage, antennule, or antenna. (see also caudal ramus). [Stachowitsch, 1992]
Branch of appendage; typically refers to inner (endopod) or outer (exopod) branch of biramous appendage. [Stachowitsch, 1992]

Raptorial claw

Generally strong, curved and toothed dactylus suited for catching prey (e.g., Squilla). [Moore and McCormick, 1969]
Toothed dactyl, generally strong, curved backward on propodus, modified for quick motion in catching prey. [McLaughlin, 1980]
Large grasping claw (subchela) at end of second thoracopod; formed by dactyl bearing down on propodus. [Stachowitsch, 1992]

Rasp

One or several rows of chitinous plates or scales on surface of pereopodal or uropodal segments. [McLaughlin, 1980]

Receptaculi

Modified setae that have bulbous recurved and denticulate tips. They are located on the medial margin of the maxilliped's basal endite and couple with their paired counterparts so that both maxillipeds can act as a single unit.
(syn. coupling hooks) [Wilson, 1989]

Receptaculum seminalis

See: Seminal receptacle [Martin, 2005]
See seminal receptacle. [McLaughlin, 1980]

Rectal cecum

(Taxon-specific: Class Secernentea) In digestive tract, unpaired dorsal cecum originating at end of midgut and extending over hindgut. [Stachowitsch, 1992]

Rectal gland

Hindgut gland. [Stachowitsch, 1992]

Rectum

In pleotelson, relatively short posterior section of digestive tract between midgut and anus. [Stachowitsch, 1992]
Posteriormost muscular and cuticle-lined section of digestive tract. May be somewhat expanded; opens to exterior through anus. Typically considered to represent only most terminal region of hindgut. [Stachowitsch, 1992]
Hindgut. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Hindgut. [Stachowitsch, 1992]

Recurved

Curved back on itself. [Wilson, 1989]

Remotor muscle

The muscle which moves the leg backwards by rotating it about the TC joint. [Warner, 1977]

Reniform

Kidney shaped. [Kensley and Schotte, 1989]

Reptantia

A division of the decapod crustacea by Boas (1880) on which the carpoprodal articulation of the pereiopods has two fixed points of attachment and the pleopods are often reduced or may be absent. Used as a suborder of the Decapods in many classifications and includes all the decapods except prawns (Natantia). [Ingle, 1992]

Respiratory area

(Taxon-specific: Order Monhysterida) On underside of carapace, one of four areas characterized by thin cuticle and functioning as a respiratory surface. One may distinguish two smaller anterior respiratory areas (flanking maxillae) and two larger posterior areas flanking thoracopods. (anterior and posterior: equal, not equal; anterior: anterior anteromesial, mesial, minute, narrow, prolonged laterally, triangular; posterior: deeply notched on inner margin, narrow, regular, symmetrical, very large, widened posteriorly). [Stachowitsch, 1992]

Reticulate

Resembling or forming a network. [Kensley and Schotte, 1989]

Reticulum

Meshwork pattern consisting of numerous spaces or depressions (sola), each surrounded by walls (muri). A single mesh is termed fossa. (first order, second order; rounded polygonal).
(syn. reticulation) [Stachowitsch, 1992]

Retinaculae

Small hooks on an appendage, used to link the left and right members of a pair of appendages. [Kensley and Schotte, 1989]

Retinacular hooks

The curved hooks on the appendices internae serving to link paired pleopods. [Hobbs, Hobbs, and Daniel 1977]

Retinaculum

Small hook at tip of appendices internae (e.g., Caridea), one of many serving to join left and right pleopods together.
(pl. retinacula) (syn. cincinnulus) [Moore and McCormick, 1969]
Small hook at tip of appendix interna, one of many serving to interlock right and left pleopods.
(pl. retinacula) (syn. cincinnulus) [McLaughlin, 1980]
In first pair of maxillipeds, one of several small, hook-like structures along inner margin of basis. Serves to interlock left and right maxillipeds.
(syn. coupling hook) [Stachowitsch, 1992]
In maxilliped, one in a series of small, hook-like structures along margin of endite of second segment (basis). Serves to interlock left and right maxillipeds.
(syn. coupling seta, coupling hook) [Stachowitsch, 1992]
One in a series of hooks on appendix interna of each abdominal appendage (pleopod); interlocks with retinacula of second member of pleopod pair and permits both pleopods to move in unison. [Stachowitsch, 1992]
In male anaspidacean, one in a series of small, hook-like structures along inner branch (endopod) of modified first and second pairs of pleopods. Serves to interlock left and right pleopods. [Stachowitsch, 1992]

Retrostylet

(Taxon-specific: Family Cyatholaimidae) A movable stylet projecting posteriorly from the margin of the dorsal cephalic shield. [Boxshall and Halsey, 2004]

Rib

One in a series of cuticular reinforcements of oostegites; serves to maintain form and position of brood pouch. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One in a parallel series of longitudinal supporting structures around rim of each suction disc. Consists of up to 50 segments. (segment: bead-like, cone-shaped, imbricated, doubly imbricated, quadrangular, rod-like). [Stachowitsch, 1992]

Ridge

Carina. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Elevated ridge along carapace. Refers either to pair on longitudinal ridges delimiting cephalon laterally or to pair of median ribs between compound eyes. (simple, bifurcate anteriorly). [Stachowitsch, 1992]

Ring

Body ring. [Stachowitsch, 1992]

Rome's organ

In antennule, sensory organ on posterior border of second segment; derived from seta and may be bell-shaped. [Stachowitsch, 1992]

Rootlet

Long, branching hollow processes of vermigon larvae that penetrate the host's body and draw nutrients from the hemocoel. [Brusca and Brusca, 2002]

Rostral angle

In cirripeds angle of plate directed toward rostrum. [Moore and McCormick, 1969]
Intersection of basal and occludent margins of scutum in lepadomorph Cirripedia. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in stalked form, corner of scutum formed by junction of basal and occludent margins. [Stachowitsch, 1992]

Rostral carina

See: Carapace carina j [Martin, 2005]
See: Carapace carinae j [McLaughlin, 1980]
On carapace, narrow, longitudinal ridge continuous with lateral margin of rostrum; may join submedian carina. [Stachowitsch, 1992]

Rostral filaments

(Taxon-specific: Family Cyatholaimidae) The paired filaments, containing elements of the organ of Bellonci, arising from the rostrum. [Boxshall and Halsey, 2004]

Rostral formula

Number of spines on dorsal surface of rostrum (including those on carapace) / number of ventral spines. [Butler, T. H.]

Rostral hood

In certain amphipods, broad anterodorsal extension of head; covers basal segments of antennae. [Stachowitsch, 1992]

Rostral incisure

Gap below rostrum in anterior margin of valve for protrusion of antenna.
(syn. rostral notch) [McLaughlin, 1980]
Rostral notch. [Stachowitsch, 1992]

Rostral latus

See latus. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) Barnacle plate: paired plates (latera) in stalked form, one on each side of rostrum or below scutum. Homologous with rostrolateral of unstalked form. [Stachowitsch, 1992]

Rostral notch

See rostral incisure. [McLaughlin, 1980]
In anteroventral region of carapace, indentation of each valve below (posterior to) rostrum. Gaping, thus permitting protrusion of antennae when valves are closed (gape itself occasionally referred to as rostral incisure). [Stachowitsch, 1992]

Rostral plate

A flat rostrum. [Mauchline, 1984]
Anteriorly projecting, unpaired, movably articulated, median extension of carapace (e.g., Phyllocarida).
See: Rostrum, Compound rostrum [Moore and McCormick, 1969]
(Taxon-specific: Class Adenophorea) Anteriorly projecting, unpaired, movably articulated, median extension of carapace; antennulary portion of cephalon. [McLaughlin, 1980]
(Taxon-specific: Class Secernentea) Plate-like structure extending over head. Articulated with carapace and movable by series of muscles. (simple, with ventral kell and spine).
(syn. rostrum) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Rostrum. [Stachowitsch, 1992]
Term applied to two anteromedian lobes of anterior (antennulary) part of head (cephalon). [Stachowitsch, 1992]

Rostral sinus

(Taxon-specific: Order Rhabditida) In circulatory system, main pumping organ located in anterior region of body.
(syn. blood pump) [Stachowitsch, 1992]

Rostral spine

Median spine resembling a rostrum, adjacent to frontal margin of carapace on shrimps or genus Argis. [Butler, T. H.]

Rostral tooth

See: Carapace tooth g [Martin, 2005]
See: Carapace teeth g [McLaughlin, 1980]
One in a series of tooth- or spine-like projections along anterior extension (rostrum) of carapace. According to position one may distinguish upper, lower, and lateral teeth. [Stachowitsch, 1992]

Rostrolateral

In cirripeds, one of pair of compartment plates lying between and overlapping rostrum and laterals, having radii on both rostral and cardinal sides and tending to fuse with rostrum; See Latus (rostral), e. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: in symmetrical unstalked form, paired anterolateral plate, one between rostrum and each lateral plate. Consists of median paries and lateral radii. May be fused with rostrum or with each other (i.e., rostrum absent) to form compound rostrum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One pair of compartmental plates typically overlapping rostrum on each side, with radii on both sides, somtimes fused with rostrum, laterally or to eachother; homologous with lepadomorph rostral latus. [McLaughlin, 1980]

Rostrum

(1) Anteriorly projecting, unpaired, usually rigid median extension of carapace between eyes or ocular peduncles; (2) anterior beaklike projection of valve margins overhanging incisure or notch (Ostracoda); (3) unpaired anteroventral plate of thoracic Cirripedia; in lepadomorphs, 1 of up to 4 unpaired plates of capitulum; in verrucomorphs, compartmental plate between carina and fixed scutum; in balanomorphs, compartmental plate overlapping adjacent plates, sometimes compound, either fused with rostrolaterals or missing and formed of fused rostrolaterals; simple or compound with or without radii on each side. [McLaughlin, 1980]
A beak-like structure projecting anteriorly from the carapace. [Mauchline, 1984]
A median outgrowth of the anterior frontal region forming a signal or two distinct horns. [Ingle, 1983]
A projection of the cephalic frons that may also include the dorsal surface of the cephalon.
(pl. rostra) [Wilson, 1989]
An anterior projection of the carapace that usually extends beyond the head region. [Brusca and Brusca, 2002]
Anteriomedian projection of the carapace between the eyes (Fig. 1).
(pl. rostra) [Perez Farfante and Kensley, 1997]
Anteriorly projecting, unpaired, usually rigid median extension of carapace between eye or eyestalks; in cirripeds (Thoracica) unpaired valve between laterals and opposite carinal at basiscutal end of capitulum, simple and provided with alae in lower balanomorphs but compound and overlapping laterals in higher balanomorphs.
See: Compound rostrum [Moore and McCormick, 1969]
Anterodorsal projection of carapace. [Holdich and Jones, 1983]
Dorsomedian anterior projection of cephalothorax, in crayfishes partly covering eyestalks and bases of antennae and antennules. [Hobbs and Jass, 1988]
Prolongation of median part of anterior carapace between eyes. [Poore, 2004]
The "head spine" or anterior projection of cephalothorax between the eyes of shrimps.
(pl. rostra) [Butler, T. H.]
The "head spine" or anterior projection of the cephalothorax between the eyes of shrimps or crayfishes.
(pl. rostra) [Chace and Hobbs, 1969]
The anterior projection of the cephalothorax between the eyes. [Hobbs, Hobbs, and Daniel 1977]
(Taxon-specific: ) Anterior (ventrally directed) extension of head. Relative length compared to antennules and antennae may be of taxonomic importance. (bent into hook, curved forward, recurved, straight; acute, blunt). [Stachowitsch, 1992]
Prolongation of anterior end (underside) of head; located in front of upper lip (labrum) and therefore occasionally termed epistome. (armed, unarmed; acute, notched, pointed, rounded, spatulate = spatuliform, subtriangular).
(syn. frontal process, rostral process, beak) [Stachowitsch, 1992]
Relatively short anteromedian extension of carapace. [Stachowitsch, 1992]
Unpaired anterior extension of carapace. Projects between eyestalks (ocular peduncles) and represents extension of frontal region. (compressed, depressed; acute, arched, circular, deflexed, obsolete, obtuse, sinuous, straight, triangular; tip: attenuate, bifid, bifurcate, styliform, subtruncate, truncate, upturned; unarmed, armed: ciliated, spinuliferous, toothed, tridentate, trifid). [Stachowitsch, 1992]
Unpaired, immovable anterior extension of head between bases of antennules. (deflected, spine-like, triangular). [Stachowitsch, 1992]
Anterior median extension of head (cephalon). [Stachowitsch, 1992]
Anterior middorsal projection of cephalon. [Kensley and Schotte, 1989]
Anteromedial projection of frontal margin of cephalon. [Wetzer et al. 1997]
Unpaired, imovable anterior extension of carapace. (pointed, rounded, simple, serrate). [Stachowitsch, 1992]
Unpaired, flattened anterior projection of carapace; relatively small, movable, and partially or entirely covering acron and antennular somite. (elongate triangular, subquadrate, subtriangular, triangular; with/without carina; deflexed).
(syn. rostral plate) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Rostral plate. [Stachowitsch, 1992]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: unpaired anterior plate. In stalked form, anteroventral plate on capitulum. In asymmetrical unstalked form, compartmental plate between carina and fixed scutum. In symmetrical unstalked form, anterior compartmental plate with median paries and lateral alae (simple or true rostrum) or with median paries and lateral radii (compound rostral plate: formed by fusion of rostrolaterals with rostrum or by fusion of rostrolaterals, with rostrum missing). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The unpaired frontal projection of the dorsal cephalic shield, located between the antennules. [Boxshall and Halsey, 2004]
Anterior gaping, beak-like extension of carapace. Serves, along with associated rostral notch, to permit protrusion of antennae when valves are closed. (see also beak). [Stachowitsch, 1992]
Anterior projection of valves of many myodocopans, overhangs incisur. [Cohen, Peterson, and Maddocks, in press]
Anteriorly projecting part of cephalic shield; may fold over anterior margin. (paired, unpaired; pointed, long, short). [Stachowitsch, 1992]
Unpaired, unmovable anterior extension of head (cephalon). (deeply cleft, quadrate, strap-shaped, ventrally deflected). [Stachowitsch, 1992]
Unpaired, immovable anterior extension of carapace; projects between eyestalks (ocular peduncles). (absent, obsolete, weakly produced, reaching/not reaching beyond eyes; acute, triangular). [Stachowitsch, 1992]

Rudimentary oostegite

In second maxillipeds of female, flattened plate extending from first segment (coxa). Posterior margin bears series of of elongate setae extending into brood chamber. [Stachowitsch, 1992]

Rugose

Having a rough or ridged surface. [AHD]

Saccule

In antennal gland, proximalmost of two divisions (saccule, labyrinth) of end sac. Consists of simple vesicle or is partitioned internally. [Stachowitsch, 1992]

Sacculus

Inner "blind" end of a nephridial excretory organ; a coelomic remnant. [Brusca and Brusca, 2002]

Sagittate

Arrow shaped. [Kensley and Schotte, 1989]

Saw bristles

Heavy setae in row on gnathal lobe of mandible between molar and incisor processes. [McLaughlin, 1980]
Row of heavy setae on gnathal lobe of mandible between molar and incisor processes in many Eumalacostraca, especially Peracarida. [Moore and McCormick, 1969]

Scale

A non-articulated cuticular extension of which the base is generally very wide relative to its length; microscopic secondary features may arm the outer margin; this term should not be used to describe very small extensions of setal shafts. [Watling, 1989]
In cirripeds (Lepadomorpha), platelet on side of peduncle.
See: Scaphocerite [Moore and McCormick, 1969]
see Antennal scale. [Butler, T. H.]
Small calcareous plates on peduncle of lepadomorph Cirripedia; see also scaphocerite. [McLaughlin, 1980]
A small articulate piece occurring on the antennules or antennae in some crustaceans, thought to be a remnant of the second ramus (presumably the exopod). Scales rarely occur in isopods. [Wetzer et al. 1997]
(Taxon-specific: Order Rhabditida) One of numerous small calcareous elements on stalk (peduncle) of barnacle. [Stachowitsch, 1992]

Scape

Term occasionally applied to basal part of antenna. [Stachowitsch, 1992]

Scaphocerite

Antennal scale (Fig. 2). [Williams, 1984]
Exopod of antenna.
(syn. scale, squama) [McLaughlin, 1980]
Exopod(ite) of antenna in Eumalacostraca;[Similar structure occurs on antennules of Leptostraca.].
(syn. scale) [Moore and McCormick, 1969]
Lateral plate attached to distal margin of second article of antenna, equivalent to exopod (sometimes anntennal scale or acicle when small).
(syn. antennal scale, acicle) [Poore, 2004]
Laterally rigid lamellate exopod of the antenna; the antennal scale (Fig, 1). [Perez Farfante and Kensley, 1997]
Platelike exopod of antenna of shrimps (see "Antennal scale") (Fig. 13). [Hobbs and Jass, 1988]
See antennal scale. [Hobbs, Hobbs, and Daniel 1977]
In antenna, variously shaped outer branch (exopod) projecting from peduncle. (broad, flat, lanceolate, ovoid, rounded, slender; serrate, setose).
(syn. antennal scale, squama) [Stachowitsch, 1992]
Antennal scale. [Stachowitsch, 1992]
Antennal scale. [Stachowitsch, 1992]
In antennae of anaspidacean, scale-like outer branch (exopod) arising from second segment of peduncle. May also refer to small exopod in antenna of bathynellacean. (anaspidacean: longer/shorter than first two segments of endopod).
(syn. antennal scale) [Stachowitsch, 1992]
Scale-shaped outer branch (exopod) of each antenna.
(syn. antennal scale, squama) [Stachowitsch, 1992]

Scaphognathite

A lateral flap on the 2nd maxilla which, by beating within a narrow pump chamber, draws a respiratory stream of water through the branchial chamber (Figs. 3, 10). [Warner, 1977]
A thin lateral lobe on the outer maxilla that assists the pumping of water through the branchial chamber. [Ingle, 1983]
Elongate exopods of the maxillae that vibrate to create ventilating currents through the branchial chambers. [Brusca and Brusca, 2002]
Exopod comprising boat-shaped extension of maxilla opposite endopod. [Moore and McCormick, 1969]
Exopod of maxilla, often used to produce respiratory current in gill chamber. [McLaughlin, 1980]
Relatively large outer branch (exopod) of each maxilla. Typically consists of two branches or lobes with setose margins, one of which may extend under carapace to generate respiratory current.
(syn. gill bailer) [Stachowitsch, 1992]

Schizodont hinge

Entomodont hinge in which the anterior and anteromedian elements are bifid, and the posterior element is bifid or crenulate (Family Schizocytheridae only). [Cohen, Peterson, and Maddocks, in press]

Schizopod larva

Ontogenetic stage characterized by presence biramous limbs on all thoracic somites.
(syn. mysis stage) [Moore and McCormick, 1969]
See mysis stage. [McLaughlin, 1980]
Mysis. [Stachowitsch, 1992]

Sclerite

Term occasionally applied to any one of several, difficult to identify, proximal segments of mouthparts. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A hardened area of cuticle in the exoskeleton. [Boxshall and Halsey, 2004]
Internal chitinous struts supporting body and limbs. [Cohen, Peterson, and Maddocks, in press]

Sclerotized

With thick and sometimes calcified cuticle. [Wilson, 1989]
Hardened, usually with chitin. [Kensley and Schotte, 1989]

Scutal adductor

Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Scutal adductor scar

Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Scutal margin

In cirripeds, articular edge of tergum adjoining scutum, or edge of any other plate abutting scutum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: edge of tergum or edge of any other plate articulating with or directly adjoining scutum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Edge of tergum articulating with scutum or edge of any other adjacent to scutum. [McLaughlin, 1980]

Scutellate

A process with a broad base that is distally expanded into a dorso-ventrally flattened, broad, sub-triangular to oblong process. [Ingle, 1980]

Scutum

Paired plate or valve of thoracic Cirripedia; in lepadomorphs, 1 on each side of occludent margin of capitulum. In verrucomorphs, of two types: fixed scutum, 1 of 4 compartmental plates; movable scutum, 1 of 2 opercular plates. [McLaughlin, 1980]
Valve of cirriped shell opposite carina and adjacent to peduncle in some forms (Lepadomorpha) or opercular in others (Balanomorpha).
(pl. scuta) [Moore and McCormick, 1969]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) One of five primary plates (carina, two scuta, two terga) on outer surface of barnacle. Paired, one scutum located on each side of aperture. In unstalked barnacle, variously associated with tergum to form operculum. Features of scutum include angles (basioccludent, basitergal), apex, articular furrow, margins (basal, occludent, tergal, tergolateral), and ridges (apicobasal, apicoumbonal, articular). Bears markings (muscle pits) of muscle attachments on inner surface. (rhomboidal, triangular, split/not split into two parts). [Stachowitsch, 1992]

Second antenna

See: Antenna [Martin, 2005]
See antenna. [McLaughlin, 1980]
Antenna. [Stachowitsch, 1992]
Antenna. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Antenna. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Antenna. [Stachowitsch, 1992]
2nd (cephalic) pair of limbs.
(syn. antenna) [Cohen, Peterson, and Maddocks, in press]
Antenna. [Stachowitsch, 1992]
Antenna. [Stachowitsch, 1992]
Antenna. [Stachowitsch, 1992]

Second form male

One of two morphological forms of male cambarids; sexually nonfunctional male (Male insignia II) lacking corneous terminal element of first pleopod (gonopod). [Hobbs and Jass, 1988]
The sexually nonfunctional male cambarid, most easily recognized by the lack of a corneous terminal element on the first pleopod. [Hobbs, Hobbs, and Daniel 1977]

Second maxilla

See: Maxilla [Martin, 2005]
See maxilla. [McLaughlin, 1980]
Maxilla. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The paired limb of the somite of the cephalon posterior to the maxilla 1. [Ferrari and Dahms, in press]
Maxilla. [Stachowitsch, 1992]
Maxilla. [Stachowitsch, 1992]
Maxilla. [Stachowitsch, 1992]

Secondary bud

(Taxon-specific: Family Cyatholaimidae) A small, poorly differentiated limb which has been reconfigured from a limb bud or a transformed limb of a copepodid; a seconday bud usually is found on a chalimus (see bud and transformed limb). [Ferrari and Dahms, in press]

Secondary denticle

Secondary denticle located on primary one and disposed normal to it.
See: Denticule [Moore and McCormick, 1969]

Secondary plate

(Taxon-specific: Order Rhabditida) Any one of numerous accessory calcareous elements on body (as opposed to primary plates). May include single rostrum, subrostrum, subcarina, and numerous lateral plates (latera, lateralia). [Stachowitsch, 1992]

Segment

Division of an appendage. [Perez Farfante and Kensley, 1997]
Individual component of crustacean limb connected by movable articulation with adjoining segments.
(syn. podomere (not equivalent to somite, though used by some authors in this sense). (not joint.)) [Moore and McCormick, 1969]
Individual component of curstacean appendage connected by movable articulation with adjoining segments.
(syn. podomere)
See: Article [McLaughlin, 1980]
One in a series of units of appendage (then also termed article or joint). May also refer to segment of body (then also termed somite). Shape and number of setae of appendage segments are of taxonomic importance. [Stachowitsch, 1992]
One in a series of divisions of an appendage. May also refer to segment of body (then also termed somite). Segments of flagella of antennule or antenna often termed articles.
(syn. article, joint) [Stachowitsch, 1992]
One in a series of units of an appendage, e.g., coxa, basis, ischium, merus, carpus, propodus, and dactylus of pereopod. May also refer to segment of body (then also termed somite). Segments of flagella of antennule or antenna are often termed articles. (segment of pereopod: not subdivided, subdivided = many-jointed = multiarticulate; compressed, cylindrical, flattened, obcordate, prismatic, subcubical, subcylindrical, subquadrate; bispinose, ciliate, granulate, rugose, serratogranulate, smooth, spinous, spinulose, with crest). [Stachowitsch, 1992]
Segment of body or appendage, those of former often being termed somites. Segments of flagella of antennules, antennae, or thoracic exopods often termed articles. [Stachowitsch, 1992]
One in a series of divisions either of body (also termed somites) or appendage. Segmetns of flagella at tip of antennules or antennae are often termed articles. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One in a series of divisions of an appendage. May also refer to segment of body (then also termed somite). Segments of flagella of antennule or antenna are often termed articles. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One in a series of units of an appendage (e.g., coxa, basis). May also refer to segment of body (then also termed somite). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A composite group of elements which are serially repeated components of a limb; these elements usually include formation and post-formation setae, muscles, and a finishing arthrodial membrane. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) An article or division of an appendage separated from the next such article by an articulation. [Boxshall and Halsey, 2004]
One in a series of units of appendage. May also refer to segment of body (then also termed somite). [Stachowitsch, 1992]
One in a series of units of appendage (e.g. coxa, basis) or of branch (endopod, exopod) of appendage.
(syn. podomore) [Stachowitsch, 1992]
One in a series of units of appendage (e.g., coxa, basis). May also refer to segment of body (then also termed somite). Segments of flagella of antennules are termed articles. (cylindrical, flattened; setose, smooth, spinose, spinulose). [Stachowitsch, 1992]
One in a series of divisions of body. Typically refers to one of approximately 30 trunk segments, the first being partially fused to cephalon, the last being reduced and partially fused to anal segment. Each trunk segment consists of dorsal tergite and ventral sternite, is produced laterally into pleurite, and bears pair of biramous appendages. May also refer to segment of limb. (see also article). [Stachowitsch, 1992]
Segment of body or appendage, those of the former often termed somites. Segments of flagella of antennules or antennae often termed articles. [Stachowitsch, 1992]

Segmental artery

Artery. [Stachowitsch, 1992]

Sella turcica

In endoskeleton of crab-like (brachyuran) decapod, fused and anteriorly extended endosternite on posterior border of last thoracic somite. [Stachowitsch, 1992]

Seller groove

See: Carapace grooves o [McLaughlin, 1980]
On carapace, short. transverse groove extending across dorsomedian surface in front of cervical groove. [Stachowitsch, 1992]

Selvage

In closing apparatus of valve, ridge-like elevation along inner margin; fits into groove (selvage groove) of opposite valve. If margin is simple, selvage represents only ridge; if margin is complex (i.e., inner lamella with duplicature), selvage represents middle or principal ridge. (See also flange, hinge selvage, list). [Stachowitsch, 1992]
Middle (prinicipal) ridge of contact margin sealing valves closed. [McLaughlin, 1980]

Selvage groove

In closing apparatus of valve, groove-like depression along inner margin. Separates major ridge (selvage) from minor ridge (list). [Stachowitsch, 1992]

Semi-closed petasma

The lateral lobes are rather flexable, markedly folded, supported by strong ribs, with the ventral costae approaching rather closely, delimiting moderately large space, narrowly open distally where usually overlapped by well developed distomedian projections.
See: Petasma [Perez Farfante and Kensley, 1997]

Semi-open petasma

The lateral lobes are flexable but folded, with the ventral costae distinctly turned ventromesially, delimiting relatively ample space extending from proximal to distal ends.
See: Petasma [Perez Farfante and Kensley, 1997]

Seminal papilla

(Taxon-specific: Order Monhysterida) In female reproductive system, one of two papilla-like elevations flanking gonopore (vagina). Each seminal papilla is connected via duct to separate seminal receptacle. Fertilizes egg emerging from oviduct. [Stachowitsch, 1992]

Seminal receptacle

Diverticulum of oviduct or external pouch (some pygocephalomorph eocarids, isopod peracarids, and decapods) for storing spermatozoa delivered by male.
(syn. receptaculum seminalis) [Moore and McCormick, 1969]
Diverticulum of oviduct or external pouch for storing spermatozoa delivered by male.
(syn. receptaculum seminalis, spermatheca) [McLaughlin, 1980]
In females of lobsters and some shrimps, an area on the ventral surface of the thorax that receives the spermatophore from the male during mating; in crabs, an enlarged portion of each oviduct that serves the same function. [Bliss, 1982]
(Taxon-specific: ) In female reproductive system, term occasionally applied to terminal section of oviduct. [Stachowitsch, 1992]
In female reproductive system, sperm-receiving structure consisting of either expanded terminal section of each oviduct or single median pouch (thelycum). [Stachowitsch, 1992]
Unpaired expansion of female reproductive system; located ventromedially in sixth thoracic somite (thoracomere), opens to exterior via gonopore. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In female reproductive system, one of two sperm-receiving structures in anterior region of abdomen; each seminal receptacle is connected by duct to separate seminal papilla flanking gonopore (vagina). (circular, irregularly ovate).
(syn. spermatheca) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Within brood chamber of female rhizocephalan, small cavity in which sperm are stored. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Chamber of the female reproductive system for the reception and storage of sterm. [Boxshall and Halsey, 2004]
In female reproductive system, one of two sperm-receiving organs. Each typically opens to exterior via vagina and is connected to end of oviduct by canal (spiral canal). [Stachowitsch, 1992]
In female reproductive system, sperm receiving structure in first abdominal segment (genital somite). Either paired, each receptacle opening into common atrium, or unpaired and joined to end of each oviduct via separate fertilization duct. (paired, unpaired). [Stachowitsch, 1992]

Seminal receptacles

Sacs for storage of spermatophores or sperm, usually on sternite of thoracic somite 7 (sometimes spermathecae), associated with thelycum in Dendrobranchiata. [Poore, 2004]
Unpaired or paired bulbous or tubular sacs associated with the thelycum for the storage of spermatophores or sperm, situated immediately dorsal to plate(s) of sternite XIV, sometimes XIII and/or XII. [Perez Farfante and Kensley, 1997]

Seminal vesicle

Organ which stores sperm of male. [Holdich and Jones, 1983]
Sac in male independent of testes for storage of spermatozoa (e.g., some anostracans, Chirocephalidae).
(syn. vesicula seminalis) [Moore and McCormick, 1969]
Sac in male, independent of testes, for storage of spermatozoa.
(syn. vesicula seminalis) [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) In male reproductive system, expanded section of vas deferens at base of penis. [Stachowitsch, 1992]
Unpaired median expansion of male reproductive system into which both testes open. Located in last thoracic somite (= eighth thoracomere or seventh pereonite). Opens to exterior via two gonopores.
See: Genital cone [Stachowitsch, 1992]
Elongate section of male reproductive system in which sperm are stored after leaving spermatic sacs. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In thorax, unpaired section of male reproductive system in which sperm are stored. Connected to testes by paired vasa efferentia, to common ejaculatory duct by paired vasa deferentia. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In male reproductive system, expanded section of sperm duct (vas deferens). [Stachowitsch, 1992]
In male reproductive system, enlargement of vas deferens for storing sperm. [Stachowitsch, 1992]
In male reproductive system, somewhat expanded section of vas deferens in which sperm are stored. [Stachowitsch, 1992]
In male reproductive system, expanded terminal section of each vas deferens. Serves to store sperm. [Stachowitsch, 1992]
In male reproductive system, expanded section of each vas deferens. Serves to store sperm. [Stachowitsch, 1992]

Sensilla

A modified seta found on the dactylus of the pereopods. It is similar to an aesthetasc, but has a heavier cuticle that is covered with many tiny lobes (often only visible in a scanning electron micrograph).
(pl. sensilla) [Wilson, 1989]

Sensoriform filament

(Taxon-specific: Family Cyatholaimidae) A modified setal element typically with thin walls and either blunt ending (vermiform), or ending in brush of fine setules (brush-like), found on the maxilla and sometimes maxillipeds of calanoids. [Boxshall and Halsey, 2004]

Sensory pore X-organ

X-organ. [Stachowitsch, 1992]

Sensory pore of the mandibular molar

A small pit in the distal surface of the mandibular's molar process that can be Seen to connect internally to a nerve process. [Wilson, 1989]

Septum

A basal constriction of the lumen of the setal shaft. [Watling, 1989]

Serrate

Having a row of short, tooth-like denticles. [Wilson, 1989]
Notched or with spines along edge. [Butler, T. H.]
Edged with toothlike projections as in a saw. [Kensley and Schotte, 1989]

Serrate seta

Shaft of variable length and thickness without setules; denticles varying from numerous and fine to few and stout, investing most of shaft, or confined to apical region; sometimes modified; annulus sometimes present; pore absent; socket usually apparent. [Ingle, 1992]

Serration

Irregular saw-toothed outline on dorsal edges on some conchostracan valves where growth bands do not end on same hinge line; may have various expression from strongly serrate (e.g., Paleolimnadiopsidae) to subdued serrate (e.g., extant Caenestheriellia) and pseudoserrate (e.g., some extant Cyzicus). [Moore and McCormick, 1969]
Irregular saw-toothed outline, e.g., on conchostracan valves. [McLaughlin, 1980]

Seta

A cuticular hair arising from the outside of the exoskeleton. [Warner, 1977]
A cuticular outgrowth having recognizable basal articulation. [Ingle, 1992]
A cuticular process that is clearly articulated with the basal cuticle. This structure comes in many forms. Some authors call heavily sclerotized setae "spines," even though there are smaller counterparts of the same form named "setae" by the same authors. "Spinose seta" or "spine-like seta" is more accurate.
(pl. setae) [Wilson, 1989]
An articulated cuticular extension of virtually any shape or size; may vary from very small (10-20 m) to very large (> 1 mm in length) and robust, often with a very wide base; contrary to Thomas (1970), a seta does not always have an apical pore, nor does it always have an annulus. [Watling, 1989]
Bristle-like, hair-like, or tooth-like, processes on limbs and mouth parts on many crustaceans. [Bliss, 1982]
Hair-like process of cuticle with which it is articulated; in cirripeds, bristle or spine on trophi and cirri. [Moore and McCormick, 1969]
Hairlike or needlike projection from shell of shrimps; may be simple or plumose.
(pl. setae) [Butler, T. H.]
Hairlike process of cuticle with which it articulates or through which it protrudes.
(pl. setae) [McLaughlin, 1980]
(Taxon-specific: ) Abdominal seta, antennal setae formula, olfactory seta, trunk appendage. [Stachowitsch, 1992]
One of numerous bristle-shaped projections of appendage. Setae of trunk appendages serve in feeding. According to shape one may distinguish, e.g., simple and spine-like, or brush-like setae on flagellum of antenna. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of numerous, bristle-like projections extending from appendage. Those along thoracopod margins serve in feeding. Caudal rami typically fringed with plumose setae. [Stachowitsch, 1992]
One of numerous bristle-shaped projections extending from appendage. number and type are of taxonomic importance. According to shape one may distinguish, e.g., simple, bifid, brush, or plumose setae. [Stachowitsch, 1992]
Small, bristle-like projection articulating with or extending through cuticle. According to shape one may distinguish brush, cuspidate, feathered, hamate, nonplumose, pappose, plumodenticulate, plumose, serrate. setose, simple, triserrate, and triserrulate setae.
(syn. bristle, hair) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of numerous bristle-like projections extending from appendage or body. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of numerous bristle-like projections extending from appendage. Number, shape, and arrangement are of taxonomic importance. (lanceolate, plumose, simple). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) An articulating extension of a segment, usually not directly along the proximodistal axis (see denticle and setule). [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Slender, often plumose, armature element on paired appendages or caudal rami, with internal tissue connection through integument. [Boxshall and Halsey, 2004]
One of numerous bristle-like projections exending from appendage or body. Number and type of setae are of taxonomic importance. Large setae on supra-anal plate and caudal rami are termed major setae. According to shape one may distinguish, e.g., simple and brush setae. (See also setule). [Stachowitsch, 1992]
Innervated cuticular projection of body or appendage. Typically bipartite, being divided into proximal base and distal shaft by annulation. With both sensory and mechanical functions. (chelate, compound, pappose, plumed, plumose, serrate, simple) (See also hair, pseudochaeta). [Stachowitsch, 1992]
One in a series of variously developed bristles projecting from margin or tip of appendage (e.g., caudal setae of caudal ramus). (simple, pinnate, plumose). [Stachowitsch, 1992]
One of variously shapedm hair-like processes projecting from antennules, antennae, labum, paragnaths, maxillules, maxillipeds, or trunk limbs. According to shape one may distinguish comb, plumose, ribbon, simple and subsetulate setae. [Stachowitsch, 1992]

Setal row

Row of regularly spaced plumose setae, attached in pits on carapace and some limbs (Thalassinidea). [Poore, 2004]
In mandible, row of spine-like projections between molar process and lacinia mobilis (or between molar and incisor processes when lacinia mobilis is absent).
(syn. spine row) [Stachowitsch, 1992]
Row of spine-like projections between molar process and lacinia mobilis on each mandible. [Stachowitsch, 1992]
Row of setae between lacinia mobilis and molar process on mandible. [Stachowitsch, 1992]

Setiferous

Bearing setae, as an appendage. [Butler, T. H.]
Bearing setae. [Kensley and Schotte, 1989]

Setophore

(Taxon-specific: Family Cyatholaimidae) A long process carrying a seta, often used of the process bearing the outer basal seta on the fifth legs of harpacticoids. [Boxshall and Halsey, 2004]

Setose

Bearing bristles. [Butler, T. H.]
Hairy. [Ingle, 1983]
Bearing setae. [Kensley and Schotte, 1989]

Setulate seta

A seta with one or more rows of setules. It is different from plumose or hemiplumose setae in that the row is limited to a section of the shaft, and does not extend from base to tip. [Wilson, 1989]

Setule

A spine on a seta. [Wilson, 1989]
An extension of the shaft of a seta, usually of uniform width from base to tip, and forming an articulated or flexible junction with the shaft. [Watling, 1989]
One of numerous minute projections of seta. May also refer to any small setae, e.g., those forming comb on 19th abdominal somite. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A solid extension of the epicuticle of a seta (see denticle and seta). [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) Setiform epicuticular ornamentation element, without tissue connection through integument. [Boxshall and Halsey, 2004]
One in a series of minute secondary projections on seta. (flexible, suctorial, tooth-like). [Stachowitsch, 1992]

Seventh limb

7th limb (and 2nd trunk/thoracic limb); controversially considered to be and labeled "3rd trunk limb" by some podocopid specialists; use care in reading descriptions. [Cohen, Peterson, and Maddocks, in press]

Sexual pore

See: Gonopore [Martin, 2005]
See gonopore. [McLaughlin, 1980]

Sheath

In cirripeds (Balanomorpha), thickened upper part of internal shell wall and alae forming cylindrical collar to which opercular membrane is attached. [Moore and McCormick, 1969]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Barnacle shell feature: in unstalked form, collar-like structure inside shell. Formed by thickened upper parts (parieties, alae) of compartmental plates; serves as site of attachment of opercular membrane. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Cyrlindrical structure inside shell, consisting of alae and thickened upper part of parietes, greatly strengthening orifice and providing for attachment of opercular membrane. [McLaughlin, 1980]

Shell

In cirripeds, general term for hard parts of balanomorphs including compartment plates, basis (if calcareous), and opercular valves. [Moore and McCormick, 1969]
(Taxon-specific: ) Carapace. [Stachowitsch, 1992]
Carapace. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In unstalked barnacle, general term for hard elements surrounding body; includes compartmental plates, basis (if calcareous), and opercular valves. [Stachowitsch, 1992]
Carapace. [Stachowitsch, 1992]

Shell fold

Part of carapace behind cephalon. [McLaughlin, 1980]
Portion of carapace behind cephalic shield. [Moore and McCormick, 1969]

Shell gland

See: Maxillary gland [Martin, 2005]
See maxillary gland. [McLaughlin, 1980]
(Taxon-specific: ) Carapace spine. [Stachowitsch, 1992]
(Taxon-specific: ) Maxillary gland. [Stachowitsch, 1992]
Maxillary gland. [Stachowitsch, 1992]

Shield

Anterior part of cephalothorax in hermit crabs. [McLaughlin, 1980]
Anterior, better calcified section of cephalothorax in front of cervical groove in hermit crabs. (subcordate, subquadrate; convex, flattened; with granules, with tufts of hair).
(syn. anterior shield) [Stachowitsch, 1992]

Sieve plate

Minute, perforated plate covering pore in valve; may be associated with seta. [Stachowitsch, 1992]

Simple rostrum

(Taxon-specific: Order Rhabditida) Rostrum. [Stachowitsch, 1992]

Simple seta

Shaft thin, usually naked, but sometimes with small denticles scattered over shaft; post-annular part often bent at an angle; socket prominent; annulus sometimes not apparent; pore sometimes present. [Ingle, 1992]

Simple velum

Velate structure having simple flangelike form or forming ridge. [McLaughlin, 1980]

Sinuate

Having a wavy margin. [Kensley and Schotte, 1989]

Sinuous

An undulating margin. [Ingle, 1980]
Having curves. [Kensley and Schotte, 1989]

Sinus

A blood-filled space on the venous side of the circulatory system. [Warner, 1977]
Any space or cavity in body tissues; also, refers to broad concavity in margin of shell. [Butler, T. H.]
Posterior emargination of carapace; bears series of small denticles.
(syn. notch) [Stachowitsch, 1992]
In circulatory system, one of several spaces in which deoxygenated blood collects before entering gill and returning to pericardium and heart. According to position one may distinguish branchial, dorsal, infrabranchial, and sternal sinuses. [Stachowitsch, 1992]
In circulatory system, more clearly delimited space in which blood collects. Blood coming from gills passes through segmentally arranged, dorsally directed sinuses before entering large pericardial cavity surrounding heart. (See also lacuna). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Term referring to either cleft between posterior lobes of abdomen or to blood sinus such as that surrounding compound eyes. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In circulatory system, one of several blood-filled spaces. According to cirriped group and position one may distinguish epineural, mantle, prosomal, rostral, and thoracic sinuses. (See also rostral sinus). [Stachowitsch, 1992]
In circulatory system, space in which blood collects. Typically refers to system of ventral sinuses (supraneural sinus, sternal sinus). [Stachowitsch, 1992]

Sinus gland

Storage release site for molt-inhibiting and other hormones produces by x-organ and other sites of central nervous system. [McLaughlin, 1980]
Small structure located in eyestalk (ocular peduncle) and serving to store and release hormones produced by X-organ. [Stachowitsch, 1992]
Mouth cone. [Stachowitsch, 1992]

Siphon

Tubular, exhalant respiratory structure consisting dorsally of pseudorostral lobes (pseudorostrum) of carapace and laterally of anteriorly directed lobes (according to interpretation: siphonal lobe of epipod or exopod) of first maxilliped pair. Water from branchial chamber exists via siphon extended in front of head. [Stachowitsch, 1992]

Sixth limb

6th limb (and 1st trunk/thoracic limb); controversially considered to be and labeled "2nd trunk leg" by some podocopid specialists; use care in reading descriptions. [Cohen, Peterson, and Maddocks, in press]

Skeletal duplicature

Outer chitinous body cover of conchostracans shed during ecdysis, individual duplicatures being very thin whitish translucent layer resembling entire animal when floating in water; may occur also in notostracans and cladocerans. [Moore and McCormick, 1969]
(Taxon-specific: ) Outer chitinous body cover shed during ecdysis. [McLaughlin, 1980]

Socket

(Taxon-specific: Order Monhysterida) On third pair of thoracic appendages (thoracopods) of male, socket-like depression in protopod. Receives peg of fourth thoracopod in a peg-and-socket arrangement and serves to hold both thoracopods together during copulation. [Stachowitsch, 1992]
Hinge structure: pit-like (typically anterior or posterior) depression in hinge margin. Receives tooth of opposite valve. Major depression at end of hinge is termed cardinal socket; those with subdivided floors are termed compound sockets. [Stachowitsch, 1992]

Soft crab

A crab that has just shed its shell and has not yet hardened its new shell; may be any species of crab, but the commercial soft-shelled crab of the Atlantic and Gulf coasts is the blue crab, Callinectes sapidus.
(syn. soft-shelled crab) [Bliss, 1982]

Solum

Type of valve sculpture: in single mesh (fossa) or reticulate pattern, central space or depression surrounded by walls (muri). [Stachowitsch, 1992]

Solus

(Taxon-specific: Family Cyatholaimidae) A short seta on the antennule of some siphonostomatoids. [Boxshall and Halsey, 2004]

Somite

A body segment, especially of the abdomen. [Chace and Hobbs, 1969]
Body segment, as in abdominal somites 1-6. [Poore, 2004]
Body segment, especially of the abdomen. [Butler, T. H.]
Division of body (head, thorax, abdomen) with exoskeleton comprising body-ring that is generally divisible into dorsal (tergite) and ventral (sternite) portions. [Moore and McCormick, 1969]
Division of body, including exoskeleton, usually with pair of appendages. [McLaughlin, 1980]
Each of the main divisions of the body. [Perez Farfante and Kensley, 1997]
Segment of the body usually differentiated into dorsal tergite and ventral sternite and with a pair of appendages. [Holdich and Jones, 1983]
(Taxon-specific: ) One in a series of divisions of body. Head consists of five somites (bearing antennules, antennae, mandibles, maxillules, and reduced maxillae). Somites of trunk, especially of posterior region ("abdomen") , are indistinguishable, although trunk appendages reflect segmentation of anterior region ("thorax"). [Stachowitsch, 1992]
One in a series of original divisions of body. Head consists of five somites, while somites of thorax and abdomen are variously fused to form units termed either segments or body rings. [Stachowitsch, 1992]
One in a series of divisions of body. Head consists of five somites, trunk of 10-32 somites (excluding telson). Posteriormost somites drawn out into series of spine-like projections dorsally. Telson occasionallu termed anal somite.
(syn. segment) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One in a series of divisions of body. Head consists of five somites, followed by 11 (occasionally 17 or 19) thoracic somites (thoracomeres) and 8 abdominal somites. Last abdominal somite bears telson (anal somite).
(syn. segment) [Stachowitsch, 1992]
One in a series of divisions of body. Head (cephalon) consists of 5 somites (fused dorsally to form cephalic shield), followed by 8 thoracic somites (thoracomeres) and 11 abdominal somites. Last abdominal somite bears telson (anal somite).
(syn. segment) [Stachowitsch, 1992]
One in a series of divisions of body. Head consists basically of five somites, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres). [Stachowitsch, 1992]
One in a series of divisions of body. Head consists of five somites (plus first thoracic somite), pereon of seven somites (pereonites), and abdomen (pleon) of six somites (pleomeres). [Stachowitsch, 1992]
One in a series of divisions of body. Head consists of five somites (plus first thoracic somite), pereon of seven somites (pereonites), and abdomen (pleon) of six somites (pleomeres). [Stachowitsch, 1992]
One in a series of divisions of body. Head (cephalon) consists of five somites (antennular, antennal, mandibular, maxillular, maxillar somites) excluding acron, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres) excluding telson. Each somite basically consists of dorsal tergite, ventral sternite, and lateral pleurites. [Stachowitsch, 1992]
One in a series of divisions of body. Cephalon consists of five somites (cephalothorax of these five plus first thoracic somite), pereon of four to seven somites (pereonites), and pleon of six somites (pleomeres).
See: Urosomite [Stachowitsch, 1992]
Body segment, usually having a pair of appendages. [Kensley and Schotte, 1989]
One in a series of divisions of body. Cephalon consists of five somites (cephalothorax of these five plus first thoracic somite), pereon of six or seven somites (pereonites), and pleon of basically six somites (pleomeres). [Stachowitsch, 1992]
One in a series of divisions of body. Head consists basically of five somites, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres). Anterior thoracomeres (bearing maxillipeds) may be fused with head.
(syn. segment) [Stachowitsch, 1992]
One in a series of divisions of body. Head (cephalon) consists of five somites (excluding acron), thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres) excluding telson. Each somites consists of dorsal tergite and ventral sternite and may be produced into lateral pleurites. (smooth, which carinae, denticulate) (See also antennular somite, ophthalmic somite).
(syn. segment) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One in a series of divisions of body. Head (cephalon) consists of five fused somites, thorax of eight, and abdomen of seven somites (excluding posterior telson). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One in a series of divisions (segments) of body. Head (cephalon) consists of five somites plus first thoracic somite, pereon of three somites; abdomen is unsegmented.
(syn. segment) [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One in a series of division of body. Head consists of five somites, thorax of six, and in ascothoracican, abdomen of four to five somites.
(syn. segment) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A composite group of elements, usually exoskeletal, musculature, and nerve, which makes up a serially repeated component of the body. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) A segment or division of the body. [Boxshall and Halsey, 2004]
One in a series of divisions of body. Cephalon consists of five (fused) somites, followed by maxillipedal somite and nine thoracoabdominal somites. Last thoracoabdominal somite bears telson ("anal somite").
(syn. segment) [Stachowitsch, 1992]
One in a series of divisions of body. Basically, head (cephalon) consists of five cephalic somites, thorax of five thoracic somites (thoracomeres), and abdomen (pleon) of five abdominal somites (pleomeres). Variously fused to form more or less distinct body divisions (cephalosome, metasome, urosome).
(syn. segment) [Stachowitsch, 1992]
One in a series of divisions of body. Head consists basically of five somites, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres). First thoracomere may be fused with head. [Stachowitsch, 1992]
One in a series of division of body. Cephalon consists basically of five somitesd, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres). Because first thoracomere is fused to cephalon, an alternate interpretation disintguishes six cephalic somites, seven thoracomeres or pereonites, and six pleonites. [Stachowitsch, 1992]
One in a series of divisions of body. Head (cephalon) consists of five somites, thorax of eight somites (thoracomeres), and abdomen of six somites (pleomeres). Each somite basically consists of dorsal tergite, ventral sternite, and lateral pleurites.
(syn. segment) [Stachowitsch, 1992]

Spatulate

Shaped like a spatula. [Kensley and Schotte, 1989]

Spawning

Emission, or "laying," of eggs. [Bliss, 1982]

Species

A major subdivision of a genus or subgenus; regarded as the basic category of biological classification; composed of related individuals that resemble one another; are able (or potentially able) to breed among themselves, but are not able to breed with members of another species. [Bliss, 1982]

Sperm duct

(Taxon-specific: ) Vas deferens. [Stachowitsch, 1992]
Vas deferens. [Stachowitsch, 1992]
Vas deferens. [Stachowitsch, 1992]
Vas deferens. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Vas deferens. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Vas deferens, vas efferens. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Vas deferens. [Stachowitsch, 1992]
Vas deferens. [Stachowitsch, 1992]
Vas deferens. [Stachowitsch, 1992]
In male reproductive system, pair of ducts extending from about 10th to 14th trunk segments. Joins testes with opening on genital papilla on base of 14th trunk limb.
(syn. vas deferens) [Stachowitsch, 1992]

Sperm plug

A structure plugging the opercula and distal part of each genital duct of female crabs to prevent loss of sperm after copulation. [Ingle, 1983]

Sperm tube

A structure found only in male janiroidean Asellota taking one of two forms: 1. A cuticular tube in the stylet (distal segment of the endopod) of the male second pleopod, consisting of a ventral opening to a rounded chamber in the center of the stylet and a confluent tube to the tip of the stylet; 2. A cuticular tube formed by the medial fusion of the male first pleopods, consisting of a funnel-like proximal opening often covering the penile papillae and a confluent tube to a dorsal orifice roughly one quarter the length of the pleopods from their tips. During copulation, both tubes may form a single channel from the penile papillae to the female's cuticular organ. [Wilson, 1989]

Spermatheca

A sperm reservoir inside the female oviduct, with an opening to the cuticular organ. [Wilson, 1989]
Pouch in oviduct of females for reception and retention of spermatozoa. [Moore and McCormick, 1969]
See seminal receptacle. [McLaughlin, 1980]
(Taxon-specific: Order Monhysterida) Seminal receptacle. [Stachowitsch, 1992]
In female, modification of ventral surface (sternite) of last thoracic somite as sperm storage organ. [Stachowitsch, 1992]

Spermathecum

Storage chamber in the female copulatory organs, thelycum, for storage of spermatozoa. [Mauchline, 1984]

Spermatic sac

One in a series of sac-shaped structures into which testes are subdivided.
(syn. spermatic pouch, follicle) [Stachowitsch, 1992]

Spermatophore

A packet of sperms transferred by a male shrimp, lobster or crab to the female during mating. [Bliss, 1982]
Mass of spermatozoa deposited by gonopods of male on to thoracic sternum or into seminal receptacle of female. [Poore, 2004]
Packet containing spermatozoa which is produced by the male genital system for transfer to the female. [Mauchline, 1984]
Packet of spermatozoa for transfer from male to female. [Moore and McCormick, 1969]
Packet or capsule of spermatozoa. [McLaughlin, 1980]
The sperm-carrying, variously complex mass, issuing from the male gonopore during copulation. [Perez Farfante and Kensley, 1997]
Packet of sperm formed in vas deferens, emerging from gonopore, and transferred to female with the aid of modified first pleopod pair(s) (gonopods, petasma, appendix masculina). (stalked, unstalked; pear-shaped, rod-shaped, lobed, bilobed). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Packet of sperm produced in male reproductive system. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A cuticular capsule containing sperm, transferred from male to female during mating. [Boxshall and Halsey, 2004]
Packet of sperm formed in vas deferens. [Stachowitsch, 1992]
Packet of sperm formed in modified region (spermatophoric sac) of vas deferens. [Stachowitsch, 1992]
Packet of sperm formed in distal end of each vas deferens. Emerges from gonopore and is transferred by modified pleopods (petasma) to female thelycum. [Stachowitsch, 1992]

Spermatophoric sac

In male reproductive system, somewhat expanded distal section of vas deferens in which spermatophores are produced. [Stachowitsch, 1992]

Spicate

Shaped like a spike. [Kensley and Schotte, 1989]

Spine

Carapace, spines, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Anterior part of carapace, including ocular peduncles, based on Munidopsis. [Baba, 2005]
(Figure only.) [Baba, 2005]
A cuticular outgrowth without a recognizable basal articulation. [Ingle, 1992]
A non-articulated cuticular extension that has a base that is generally not as wide as the structure is long; regardless of its size or shape, a spine has no socket. [Watling, 1989]
A pointed outpocketing of the cuticle that is confluent with the cuticle at its base (not articulated). [Wilson, 1989]
Sharp, stiff, fairly robust protuberance on body or appendages. [Butler, T. H.]
(Taxon-specific: ) Anal spine, carapace spine. [Stachowitsch, 1992]
One of numerous small, spine-like projections of body rings, telson, or supra-anal plate. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Abdominal spine. [Stachowitsch, 1992]
One of numerous sharp, spine-like projections on carapace. Typically refers to anterior projections in shrimp-like (natantian) decapod. According to position and group one may distinguish, e.g., antennal, branchiostegal, hepatic, postorbital, postrostral, pterygostomial, suborbital, and supraorbital spines. [Stachowitsch, 1992]
One of several thorn-like projections on carapace, body, or appendages. According to position, those on carapace may be termed antennal, branchiostegal, posterolateral, and posterodorsal spines (the latter unpaired). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Stout, often thickened and rigid, armature element on paired appendages or caudal rami, with internal tissue connection through integument. [Boxshall and Halsey, 2004]
Type of valve sculpture: elongate, larger, typically pointed projection. (clavellate, conjunctive, disjunctive, mamillate, marginal, perforate). [Stachowitsch, 1992]
One of various spine-like projections of body. According to position one may distinguish median preanal spine on ventral surface of last abdominal somite (pleomere), dorsal or middorsal spine on dorsal midline of one or more pleomeres, as well as interior or posterior spine associated with lateral margin of carapace.
See: Subapical spine [Stachowitsch, 1992]

Spine row

Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
Spinose lobe on the mandible, between the molar and incisor processes. [Wetzer et al. 1997]

Spine row, mandibular

A row of spine on the medial side of the mandible's incisor process. The lacinia mobilis on the left mandible is actually an enlarged member of the spine row. [Wilson, 1989]
In mandible, row of spine-like projections between molar process and lacinia mobilis (or between molar and incisor processes when lacinia mobilis is absent). [Stachowitsch, 1992]
Setal row. [Stachowitsch, 1992]
Row of spines situated between the incisor and molar processes of the mandible. [Kensley and Schotte, 1989]
Row of spine-like projections in central postition on cutting edge of either mandible. [Stachowitsch, 1992]

Spiniform seta

Shaft very stout; very broadly basally; surface smooth and unarmed; pore may be present. [Ingle, 1992]

Spinnaret gland

Gland (connected to 2nd antenna) secreting adhesive thread. [Cohen, Peterson, and Maddocks, in press]

Spinneret

Gland, located in forehead and opening to exterior via seta-like exopod of antenna. Secretes thread-like material used in locomotion. [Stachowitsch, 1992]

Spinning gland

One in a series of paired glands located in first pereonites. Opens at tip (dactylus) of corresponding pereopod. Serves in tube construction. [Stachowitsch, 1992]

Spinose

Bearing spines. [Butler, T. H.]
Bearing spines. [Kensley and Schotte, 1989]

Spinulate

A surface with very small spines. [Ingle, 1980]

Spinule

Small, or secondary spine; may be shorter or longer than spine, but usually more flexible. [Butler, T. H.]
(Taxon-specific: ) Small spine along dorsal margin of carapace or along vertex. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Spiniform epicuticular ornamentation element, without tissue connection through integument. [Boxshall and Halsey, 2004]

Spiny lobsters

Members of the family Palinuridae; lack large claws and have a flexible, leathery tail fan.
(syn. rock lobsters) [Bliss, 1982]

Spiracle

Opening to pseudotracheae on pleopods of certain terrestrial isopods. [Stachowitsch, 1992]

Spiral canal

In female reproductive system, very long, coiled tube connecting seminal receptacle to oviduct. [Stachowitsch, 1992]

Sponge

The egg mass of a female crab, which she carries attached to long hairs on her pleopods. [Bliss, 1982]

Spur

In cirripeds (Balanomorpha), dependent projection on basal margin of tergum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, calcareous projection of basal margin of tergum. [Stachowitsch, 1992]
Pendent projection from basal margin of tergum (sessile Cirripedia); also velate structure modified sa flattened spinelike projection in some dimorphic genera. [McLaughlin, 1980]
Type of valve sculpture: flattened, spine-like projection. Represents modified, wing-like (velate) structure. [Stachowitsch, 1992]

Spur fasciole

See: Spur furrow [Martin, 2005]
(Taxon-specific: Order Rhabditida) Nearly level, slightly depression on outer surface of tergum extending to apex in line with spur; usually delimited on 1 or both sides by narrow groove. [McLaughlin, 1980]

Spur furrow

In cirripeds (Balanomorpha), groove on outer surface of tergum extending to apex in line with spur.
(syn. spur fasciole) [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in unstalked form, groove on outer surface of tergum, in line with spur and extending to upper angle (apex). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Groove on outer surface of tergum extending to apex in line with spur, with sides sometimes folded in. [McLaughlin, 1980]

Squama

See: Scaphocerite [Martin, 2005]
See scaphocerite. [McLaughlin, 1980]
Antennal scale. [Stachowitsch, 1992]
Scaphocerite. [Stachowitsch, 1992]
Antennal scale. [Stachowitsch, 1992]

Stadia

A stage in the life history of an organism; interval between successive molts. [Hobbs and Jass, 1988]

Stage

(Taxon-specific: Family Cyatholaimidae) A period of development between two molts in which the exoskeleton does not change; synonymous terms are instar and stadium. [Ferrari and Dahms, in press]

Stalked eyes

Eyes borne on distinct movable stalks. [Brusca and Brusca, 2002]

Standard measurements

Carapace length and width
relative dimensions of appendage segments
relative length of appendages.
See: Gill formula [Stachowitsch, 1992]

Statocyst

Cavity filled with fluid and particles acting as organ of orientation. [Poore, 2004]
Diminutive organ providing sense of balance. [McLaughlin, 1980]
Organ of balance at base of antennular peduncle in brachyurans. [Ingle, 1992]
Sensory organ of awareness of rotation and position located at base of first antenna. [Perez Farfante and Kensley, 1997]
Organ of equilibrium, one located in first segment of peduncle of each antennule. Innervated by branch of antennular nerve coming from brain and may contain statolith supported by sensory hairs. (open, closed; with/without statolith). [Stachowitsch, 1992]
One of two small organs of equilibrium located dorsally in head; each statocyst contains one to five statoliths. [Stachowitsch, 1992]
Organ of equilibrium located in telson of certain isopods; contains statolith. [Stachowitsch, 1992]
Small saclike sensory organ, often containing granules, used to indicate to the animal its orientation. [Kensley and Schotte, 1989]
Organ of equilibrium, one located at base of inner branch (endopod) or each uropod. Contains statolith and is innervated by last abdominal ganglion. [Stachowitsch, 1992]
In anaspidacean and stygocaridacean, organ of equilibrium located in first segment of each antennule. [Stachowitsch, 1992]

Statocysts

A complex fluid filled invagination contained within the swollen base of the antennule and responsible for the sense of balance. [Ingle, 1983]
Diminutive organ providing sense of balance, present in most crustaceans. [Moore and McCormick, 1969]
Small saclike sensory organ, usually containing a granule(s), used to indicate to the animal its orientation; present singly or paired on the pleotelson of some anthurideans. [Wetzer et al. 1997]

Statolith

Solid body within statocyst; supported by rows of sensory hairs. May be composed of sand grains. [Stachowitsch, 1992]
Solid body within statocyst; supported by rows of sensory hairs. [Stachowitsch, 1992]

Stenopod

Any slender, elongate appendage composed of rod-like segments. May refer to inner branch (endopod) of third maxillipeds or main part (endopod) of pereopods.
(syn. stenopodium) [Stachowitsch, 1992]
Slender, elongate appendage composed of rod-like segments. Refers to three pairs of slender appendages (thoracopods) on sixth through eighth thorax somites (thoracomeres). [Stachowitsch, 1992]

Stenopodial

(Taxon-specific: Family Cyatholaimidae) Used of non-prehensile maxillipeds, typically with three long narrow segments. [Boxshall and Halsey, 2004]

Stenopodium

Slender, elongate appendage, composed of rodlike segments. [McLaughlin, 1980]
Slender, elongate limb composed of rod-like segments. [Moore and McCormick, 1969]

Stenopodous

Term referring to a walking leg with relatively stout, cylindrical articles. [Brusca and Brusca, 2002]

Sternal artery

Artery. [Stachowitsch, 1992]
Artery. [Stachowitsch, 1992]

Sternal bar

In trunk segment, transverse thickening sometimes reinforcing or even replacing sternite. Sternite bar of 14th trunk segment may bear lateral flap (genital flap) which covers gonopore. (bar-like, subtriangular; posterior margin: concave, convex).
(syn. sternite bar) [Stachowitsch, 1992]

Sternal canal

Internal skeletal structure of some crabs formed by meeting of of sternal apodemes of opposite sides above nerve cord. [McLaughlin, 1980]
Internal skeletal structure of some crabs formed by meeting of sternal apodemes of opposite sides above nerve cord; may be developed as firm plate (endosternite) in anterior part of thorax. [Moore and McCormick, 1969]

Sternal cornuae

Large and prominent spines on most posterior sternal segment. [Ingle, 1992]

Sternal furca

On ventral surface of parasitic copepod, fork-shaped median projection between maxillipeds and first pereopods.
(syn. sternal fork) [Stachowitsch, 1992]

Sternal gill

One in a series of small structures projecting from ventral surfaces (sternites) of pereon segments. Considered to have respiratory or osmoregulatory function. [Stachowitsch, 1992]

Sternal grooves

A pair of obliquely placed grooves on the sternum of female crabs belonging to the Section Dromiacea. [Ingle, 1980]
On ventral surface of cephalothorax in certain crab-like (brachyuran) decapods, one of two oblique grooves along sternum. [Stachowitsch, 1992]

Sternal plastron

See: Sternum [Martin, 2005]
See sternum. [McLaughlin, 1980]
Sternal plate. [Stachowitsch, 1992]

Sternal plate

Plate-like ventral surface of cephalothorax formed by fusion of sternites. May be depressed in decapods whose abdomen is folded up against cephalothorax.
(syn. sternalplastron) [Stachowitsch, 1992]

Sternal process

Projection from mid-section of sternite of mysidaceans and pygocephalomorph eocarids, unknown as to function. [Moore and McCormick, 1969]
Projection from midsection of sternite. [McLaughlin, 1980]
In certain mysidaceans, medial unpaired process on thoracic sternite. [Stachowitsch, 1992]

Sternite

Sternal plastron, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
A calcified plate on the ventral side of a segment between the bases of the appendages. [Warner, 1977]
A segment of the ventral wall of the thorax. [Ingle, 1983]
One of five transverse fused plates of sternum indicating basic segmentation of cephalothorax. [Butler, T. H.]
One of the five transverse fused plates of the sternum indicating the basic segmentation of the cephalothorax. [Chace and Hobbs, 1969]
Sclerotized ventral surface of body somite. [McLaughlin, 1980]
Sclerotized ventral surface of single body somite. [Moore and McCormick, 1969]
The ventral surface of a thoracic body segment. [Wilson, 1989]
Ventral part of the thoracic or abdominal somite. [Perez Farfante and Kensley, 1997]
Ventral plate of integument (cf. tergite). [Poore, 2004]
(Taxon-specific: Family Pycnogonidae) Ventral surface of body segment (somite). Sternite of genital segment considered to form ovisac. [Stachowitsch, 1992]
Ventral surface of body segment (somite). (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite). In male, sternite of last (fifth) pereonite bears gonopores. First segments (coxae) of thoracopods may be more or less fused with sternites. (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite). Gonopores of male located on sternite of last (eighth) thoracic somite (thoracomere).
See: Tergite [Stachowitsch, 1992]
Ventral surface of body segment (somite). May be fused with other sternites to form sternal plate in cephalothorax.
See: Episternum, Pleurite, Tergite [Stachowitsch, 1992]
Ventral surface of body segment (somite). Sternites of anterior division (pleosome) of abdomen may bear sternal gills; in male, sternite of last (seventh) pereon segment bears penes. [Stachowitsch, 1992]
Ventral surface of body segment (somite). Sternite of fifth (female) or seventh (male) pereon segment bears gonopores.
(syn. sternal plate) [Stachowitsch, 1992]
Ventral surface of body segment (somite). May be well developed in thoracic of female to accommodate brood pouch (marsupium). (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite); female gonopore located on middle of sixth thoracic somite. (See also pleurite, tergite). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Ventral surface of body segment (somite). More clearly delimited only on thorax and between maxillae. Postmaxillary spines located on sternite between maxillae, gonopore on sternite of last thoracic somite (fourth thoracomere). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The ventral chitinous plate of a body somite. [Boxshall and Halsey, 2004]
Ventral surface of body segment (somite). (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite). Occasionally specified in connection with genital somite of female, with fold (intercoxal plate) of sternites which unites coxae of pereopod pairs, or with sternal furca. [Stachowitsch, 1992]
Ventral surface of body segment; sternites of trunk segment are sometimes plate-like, sometimes reinforced or reduced to sternal bar. (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite). In anaspidacean, sternite of eighth thoracomere bears opening of reproductive system (male) or is modified to form spermatheca (female). (See also tergite). [Stachowitsch, 1992]
Ventral surface of body segment (somite). In male, sternite of last (eighth) thoracomere bears pair of penes; in female, sternite of sixth thoracomere bears gonopores. [Stachowitsch, 1992]
Ventral surface of body segment (somite). Sternites of first four abdominal somites (pleomeres) bear median photophores.
See: Pleurite, Tergite [Stachowitsch, 1992]

Sternum

Midventral platelike surface of body, situated posterodorsal to orbit. [Hobbs and Jass, 1988]
Sternites of all body somites taken together, and abdomen; ventral segmented floor of thorax.
(syn. sternal plastron) [Moore and McCormick, 1969]
Structure comprised of ventral portions of somites taken together.
(pl. sterna) (syn. sternal plastron) [McLaughlin, 1980]
The calcified underside composed of fused sternites. [Warner, 1977]
The midventral surface of the body, between the coxae of the appendages. [Hobbs, Hobbs, and Daniel 1977]
The totally or partly fused segments of the thoracic ventral wall; collective terms for the total number of sternites. [Ingle, 1983]
The ventral surfaceof the cephalothorax between the coxae of the pereiopods.
(pl. strena) [Chace and Hobbs, 1969]
Ventral surface of body, to which limbs are attached, or between limbs. [Poore, 2004]
Ventral surface of body. [Holdich and Jones, 1983]
Ventral surface of cephalothorax between coxae or pereiopods. [Butler, T. H.]
Ventral surface of the cephalothorax or abdomen. [Perez Farfante and Kensley, 1997]
Collective term for all sternites. Occasionally used as synonym for individual sternite or for fused sternites (sternal plate) of cephalothorax region. [Stachowitsch, 1992]
Collective term for all sternites. [Stachowitsch, 1992]

Sternum canal

In endoskeleton of crab-like (brachyuran) decapod, tube-like structure enclosing nerve cord; formed by fused inward projections (endosternites) of sternites. [Stachowitsch, 1992]

Stipe

Stem-like part of limb bearing squamate or other-shaped exopod (e.g., various eocarids). [Moore and McCormick, 1969]
Stemlike basal part of appendage with exopod sometimes squamate. [McLaughlin, 1980]

Stomach

Expanded section of digestive tract between esophagus and midgut. Characterized by various lateral folds, channels, and ridges and may be differentiated in anterior cardiac and posterior pyloric regions. One to four pairs of hepatic ceca open into stomach at stomach/midgut border. [Stachowitsch, 1992]
Expanded section of digestive tract between esophagus and midgut. If fully developed, divided into anterior cardiac and posterior py-loric sections. Digestive diverticula open into digestive tract at border of stomach and midgut. [Stachowitsch, 1992]
Cardiac stomach, pyloric stomach. [Stachowitsch, 1992]
Posterior expanded section of foregut (esophagus, stomach). Characterized by various internal folds, channels, and ridges and may be differentiated into cardiac and pyloric regions. Opens into midgut and may give rise to series of ceca at stomach/midgut border. [Stachowitsch, 1992]
Expanded section of digestive tract between esophagus and midgut. Divided into larger anterior cardiac stomach and smaller posterior pyloric stomach. Characterized internally by numerous ridges and armed with spine- or tooth-like projections. Unpaired dorsal cecum and series of lateral ceca open into digestive tract at junction of stomach and midgut. [Stachowitsch, 1992]
Expanded anterior section of digestive tract. Directly follows mouth and occupies most of head (cephalon). Consists of larger anterior cardiac stomach and smaller posterior pyloric stomach; opens posteriorly into midgut. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Enlarged section of digestive tract between esophagus and midgut. If fully developed, consists of anterior cardiac region with grinding apparatus and posterior pyloric region with setose internal lobes. Forms foregut together with esophagus. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Enlarged anterior region of midgut. [Stachowitsch, 1992]
Expanded anterior section of midgut (stomach, intestine). May bear single pair of large ceca or numerous smaller ceca. [Stachowitsch, 1992]
Expanded anterior section of midgut. May bear median anterior outpocketing (cecum) and lateral diverticula. [Stachowitsch, 1992]
In anaspidacean, expanded section of digestive tract between esophagus and midgut. Contains ridges internally and is divided into anterior cardiac stomach and posterior pyloric stomach. [Stachowitsch, 1992]
Expanded anterior section of digestive tract between esophagus and midgut. May be divided into anterior cardiac and posterior pyloric sections. Digestive ceca open into digestive tract at border of stomach and midgut. [Stachowitsch, 1992]
Cardiac stomach, pyloric stomach. [Stachowitsch, 1992]

Stomatopod integumental ornamentation

Armature and ornamentation of carapace, thoracic somites, abdomen, and telson; name types include:
Carinae:
(a) intermediate. Between sudmedian and lateral carinae on each side of carapace.
(b) lateral. Between intermediate and marginal carinae on each side of carapace and abdomen; extending posteriorly from near anterolateral angle nearly to margin on carapace.
(c) marginal. Carinae of lateral margins on abdomen; extending along each lateral margin of carapace, often curving upward posteriorly to loop around lateral carinae.
(d) median. Middorsal carina, sometimes bifurcate anteriorly on either side of cervical groove.
(e) submedian. Slightly lateral of midline and medin carina in abdominal region, not present on carapace.
Denticles:
(a) intermediate. Row of small projections between intermediate and submedian teeth on lateroterminal margin of telson.
(b) lateral. small projection(s) at medial base of each lateral tooth on telson.
(c) submedian. Small projection(s) just lateral of midline on terminal margin of telson (medial to submedian teeth).
Grooves:
(a) cervical. Distinct transverse depression or groove in posterior half of carapace.
(b) gastric. Longitudinal pair of grooves, extending from base of rostrum to posterior margin of carapace.
Teeth:
(a) intermediate. Strong spinelike or blunt projection at distolateral angle of telson, between submedian and lateral teeth.
(b) lateral. Strong spinelike or blunt projection on lateral margin of telson distally, between intermediate tooth and prelateral lobe.
(c) submedian. Strong spinelike or blunt projection just lateral of midline on terminal margin of telson. [McLaughlin, 1980]

Stomodaeum

See: Stomodeum [Martin, 2005]
See stomodeum. [McLaughlin, 1980]

Stomodeum

Anterior part of alimentary tract, ectodermal in origin and line with cuticle; cast with molt.
(syn. foregut) [McLaughlin, 1980]
Anterior part of alimentary tract, ectodermal in origin and lined with cuticle continuous with mouth; includes esophagus and dilated part corresponding to stomach, and may contain so-called gastric mill of varying complexity for trituration of food.
(syn. foregut, stomodeum) [Moore and McCormick, 1969]
Foregut.
(syn. stomodaeum) [Stachowitsch, 1992]
Anterior cuticle-lined region of digestive tract. Relatively long, extending through cephalon. Anterior section or entire region may be termed esophagus. (See also proctodeum). [Stachowitsch, 1992]

Stretcher muscle

The muscle which bends the leg backwards at the CP joint (stretches the cheliped). [Warner, 1977]

Stria

Type of valve sculpture: very fine groove. [Stachowitsch, 1992]

Striate

A surface bearing fine carinae placed parallel to each other. [Ingle, 1980]

Stridulating organ

Sound-producing organ formed by interacting areas of regularly ridged or beaded integument (e.g. paired chelipeds in Strigopagurus or cheliped and carapace in ocypodids). [Poore, 2004]
Structure in which two parts of exoskeleton are rubbed together in order to produce sound, one part consisting of ridge or tuberculate or cross-ridged surface which is apposed to another part usually having single transverse ridge or tubercle. [Moore and McCormick, 1969]
Structure producing sound by 2 parts of exoskeleton being rubbed together; surface with ridge or tubercles or cross-ridges surface and opposing surface with single transverse ridge or tubercle. [McLaughlin, 1980]

Stygobiont

An organism that lives in an aquatic subterranean ecosystem. [Brusca and Brusca, 2002]
Cave organism. [Kensley and Schotte, 1989]

Stylamblys

See: Appendix interna [Martin, 2005]
See appendix interna. [McLaughlin, 1980]
Specialised second endopodal article of pleopod 2 of female Palinura. [Poore, 2004]
Appendix interna. [Stachowitsch, 1992]

Style

See: Telson [Martin, 2005]
See telson. [McLaughlin, 1980]

Stylet

See: Caudal ramus [Martin, 2005]
Hollow cuticular structure of the kentrogon larva used for injecting a motile, multicellular, vermiform larval stage (called the vermigon or vermiform instar) into the host. [Brusca and Brusca, 2002]
See caudal ramus. [McLaughlin, 1980]
(Taxon-specific: Order Rhabditida) In Rhizocephalan, hollow tube used by kentrogon to pierce and enter host. [Stachowitsch, 1992]

Styliform

A dactylar segment terminating to a narrow pointed apex. [Ingle, 1980]
In the shape of a spear or needle. [Butler, T. H.]
Having a long, slender, stilettolike shape. [Kensley and Schotte, 1989]

Stylocerite

A spine arising from the lateral margin of the first segment of the antennular peduncle in shrimps. [Chace and Hobbs, 1969]
Pointed scale arising from the lateral base of the first segment of the antennular peduncle (Fig. 3B). [Perez Farfante and Kensley, 1997]
Rounded or spiniform process on outer part of proximal segment of antennular peduncle in some decapods (e.g., natantian decapods).
(syn. antennular scale) [Moore and McCormick, 1969]
Rounded or spiniform process on outer part of proximal segment of antennular peduncle.
(syn. antennular scale) [McLaughlin, 1980]
Scale arising from lateral base of first article of antennular peduncle. [Poore, 2004]
Spine arising from lateral margin of first segment of antennular peduncle. [Butler, T. H.]
Spine or rounded lobe on lateral aspect of basal article of antennule. [Williams, 1984]
In antennule of shrimp-like (natantian) decapod, process projecting from outer (lateral) part of first segment of peduncle. Extending over and considered to protect statocyst. (scale-like, spiniform; tip: lanceolate, pointed, rounded, truncate; margins: convex, fringed with hairs, linear, sinuous, straight).
(syn. antennular scale, antennular spine) [Stachowitsch, 1992]

Sub-

A prefix indicating "almost" or "just less than," e.g., submarginal—almost on the margin. [Kensley and Schotte, 1989]

Subapical spine

One of two movable spines at end of telson.
(syn. caudal furca) [Stachowitsch, 1992]

Subbranchial region

Ventrally placed part of brachyuran carapace corresponding in position to branchial region of dorsal part of carapace. [Moore and McCormick, 1969]

Subcarina

In cirripeds (e.g., scalpellids), small unpaired plate below carina. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate: in stalked form, relatively small, unpaired plate below carina. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Unpaired plate below carina. [McLaughlin, 1980]

Subcentral tubercle

Node.
(syn. submedian tubercle) [Stachowitsch, 1992]

Subchela

Claw where the dactyl and propodus of an appendage articulate at right angles to the long axis of the limb. Used incorrectly in euphausiids to describe grouping of setae that, with some imagination, form a claw. [Mauchline, 1984]
Distal end of appendage developed as prehensile structure by folding back of dactyl against propodus or some broadened part of it; also may result from propodus folded back against carpus; e.g., gnathopod. [McLaughlin, 1980]
Distal extremity of limb developed as prehensile structure by folding back of dactylus against propodus or broadened part of it (e.g., Stomatopoda); may compromise propodus folded back against carpus.
(syn. gnathopod) [Moore and McCormick, 1969]
Prehensile structure in family Crangonidae, where terminal segment (dactylus) folds back against the more robust penultimate segment (propodus). [Butler, T. H.]
Pincer-like structure at end of cheliped (first pereopod). Formed by terminal segment (dactylus) bearing down on next to last segment (propodus). [Stachowitsch, 1992]
Pincer-like structure formed by terminal segment of appendage (dactylus) bearing down on next to last segment (propodus).
See: Chela [Stachowitsch, 1992]
Pincer-like structure of first two pereopod pairs (gnathopods). Formed by terminal segment (dactylus) bearing down on posterior margin (palm) of enlarged next to last segment (propodus); occasionally also formed by dactylus and propodus bearing down on carpus. [Stachowitsch, 1992]
In modified anterior pereopod(s), pincer-like structure formed by dactylus bearing down on propodus or propodus down on carpus. [Stachowitsch, 1992]
Typically relatively small, pincer-like structure of thoracopod. Formed by terminal segment (dactylus) bearing down on propodus. Certain bottom-dwelling mysidaceans have powerful subchela on third thoracic endopod. [Stachowitsch, 1992]
On thoracic appendages (thoracopods) 1-5, pincer-lie structure formed by dactyl folded back and bearing down on propodus. Subchela of second thoracopod particularly well developed as a raptorial claw.
(syn. subcheliped, subchelipede) [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The terminal, movable part of an appendage, which adducts to oppose the surface of the subterminal segment. [Boxshall and Halsey, 2004]

Subchelate

An appendage in which the dactylus is shorter and less robust than the propodus or vice versa. [Ingle, 1980]
Claw-like, formed of transverse end of propodus and opposing dactylus (cf. chelate). [Poore, 2004]
Having the ability to grasp by folding together two adjacent podomeres of a limb. [Hobbs and Jass, 1988]
Provided with subchela. [McLaughlin, 1980]
Provided with subchelae. [Moore and McCormick, 1969]
The state of a limb in which the dactylus can be closed so as to bite against the propodus. Unlike the case in a true chela, a fixed finger is not developed and the dactylus bites either against an enlarged edge of the propodus or against projecting spines (Fig. 23B, C). [Warner, 1977]
Having a subchela, foming a pincerlike structure, especially by the dactylus folding back on the propodus. [Kensley and Schotte, 1989]
Having a subchela; forming a pincerlike structure by the dactylus folding back on the propodus. [Wetzer et al. 1997]

Subchirocerate

(Taxon-specific: Family Cyatholaimidae) Used of male antennules with moderately swollen middle segments and with only two segments distal to geniculation. [Boxshall and Halsey, 2004]

Subenteric ganglion

See subesophageal ganglion. [Brusca and Brusca, 2002]

Subesophageal ganglion

Anterior ganglion of the ventral nerve cord, located beneath (posterior to) the esophagus and connected dorsally to the tritocerebrum.
(syn. subenteric ganglion) [Brusca and Brusca, 2002]
Nerve plexus below esophagus in head of malacostracans. [Moore and McCormick, 1969]
Nerve plexus below esophagus. [McLaughlin, 1980]
Brain. [Stachowitsch, 1992]
Concentration of nerve tissue below (posterior to) esophagus. Connected to brain by connectives surrounding esophagus. (See also ventral nerve cord). [Stachowitsch, 1992]
Main concentration of nerve tissue above (anterior to) esophagus. Connected to subesophageal mass by esophageal connectives. [Stachowitsch, 1992]
Concentration of nerve tissue below (posterior to) esophagus. Consists of fused ganglia of somites bearing mouthparts (mandibles to third maxillipeds) and is connected to supraesophageal ganglion by pair of circumesophageal connectives. Continues posteriorly as ventral nerve cord.
See: Postesophageal ganglion [Stachowitsch, 1992]
Concentration of nerve tissue below (posterior to) esophagus. Consists of fused ganglia of mouthparts (mandibles, maxillules, maxillae, maxillipeds) and is connected to brain (supraesophageal ganglion) by pair of esophageal connectives. Continues posteriorly as ventral nerve cord. [Stachowitsch, 1992]
Concentration of nerve tissue below (posterior to) foregut. Consists of fused ganglia of mouthparts (mandibles, maxillules, maxillae, maxillipeds). Continues posteriorly as ventral nerve cord. [Stachowitsch, 1992]
In certain mysidaceans, concentration of nerve tissue below (posterior to) esophagus. Joined to supraesophageal ganglion by pair of esophageal connectives and continues posteriorly as ventral nerve cord. [Stachowitsch, 1992]
Postoral ganglion. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Concentration of nerve tissue below (posterior to) esophagus. Connected to supraesophageal ganglion by pair of circumesophageal connectives and adjoined posteriorly by partially fused thoracic ganglia. Innervates mandibles, maxillules, and maxillae. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Concentration of nerve tissue below (posterior to) esophagus. Joined to supraesophageal ganglion by pair of esophageal connectives. Continuous posteriorly with ventral nerve cord or fused with ganglia of ventral nerve cord to form ventral nerve mass. [Stachowitsch, 1992]
Concentration of nerve tissue posterior to esophagus. Fused to more or less concentrated ventral nerve cord to form posterior part of circumesophageal nerve ring. [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]

Subesophageal mass

Concentration of nerve tissue below (posterior to) esophagus. Connected to supraesophageal ganglion by pair of esopha-geal connectives. Consists of ganglia of mandibles, maxillules, maxillae, maxillipeds, and chelipeds. Continues posteriorly as ventral nerve cord. [Stachowitsch, 1992]

Subfrontal plate

Broad, flattened, underturned anterior part of carapace; adjoins basal part of labrum on underside of head and partially covers antennules and antennae. [Stachowitsch, 1992]

Subhepatic carina

See: Carapace carina k [Martin, 2005]
See: Carapace carinae k [McLaughlin, 1980]
On each side of carapace, narrow, longitudinal ridge extending posteriorly from branchiostegal spine. [Stachowitsch, 1992]

Subhepatic region

See: Carapace region l [Martin, 2005]
Area below hepatic region and anterolateral border of carapace. [Williams, 1984]
The region on the ventral surface of the carapace bounded by the antero-lateral margin, outer margin of the pterygostomial region and lower margin of the orbit. [Ingle, 1983]
See: Carapace regions l [McLaughlin, 1980]
On ventral side of carapace, region below each hepatic region. Adjoining regions include pterygostomial and suborbital regions. [Stachowitsch, 1992]

Subhepatic sulcus

Groove located well ventral to the hepatic region of the carapace and the hepatic spine. [Perez Farfante and Kensley, 1997]

Subitaneous

(Taxon-specific: Family Cyatholaimidae) Used of eggs that hatch immediately, without a period of dormancy. [Boxshall and Halsey, 2004]

Sublateral sulcus

Groove located ventral to lateral carina of carapace. [Perez Farfante and Kensley, 1997]

Submarginal carina

An almost longitudinal ridge extending between rigid, and membranous part of the branchiostegite. [Perez Farfante and Kensley, 1997]

Submedian carina

See: Carapace carina l [Martin, 2005]
See: Carapace carinae l, Stomatopod integumental ornamentation [McLaughlin, 1980]
On carapace, narrow, longitudinal ridge extending along each side of median postrostral carina; may join rostral carina. [Stachowitsch, 1992]

Submedian denticle

See: Stomatopod integumental ornamentation [McLaughlin, 1980]

Submedian groove

See: Carapace groove j [Martin, 2005]
See: Carapace grooves p [McLaughlin, 1980]
On each side of carapace, submedian longitudinal groove to each side of postrostral carina. [Stachowitsch, 1992]

Submedian lobes

Lobes on the anterior margin of the frontal region on either side of the median lobe. [Ingle, 1983]

Submedian spine

Lateral spine between median and hepatic spines on carapace. [Butler, T. H.]

Submedian tooth

See: Stomatopod integumental ornamentation [McLaughlin, 1980]
Tooth. [Stachowitsch, 1992]

Subneural artery

Artery.
(syn. posterior subneural artery, inferior abdominal artery, ventral abdominal artery) [Stachowitsch, 1992]

Suborbital region

Narrow area bordering lower margin or orbit; may be ill-defined or indistinguishable. [Moore and McCormick, 1969]
On anteroventral surface of carapace, region below each orbit.
(syn. posterior subneural artery, inferior abdominal artery, ventral abdominal artery) [Stachowitsch, 1992]
Narrow region bordering lower margin of orbit, sometimes defined, sometimes indistinguishable.
See: Carapace regions m [McLaughlin, 1980]

Suborbital spine

See: Carapace spine h [Martin, 2005]
Spine on anterior margin or carapace. [Butler, T. H.]
Spine on lower rim of orbit (Fig. 2). [Williams, 1984]
See: Carapace spines h [McLaughlin, 1980]
Anteriorly directed, spine-like projection on orbital region on each side of carapace; located at anterior edge, on lower rim of orbit, between supraorbital and antennal spines. [Stachowitsch, 1992]

Subrostral sulcus

A longitudinal elongate groove extending along dorsal limit of the orbital region. [Perez Farfante and Kensley, 1997]

Subrostrum

In cirripeds (e.g., scalpellids), small unpaired plate below rostrum. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle shell plate: in stalked form, relatively small, unpaired plate below rostrum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Unpaired plate below rostrum. [McLaughlin, 1980]

Suction disc

(Taxon-specific: Order Monhysterida) Modification of each maxillule in prominent, stalked, disc-shaped sucker; margins of sucker supported by series of ribs.
(syn. sucking disc, suction cup) [Stachowitsch, 1992]

Suctorial structures

Mouth parts of ectoparasites modified for piercing body wall of host and for sucking out body fluids. [Moore and McCormick, 1969]
Mouthparts of ectoparasites modified for piercing bodywall of host and for sucking out body fluids. [McLaughlin, 1980]

Sulcus

Groove or furrow. [McLaughlin, 1980]
Groove.
(pl. sulci) [Perez Farfante and Kensley, 1997]
Groove. [Stachowitsch, 1992]
Type of valve sculpture: relatively prominent groove, typically running dorsoventrally. May be termed S1, S2, and S3, and be separated by lobes. (deep, shallow; bisulcate, trisulcate, unisulcate; anterior, median, posterior, postocular). [Stachowitsch, 1992]

Superior abdominal aorta

Dorsal aorta. [Stachowitsch, 1992]

Support ridge, posterior mandibular

A cuticular ridge on the body of the mandible that is a continuation of the dorsal condyle, but does not articulate with the fossa in the clypeus. [Wilson, 1989]

Supra-anal plate

Portion of notostracan telson, usually tongue-shaped but may be spatulate to round; produced backward on dorsal side as a plate. [Moore and McCormick, 1969]
posteriorly directed median extension of telson. (simple, bilobed; with/without median keel; median spines place on/not place on keel). [Stachowitsch, 1992]
Tongue-shaped, spatulate, or rounded plate produced posteriorly on dorsal side of telson. [McLaughlin, 1980]
Unpaired median projection extending from posterodorsal end of last segment (telson). Posterior end characterized by large seta (major seta) and, ventral to it, variously shaped process with minute spines. Flanked on each side by spinous process.
(syn. supra-anal process) [Stachowitsch, 1992]

Supra-esophageal ganglion

Nerve plexus above esophagus in head of malacostracans. [Moore and McCormick, 1969]
Nerve plexus above esophagus, equivalent to brain. [McLaughlin, 1980]
(Taxon-specific: ) Main part of brain above (in front of) esophagus. Consists of protocerebrum (preantennular ganglion) and deutocerebrum (antennular ganglion). [Stachowitsch, 1992]
Main part of brain above (in front of) esophagus. Consists of protocerebrum (preantennular ganglion) and deuterocerebrum (anetennular ganglion). (See also tritocerebrum). [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Main part of brain above (in front of) esophagus. Consists of protocerebrum (preantennular ganglion) and deuterocerebrum (antennular ganglion); joined to tritocerebrum by connectives. [Stachowitsch, 1992]
Main concentration of nerve tissue above (anterior to) esophagus. Continues posterior to esophagus as ventral nerve cord. [Stachowitsch, 1992]
Main concentration of nerve tissue lying above esophagus
at anterior end of cephalothorax; consists basically of protocerebrum, deutocerebrum, and tritocerebrum. Gives rise to numerous nerves extending to anterior appendages and is connected to subesophageal ganglion and ventral nerve cord by pair of circumesophageal connectives.
(syn. brain) [Stachowitsch, 1992]
Main concentration of nerve tissue above (anterior to) esophagus. Connected to ventral nerve cord (in certain mysidaceans to subesophageal ganglion) via pair of esophageal connectives. [Stachowitsch, 1992]
Major concentration of nerve tissue in anterior region of head (cephalon); joined to ventral ganglia (postoral ganglia) and ventral nerve cord by pair of long circumoral connectives. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Main concentration of nerve tissue in head (cephalon). Connected to ventral nerve cord by pair of esophageal connectives. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Anterior concentration of nerve tissue. Joined to subesophageal ganglion by pair of esophageal connectives.
(syn. brain, cerebral ganglion) [Stachowitsch, 1992]
In anaspidacean, main concentration of nerve tissue above (anterior to) esophagus. Connected to ventral nerve cord via pair of esophageal connectives.
(syn. brain) [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]

Supra-ocular spines

Spines present on or just above the ocular eaves. [Ingle, 1992]

Supraclypeal

Above the clypeus. [Wilson, 1989]

Supraesophageal ganglion

Concentration of nerve tissue above (anterior to) esophagus in head. Connected to subesophageal ganglion by pair of esophageal connectives.
(syn. brain) [Stachowitsch, 1992]
Concentration of nerve tissue above (anterior to) foregut. Connected to subesophageal ganglion by pair of esophageal connectives.
(syn. brain) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Concentration of nerve tissue anterior (dorsal) to esophagus. A proto-, deutro- and tritocerebrum may be distinguished. Connected to subesophageal ganglion by pair of circumesophageal connectives. Innervates antennules and eyes. [Stachowitsch, 1992]
Concentration of nerve tissue anterior (dorsal) to esophagus. Connected to ventral nerve cord by pair of circumesophageal connectives.
(syn. brain) [Stachowitsch, 1992]
Concentration of nerve tissue anterior to esophagus and innervating, among others, compound eyes. Fused with circumesophageal connective to form circumesophageal nerve ring.
(syn. brain) [Stachowitsch, 1992]
Concentration of nerve tissue in anterior region of cephalothorax; located above (anterior to) esophagus and somewhat anteroventral to stomach. Joined to chain of postoral ganglia by pair of esophageal connectives.
(syn. brain) [Stachowitsch, 1992]

Suprahepatic spine

Spine arising from the edge of the cervical carina dorsal to the hepatic spine (Fig. 2A). [Perez Farfante and Kensley, 1997]

Supralabrum

(Taxon-specific: Family Cyatholaimidae) A median lobe located on the ventral cephalic surface anterior to labrum, often ornamented with setule rows. [Boxshall and Halsey, 2004]

Supraneural artery

Artery. [Stachowitsch, 1992]

Supraorbital carina

See: Carapace carina m [Martin, 2005]
See: Carapace carinae m [McLaughlin, 1980]
Gastroorbital carina. [Stachowitsch, 1992]

Supraorbital eave

The projecting lateral part of the orbital region above the eyestalk (Majidae). [Ingle, 1983]

Supraorbital spine

See: Carapace spine i [Martin, 2005]
A spine on the carapace situated posterodorsal to the orbit. [Hobbs, Hobbs, and Daniel 1977]
Spine above and behind orbit (Fig. 2). [Williams, 1984]
Spine located posterior to the orbital margin of the carapace. [Perez Farfante and Kensley, 1997]
Spine on carapace of shrimps, situated posterodorsal to orbit. [Hobbs and Jass, 1988]
Anteriorly directed, spine-like projection on orbital region on each side of carapace; located at anterior edge, above and behind orbit. [Stachowitsch, 1992]

Sutural edge

In cirripeds, margin of compartment plate along suture. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Margin of compartmental plate along suture. [McLaughlin, 1980]

Suture

Either transverse or longitudinal, weakly sclerotized line or seam on the carapace. [Perez Farfante and Kensley, 1997]
In cirripeds (Balanomorpha, Verrucomorpha), line or seam at juncture of two compartment plates; also articulation line between joints. [Moore and McCormick, 1969]
The junction between two closely apposed margins. [Ingle, 1980]
Weakly calcified areas of integument separating at ecdysis. [McLaughlin, 1980]
Weakly calcified lines along which exoskeleton splits during molting (e.g., pleural suture). [Stachowitsch, 1992]
A line indicating an area of articulation, or of incomplete fusion. [Kensley and Schotte, 1989]

Swimmeret

See: Pleopod [Martin, 2005]
see Pleopod [Butler, T. H.]
See pleopod. [McLaughlin, 1980]
Pleopod. [Stachowitsch, 1992]

Swimming leg

Term referring either to pereopod modified (flattened) for swimming or to pleopods used in swimming. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A contralateral pair of thoracic limbs which are flattened anterioposteriorly and united by an interpodal bar; these attributes are shared only in the transformed limb and later steps of limb development (see also appendage and limb). [Ferrari and Dahms, in press]

Symbiosis

Living together of two or more dissimilar organisms.
(syn. symbiotic) [Ingle, 1983]
(Taxon-specific: Family Cyatholaimidae) Living in association with another organism.
(syn. Symbiotic)
See: Symbiosis [Boxshall and Halsey, 2004]

Sympod

(syn. sympodite)
See: Protopod [Martin, 2005]
An appendage segment made of the fused basis and coxa.
(syn. protopod, protopodite) [Wilson, 1989]
See protopod. [McLaughlin, 1980]
Proximal part of an appendage, often formed by the fusion of the coxa and basis. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) A compound segment formed by fusion or failure to separate of coxa and basis. [Boxshall and Halsey, 2004]

Syncerebrum

See: Supra-esophageal ganglion [Moore and McCormick, 1969]

Syncoxa

(Taxon-specific: Family Cyatholaimidae) A segment complex of the praecoxa and the coxa of a protopod. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) A segment formed by the fusion or failure to separate of praecoxa and coxa. [Boxshall and Halsey, 2004]

TC

The junction between the thorax and the coxa (Fig. 12). [Warner, 1977]

Tagma

Major division of body (e.g., head, thorax, abdomen), each composed of varying number of somites.
(pl. tagmata) [McLaughlin, 1980]
Major division of body (e.g., head, thorax, abdomen). each composed of varying number of somites. [Moore and McCormick, 1969]
(Taxon-specific: ) Major division of body. Typically a head and trunk are distinguished, although the body may be considered to consists of head, thorax, abdomen, and postabdomen. Fully developed carapace covers only trunk. [Stachowitsch, 1992]
Major division of body (head, thorax, abdomen). [Stachowitsch, 1992]
Major division of body (head, trunk). Both tagmata are covered by carapace. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Major division of body (head, thorax, abdomen). (See also trunk). [Stachowitsch, 1992]
Major division of body (cephalon, thorax, abdomen). (See also trunk). [Stachowitsch, 1992]
One of three major divisions of body (according to interpretation: head, thorax, pleon = abdomen; head, pereon, pleon; cephalothorax, pereon, pleon). [Stachowitsch, 1992]
Major division of body (cephalothorax, abdomen). [Stachowitsch, 1992]
One of three major divisions of body (cephalon = head, pereon, abdomen = pleon).
See: Cephalothorax [Stachowitsch, 1992]
One of three major divisions of body (cephalon, pereon, pleon).
See: Cephalothorax [Stachowitsch, 1992]
One of basically three major divisions of body (head, thorax, abdomen). (See also cephalothorax). [Stachowitsch, 1992]
Major division (cephalon, thorax, abdomen) of body. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Major division of body (cephalon, thorax, abdomen). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Major division of body. According to interpretation, one may distinguish either cephalothorax and abdomen or head (cephalon), pereon, and abdomen (pleon). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Major division of body (head, thorax; in ascothoracican, head, thorax, abdomen). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) A major region of the body defined by a common function. [Boxshall and Halsey, 2004]
Major division of body. According to interpretation, one may distinguish either head (cephalon), maxillipedal somite, and thoracoabdomen or head, thorax, and abdomen. [Stachowitsch, 1992]
Major division of body (cephalosome, metasome, and urosome, or prosome (cephalosome + metasome) and urosome). [Stachowitsch, 1992]
One of three major divisions of body (head, thorax, abdomen). [Stachowitsch, 1992]
One of three major division of body (cephalon, thorax, abdomen). [Stachowitsch, 1992]
One of two major divisions of body (cephalothorax, abdomen). [Stachowitsch, 1992]

Tagmosis

(Taxon-specific: Family Cyatholaimidae) The division of the body into functional regions. [Boxshall and Halsey, 2004]

Tailfan

See: Caudal fan [Martin, 2005]
As a unit, telson and two pairs of uropods. [Butler, T. H.]
Combination of broad, flat uropods lying alongside the telson. [Brusca and Brusca, 2002]
Combined telson and uropods in many malacostracans. [Brusca and Brusca, 2002]
See caudal fan. [McLaughlin, 1980]
Telson plus pair of uropods. [Poore, 2004]
Posterior fan-like structure formed by combination of uropods and telson. (asymmetrical, symmetrical).
(syn. caudal fan) [Stachowitsch, 1992]
Posterior fan-like structure formed by combination of uropods and telson. [Stachowitsch, 1992]
Posterior fan-like structure formed by combination of uropods and telson. [Stachowitsch, 1992]
In anaspidacean, posterior fan-like structure formed by combination of uropods and telson. [Stachowitsch, 1992]
Posterior fan-like structure formed by combination of uropods and telson.
(syn. caudal fan) [Stachowitsch, 1992]

Tarsus

Portion of thoracic endopod distal to knee. Conists of carpoprodus and dactylus. [Stachowitsch, 1992]

Taxonomist

A scientist concerned with the classification of animals or plants. [Bliss, 1982]

Tectum

Central part of carina in cirripeds (Lepadomorpha). [Moore and McCormick, 1969]

Tegmen

Elaboration of outer layer of valve which overlaps and obscures underlying ornamentation. [Stachowitsch, 1992]

Tegumental gland

One of numerous glands located within or below epidermis; opens to exterior via tegumental duct. [Stachowitsch, 1992]

Tegumental glands

Compound glands situated in pereonal cavity which secrete a silk-like substance used in construction of the animal's tube. [Holdich and Jones, 1983]

Telopod

Part of appendage distal to coxa (limited usage). [McLaughlin, 1980]
Part of limb distal to coxa. [Moore and McCormick, 1969]

Telson

Entire animal, right appendages omitted, dorsal view, based on Munida. [Baba, 2005]
(Figure only.) [Baba, 2005]
Last somite of body, bearing arms and commonly caudal furca or pair of cerci, growth zone for postcephalic somites located at its anterior edge.
(syn. postabdomen, style (Archaeostraca)) [Moore and McCormick, 1969]
Plate attached medially to terminal segment of abdomen. [Poore, 2004]
Postsegmental plate or lobe bearing anus. [Brusca and Brusca, 2002]
Terminal (posterior) portion of abdomen; caudomedian element of "tail fan" (see Figs. 13, 14). [Hobbs and Jass, 1988]
Terminal appendix attached to the sixth (terminal) abdominal segment and not considered as a true segment.
See: Abdomen [Ingle, 1983]
Terminal portion of body (not considered to be true somite), usually bearing anus, sometimes with caudal furca.
(syn. postsegmental region, style) [McLaughlin, 1980]
Terminal somite of abdomen. [Williams, 1984]
Terminal somite of the body which is always fused to pleonite 6 to form the pleotelson. [Holdich and Jones, 1983]
Terminal unit of the abdomen bearing the anus (Fig. 1, 3D). [Perez Farfante and Kensley, 1997]
The median tail of a crustacean. [Mauchline, 1984]
The terminal (posterior) unit of the abdomen. [Hobbs, Hobbs, and Daniel 1977]
The terminal part of the body which bears the anus; it articulates with the last (6th) abdominal segment. [Warner, 1977]
The terminal segment of a crustacean's body, bearing the anus. In most isopods, the telson is fused to the anterior pleonite. [Wilson, 1989]
The terminal segment of the abdomen. [Chace and Hobbs, 1969]
The terminal somite of abdomen; part of tail fan. [Butler, T. H.]
(Taxon-specific: ) Postabdomen. [Stachowitsch, 1992]
Last segment of body; bears anus and pair of elongate caudal rami. (with/without supra-anal plate). [Stachowitsch, 1992]
Last segment of body; directed ventrally and bears pair of terminal anal spines as well as pair of caudal rami. Bears anus and is therefore occasionally termed anal segment or anal somite (in which case terminal lobe is interpreted as representing telson). Number of dorsal spines and position of forked filament are of taxonomic importance. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Last segment of body; bears pair of caudal rami. Bears terminal anus and therefore occasionally termed anal somite. [Stachowitsch, 1992]
Last segment of body (20th postcephalic segment) with ventral comb and pair of caudal rami. Bears terminal anus and therefore occasionally termed anal segment or anal somite. [Stachowitsch, 1992]
Posteriormost segment of body. May be fused to last (sixth) abdominal somite (pleonite) to form pleotelson. May bear anus and thus be divided into preanal and postanal parts. (free, fused; elongate, short; pointed, semicircular, truncate; with/without apical spines). [Stachowitsch, 1992]
Posteriormost segment of body. May be fused to last (sixth) or to fifth and sixth abdominal somites (pleomeres) to form pleotelson. [Stachowitsch, 1992]
Posteriormost segment of body (although not considered to be a true somite). May form tailfan together with uropods and bears anus ventrally. (single element, several elements; rectangular, rounded, spiniform, styliform, subquadrangular, subrectangular, subtriangular, subtruncate, triangular; tip: acuminate, rounded, subacute, truncate; armed: laterally serrate, with carina, with median groove, with movable spines, with spines, with spinules). [Stachowitsch, 1992]
Posteriormost, relatively small segment of body. Shape is of taxonomic importance, (fleshy, laminar; entire, emarginate = bilobed = cleft; acute, rounded; naked, setose, spinose). [Stachowitsch, 1992]
Terminal part of the body, usually bearing the anus. [Kensley and Schotte, 1989]
Terminal segment of body, typically fused with one or more abdominal segments (pleonites) to form pleo-telson. (lanceolate, ovate, pointed, with sub-parallel margins; posterior margin: concave, convex). [Stachowitsch, 1992]
Terminal segment of body. Forms tailfan together with uropods and bears anus vantrally. [Stachowitsch, 1992]
Well-developed posterior most segment of body (although not considered to be a true somite); may be fused with sixth abdominal somite (pleomere) to form pleotelson. Dorsal surface typically sculptured with various carinae, margins bearing prelateral lobes and numerous teeth and denticles. (armed, smooth). [Stachowitsch, 1992]
Last segment of body with telsonic combs ventrally, supra-anal plate posterodorsally, and caudal furca. Bears anus ventrally and therefore occasionally termed anal somite. [Stachowitsch, 1992]
Anal somite. [Stachowitsch, 1992]
Anal segment. [Stachowitsch, 1992]
Terminal segment of body. Forms tailfan together with uropods an anaspidacean, bears rudimentary caudal furca in stygocaridacean, and is fused with last (sixth) abdominal somite to form pleotelson in bathynellacean. [Stachowitsch, 1992]
Posteriormost segment of body. May be fused to last (sixth) abdominal somite (pleomere) to form pleotelson. [Stachowitsch, 1992]
Narrow and pointed posteriormost segment of body. Forms tailfan together with appendages (uropods) of sixth (last) abdominal somite. Typically bears pair of posterior subapical spines. [Stachowitsch, 1992]

Telson head

Enlarged part of telson in Archaeostraca, with which furcal rami articulate. [Moore and McCormick, 1969]

Telsonic comb

One of two pairs of comb-like cuticular strcutures on ventral surface of last segment (telson). Anterior and posterior pairs differ in configuration and tooth number. (stalked, not stalked).
(syn. comb, ventral comb) [Stachowitsch, 1992]

Tendon

Pair of dorsal and ventral supporting elements forming endoskeletal structures within body. Serves as site of muscle attachment. [Stachowitsch, 1992]

Tergal depressor insertion

Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Tergal fold

See: Epimere [Martin, 2005]
See epimere. [McLaughlin, 1980]
Pleurite. [Stachowitsch, 1992]

Tergal margin

(Taxon-specific: Order Rhabditida) Barnacle plate feature: edge of scutum of edge of any other plate directly adjoining tergum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Edge of scutum adjacent to tergum, or edge of any plate bordering tergum. [McLaughlin, 1980]

Tergal spur

Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]

Tergite

Dorsal plate of integument (cf. sternite). [Poore, 2004]
Dorsal plate of segment. [Williams, 1984]
Sclerotized dorsal surface of single body somite. [Moore and McCormick, 1969]
Sclerotized dorsal surface of single body somite. [McLaughlin, 1980]
The dorsal surface of a body segment. [Wilson, 1989]
Dorsal surface of body segment. Tergite of first five somites are fused to form cephalic shield. (see also sternite). [Stachowitsch, 1992]
Dorsal surface of body segment (somite). (See also sternite). [Stachowitsch, 1992]
Dorsal surface of body segment (somite).
See: Sternite [Stachowitsch, 1992]
Dorsal surface of body segment (somite). Tergites of thoracic somites (thoracomeres) typically replaced by carapace.
See: Pleurite, Sternite [Stachowitsch, 1992]
Dorsal sclerite of exoskeleton on arthropods. [Wetzer et al. 1997]
Dorsal surface of body segment (somite); often expanded laterally.
(syn. tergal plate) [Stachowitsch, 1992]
Dorsal surface of body segment (somite). May extend ventrolaterally to form pleura in abdominal somites (pleomeres). (See also sternite). [Stachowitsch, 1992]
Dorsal surface of body segment (somite). (See also sternite). [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Doral surface of body segment (somite). More clearly delimited only in last three thoracic somites (pereon). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The dorsal chitinous plate of a body somite. [Boxshall and Halsey, 2004]
Dorsal surface of body segment (somite). More clearly delimited only in free thoracic somites and abdominal somites. [Stachowitsch, 1992]
Dorsal surface of body segment. Tergites of first and last trunk segments are reduced and/or partially fused to head (cephalon) and anal segment; Typically produced laterally into pleurites. (posterolateral corner: rounded pointed). [Stachowitsch, 1992]
Dorsal surface of body segment (somite). (See also sternite). [Stachowitsch, 1992]
Dorsal surface of body segment (somite). Carapace fused to cephalon and to tergite of first thoracic segment (thoracomere). [Stachowitsch, 1992]
Dorsal surface of body segment (somite). Tergite of first abdominal somite (pleomere) has clearly delimited anterior section which may give the impression of a separate body segment.
See: Pleurite, Sternite [Stachowitsch, 1992]

Tergolateral margin

Angular inner edge of scutum in cirriped shells having upper laterals. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in stalked form bearing upper latera, angular edge of scutum adjoining tergum and upper latus. [Stachowitsch, 1992]

Tergum

Arched dorsal part of abdominal somites. [Poore, 2004]
Arched dorsal part of each of the anterior five abdominal somites (Fig. 1).
(pl. terga) [Perez Farfante and Kensley, 1997]
Dorsal part of exoskeleton comprising tergites of all body somites taken together; also valve of cirriped shell adjacent to carina and generally opercular. [Moore and McCormick, 1969]
Dorsal surface of the body. [Holdich and Jones, 1983]
Paired plate or valve of thoracic Cirripedia; in lepadomorphs, 1 on each side of occludent margin at apex of capitulum. In verrucomorphs, of two types: fixed tergum, 1 of 4 compartment plates, movable tergum, 1 of 2 opercular plates. In balanomorphs, 1 of 4 opercular plates.
(pl. terga) [McLaughlin, 1980]
The dorsal (and dorsolateral) portion of each of first five abdominal somites between pleura.
(pl. terga) [Butler, T. H.]
The dorsal portion of each of the first five abdominal somites between the pleura.
(pl. terga) [Chace and Hobbs, 1969]
Collective term for all tergites; occasionally used as synonym for tergite. [Stachowitsch, 1992]
Collective term for all tergites. (See also sternum). [Stachowitsch, 1992]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Lepas anatifera: rostral view; and left valve and cirri removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: apical view; left lateral view; and operculum, body, and branchiae. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
Balanus trigonus: wall plates, exploded; and interior of operculum. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) One of five primary plates (carina, two scuta, two terga) on outer surface of barnacle. Paired, one tergum located on each side of aperture. In unstalked barnacle, variously associated with scutum to form operculum. Features or regions of tergum include angles (basicarinal, basiscutal), apex, articular ridge, margins (basal, carinal, occludent, scutal), spur, and spur furrow. (fixed, movable). [Stachowitsch, 1992]

Terminal

At the end. [Butler, T. H.]

Terminal claw spines

Tooth-like projections of varying size at concave end of postabdomen in cladocerans, having taxonomic value; few large basal spines near base of claw, minute denticles along greater part of claw, and spines of intermediate foreign particles and parasites. [Moore and McCormick, 1969]
(Taxon-specific: ) Toothlike projections of varying size at concave end of postabdomen. [McLaughlin, 1980]

Terminal element

Hinge. [Stachowitsch, 1992]

Terminal pegs

Minute or microscopic projections of dactylus and propodus on first pereiopod, with limited function as chela, e.g. in Pandalus. [Butler, T. H.]

Testis

Male reproductive organ, producing sperm.
(pl. testes) [Butler, T. H.]
The organ which produces the male gametes or spermatozoa. [Ingle, 1983]
(Taxon-specific: ) Paired section of male reproductive system in which sperm are produced. Testes extend through anterior part of trunk, one to each side of midgut; opens to exterior via ventrally directed vas deferens. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Paired section of male reproductive system in which sperm are produced; extends from third or fourth abdominal somite anteriorly to first and second abdominal somites (= genital somites). Each testis opens to exterior via vas deferens and penis. [Stachowitsch, 1992]
One of two sausage-shaped sections of male reproductive system in which sperm are produced. Located dorsal to digestive tract and extends from 12th to 7th postcephalic segments; anterior ends joined. Each testis opens to exterior on sixth thoracomere via vas deferens and gonoduct (common male and female duct). [Stachowitsch, 1992]
Section of male reproductive system in which sperm are produced. Paired, tube-like, located on each side of pereon. Each testis opens to exterior on last (fifth) pereon segment via vas deferens. [Stachowitsch, 1992]
Paired, relatively short section of male reproductive system in which sperm are produced. Both testes open into common seminal vesicle. [Stachowitsch, 1992]
Typically paired, expanded section of male reproductive system in posterodorsal region of cephalothorax. Connected by bridge, each testis opening to exterior on basal segment (coxa) of last pereopod via vas deferens. (paired, fused; multilobed, tubular). [Stachowitsch, 1992]
Paired section of d reproductive system in which sperm are produced. Elongate, cylindrical, extending between heart and digestive tract from third to sixth pereon segments (pereonites); each testis opens to exterior on last (seventh) pereonite via vas deferens and penis. [Stachowitsch, 1992]
Paired section of d reproductive system in which sperm are produced. Located dorsolateral to digestive tract in pereon, each testis opening to exterior on last (seventh) pereon segment via vas deferens. [Stachowitsch, 1992]
Paired section of male reproductive system in which sperm are produced. Located in thorax and differentiated into series of spermatic sacs. Opens to exterior via seminal vesicles, vasa deferentia, ejaculatory ducts, and penes. [Stachowitsch, 1992]
Section of male reproductive system in which sperm are produced. Elongate, paired, extending from third abdominal somite (pleomere) to telson between heart and digestive glands. Fused posteriorly in telson and opening to exterior on eighth thoracic somite (thoracomere) via vasa deferentia and penes. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) In male reproductive system, pair of slender, tubular organs in which sperm are produced. Located between digestive tract and heart and extending through most of body; each tesis opens on coxa of eighth thoracopod via vas deferens. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Paired, expanded section of male reproductive system in abdomen. Each testis is connected to unpaired seminal vesicle in thorax by vas efferens. (elongate elliptical, elongate ovate, lunate). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Large, paired section of male reproductive system in which sperm are produced. Located in anterior region of body and opening to exterior via pair of vasa deferentia and unpaired penis. [Stachowitsch, 1992]
Unpaired section of male reproductive system in which sperm are produced; extends throughout posterior region of thoracoabdomen. Bears several pairs of dorsal diverticula and opens to exterior through anteriorly directed vas deferens. [Stachowitsch, 1992]
In free-living copepod typically unpaired, in parasitic copepod typically paired, expanded section of male reproductive system in which sperm are produced. Located dorsally, above midgut, near border of head and thorax. Opens to exterior on first abdominal segment (genital somite) via regionated vas deferens. (paired, unpaired). [Stachowitsch, 1992]
Section of male reproductive system in which sperm are produced. Located in posterior region of trunk or between body and valve and opening to exterior via vasa deferentia. (paired, unpaired; coiled, elongate, four-lobed = quadripartite, lobed, simple, spheroid, tube-shaped). [Stachowitsch, 1992]
Paired section of male reproductive system in which sperm are produced; located ventral and dorsal to midgut in posteriormost seventh to about tenth trunk segment. [Stachowitsch, 1992]
In anaspidacean, section of male reproductive system in which sperm are produced. Paired, extending from fifth thoracic somite to posterior end of abdomen. Each testis opens to exterior via vas deferens. Restricted to abdomen in bathynellacean. [Stachowitsch, 1992]
Section of male reproductive system in which sperm are produced. Paired, relatively short, located anteriorly in posterior cephalon/first thoracomere region. Each testis opens to exterior on last (eighth) thoracomere via elongate vas deferens. [Stachowitsch, 1992]
Section of male reproductive system in which sperm are produced; located between heart and digestive tract in thorax. Each testis (or each side of unpaired testis) opens to exterior on last (eighth) thoracomere via vas deferens. (single, paired). [Stachowitsch, 1992]

Thaumatopsylloid

(Taxon-specific: Family Cyatholaimidae) Copepods for which there is a significant difference in size between the fourth and the fifth thoracic somites of the adult (see also podoplean and gymnoplean). [Ferrari and Dahms, in press]

Thelycum

A specialized genital modification of the three posterior sternites in female penaeidean shrimps.
(pl. thelyca) [Chace and Hobbs, 1969]
External pocket on ventral side of thorax in panaeid female serving as seminal receptacle. [McLaughlin, 1980]
External pocket on ventral side of thorax in penaeid females which functions as seminal receptacle (receptaculum seminalis). [Moore and McCormick, 1969]
External seminal receptacle, variously developed, lying on sternum of thorax and formed by outgrowths from last and next to last thoracic somites. [Williams, 1984]
Female copulatory organs situated in the ventral region of the thorax. [Mauchline, 1984]
Female genitalia comprising modified posterior two or three sternal plates (Dendrobranchiata). [Poore, 2004]
On the ventral surface of the thorax of a female penaeid shrimp; receives the spermatophore from the male during mating. [Bliss, 1982]
Specialized genital structure of the three posterior sternites in female penaeidean shrimps.
(pl. thelyca) [Butler, T. H.]
The female genetalia consisting of modifications of the posterior two, or sometimes three thoracic sternites (XII-XIV) serving for the storage or transfer of the sperm, usually in spermatophores, and often shielding seminal receptacles (Fig. 4A).
(pl. thelca) [Perez Farfante and Kensley, 1997]
In female reproductive system of certain shrimp-like (natantian) decapods, pouch-like accessory copulatory structure formed by sternites of last and next to last thoracic somites. Serves as seminal receptacle and may be composed of several lobes or plates. [Stachowitsch, 1992]
In female reproductive system, pouch-like accessory copula-tory structure on underside of thorax; associated with female gonopores and formed by sternite and coxal plates of posterior thoracic somite. Receives spermatophore of male. [Stachowitsch, 1992]

Third maxillipeds

Outermost pair of mouth parts of a decapod crustacean; used, with the assistance of two other pairs of maxillipeds and two pairs of maxillae, for holding food until it can be pushed into the esophagus by the mandibles. [Bliss, 1982]

Thixotropic

A colloidal sediment that becomes liquid as a result of agitation or pressure. [Ingle, 1983]

Thoracic

Of postcephalic segments 1 through 8. [Wilson, 1989]

Thoracic appendage

Any appendage attached to somite of thorax. [McLaughlin, 1980]
(Taxon-specific: ) Trunk appendage. [Stachowitsch, 1992]

Thoracic ganglion

(Taxon-specific: Order Monhysterida) One in a series of four partially fused ganglia of thorax region. Innervates thoracic appendage (thoracopod). Adjoined anteriorly to subesophageal ganglion and posteriorly to abdominal ganglion to form six-lobe mass in anterior region of thorax. [Stachowitsch, 1992]

Thoracic legs

The five posterior pairs of thoracic appendages of a decapod crustacean; generally used for walking, although the first or second pair may be modified as large claws and the fifth pair as swimming paddles. [Bliss, 1982]

Thoracic limb

Any limb attached to somite of thorax.
(syn. thoracopod) [Moore and McCormick, 1969]

Thoracic ridge

Highly sclerotized rib-like transverse structure across posterior margin of sternite XIV. [Perez Farfante and Kensley, 1997]

Thoracoabdomen

According to interpretation dividing body into cephalon, maxillipedal somite, and thoracoabdomen, tagma including last nine somites as well as telson and caudal furca. First four thoracoabdominal somites bear appendages (thoracoabdominal appendages). [Stachowitsch, 1992]

Thoracomere

A segment of the thorax (regardless of whether any of these segments is fused to the head). [Brusca and Brusca, 2002]
Somite of thorax. [Moore and McCormick, 1969]
Somite of thorax. [McLaughlin, 1980]
Thoracic segments. [Brusca and Brusca, 2002]
Thoracic somite, the first two of which are incorporated into the head and bear the maxillipeds and chelipeds respectively. [Holdich and Jones, 1983]
(Taxon-specific: Family Pycnogonidae) One of typically 11 (in certain anostracans 17 or 19) somites of thorax; each bears pair of biramous appendages (thoracopods). [Stachowitsch, 1992]
One of eight segments (somites) of thorax, of which seven or eight bear biramous appaendages (thoracopods).
(syn. thoracic segment) [Stachowitsch, 1992]
One if basically eight segments (somites) between head (cephalon) and abdomen (pleon). First three thoracomeres are fused with cephalon, with remaining thoracomeres (forming pereon) therefore also termed pereonites.
(syn. thoracic somite) [Stachowitsch, 1992]
One of basically eight segments (somites) of thorax between head proper and abdomen (pleon). First thoraco-mere fused with head, with first and second being fused with and covered by carapace. Accordingly, last seven or six thoracomeres are termed pereonites. [Stachowitsch, 1992]
One of eight segments (somites) of thorax, the first three being incorporated into head; each bears pair of appendages (thoracopods).
(syn. thoracic somite) [Stachowitsch, 1992]
One of basically eight segments (somites) between head (cephalon) and abdomen (pleon). First (and occasionally second) thoracomere is fused with cephalon, and remaining thoracomeres (forming pereon) therefore also termed pereonites. [Stachowitsch, 1992]
One of basically eight segments (somites) between head (cephalon) and abdomen (pleon). First (and occasionally second) thoracomere is fused to cephalon, and remaining thoracomeres (forming pereon) therefore also termed pereonites. [Stachowitsch, 1992]
One of basically eight segments (somites) between head and abdomen. Each thoracomere bears pair of appendages (thoracopods). (entirely/not entirely covered by carapace). [Stachowitsch, 1992]
One of eight segments (somites) of thorax, the first four being covered by carapace; each bears pair of appendages (thoracopods).
(syn. thoracic segment) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One if eight segments (somites) of thorax, each bearing pair of appendages (thoracopods). All thoracomeres are covered by carapace.
(syn. thoracic somite) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of four segments (somites) of thorax, the first being partially fused to head; each bears pair of appendages (thoracopods).
(syn. thoracic somite) [Stachowitsch, 1992]
According to interpretation dividing body into cephalon, thorax, and abdomen, one of five segments (somites) of thorax, the first bearing maxillipeds and the remaining bearing thoracopods. [Stachowitsch, 1992]
One of basically six segments (somites) of thorax, the first being incorporated into head; each thoracomere typically bears one pair of appendages (thoracopods).
(syn. thoracic somite) [Stachowitsch, 1992]
One of basically eight segments (somites) between head and abdomen. In anaspidacean and stygocaridacean, first thoracomere (bearing maxillipeds) is fused with head. Each thoracomere bears pair of appendages (thoracopods), although in bathynellacean last pair may be absent. (anaspidacean: increasing/not increasing in length posteriorly). [Stachowitsch, 1992]
One of basically eight segments (somites) of thorax between cephalon proper and abdomen. First thoracomere (bearing maxillipeds) is fused with head; accordingly, last seven thoracomeres may be interpreted as being pereonites. [Stachowitsch, 1992]
One of eight segments (somites) of thorax, each bearing pair of appendages (thoracopods, the most posterior pairs occasionally reduced or vestigial). [Stachowitsch, 1992]

Thoracopod

(syn. thoracopodite) [Martin, 2005]
An appendage of the thorax. [Brusca and Brusca, 2002]
Appendage of any thoracic somite; see thoracic appendage, phyllopod, maxilliped, pereopod.
(syn. cormopod) [McLaughlin, 1980]
Limb attached to any thoracic somite.
(syn. thoracic limb. [Maxillipeds and pereiopods are thoracopods.]) [Moore and McCormick, 1969]
(Taxon-specific: ) Trunk appendage. [Stachowitsch, 1992]
One of two appendages of each thoracic segment (body ring). Consists of proximal protopod (with endites and epipod), endopod ( = sixth endite), and exopod (flabellum). (See also leg).
(syn. thoracic appendage) [Stachowitsch, 1992]
Trunk appendage. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) One of two appendages of each thoracic somite (thoracomere). Consists of proximal protopod (with endites, preepipod, and epipod), inner branch (endopod), and outer branch (exopod). Basically biramous, although occasionally referred to as multi- or polyramous due to large number of lobes; also termed phyllopod due to broad, flattened shape. [Stachowitsch, 1992]
One of two appendages of each thoracic somite (thoracomere). Consists of protopod with four to six endites and pseudepipod, five- to six-segmented endopod, and two-segmented exopod. More posterior thoracopods may be somewhat modified, those of last (eighth) thoracomere may be reduced or absent. Basically biramous, although occasionally referred to as tri-, multi-, or polyramous due to large pseudepipod and numerous endites. [Stachowitsch, 1992]
One of basically eight pairs of appendages of thorax. First three pair of thoracopods (those of thoracic somites fused to head) are developed as maxillipeds, with the remaining five pairs being termed pereopods. [Stachowitsch, 1992]
One of eight pairs of appendages of thorax. Firsi pair developed as maxillipeds, second pair as chelipeds (with either second through eighth or third through eighth pairs thus being termed pereopods). Basically consists of seven segments (coxa, basis, ischiurn, merus, carpus, propodus, dactylus). [Stachowitsch, 1992]
One of two appendages of each thoracic somite (thoracomere). First three pairs are modified as mouthparts (maxillipeds), the remaining five pairs serve in locomotion (pereopods).
(syn. thoracopodite) [Stachowitsch, 1992]
One of two appendages of each somite (thoracomere) of thorax. First pair developed as maxillipeds; second through eighth pairs may be termed pereopods, second and third differentiated as gnathopods. (chelate, subchelate; ambulatory, raptorial). [Stachowitsch, 1992]
One of two appendages of each somite (thoracomere) of thorax. First pair developed as max-illipeds; second through eighth pairs may be termed pereopods, second and third differentiated as gnathopods.
See: Pylopod [Stachowitsch, 1992]
One of two appendages of each somite (thoracomere) of thorax. First and second pairs typically developed as maxillipeds. Basically biramous, consisting of two-segmented base (coxa, basis) bearing inner branch (endopod) and flagellum-shaped outer branch (exopod). Those thoracopods not developed as maxillipeds occasionally termed pereopods. (with subchela = subchelate, with terminal claw; with/without exopod). [Stachowitsch, 1992]
One of two appendages of each thoracic somite (thoracomere). First five pairs are uniramous (one through four subchelate, the second with raptorial claw), the last three (stenopods) biramous and used for walking. The former are composed of seven segments: precoxa, coxa, basis, merus, carpus, propodus, dactyl (also interpreted as coxa, basis, ischium, merus, propodus, dactyl). The latter are composed of three-segmented protopod with one-segmented outer ramus (considered to be endopod) and two-segmented inner branch (considered to be exopod).
(syn. thoracic appendage) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) One of eight pairs of appendages of thorax, one pair per thoracic somite (thoracomere). Biramous, typically flattened and consisting of proximal section (protopod) with inner branch (endopod) and outer branch (exopod). (foliaceous, phyllopodous; with/without epipods; projecting/ not projecting beyond ventral margin of carapace).
(syn. thoracic appendage) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) One of two appendages of each thoracic segment (thoracomere). Biramous, consisting of three-segmented protopod bearing endopod and exopod. (See also flabellum, natatory lobe, peg). [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) One of up to six pairs of appendages of thorax. Typically refers to appendages of ascothoracican, those of other cirripeds being termed cirri. (uniramous, biramous) (See also maxilliped). [Stachowitsch, 1992]
According to intperpretation dividing body into cephalon, thorax, and abdomen, one of two appendages of each thoracic somite (thoracomere). Thus, first thoracopod represents maxilliped and the following four thoracopods are reduced to a single flap-like structure with two large terminal setae. [Stachowitsch, 1992]
One of two appendages of each thoracic somite (thoracomere). First (occasionally second) pair modified as mouthparts (maxillipeds), the remaininf typically serving in locomotion (pereopods). Maxillipeds uniramous, the remaining biramous and consisting of basal protopod with distal inner branch (endopod) and outer branch (exopod). (See also leg).
(syn. thoracic appendage) [Stachowitsch, 1992]
Sixth and seventh paired appendages of body; represents one of two pairs of limbs originating from (not clearly delimited) thoracic region. Basically consists of protopod, endopod, and exopod, although the latter may be modified as branchial plate or be reduced. (biramous, uniramous; lamelliform, multiarticulate, pediform, vermiform; locomotory, nonlocomotory) (See also brush-shaped organ).
(syn. thoracic appendage, trunk appendage) [Stachowitsch, 1992]
One of two appendages of each somite (thoracomere) of thorax. In anaspidacean and stygocaridacean, first pair is developed as maxillipeds. Basically biramous, consisting of two-segmented (coxa, basis) protopod bearing inner branch (endopod) and outer branch (exopod). (biramous, uniramous = with/without exopod; with/without epipods). [Stachowitsch, 1992]
One of basically eight pairs of appendages of thorax. First pair developed as maxillipeds. Typically biramous, consisting of protopod bearing larger endopod and smaller exopod. (excluding maxillipeds: five pairs, seven pairs; equal/not equal in length; uniramous, biramous) (See also pereopod). [Stachowitsch, 1992]
One of two appendages of each thoracic somite (thoracomere). Basically biramous, consisting of proximal part (protopod) bearing gill (epipod) as well as distal five-segmented endopod and two-segmented exopod. Posterior pair(s) may be reduced except for gill. (chelate, prehensile, rudimentary, vestigial).
(syn. pereopod) [Stachowitsch, 1992]

Thorax

Anteriormost division of the crustacean trunk. [Brusca and Brusca, 2002]
Middle body region of eight somites bearing maxillipeds and pereopods. [Poore, 2004]
see Cephalothorax. [Butler, T. H.]
Tagma between cephalon and abdomen comprising anterior portion of trunk, last somite bearing most posterior genital pore or just anterior to this pore-bearing somite and nearly always limb-bearing.
(syn. cormus (not precise equivalent of pereion)) [Moore and McCormick, 1969]
Tagma between cephalon and abdomen, i.e., anterior part of trunk. [McLaughlin, 1980]
The anterior region of the trunk (body). [Brusca and Brusca, 2002]
The central region of a crustacean body: in Brachyura, the seventh to fourteenth segments which are always fused with the six head segments. [Ingle, 1983]
(Taxon-specific: ) Trunk. [Stachowitsch, 1992]
Division (tagma) of body between head and abdomen. Consists of 11 segments ("thoracic segments" or body rings), each bearing pair of polyramous appendages (thoracopods). Covered, along with head, by carapace. (See also trunk). [Stachowitsch, 1992]
Trunk. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Division (tagma) of body between head and abdomen. Typically consists of 11 somites (thoracomeres), each of which bears pair of biramous appendages (thoracopods). Ventral midline forms food groove. Thorax and abdomen together occasionally termed trunk. [Stachowitsch, 1992]
Division (tagma) of body between head (cephalon) and abdomen. Consists of eight somites (thoracomeres), of which seven or eight bear biramous appendages (thoracopods). Thorax and abdomen together occasionally termed trunk. [Stachowitsch, 1992]
Region of body comprising eight somites between head and abdomen. First three thoracic somites fused with head to form cephalothorax, with remaining thoracic somites collectively forming pereon. [Stachowitsch, 1992]
Region of body comprising eight somites between head proper and abdomen (pleon). First thoracic somite (thoracomere) fused with head, with first and second thoracomeres being covered by and fused with carapace.
See: Pereon [Stachowitsch, 1992]
Posterior part of cephalothorax. Consists of eight somites (thoracomeres), each bearing pair of appendages (thoracopods). Covered, along with cephalon, by carapace. [Stachowitsch, 1992]
Region of body basically comprising eight somites between cephalon and pleon. First thoracic somite (and occasionally second) is fused with cephalon to form cephalothorax; remaining somites of thorax collectively form pereon. [Stachowitsch, 1992]
Region of body basically comprising eight somites between head (cephalon) and abdomen (pleon). First thoracic somite (and occasionally second) is fused with cephalon to form cephalothorax; remaining somites of thorax collectively form pereon. [Stachowitsch, 1992]
Tagma or body region between the cephalon and the abdomen. [Kensley and Schotte, 1989]
Major division (tagma) of body between head and abdomen. Consists of eight somites (thoracomeres) and is covered by carapace. (See also cephalothorax). [Stachowitsch, 1992]
Division (tagma) of body between head (cephalon) and abdomen (pleon); consists of eight somites (thoracomeres), each bearing pair of appendages (thoracopods). First four somites are covered by carapace. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Division (tagma) of body between head (cephalon) and abdomen. Consists of eight somites (thoracomeres), each bearing pair of thoracopods. Covered, along with part of head and abdomen, by carapace. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Region of body between head (cephalon) and abdomen (pleon). First thoracic somite (thoracomere) is fused to head, the remaining three thoracomeres form pereon. [Stachowitsch, 1992]
Lepas anatifera: left valve removed. [Anderson, 1980]
(Taxon-specific: Order Rhabditida) (Figure only.) [Anderson, 1980]
(Taxon-specific: Order Rhabditida) Posterior of typically two basic divisions (tagmata) of body (head, thorax; in ascothoracican, head thorax, abdomen). Consists of six segments (somites) bearing appendages (cirri). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) That part of the body of a copepod posterior to the cephalic somite (bearing maxilla 2) and including the somite bearing the genital opening. [Ferrari and Dahms, in press]
According to interpretation dividing body into cephalon, thorax, and abdomen, five-segmented tagma including maxilliped-bearing (maxillipedal) somite and following four thoracopod-bearing somites (thoracomeres). [Stachowitsch, 1992]
Posterior of two major regions (head, thorax) of body; unsegmented and not clearly delimited from head. Typically bears two pairs of appendages (thoracopods) and is indistinguishably fused with rudimentary abdomen. Entirely enclosed in carapace. [Stachowitsch, 1992]
Second of three basic divisions of body (cephalon, thorax, abdomen). Consists of six somites (thoracomeres), of which at least the first is fused to head (to form cephalosome). Main flexure point of body may lie within thorax. (See also metasome, urosome). [Stachowitsch, 1992]
Major division (tagma) of body between head and abdomen. Basically consists of eight somites (thoracomeres), although in anaspidacean and stygocaridacean, first thoracomere (bearing maxillipeds) is fused with head. [Stachowitsch, 1992]
Region (tagma) of body comprising eight somites between cephalon proper and abdomen. First thoracic somite (thoracomere) fused with cephalon. (See also pereon). [Stachowitsch, 1992]
Posterior part of cephalothorax. Consists of eight somites (thoracomeres), most bearing well-developed appendages (thoracopods). Fused with and largely covered by carapace.
(syn. pereopod) [Stachowitsch, 1992]

Thumb

See: Fixed finger [Martin, 2005]
Finger. [Stachowitsch, 1992]

Tomentum

Mat of fine hairs. [Poore, 2004]

Tooth

Tooth-like structure, either in gastric mill of cardiac stomach or referring to blunt, relatively broad projection on outer surface of carapace. In cardiac stomach, one may distinguish one median and two lateral teeth. On carapace, one may distinguish, according to position and according to group, cardiac, gastric, lateral, orbital, pregastric, and rostral teeth. [Stachowitsch, 1992]
One of typically six larger tooth-like projections along telson margin; according to position (from midline outward) one may distinguish submedian, intermediate, and lateral teeth. May also refer to teeth on distal segments (propodus, dactyl) of thoracopods. [Stachowitsch, 1992]
Hinge structure: tooth-like (typically anterior or posterior) element projecting beyond hinge margin. Fits into socket of opposite valve. (bifid, conical, elongate, hemispherical, lobate, multilobate, reniform, simple, smooth, trilobate).
(syn. hinge tooth) [Stachowitsch, 1992]

Toothed furrow

Pair of elongate, toothed depressions, one in dorsolateral surface of each thoracoabdominal somite, in maxillipedal somite (maxillipedal lateral toothed furrow), and in posterior region of cephalon (maxillary lateral toothed furrow). Number of teeth may be of taxonomic importance. (undivided, bifid). [Stachowitsch, 1992]

Tracheate

Bearing tubular respiratory trachea (more correctly pseudotrachea) on pleopods, as in Oniscidea. [Kensley and Schotte, 1989]

Transverse groove

Transverse suture superficially subdividing last (sixth) abdominal somite (pleomere). [Stachowitsch, 1992]

Transverse septum

Thin wall of cirripeds normal to longitudinal septum and parallel to basis, dividing parietal tubes into series of cells. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Thin wall normal to longitudinal septum and parallel to basis, dividing longitudinal tubes into series of cells. [McLaughlin, 1980]

Transverse suture

Fine short vertical line extending dorsally from the ventral margin of the carapace. [Perez Farfante and Kensley, 1997]

Trichobranch

A type of decapod gill bearing a series of radiating unbranched filaments. [Brusca and Brusca, 2002]
Gill of filamentous structure with hair-like projections from axis (e.g., crayfish).
(syn. trichobranchia) [Moore and McCormick, 1969]
Gill with filamentous structure of hairlike projections from axis. [McLaughlin, 1980]
Type of gill whose axis bears series of undivided, filament-shaped branches.
See: Dendrobranch, Phyllobranch [Stachowitsch, 1992]

Trichobranchiate

(noun) A decapod bearing trichobranch gills, or (adjective) the condition of having trichobranch gills. [Brusca and Brusca, 2002]

Trichobranchiate gill

A gill in which the branches are fingerlike and project from a central axis. [Perez Farfante and Kensley, 1997]
Gill with fine branches on a central axis. [Poore, 2004]

Trichogon

Minute, sexually mature instar of a settling male rhizocephalan cyprid that settles on the overy-filled externa of rhizocephalan barnacles. [Brusca and Brusca, 2002]

Tricobranchia

See: Trichobranch [Martin, 2005]

Tricuspid

Bearing three cusps or points. [Kensley and Schotte, 1989]

Tridentate

With three denticles. [Wilson, 1989]
Having three teeth. [Kensley and Schotte, 1989]

Trifid

Divided into three parts of lobes. [Kensley and Schotte, 1989]

Trilobed

Divided into three lobes. [Kensley and Schotte, 1989]

Trisinuate

Having three curves. [Kensley and Schotte, 1989]

Tritocerebrum

See: Metacerebrum [Martin, 2005]
See metacerebrum. [McLaughlin, 1980]
Third ganglion of the crustacean brain, a postoral ganglion that probably represents the first postoral somite and that forms a pair of circumenteric connectives that extend around the esophagous to a subesophageal or subenteric ganglion, linking the brain to the ventral nerve cord. [Brusca and Brusca, 2002]
(Taxon-specific: ) Brain. [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Brain. [Stachowitsch, 1992]
Supraesophageal ganglion. [Stachowitsch, 1992]
Brain. [Stachowitsch, 1992]

Triturating surface

The truncate distal surface of the mandible's molar process. [Wilson, 1989]

Trituratory

Chewing or grinding. [Holdich and Jones, 1983]

Triunguiculate

Bearing three claws, as in a trifid dactylus. [Kensley and Schotte, 1989]

Troglobitic

Pertaining to obligate inhabitants of caves and underground water systems. [Chace and Hobbs, 1969]

Trophi

All mouthparts of cirripeds. [McLaughlin, 1980]
Mouthparts of cirripeds, including labrum, mandibles, maxillules, maxillae, palpi, and in some, first pair of cirri. [Moore and McCormick, 1969]
(Taxon-specific: Order Rhabditida) Collective term for mouthparts (mandible, maxillules, maxillae). Closely associated with labrum with which, in ascothoracican, they form oral pyramid. [Stachowitsch, 1992]

True lobsters

Members of the family Nephropidae; have large claws and a stiff tail fan. [Bliss, 1982]

Truncate

Having the appearance of having been abruptly cut off. [Kensley and Schotte, 1989]

Trunk

Postcephalic portion of body.
(syn. thorax) [Moore and McCormick, 1969]
Postcephalic portion of body. [McLaughlin, 1980]
The postcephalic body of a crustacean, sometimes divisible into an anterior thorax and posterior abdomen. [Brusca and Brusca, 2002]
(Taxon-specific: ) Posterior of two divisions (tagmata) of body (head, trunk). Trunk may be considered to consist of thorax, abdomen, and postabdomen, whereby thorax refers to anterior appendage-bearing region of trunk, abdomen to (reduced) region posterior to trunk appendages, and postabdomen to recurved posteriormost region. Somite border indistinguishable in posterior region of trunk. (covered/not covered by valves). [Stachowitsch, 1992]
Region of body posterior to head. Consists of thorax with 11 segments and abdomen with large and variable number of body rings; anterior region covered by carapace. Term is frequently applied due to poorly delimited border between thorax and abdomen. [Stachowitsch, 1992]
Posterior of two divisions (tagmata) of body (head, trunk); consists of 10-32 somites (excluding telson), each bearing pair of appendages. Considered to basically consist of thorax and abdomen, although the two are indistinguishable.
(syn. postcephalic body) [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Region of body posterior to head. Typically consists of 19 postcephalic segments (excluding telson), of which the first 11 represent the thorax, the last 8 the abdomen. [Stachowitsch, 1992]
Region of body posterior to head (cephalon). Consists of 19 segments (excluding telson), of which first 8 represent the thorax, the last 11 the abdomen. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) The postcephalic region of the body. [Boxshall and Halsey, 2004]
Entire region of body following head (cephalon); according to interpretation, may be subdivided into thorax and abdomen or maxillipedal somite and thoracoabdomen. [Stachowitsch, 1992]
Region of body posterior to head; corresponds to thorax (and rudimentary abdomen). Unsegmented, typically bearing two pairs of appendages (thoracopods) and caudal rami. Entirely enclosed in carapace. [Stachowitsch, 1992]
Term applied to region of body posterior to head (i.e., thorax and abdomen). Refers also to more expanded part of thorax posterior to neck in parasitic copepod. [Stachowitsch, 1992]
Posterior division of body (cephalon, trunk). Consists of up to approximately 30 similar segments, the first (i.e., maxillipedal) being fused to head (cephalon), the second (= apparent first) being sometimes partially covered by head (cephalon), the last reduced and partially fused anal segment; each segment is produced laterally into pleurites and bears pair of biramous appendages. [Stachowitsch, 1992]

Trunk appendage

(Taxon-specific: ) One of four to six pairs of appendages of anterior region ("thorax") of trunk. Basically biramous, consisting of indistinct proximal protopod (with endites and epipod) and more distal endopod and exopod. (flattened = foliaceous = phyllopodus, not clear segmented; subcylindrical = prehensile, clearly segmented; similar, dissimilar).
(syn. thoracic appendage, thoracopod) [Stachowitsch, 1992]
One of two relatively elongate appendages of each trunk somite. Basically biramous, consisting of poorly delimited, proximal protopod (with endites and epipod), endopod ( = sixth endite), and exopod (flabellum). Decreases in size posteriorly. Unmodified trunk appendages are termed phyllopods due to flattened construction.
(syn. thoracic appendage, thoracopod, trunk leg) [Stachowitsch, 1992]
Thoracopod.
(syn. postcephalic appendage) [Stachowitsch, 1992]

Tubercle

A small round firm swelling or nodule on the surface of carapace or limbs. [Ingle, 1983]
Knoblike process; tip usually blunt. [Butler, T. H.]
Low protuberance on exoskeleton. [Hobbs and Jass, 1988]
Type of valve sculpture: fairly prominent, rounded projection. Larger than granule, smaller than knob. (simple, multifurcate) (See also eye tubercle, subcentral tubercle). [Stachowitsch, 1992]

Tuberculate

Bearing knoblike or wartlike prominences or tubercles. [Kensley and Schotte, 1989]

Turret

Type of valve sculpture: large but short, spine-like projection whose summit bears series of small spines around its periphery. May be considered to be type of verruca. [Stachowitsch, 1992]

Umbo

apical portion of either valve or bivalved crustaceans (e.g., Conchostracan, Phyllocarida); in cirripeds, central point on plate from which successive growth increments extend. [Moore and McCormick, 1969]
Apical portion of either valve or bivalved crustaceans; also location on plate from which successive growth increments extend in lepadomorph Cirripedia. [McLaughlin, 1980]
Somewhat elevated, dorsalmost part of carapace; represents early growth stage of shell. Position relative to anterior end is of taxonomic importance. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Barnacle plate feature: in stalked barnacle, location on plate form which successive growth increments extend. (basal, subapical, subcentral). [Stachowitsch, 1992]

Umbonal spine

Hollow, minute to large spinose projection of conchostracan carapace that may involve entire umbo; may be curved, looped, or represented as node or nipple. [Larval condition characteristic in Vertexiidae.]. [Moore and McCormick, 1969]
Hollow, minute to large, curved, looped, or nodular spinose projection, sometimes involving entire umbo. [McLaughlin, 1980]

Unequally bifid seta

A seta that is often spine-like and has a smaller thin seta or hair just proximal to its tip. The hair has a nerve extending into the cuticle and is probably the external expression of a sensory nerve. [Wilson, 1989]

Unguis

A modified seta on the tip of the dactylus.
(syn. claw) [Wilson, 1989]
Most distal article of pereopod and cheliped. In the case of a pereopod it may be fused to the dactylus to form a claw. [Holdich and Jones, 1983]
Terminal claw-like portion of dactylus. (uniunguiculate, biunguiculate, triunguiculate). [Stachowitsch, 1992]

Ungulus

In thoracopod, elongate, claw-shaped tip of last segment (dactylus) of endopod. [Stachowitsch, 1992]

Uniarticulate

With only a single segment. [Wilson, 1989]
Composed of one article. [Kensley and Schotte, 1989]

Uniramous

Composed of a single branch. When used in reference to an appendage, it usually implies the loss of the exopod, as in a walking leg. [Warner, 1977]
Having a single branch (the endopodite) or ramus. [Holdich and Jones, 1983]
With only a single branch. [Wilson, 1989]
Having one ramus or branch. [Kensley and Schotte, 1989]
(Taxon-specific: Family Cyatholaimidae) One-branched; used of limbs possessing only one ramus (either endopod or exopod). [Boxshall and Halsey, 2004]

Uniserate

(Taxon-specific: Family Cyatholaimidae) Used of egg sacs containing only a single row of eggs, often disc-like in shape. [Boxshall and Halsey, 2004]

Uniunguiculate

Having a single claw, as in a dactylus. [Kensley and Schotte, 1989]

Unpaired receptacles

Non-invaginated, opening either through an exposed median longitudinal slit flanked by lateral plates of sternite XIV, or openinng anterior to single plate.
See: Seminal receptacles [Perez Farfante and Kensley, 1997]

Upcurved growth lines

Upwardly bent growth lines covering tear in conchostracan shell-margin at site of injury. [Moore and McCormick, 1969]
Upwardly bent growth lines covering tear in shell margin at site of injury. [McLaughlin, 1980]

Upper lateral

Plate of some cirriped shells.
See: Latus (upper) f [Moore and McCormick, 1969]

Upper latus

(Taxon-specific: Order Rhabditida) Barnacle plate: paired plates (latera) in stalked form, one on each side of capitulum between scutum and tergum or carina. [Stachowitsch, 1992]

Upper lip

See: Labrum [Martin, 2005]
See labrum. [McLaughlin, 1980]
(Taxon-specific: ) Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Labrum. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Labrum. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]
Labrum. [Stachowitsch, 1992]

Ureter

Excretory duct. [Stachowitsch, 1992]

Urogastric groove

On carapace, short, transverse groove posterior to and occasionally joined to postcervical groove. [Stachowitsch, 1992]

Urogastric lobe

A very short transverse area bordering the posterior margin of the metagastric region on the carapace of crabs. [Chace and Hobbs, 1969]
Posterior division of gastric region of decapod (brachyuran) carapace; sometimes called genital region. [Moore and McCormick, 1969]
Posteromedian lobe or subregion of gastric region, sometimes called genital region. [Williams, 1984]
See: Carapace regions f [McLaughlin, 1980]

Urogastric region

The region on the dorsal surface of the carapace bounded by part of the margins of the metagastric, metabranchial and cardiac regions. [Ingle, 1983]
Gastric region.
(syn. genital region) [Stachowitsch, 1992]

Uropod

A paired biramous appendage attached to the sixth abdominal somite in all but the true crabs and usually combining with the telson to form a tail fan. [Chace and Hobbs, 1969]
An appendage of the last (6th) abdominal segment. [Warner, 1977]
Appendage of 6th abdominal somite of Malacostraca, generally fanlike, sometimes reduced or modified; also last 3 pairs of abdominal appendages in amphipods. [McLaughlin, 1980]
Limb of sixth abdominal segment of Eumalacostraca, generally fan-like but may be reduced or modified. [Moore and McCormick, 1969]
One of paired appendages attached to sixth abdominal somite, part of tail fan. [Butler, T. H.]
Pair of appendages borne terminally on the pleotelson, usually biramous and with multi-articled flagella. [Holdich and Jones, 1983]
Paired biramous appendage attached to the sixth abdominal somite, usually combining with the telson to form a tailfan. [Perez Farfante and Kensley, 1997]
Paired biramus appendage on sixth abdominal segment, lateral parts of "tail fan" (see Figs. 13,14). [Hobbs and Jass, 1988]
Paired lateral appendages of the tail of a crustacean which, together with the median telson, for the 'tail fan'. [Mauchline, 1984]
Paired limb of sixth abdominal somite, combining with telson to form tailfan. [Poore, 2004]
Part of "tail fan"; a paired biramous appendage borne on the sixth abdominal somite. [Hobbs, Hobbs, and Daniel 1977]
Posteriorly-directed last pair of abdominal appendages, differing from other pleopods and often forming with telson a tail fan, in malacostracans. [Brusca and Brusca, 2002]
The last pair of abdominal appendages on the sixth somite rarely present in the Brachyura. [Ingle, 1980]
The terminal appendage of the body, belonging to the sixth pleonite. It consists of a basal segment - the protopod - and two uniarticulate rami - an endopod and an exopod. [Wilson, 1989]
The terminal pair of abdominal appendages, almost always lacking in the species in the Area except for Dromia in which they are vestigial. [Ingle, 1983]
Term applied to each caudal ramus if telson is interpreted as representing anal somite. [Stachowitsch, 1992]
Term applied to each caudal ramus if telson is interpreted as representing anal somite. [Stachowitsch, 1992]
Long, thin, paired appendages of last segment (pleonite) of abdomen (pleon). Biramous, consisting of one-segmented basal part (peduncle) bearing one- to three-segmented endopod and two-segmented exopod. Number of endopod segments is of taxonomic importance. (styliform). [Stachowitsch, 1992]
Paired appendage of last segment (pleomere) of abdomen (pleon). Basically consists of one-segmented (basis) proximal section, multisegmented endopod, and few-segmented exopod. (uniramous, biramous; short, flagelliform). [Stachowitsch, 1992]
One of two appendages of last (sixth) abdominal somite (pleomere); typically flattened and consisting of basal protopod and two branches (endopod, exopod). May form tailfan together with telson. (elongate, falciform, ovate; with spine, with tooth). [Stachowitsch, 1992]
Paired appendage of each segment (urosomite) of posterior subdivision (urosome) of abdomen. Basically biramous, consisting of basal segment (peduncle) and pair of rami. (lamellate, styliform). [Stachowitsch, 1992]
Paired appendage on next to last segment of abdomen (pleon); rami always a single segment, (biramous, uniramous, simple uniramous; spatu-late, styliform). [Stachowitsch, 1992]
Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]
Paired pleonal appendage of the last pleonite, usually situated at the base of the telson. [Kensley and Schotte, 1989]
Paired appendage of last somite (pleomere) of abdomen. Biramous and flattened, consisting of protopod bearing inner branch (endopod) and outer branch (exopod). Exopod and endopod may be subdivided by transverse suture (dieresis); endopod usually bears a large statocyst. [Stachowitsch, 1992]
One of two appendages of last (sixth) abdominal somite (pleomere). Well developed, flattened, consisting of one-segmented basal protopod (prolonged into forked process) bearing one-segmented endopod and two-segmented exopod. Forms tailfan together with telson. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Term applied to each caudal ramus if last body segment (telson) is interpreted as representing anal somite. [Stachowitsch, 1992]
Term applied to each caudal ramus if supra-anal plate is interpreted as representing telson. [Stachowitsch, 1992]
Paired appendage of last somite (pleomere) of abdomen. Biramous, consisting of protopod bearing inner (endopod) and outer (exopod) branches. In anaspidacean, forms tailfan with telson. In bathynellacean, bears opening of uropodal gland. (spatulate, styliform). [Stachowitsch, 1992]
Paired appendage of last segment (pleomere) of abdomen. Biramous, consisting of protopod bearing one-segmented endopod and two-segmented exopod. [Stachowitsch, 1992]
One of two appendages of last (sixth) abdominal somite (pleomere). Flattened and biramous, consisting of short, one-segmented base and two more elongate, one-segmented branches (endopod and exopod). Forms tailfan together with telson. [Stachowitsch, 1992]

Uropodal gland

In bathynellacean, relatively large accessory excretory gland located in last (sixth) abdominal somite (pleomere). Opens to exterior dorsally at base of uropod. [Stachowitsch, 1992]

Uropods

The paired biramous appendages of the isopod pleotelson, representing the appendages of the fused sixth pleonite. [Wetzer et al. 1997]

Urosoma

See: Urosome [Martin, 2005]
See urosome. [McLaughlin, 1980]

Urosomal segment

Urosome. [Stachowitsch, 1992]

Urosome

In copepods, part of body behind major articulation marking posterior boundary of prosome; in amphipods, last three abdominal somites bearing modified appendages. [Moore and McCormick, 1969]
Limbless abdomen of some copepods. [Brusca and Brusca, 2002]
Part of body behind major articulation (Copepoda); also last 3 abdominal somites bearing modified appendages (Amphipoda). [McLaughlin, 1980]
Posterior division of the abdomen in amphipods; bears appendages (uropods) and telson. [Brusca and Brusca, 2002]
Posterior of two subdivisions (pleosome, urosome) of abdomen (pleon). Consists basically of three somites (urosomites), each bearing pair of appendages (uropods). [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) That part of the adult copepod body posterior to the major body articulation. [Ferrari and Dahms, in press]
(Taxon-specific: Family Cyatholaimidae) The region of the body posterior to the major articulation, includes the fifth pedigerous somite in podopleans, but not in gymnopleans. [Boxshall and Halsey, 2004]
Posterior division (tagma) of body (prosome, urosome, or cephalosome, metasome, urosome). Corresponds to region of body posterior to main flexure point (or posterior to genital complex in forms without body articulation) and includes both thoracic and abdominal somites. [Stachowitsch, 1992]

Urosomite

If abdomen (pleon) is subdivided into anterior pleosome and posterior urosome, one of three segments (somites) of urosome. [Stachowitsch, 1992]
(Taxon-specific: Family Cyatholaimidae) Component somite of a urosome. [Boxshall and Halsey, 2004]

Uterine opening

Gonopore. [Stachowitsch, 1992]

Uterus

(Taxon-specific: Family Pycnogonidae) Oviduct. [Stachowitsch, 1992]
In female reproductive system, expanded terminal section of oviduct in which eggs are stored. Opens via gonopore (uterine opening) to exterior and may be connected to seminal receptacle by canal. [Stachowitsch, 1992]

Vagina

(Taxon-specific: Family Pycnogonidae) Oviduct. [Stachowitsch, 1992]
In female reproductive system, terminal modification of oviduct to accommodate penis of male. [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) Female gonopore on ventral surface of last thoracic somite (fourth thoracomere). Receives pair of oviducts, although only one oviduct is considered to be functional at any one time. Flanked by pair of seminal papillae.
(syn. genial atrium) [Stachowitsch, 1992]
In female reproductive system, large space leading to a seminal receptacle. Located next to gonopores (openings of oviduct = uterine openings) at posterior end of trunk. [Stachowitsch, 1992]

Valve

Lateral part of divided carapace commonly joined to opposite part by hingement along dorsal mid-line (e.g., Ostracoda, Conchostraca, Leptostraca). [Moore and McCormick, 1969]
Lateral part of divided carapace, commonly joined to opposite part by hingement along dorsal midline; also any one of opercular elements in sessile Cirripedia. [McLaughlin, 1980]
(Taxon-specific: ) Term applied to each half of carapace, one half (valve) covering each side of trunk. [Stachowitsch, 1992]
One of two shell elements comprising carapace. Covering left and right sides of body and joined together (or continuous) dorsally along hinge line. Consists of several layers and is variously ornamented on exterior. (See also carapace). [Stachowitsch, 1992]
Term applied to uropods covering branchial chamber in certain isopods. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Opercular valve. [Stachowitsch, 1992]
Aortic valve, hepatic valve. [Stachowitsch, 1992]
One of two shell-like elements covering left and right sides of body (therefore left valve, right valve). Valves joined to each other dorsally by hinge and may bear complex system of ridges and grooves around margin that inter-fit when carapace is closed. Consists of inner and outer lamellae. (equal, subequal, unequal; amplete, postplete, preplete; lateral outline: circular, elliptical, elongate, ovate, quadrate, reniform; smooth, ornamented: e.g., alate, bilobate, bisulcate, bullate, caperate, carinate, celate, clavate, costate, foveolate, granuloreticulate, granulose, lobate, papillate, pitted, punctate, quadrilobate, reticulate, setose, spinose, striate, sulcate, trilobate, trisulcate, tuberculate, unilobate, unisulcate, verrucose) (See also valve sculpture). [Stachowitsch, 1992]
Right or left half of bivalved ostracode carapace (sometimes erroneously referred to as "shell"). [Cohen, Peterson, and Maddocks, in press]

Vas deferens

Duct in male passage of sperm from testis to penis. [McLaughlin, 1980]
Ducts in males for passage of spermatozoa from testis to penis. [Moore and McCormick, 1969]
Male duct from the testis to the penile papilla for the passage of sperm. [Wilson, 1989]
(Taxon-specific: ) Section of male reproductive system extending from posterior end of each testis to gonopore(s) or penis(es) on postabdomen.
(syn. sperm duct) [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
Gonad. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Short, slender section of male reproductive system between each testis and penis; expanded at base of penis to form seminal vesicle. [Stachowitsch, 1992]
Section of male reproductive system between each tesis and gonopore. Terminal section merges with oviduct to form common duct (gonoduct) opening on sixth thoracic segment (thoracomere). [Stachowitsch, 1992]
Section of male reproductive system between each testis and gonopores on ventral surface of last (fifth) pereon segment.
(syn. sperm duct) [Stachowitsch, 1992]
Narrow section of d reproductive system extending from each dorsal testis to gonopore on basal segment (coxa) of last thoracopod. May be modified into various regions for spermatophore production; forms terminal ejaculatory duct.
(syn. sperm duct) [Stachowitsch, 1992]
Section of male reproductive system between each testis and each penis. Characterized by glandular walls and terminal modifications.
(syn. sperm duct) [Stachowitsch, 1992]
Section of male reproductive system between each testis and male gonopore(s).
(syn. sperm duct) [Stachowitsch, 1992]
Paired, slender, and elongate section of male reproductive system between seminal vesicle and ejaculatory ducts. [Stachowitsch, 1992]
Section of male reproductive system between each testis and each penis; elongate and slender, each extending from third abdominal somite (pleomere) anteriorly to penis on eighth thoracic appendage (thoracopod).
(syn. sperm duct) [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Relatively short, ventral section of male reproductive system between each testis and gonopore.
(syn. sperm duct) [Stachowitsch, 1992]
(Taxon-specific: Order Monhysterida) In male reproductive system, pair of narrow sperm ducts leading from median seminal vesicle; each vas deferens connects to duct of blind capsule and leads to common ejaculatory duct. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In male reproductive system, duct extending from each testis; ducts merge at base of penis (to form ductus ejaculatorius).
(syn. sperm duct) [Stachowitsch, 1992]
Unpaired, anteriorly directed section of male reproductive system between testis and gonopore. Produces spermatophores. [Stachowitsch, 1992]
Section of male reproductive system leading form testis to gonopore on first abdominal segment (genital somite). Originates at anterior end of testis and is typically regionated into seminal vesicle, spermatophoric sac, and ejaculatory duct. (paired, unpaired).
(syn. sperm duct) [Stachowitsch, 1992]
Section of male reproductive system leading from each testis to gonopore. May be expanded to form seminal vesicle, and distal end may be modified as an ejaculatory duct.
(syn. sperm duct) [Stachowitsch, 1992]
Section of male reproductive system arising from anterior end of each testis and extending to gonopore(s) on ventral surface (sternite) of last (eighth) thoracic somite. [Stachowitsch, 1992]
Elongate, slender section of male reproductive system between each testis and penes on last (eighth) thoracomere. Extends through thorax and abdomen before turning anteriorly to gonopores. Expanded terminally to form seminal vesicle. [Stachowitsch, 1992]
Section of male reproductive system between each testis (or from each side of unpaired testis) and gonopores on eighth thoracomere. May be expanded distally to form seminal vesicle. (coiled, straight).
(syn. sperm duct) [Stachowitsch, 1992]

Vas efferens

(Taxon-specific: Order Monhysterida) In male reproductive system, narrow sperm duct leading from each testis to median seminal vesicle. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) In male ascothoracican, one of numerous small ducts leading form testicular lobes to vasa deferentia. [Stachowitsch, 1992]

Vasa deferentia

Tubes (one on either side) conveying sperm from testes to exterior. [Holdich and Jones, 1983]

Velum

Type of valve sculpture: Wide wing-shaped structure. [Stachowitsch, 1992]

Venter

The ventral side of the body. [Wilson, 1989]

Ventral

On or toward underside. [Hobbs and Jass, 1988]
Underside, that which is normally facing downwards. [Butler, T. H.]

Ventral comb

Row of setae or bristles on posteroventral margin of last abdominal somite or telson. [McLaughlin, 1980]
Transverse series of ventral setae on telson (longer setae) and, in most cephalocarids, on posterior margin of 19th segment (shorter setae). (on telson: row shorter than ot equal to telson width).
(syn. comb row) [Stachowitsch, 1992]

Ventral costa

Ridge extending along ventromesial margin of the ventrolateral lobule of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]

Ventral cup

Element of nauplius eye in nonmalacostracans. [McLaughlin, 1980]

Ventral frontal organ

Paired sensory structure associated with the nauplius eye of nonmalacostracan crustaceans. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Frontal organ. [Stachowitsch, 1992]

Ventral ganglion

One in a series of ganglion pairs of ventral nerve cord in thorax (thoracic ganglion) or abdomen (abdominal ganglion). Segmentally arranged, each giving rise to pair of nerves. Ganglion pairs may shift anteriorly and be fused with one another to form cephalothoracic ganglion. [Stachowitsch, 1992]

Ventral groove

(Taxon-specific: Class Secernentea) Elongate median line between thoracopod bases on ventral side of thorax. Food is trapped by thoracopods, passed anteriorly along ventral groove, and transferred to mouth.
(syn. food groove) [Stachowitsch, 1992]

Ventral nerve chain

Ganglia or connectives on somites joined by single or double nerve cord running longitudinally beneath alimentary canal. [Moore and McCormick, 1969]
See ventral nerve chord. [McLaughlin, 1980]
Longitudinal nerve cord extending posteriorly from subesophageal mass. Located below digestive tract; bears segmentally arranged ganglia. [Stachowitsch, 1992]

Ventral nerve cord

Ganglia or connectives in somites joined by single or double tract of nerve fibers running longitudinally beneath alimentary canal. [McLaughlin, 1980]
(Taxon-specific: ) Pair of widely separated, longitudinal nerve cords extending into trunk from posterior part of brain; forms ladder-like chain with relatively few, occasionally fused ganglia. [Stachowitsch, 1992]
Pair of widely separated longitudinal nerve cords extending posteriorly from brain; forms ladder-like chain (with series of ganglia). [Stachowitsch, 1992]
Pair of widely separated, longitudinal nerve cords extending posteriorly from brain; forms ladder-like chain. [Stachowitsch, 1992]
(Taxon-specific: Family Pycnogonidae) Pair of widely separated, longitudinal nerve cords originating from posterior part (tritocerebrum) of brain and forming ladder-like chain (with series of ganglia) extending to second abdominal somite. [Stachowitsch, 1992]
Pair of longitudinal nerve cords extending from subesophageal ganglia to end of abdomen; bears pair of ganglia in each somite. [Stachowitsch, 1992]
Longitudinal nerve cord extending posteriorly from brain (supraesophageal ganglion). Located below digestive tract; bears 16 pairs of segmentally arranged ganglia. [Stachowitsch, 1992]
Longitudinal pair of more or less fused nerve cords extending from subesophageal ganglion to telson. Basically bears pair of (fused) ganglia in each somite. [Stachowitsch, 1992]
Longitudinal nerve cord extending below digestive tract from subesophageal ganglion to end of abdomen. Bears series of segmentally arranged (posteriorly occasionally fused) ganglia. [Stachowitsch, 1992]
Longitudinal nerve cord extending below digestive tract from subesophageal ganglion into abdomen. Bears series of segmentally arranged ganglia (anteriorly displaced in pleon). [Stachowitsch, 1992]
Longitudinal nerve cord extending below digestive tract to last abdominal somite. Extends posteriorly from subesophageal ganglion or directly from supraesophageal ganglion via esophageal connectives. Bears series of segmental ganglia. [Stachowitsch, 1992]
Longitudinal pair of fused nerve cords extending from postoral ganglion to posterior end of body; located midventrally and bearing ganglia (segmental ganglia) in each somite. [Stachowitsch, 1992]
(Taxon-specific: Class Secernentea) Longitudinal nerve cord extending below digestive tract to sixth abdominal somite (next to last somite). Joined to brain (supraesophageal ganglion) by pair of esophageal connectives; bears series of segmentally arranged ganglia. [Stachowitsch, 1992]
(Taxon-specific: Order Rhabditida) Pair of nerve cords extending posteriorly from subesophageal ganglion. Ganglia of ventral nerve cord may be fused with subesophageal ganglion to form large ventral nerve mass. [Stachowitsch, 1992]
Pair of longitudinal nerve cords extending from brain to posterior end of body; bears series of ganglia.
(syn. ventral nerve chain) [Stachowitsch, 1992]
Paired, longitudinal nerve cord extending through trunk; bears pair of ganglia near base of appendages. Typically more or less concentrated and forming, along with subesophageal ganglion, posterior part of circumesophageal nerve ring. [Stachowitsch, 1992]
Unpaired, longitudinal nerve cord extending through thorax and joined to supraesophageal ganglion by pair of circumesophageal connectives. May be concentrated anteriorly in parasitic copepod, leading to prominent nerve ring around esophagus. [Stachowitsch, 1992]
Pair of longitudinal nerve cords extending from circumesophageal connectives to posterior end of body; connected to eachoth via commissures and bearing only modestly developed trunk-segment ganglia. [Stachowitsch, 1992]
In anaspidacean, longitudinal nerve cord extending below digestive tract to end of abdomen. Band-shaped, bearing series of segmental ganglia. Connected anteriorly to supraesophageal ganglion by pair of esophageal connectives. [Stachowitsch, 1992]
Longitudinal nerve cord extending posteriorly from brain. Located below digestive tract; bears segmentally arranged ganglion pairs. [Stachowitsch, 1992]
Longitudinal nerve cord extending below digestive tract to last (sixth) abdominal somite. Joined to brain (supraesophageal ganglion) by pair of esophageal connectives; bears series of segmentally arranged ganglia. [Stachowitsch, 1992]

Ventral platform

Part of archaeotracan telson head embracing proximal extremities of furcal rami. [Moore and McCormick, 1969]

Ventral sinus

In circulatory system, large ventral space below digestive tract in which blood collects before entering appendages and gills.
(syn. sternal sinus) [Stachowitsch, 1992]

Ventrolateral lobule

Ventral part of the lateral lobe of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]

Ventromedian lobule

Lateral part of the median lobe of the petasma (Fig. 4B). [Perez Farfante and Kensley, 1997]

Vermiform instar

See vermigon. [Brusca and Brusca, 2002]

Vermigon

A motile, multicellular, vermiform larval stage injected by a kentrogon larva into the host.
(syn. vermiform instar) [Brusca and Brusca, 2002]

Verruca

Type of valve sculpture: small, wart-like outgrowth. (See also bulla, turret). [Stachowitsch, 1992]

Vertex

The anterior and medial margin of the cephalic dorsal surface. [Wilson, 1989]
Top part of head (cephalon). [Moore and McCormick, 1969]
(Taxon-specific: ) Region of head between rostrum and compound eye (i.e., morphologically, part anterior to compound eye). [Stachowitsch, 1992]
(Taxon-specific: ) Top part of head or cephalon. [McLaughlin, 1980]

Vesicula seminalis

See: Seminal vesicle [Martin, 2005]
See seminal vesicle. [McLaughlin, 1980]

Vesiculate

Thin and bladder-like. [Ingle, 1980]

Vestibule

Along inner margin of valve, space formed between outer lamella and thickened part (duplicature) of inner lamella. [Stachowitsch, 1992]
In Podocopa a marginal cavity between the outer valve lamella and calcified part of the inner valve lamella, extending from the line of concrescence to the inner margin, housing epidermal, glandular and sometimes reproductive tissues.
(syn. vestibulum) [Cohen, Peterson, and Maddocks, in press]
Space between duplicature and outer lamella. [McLaughlin, 1980]

Vibratory plate

Branchial plate. [Stachowitsch, 1992]
Flat plate (with marginal setae) located proximally and laterally on limb (an epipod in Myodocopa, but podocopan homologies uncertain); used to circulate water.
(syn. branchial plate) [Cohen, Peterson, and Maddocks, in press]

Viscera

Internal organs of shrimp. [Butler, T. H.]

Von Vaupel Klein's Organ

(Taxon-specific: Family Cyatholaimidae) On swimming leg 1 of calanoid copepods, the dorsal seta of the basis which is curved, and often recurved, over a sensory area of pores and/or denticles on the proximal anterior face of the endopod. [Ferrari and Dahms, in press]

Vulva

(Taxon-specific: ) In male reproductive system, term occasionally applied to opening of oviduct into brood chamber. [Stachowitsch, 1992]

Walking leg

See: Pereiopod [Martin, 2005]
Any nonchelate pereiopod. [Butler, T. H.]
Any nonchelate pereiopod. [Chace and Hobbs, 1969]
One of last four pairs of thoracic limbs, or thoracic limbs exclusive of maxillipeds and cheliped(s). [Poore, 2004]
See pereopod. [McLaughlin, 1980]
Pereopod. [Stachowitsch, 1992]
Pereopod. [Stachowitsch, 1992]
Posterior limbs that are long, slender, jointed, directed ventrally and used for locomotion. [Cohen, Peterson, and Maddocks, in press]

Wall

(Taxon-specific: Order Rhabditida) In unstalked barnacle, calcareous wall surrounding body; closed dorsally by operculum. Consists of series of up to eight overlapping/articulating compartmental plates (from anterior to posterior: single rostrum, paired rostrolaterals, laterals, carinolaterals, and single carina) encircling body. [Stachowitsch, 1992]

Whip seta

Similar to the unequally bifid seta, except more slender. The sensory hair on the distal tip is long and curved. [Wilson, 1989]

Wrist

See: Carpus [Martin, 2005]
Carpus. [Stachowitsch, 1992]

X-organ

Groups of neurosecretory cells situated in each eyestalk producing a moult-inhibiting hormone. [Ingle, 1983]
Site of secretion of molt-inhibiting and other hormones. Located in eyestalks of most decapods or cephalon of sessile-eyed crustaceans. Also referred to as paired frontal organ in Anostraca. [McLaughlin, 1980]
(Taxon-specific: Family Pycnogonidae) Neurosecretory structure in dorsal region of head; innervated by brain. [Stachowitsch, 1992]
Neurosecretory structure in eyestalk (ocular peduncle). Secretes hormones that inhibit molting and are involved in gonad development and metabolism. In shrimp-like (natantian) decapod one may distinguish medulla terminalis X-organ and sensory pore X-organ. [Stachowitsch, 1992]

Xeric

arid, lacking in moisture. [Chace and Hobbs, 1969]

Y-organ

A gland situated near the external adductor muscles of the mandible producing the moulting hormone. [Ingle, 1983]
Site of secretion of molting hormone in decapods. [McLaughlin, 1980]
Neurosecretory structure in maxillae or base of antennae; secretes hormones promoting molting. [Stachowitsch, 1992]

Zenker's organ

In male reproductive system, complex type of ejaculatory duct at end of vas deferens; serves as pump for elimination of giant sperm. [Stachowitsch, 1992]
Muscular sperm pump (ejaculatory pump) located dorsally within male body (Cypridocopina) or interlamellar cavity (Sigilliocopina). [Cohen, Peterson, and Maddocks, in press]

Zoea

A larva with natatory exopods on some or all thoracic appendages, but with pleopods absent or rudimentary. [Ingle, 1983]
Free-living larval stage, following protozoea, present in all shrimps. [Butler, T. H.]
Larval stage characterized by natatory exopods on some or all thoracic appendages, pleopods absent or rudimentary.
(syn. mysis, phyllosome, protozoea, schizopod larva) [McLaughlin, 1980]
Larval stage characterized by the presence of natatory exopods on some or all of the thoracic appendages and by pleopods being absent or rudimentary. [Brusca and Brusca, 2002]
One of several larval stages, first stage hatching from the egg; transforming to final megalopa stage. [Poore, 2004]
Fourth of basically five larval stages (nauplius, metanauplius, protozoea, zoea, postlarva). If hatched from egg and free-swimming, then with thoracopodal locomotion. According to group this stage may be termed acanthosoma, mysis, phyllosoma, or puerulus. [Stachowitsch, 1992]

Zoea stage

Larval stage in ontogeny of various malacostracans but unknown in some. [Moore and McCormick, 1969]
The free-swimming larval stage of anomuran or brachyuran (true) crabs; corresponds to the mysis stage of a penaeid shrimp. [Bliss, 1982]

Zone of concrescence

A clear marginal band extending from the free margin to the line of concrescence, formed by a flange-like outgrowth of the outer lamella and traversed by radial pore canals.
(syn. fused zone) [Cohen, Peterson, and Maddocks, in press]

Authorities

References marked [All] have had all terms in them incorporated into this glossary.

AHD: American Heritage Dictionary of the English Language. 3e.
Anderson, 1980: Anderson, D. T. 1980. Barnacles - structure, function, development and evolution. Chapman and Hall London.
Baba, 2005: Baba, K. 2005. Deep-sea Chirostylid and Galatheid crustaceans (Decapoda: Anomura) from the Indo-Pacific, with a list of species. Galathea Report: Scientific results of the Danish deep-sea expedition round the world 1950-52. Vol. 20. 317 pp.
Barnard, 1969: Barnard, J. L. 1969. (1981 reprint) The families and genera of marine gammaridean Amphipoda. United States National Museum Bulletin 271: i-vi, 1-535. [Amphipoda, Gammaridea]
Bliss, 1982 [All]: Bliss, D. E. 1982. Shrimps, lobsters, and crabs: their fascinating life story. New Century Publishers, Inc., New Jersey. [Decapoda, primarily east coast U.S.]
Bousfield, 1973: Bousfield, E. L. 1973. Shallow-water gammaridean Amphipoda of New England. Comstock Publishing Associates, Cornell University Press. [Amphipoda, Gammaridea, New England, USA]
Boxshall and Halsey, 2004: Boxshall, G. A. and S. H. Halsey, 2004. An Introduction to Copepod Diversity. The Ray Society, Andover, United Kingdom, 2000 pp., 2 vol., vol. 166.
Brusca and Brusca, 2002 [All]: Brusca, R. C., Brusca, G. J. 2002. Invertebrates. Sinauer Associates Sunderland, MA. 936.
Butler, T. H.: Butler, T. H. 1980. Shrimps of the Pacific Coast of Canada. Department of Fisheries and Oceans, Ottawa, Bulletin 202, 280 pp. [Caridean and dendrobranchiate shrimp. Canada and eastern Pacific.]
Chace and Hobbs, 1969: Chace, F. A., Jr., and H. H. Hobbs, Jr. 1969. The freswhater and terrestrial crustaceans of the West Indies with special reference to Dominica. Smithsonian Institution, United States National Museum Bulletin 292. [Freshwater and terrestrial decapods / Caribbean]
Cohen, Peterson, and Maddocks, in press: Cohen, A., Peterson, D., Maddocks, R. In press. Ostracoda. The Light and Smith Manual: Intertidal Invertebrates of central California to Oregon, 4th edition University of California Press Berkeley. [In Press as of 2006]
Crane, 1975: Crane, J. 1975. Fiddler crabs of the world. Ocypodidae: Genus Uca. Princeton University Press, Princeton, New Jersey. [Brachyura, family Ocypodidae, worldwide]
Felder, 1973: Felder, D. L. 1973. An annotated key to crabs and lobsters (Decapoda, Reptantia) from coastal waters of the northwestern Gulf of Mexico. Center for Wetland Resources, Louisiana State University, Baton Rouge, Publication No. LSU-SG-73-02. [Crabs and lobsters, Gulf of Mexico]
Ferrari and Dahms, in press [All]: Ferrari, F. D. and H.-U. Dahms. In press. Post-embryonic development of the Copepoda. Crustaceana Monographs 8. [received 1/25/2007 from J. Martin as email attachment]
Garm, 2004: Garm, A. 2004. Revising the definition of the crustacean seta and setal classification systems based on examinations of the mouthpart setae of seven species of decapods. Zoological Journal of the Linnean Society 142: 233-252. [2/12/2007 have pdf, passed it on to Jody - in text format, not readily manipulated to fit our glossary style - has nice SEMs etc., let Jody decide what he wants us to add.]
Hart, 1982: Hart, J. F. L. 1982. Crabs and their relatives of British Columbia. British Columbia Provincial Museum Handbook 40. [Brachyura, Anomura, and thalassinoids, British Columbia]
Hobbs and Jass, 1988 [All]: Hobbs, H. H., III, and J. P. Jass. 1988. The crayfishes and shrimp of Wisconsin (Cambaridae, Paleomonidae). Milwaukee Public Museum. [Freshwater shrimp and crayfishes, eastern / midwestern U.S]
Hobbs, Hobbs, and Daniel 1977: Hobbs, H. H. Jr., H. H. Hobbs, III, and M. A. Daniel. 1977. A review of the troglobitic decapod crustaceans of the Americas. Smithsonian Contributions to Zoology, No. 244. [Decapods cave-dwelling / Americas]
Holdich and Jones, 1983: Holdich, D. M., and J. A. Jones. 1983. Tanaids. Keys and notes for the identification of the species. Synopses of the British Fauna, no. 27. Cambridge University Press, Cambridge. [Tanaids; Great Britain]
Holthuis, 1993: Holthuis, L.B. 1993. The Recent genera of the caridean and stenopodidean shrimps (Crustacea, Decapoda): With an appendix on the order Amphionidacea. Nationaal Natuurhistorisch Museum Leiden. 328pp.
Huys and Boxshall, 1991: Huys, R., and G. A. Boxshall. 1991. Copepod Evolution. The Ray Society, London, vol. 159. [Copepoda, worldwide]
Ingle, 1980 [All]: Ingle, R. W. 1980. British Crabs. British Museum and Oxford University Press. [Brachyuran crabs, Great Britain]
Ingle, 1983 [All]: Ingle, R. W. 1983. Shallow-water crabs: keys and notes of the identification of the species. In: D. M. Kermack and R. S. K. Barnes (eds.), Synopses of the British Fauna No. 25. Linnean Society of London and The Estuarine and Brackish-Water Science Association, Cambridge University Press [Brachyura, Great Britain]
Ingle, 1992: Ingle, R. W. 1992. Larval stages of northeastern Atlantic crabs: An illustrated key. Chapman and Hall Identification Guide No. 1. Natural History Museum Publications and Chapman and Hall, London. [Larvae, mostly Brachyura and Anomura, Great Britain and North Atlantic]
Jacques, 1989 [All]: Jacques, F. 1989. The setal system of crustaceans: types of setae, groupings, and functional morphology. Functional Morphology of Feeding and Grooming in Crustacea A.A. Balkema Rotterdam 6:1-13.
Kensley and Schotte, 1989: Kensley, B. and M. Schotte. 1989. Guide to the marine isopod crustaceans of the Caribbean. Smithsonian Institution Press, Washington, D. C. [Isopoda, Caribbean Sea]
Martin, 2005: Martin, J.M., 2005. Crustacean Glossary. URL: http://crustacea.nhm.org/glossary [This online reference]
Mauchline, 1984 [All]: Mauchline, J. 1984. Euphausiid, stomatopod, and leptostracan crustaceans. Keys and notes for the identification of species. Synopses of the British Fauna, no. 30. The Linnean Society of London and The Estuarine and Brackish-Water Sciences Association. [Euphausiids, stomatopods, and leptostracans; Great Britain]
McLaughlin, 1980 [All]: McLaughlin, P. A. 1980. Comparative morphology of Recent Crustacea. W. H. Freeman and Company, San Francisco. [General crustacean morphology]
Moore and McCormick, 1969 [All]: Moore, R. C., and L. McCormick. 1969. General features of Crustacea. In: R. C. Moore (ed.), Treatise on Invertebrate Paleontology, Part R, Arthropoda 4. Geological Society of America and University of Kansas Press, Lawrence. [General crustacean glossary, probably the most comprehensive available anywhere]
Perez Farfante and Kensley, 1997 [All]: Perez Farfante, I. and B. Kensley. 1997. Penaeoid and Sergestoid Shrimps and Prawns of the World: Keys and Diagnoses for the Families and Genera. Memoires du Museum National d'Histoire Naturelle, volume 175, 233 pp. [Dendrobranchiate shrimp, worldwide]
Poore, 2004 [All]: Poore, G.C.B. 2004. Marine Decapod Crustacea of Southern Australia. A Guide to Identification with a chapter on Stomatopoda by Shane Ahyong. Museum of Victoria Melbourne 574.
Stachowitsch, 1992 [All]: Stachowitsch, M. 1992. The Invertebrates: An Illustrated Glossary. Wiley-Liss, New York, 676 pp.
Warner, 1977 [All]: Warner, G. F. 1977. The Biology of Crabs. Van Nostrand Reinhold Company, New York. [Brachyuran Crabs, general]
Watling, 1989 [All]: Watling, L. 1989. A classification system for crustacean setae based on the homology concept. Functional morphology of feeding and grooming in Crustacea A.A. Balkema Rotterdam 15-26.
Wetzer et al. 1997 [All]: Wetzer, R., Brusca, R. C., Wilson, G. D. F. 1997. Crustacea, Isopoda. Descriptions of species of the suborders Anthuridea, Epicaridea, Flabellifera, Gnathiidea, and Valvifera. In: Blake, J.A., Scott, P.H. (ed.) The Crustacea Part 2. The Isopoda, Cumacea and Tanaiacea [Taxonomic Atlas of Santa Maria Basin and Western Santa Barbara Channel, California] Santa Barbara, California: Santa Barbara Museum of Natural History 11:5-58.
Williams, 1984 [All]: Williams, A. B. 1984. Shrimps, lobsters, and crabs of the Atlantic coast of the eastern United States, Maine to Florida. Smithsonian Institution Press, Washington, D.C. [Decapod Crustacea, east coast U.S.]
Wilson, 1989 [All]: Wilson, G. D. F. 1989. A systematic revision of the deep-sea subfamily Lipomerinae of the isopod crustacean family Munnopsidae. Bulletin of the Scripps Institution of Oceanography 27: 1-138. [Deep-sea Isopoda]