Rathbun, 1909
Carapace is transversely cylindrical and the lateral borders only slightly divergent posteriorly; the dorsal surface is markedly convex from before backward but almost flat from side to side. The front is medially marked by a shallow sinus, the free margin of each lobe being rounded and well convex and projecting downwards. Orbits are circular, into which the eyes are completely embedded. The anterior half of the lateral border is furnished with some hairs but is never lobulate or dentate. The flagellum of antenna very slender and long, without any longish hairs on each segment.
The cheliped of right side is slightly heavier than that of the opposite side; the wrist has an obtuse tooth at inner angle; the palm is covered with fine granules and tomentum near the superior and inferior borders but the middle portion of the outer surface is smooth. The first and fourth ambulatory legs are subequal and shorter than the second and third pairs which are also subequal. The first tergum of male abdomen is extremely broad and extends along the posterior border and covers the whole extent of the last sternal segment. (T. Sakai, 1939: 571)
Type locality: Gulf of Thailand.
Range: Gulf of Thailand (Rathbun, 1909); Japan - Shimoda (Sakai, 1939), Izu Shimoda and Tosa Bay (Sakai, 1976a), Amakusa (Yamaguchi et al., 1976), Yamagata Prefecture (Suzuki S., 1979), off Matsuyama, Seto Inland Sea (Takeda et al., 2000); China - Fujian and Shandong (Dai & Yang, 1991); Philippines - south of Manila Bay (Serène & Vadon, 1981); Indonesia - off Edam Island, Jakarta (Serène, 1964); 30-50 m.