| Abstract |
We investigated the taxonomic status of two sympatric morphospecies of squat lobsters from southern South
America (Beagle Channel, Strait of Magellan, and Burdwood Bank), Munida gregaria and Munida subrugosa, by
DNA sequence analysis of three mitochondrial (mt)DNA gene fragments [416 bp of 16S rDNA(165), 566 bp of
cytochrome c oxidase subunit I(COI) and 418 bp of NADH dehydrogenase subunit 1 (ND1)]; and the nuclear rDNA
internal transcribed spacer (ITS) 1 (883–952 bp). We obtained a total of 79 sequences from 32 individuals. The 16S
sequences of all M. gregaria and M. subrugosa were invariant and identical, whereas COI and ND1 showed 12 and
15 variable sites, respectively. These polymorphisms were shared between morphospecies. Interspecific Tamura–
Nei distances for COI and ND1 sequences were 0.0024 and 0.0032, respectively, and were not significantly different
from intraspecific distances (Kruskal–Wallis tests: P = 0.58 and P = 0.69, for COI and ND1, respectively). Similar
to the results obtained from the mtDNA sequences, no relationship was found between the ITS1 maximum
parsimony tree topology and the morphologic classification of specimens in M. gregaria and M. subrugosa. We
conclude that M. gregaria and M. subrugosa from southern South America may either represent a case of a
dimorphic species, or a case of incomplete lineage sorting. The fact that these two morphospecies did not show fixed
differences over a total of 1947 bp analysed reinforces the hypothesis of a single dimorphic species. |
