Molecular phylogeny of mud crabs (Brachyura : Panopeidae) from the northwestern Atlantic and the role of morphological stasis and convergence

Mud crabs of the family Panopeidae are common organisms in coastal soft-bot tom, vegetated rubble, and oyster-bed communities along the temperate and t ropical coastlines of the American continent. Similar morphology among many species renders their distinction and classification difficult. Here, we p resent phylogenies of western Atlantic Panopeidae based on DNA sequences of the mitochondrial large subunit rRNA (16S; 529 basepairs) and cytochrome o xidase I (COI; 640 basepairs) genes. Results suggest that the speciose gene ra Panopeus and Eurypanopeus are not monophyletic and that their taxonomy d oes not accurately reflect evolutionary partitions. In two cases (P. herbst ii complex and E. depressus and allies), the molecular findings strongly su pport sister-species relationships that differ from previous morphology-bas ed assumptions. We suggest that convergence or morphological stasis are res ponsible for the phenotypic similarities between divergent evolutionary lin eages.