Freshwater crabs of the Potamon tannanti species group (Crustacea: Decapoda: Brachyura: Potamidae) from northern Indochina

Several species of potamid crabs with aquatic habits have been confused with Potamon tannanti Rathbun, 1904. The present study separates P. tannanti s. str., from these congeners, some of which occur in the southern Chinese province of Yunnan as well, by using carapace, gonopodal and male telson characters. Potamon tannanti is redescribed; P. orleansi Rathbun, 1904, a species previously synonymised under P. tannanti is resurrected; and four new species are described, viz., P. cua, new species, P. guttus, new species, P, ou, new species, and P. villosum, new species. An artificial key to these species is included.