de Haan, 1837
Description of male: The carapace elongate triangular in outline, the dorsal surface markedly depressed and flattish. The gastric region has three tubercles placed in a triangle, the base forwards; the cardiac region mounted with a conical tubercle. The antero-lateral border has two lobules, the anterior or hepatic one being usually smaller and very often quite rudimentary, the posterior or branchial one being usually laterally produced but it forms sometimes only an angle. The pseudorostrum is very long and laterally compressed, haired on both borders. The preocular tooth distinct but no other orbital teeth, the eyes being non-protected and lodged in circular rudimentary orbits on the lateral vertical surface of the neck.
Chelipeds are stouter than any of the ambulatory legs but a little shorter than the first leg; the arm is smooth or indistinctly tuberculated on upper surface and is cristate along the upper distal border and also sometimes along the inner border. The wrist with its outer border cristate, the palm laterally compressed with the superior and inferior borders sharply cristate, the fingers gaping at base, the movable finger being armed with a large tooth near the base. Ambulatory legs are also compressed and cristate on both borders.
Abdomen distinctly seven-segmented.
Description of female: The carapace is broader in proportion to the length, the pseudorostrum being much shorter than that of male, the preocular tooth placed not far in front of the eyes. The gastric region has only one median tubercle, the cardiac tubercle not very prominent. Of the two laminar projections on the antero-lateral borders, the anterior or the hepatic lobe is very large and broad, upturned at the lateral margin, the posterior or branchial lobe is usually smaller and laterally truncate. Chelipeds are not much stouter than the ambulatory legs, which are also compressed and cristate on both borders.
Abdomen consists of five pieces, the fourth to sixth being fused together. (Sakai, 1938: 264)
Type locality: Japan.
Range: Kenya - Mombasa (Griffin, 1974); Seychelles (Rathbun, 1911); Mauritius (Michel, 1964); Andamans (Alcock, 1895a); Japan - Katsuyama (Ortmann, 1893), Shimoda (Sakai, 1935), Tokyo Bay, Sagami Bay, Shimoda, Ise Bay, Kii Peninsula and Nagasaki (Sakai, 1938a), Hachijo-jima (Sakai, 1954), Sagami Bay (Sakai, 1965b), Tokyo Bay, Sagami Bay, Izu Peninsula, Mikawa Bay, Shima Peninsula, Kii Peninsula, Tosa Bay, Nagasaki, Amami-shoto and Yaeyama-retto (Sakai, 1976a), Koza, Kii Peninsula (Miyake, 1983), Sagami Bay (Griffin & Tranter, 1986a); Korea - Cheju-do (Kim, 1973); Taiwan; China - Guangdong (Dai & Yang, 1991); Sulu Archipelago - Jolo, near Siasi and Tawitawi Group (Griffin, 1976), Pearl Bank, north-east of Siasi and Tawitawi Bay (Griffin & Tranter, 1986a); Palau (Takeda, 1973d); Indonesia - Postillon Islands, Flores Sea (Griffin & Tranter, 1986a); Arafura Sea (Miers, 1886); Australia - Cape York (Miers, 1886), Cape Jaubert (Rathbun, 1924c), Maud's Landing, Gordon Bay, Dampier Archipelago, Broome and Point Cloates, W.A. (Griffin & Tranter, 1986a), Heron Island, Queensland (Griffin & Tranter, 1986a); Hawaiian Islands - Sandwich Island (Dana, 1852), Molokai, Auau Channel, Laysan, French Frigate Shoal, and Modu Manu (Rathbun, 1906); Kermadec Islands (Chilton, 1911); 0-36 m.