Lack of divergence between 16S mtDNA sequences of the swimming crabs Callinectes bocourti and C-maracaiboensis (Brachyura : Portunidae) from Venezuela

Lake Maracaibo, a large Venezuelan estuarine lagoon, is reportedly inhabite d by three species of the genus Callinectes Stimpson, 1860 that are importa nt to local fisheries: C. sapidus Rathbun, 1896, C. bocourti A. Milne Edwar ds, 1879, and C. maracaiboensis Taissoun, 1969. Callinectes maracaiboensis, originally described from Lake Maracaibo and assumed endemic to those wate rs, has recently been reported from other Caribbean localities and Brazil, However, because characters separating it from the morphologically similar C. bocourti are noted to be vague, we have compared these species and sever al congeners by molecular methods. Among our specimens from Lake Maracaibo and other parts of the Venezuelan coast, those assignable to C. bocourti an d C. maracaiboensis on the basis of putatively diagnostic characters in col oration and structural characteristics do not differ in their 16S mtDNA seq uences. These molecular results and our re-examination of supposed morpholo gical differences between these species suggest that C. maracaiboensis is a junior synonym of C. bocourti, which varies markedly in minor features of coloration and structural characteristics. Genetic relationships of this sp ecies to other species of swimming crabs of the genus Callinectes are also explored and presented as phylogenetic trees.