ABSTRACT
Species of the brachyuran crab genus Hexapanopeus Rathbun, 1898, are common benthic inhabitants in coastal and nearshore waters of the Americas. Despite the frequency with which they are encountered, they are taxonomically problematic and commonly misidentified by non-experts. Little previous work has been undertaken to explain relationships among the 13 nominal species of Hexapanopeus or their relationship to other phenotypically similar genera of the family Panopeidae. In the present study we examine partial sequences for 16S and 12S mitochondrial rDNA for 71 individuals representing 46 species of Panopeidae and related families of the Brachyura. Phylogenies inferred from both of these datasets are largely congruent and show, with one exception, the included genera and species of the Panopeidae to represent a monophyletic grouping. Within this group, Hexapanopeus is polyphyletic, being distributed among several separate major clades and clearly warranting taxonomic subdivision.
