Taxonomic status of two South American sympatric squat lobsters, Munida gregaria and M. subrugosa (Crustacea: Decapoda: Galatheidae), challenged by DNA sequence information.

PÉREZ-BARROS, P., D´AMATO, M.E., GUZMÁN, N.V., LOVRICH G.A.

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

Blackwell Publishing

Año: 2007

0024-4066

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 M. subrugosa, by DNA sequence analysis of three mtDNA gene fragments (416 bp of 16S, 566 bp of COI and 418 bp of ND1); and the nuclear rDNA ITS1 (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 analyzed reinforces the hypothesis of a single dimorphic species.