a New Genus of Potamonautid Freshwater Crab from Madagascar, with Descriptions of Two New Species By

the family Potamonautidae, is redefined and restricted to only one species, M. humberti BOTT, 1965. A new genus, Skelosophusa, is established for Madagapotamon gollhardi BOTT, 1965, and two new species, Skelosophusa eumeces and S. prolixa, are described. The genus is characterized by the shape of the male abdomen, form of the anterolateral margin and shape of the carapace. Several years ago, the second author received three specimens of freshwater crabs (family Potamonautidae) collected from caves in Madagascar, all of which had very long ambulatory legs. A joint study of these crabs revealed that these specimens belonged to two undescribed species. The study also required a reappraisal of the genus Madagapotamon BOTT, 1965, and a new genus, Skelosophusa, is established here as a result of these revisions. The present paper serves to characterize this new genus and describe the two new species. The affiliations of the new genus and species are also discussed. The abbreviations Gl and G2 are used for the male first and second pleopods, respectively. Measurements, in millimetres, are of the carapace width and length