| Abstract: | One species of Trichodactylidae and four species of Pseudothelphusidae are present on continental islands in three areas of Central and South America. (1) Trinidad and Margarita Island have, in common with the Venezuelan mainland, the pseudothelphusid Eudaniela garmani (Rathbun, 1898); additionally, Trinidad shares with the mainland the trichodactylid Dilocarcinus dentatus (Randall, 1839). These disjunct distributions can be attributed to changes in sea level during the Quaternary, but the presence of the endemic pseudothelphusid Microthelphusa odaelkae (Bott, 1970) in Trinidad probably reflects an older connection with the continent. (2) A new species, Potamocarcinus roatensis, was found on Roatan Island, off the coast of Honduras. A cladistic analysis of the genus Potamocarcinus (H. Milne Edwards, 1853) revealed a close association of P. roatensis with P. magnus (Rathbun, 1896), a widely distributed Central American pseudothelphusid. Possibly both species originated in a pre-Quaternary vicariant event. (3) Another pseudothelphusid, Hypolobocera gorgonensis von Prahl, 1983, inhabits disjunct areas on Gorgona Island, off the Pacific coast of Colombia, and on the mainland of Ecuador, reflecting either a wider distribution before the last Holocene transgression or accidental dispersal through natural rafts. |
