Molecular barcode and morphological analyses reveal the taxonomic and biogeographical status of the striped-legged hermit crab species Clibanarius sclopetarius (Herbst, 1796) and Clibanarius vittatus (Bosc, 1802) (Decapoda: Diogenidae)

The taxonomic status of the species Clibanarius sclopetarius (Herbst, 1796) and Clibanarius vittatus (Bosc, 1802), which have sympatric biogeographical distributions restricted to the western Atlantic Ocean, is based only on differences in the colour pattern of the walking legs of adults. Their morphological similarity led to the suggestion that they be synonymised. In order to investigate this hypothesis, we included species of Clibanarius Dana, 1892 in a molecular phylogenetic analysis of partial sequences of the mitochondrial 16S rDNA gene and the COI barcode region. In addition, we combined the molecular results with morphological observations obtained from several samples of these two species. The genetic divergences of the 16S rDNA and COI sequences between C. sclopetarius and C. vittatus ranged from 4.5 to 5.9% and 9.4 to 11.9%, which did not justify their synonymisation. Differences in the telson morphology, chela ornamentation, and coloration of the eyestalks and antennal peduncle provided support for the separation of the two species. Another interesting result was a considerable genetic difference found between populations of C. vittatus from Brazil and the Gulf of Mexico, which may indicate the existence of two homonymous species.

A review of the genus Speocarcinus Stimpson, 1859 (Crustacea: Brachyura: Xanthidae), with a key to its species and the description of one new species

Speocarcinus dentatus n. sp. is described from the southwestern Atlantic. The new species can be easily separated from its congeners by a suite of carapace and appendage characters. Speocarcinus Stimpson, 1859, now includes eight extant species, all from the Atlantic or Pacific coasts of the Americas. Additional characters to further differentiate between S. carolinensis Stimpson, 1859, and S. lobatus Guinot, 1969, and between S. granulimanus Rathbun, 1894, and S. spinicarpus Guinot, 1969 are documented. The lectotype of S. granulimanus is first described and a key to the species of Speocarcinus is provided.