Two new species and the molecular phylogeography of the freshwater crab genus (Crustacea: Decapoda: Brachyura: Potamidae).

sp. n. and sp. n. are described from Hunan Province and Jiangxi Province, respectively. These species both have diagnostic features of the genus and discernible characteristics as new species. sp. n. can be distinguished from co-geners by features such as the G1, which has a fold covering the surface of the entire subterminal article with a distal region. sp. n. has an elliptical carapace, and a sturdy and blunt terminal article of G1. The molecular phylogeny and biogeography of the genus (Decapoda: Brachyura: Potamidae) were studied, using mitochondrial cytochrome oxidase I (mtDNA COI), 16S rRNA and nuclear histone H3 gene fragments. The results support the assignment of the two new species to the genus . In addition, the divergence time of the genus was estimated to be 3.49-1.08 Ma, which coincided with various vicariant and dispersal events that occurred in the geological area where the genus is commonly distributed. Mountains appear to have played an important role in the distribution of this genus. The Wuyi Mountains gradually formed offshore and inland of southeastern China by the compression of the Pacific plate and the Indian plate in the Neogene-Quaternary, and the Luoxiao Mountains formed continuously in the continued forming in the north-south direction because of neotectonic movement, have resulted in the geographical distribution pattern of the genus , which was also established gradually.