(Stimpson, 1858)
The carapace is broadly subelliptical, and is broader than long, the proportion between length and width being as 1: 1.38. The upper surface is rugose and eroded, covered with mushroom-like granules everywhere. Along and parallel to the antero-lateral borders are grooves, which are pitted or eroded and also furnished with granules. The same grooves run parallel to the postero-lateral borders. The branchial regions are much projecting laterally and its inner surface somewhat convex and covered with confluent granules. The intestinal and cardiac regions are defined by the same longitudinal grooves on either side, the latter region is strongly convex. The front and also the posterior border project far beyond the general outline of the carapace.
The chelipeds are symmetrical, rugose and eroded. The immovable finger is broad and concave along the cutting edge. The dactylus is slender and curved. The ambulatory legs are tuberculated on both edges and are somewhat concealed beneath the branchial regions. The abdomen is also covered with fine granules, marked by two interrupted impressed lines along the middle line. (Sakai, 1937)
Type locality: Oshima Passage, Amami-oshima Is., Japan (neotype, see Tan & Ng, 1995).
Range: Mauritius (Bouvier, 1915b, Michel, 1964); Christmas Islands; Japan - Okinawa (Stimpson, 1858c, 1907), Kagoshima (Ortmann, 1892), Nagasaki (Sakai, 1937a, 1976), Amakusa (Miyake et al., 1962), Oshima Passage, Amami-Oshima (Takeda, 1989); Vietnam (A. Milne Edwards, 1865); Thailand; Palau (Takeda, 1973d); Singapore (Tan & Ng, 1995); Thailand (Tan & Ng, 1995); Indonesia - Sape Strait, Gisser Island, Kepulauan Kai and Roti (Ihle, 1918); New Caledonia.