Definitions

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]
(Taxon-specific: Order Cumacea) 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]
(Taxon-specific: Order Isopoda) 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]
(Taxon-specific: Order Stomatopoda) 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]
(Taxon-specific: Superorder Syncarida) 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]