Two new species of freshwater crab (Crustacea: Decapoda: Potamidae) from Tokashiki Island, central Ryukyu Islands, Japan

Abstract

Two new species of freshwater crabs are described from Tokashiki Island, the central Ryukyu Islands, Japan. Candidiopotamon tokashikense sp. nov. can be distinguished from the closest congener, C. kumejimense, by the shape of the terminal segment of the male first gonopod and the armature of the outer dorsal margin of the second ambulatory propodus. Amamiku occulta, sp. nov. is differentiated from its only congener, A. amamensis, by the shape of the terminal segment of the male first gonopod and the form of the supraorbital margin of the carapace. Candidiopotamon tokashikense and A. occulta are superficially very similar, but they can be differentiated from each other by the relative length of the antenna, the shape of the male first gonopod, and the relative width of female abdominal segments. A key to the species of Candidiopotamon and Amamiku is provided. © The Natural History Museum 2007.