(Herbst, 1783)
The carapace is elongate rhomboidal in outline, and its upper surface strongly convex, with no indication of the regions. The edge of the front is obtusely triangular and slender, the postorbital region forming a rather long "neck" which projects obliquely upwards. The hepatic regions are very slightly convex. The lateral angles of the branchial regions are sinuous and beaded with flat tubercles forming a roof overhanging the thoracic sinus. The true postero-lateral borders are smooth and convex, while the epimeral edges are obtusely ridged, the ridge being defined by flat granules. The posterior border is rounded and defined by microscopically granulated ridge continued from the epimeral ridge; below this ridge, the posteriorly deflexed surface is thick and quite smooth. The lower surface of the carapace is smooth and polished.
The chelipeds are robust and symmetrical; the arm is somewhat depressed and its upper and lower surfaces covered with several granules toward the proximal end; its anterior and posterior borders are also defined by a distally incomplete row of tubercles. The wrist is small and quite smooth; palm is broad and horizontally depressed, its inner and outer edges are usually smooth and obtuse, but in a juvenile form, they are considerably thinner and sharper. The fingers are distinctly shorter than the palm and their cutting edges are crenulate only in the distal two thirds.
The ambulatory legs are stout and regularly decrease in length; each segment is quite smooth and cylindrical, but the propodus and dactylus are compressed, the latter being longer than the former and is lanceolate in shape.
The abdomen of male consists of five pieces (not four pieces as observed by previous authors !), its formula being as 1 + 2 + R + 6 + T, the second tergum is very short and only its middle point is visible from outer side. Abdomen of female consists of four pieces. (Sakai, 1937)
Type locality: Ambon, Indonesia.
Range: Madagascar - Nosy Bé (Lenz & Richters, 1881); Mauritius (Bouvier, 1915b, Michel, 1964); Persian Gulf (Alcock, 1896, Stephensen, 1945); Pakistan - Karachi (Kazmi & Tirmizi, 1990); Sri Lanka (Miers, 1877b, Alcock, 1896); Andaman Islands (Alcock, 1896); Mergui Archipelago (Alcock, 1896); Japan - (de Haan, 1841), Sagami Bay, Tanagawa, and Kagoshima (Ortmann, 1892), Inubo-zaki, Uwajima, Suruga Bay, Omae-zaki (Yokoya, 1933), Shimoda (Sakai, 1935), Tateyama Bay, Manazuru, Shimoda, Suruga Bay, Ise Bay, Nanki Shirahama, Gobo, and Nagasaki (Sakai, 1937a), Amakusa, Sea of Ariake, Tsuyazaki, Fukui, Toyama, and Niigata (Miyake et al., 1962), Sagami Bay (Sakai, 1965b), Inubo-zaki, Tokyo Bay, Sagami Bay, Mikawa Bay, Wagu, Kii Nagashima, Kii Minabe, Tosa Bay, Oga Peninsula, Noto Peninsula, coast of Fukui, Yonago, and Nagasaki (Sakai, 1976a), Amakusa (Yamaguchi et al., 1976), Ogasawara-shoto (Takeda & Kurata, 1977), Yamagata Prefecture (Suzuki S., 1979), Shiono-misaki (Takeda, 1979a), Tanabe Bay (Miyake, 1983), Oshima Passage, Amami-Oshima (Takeda, 1989), off Matsuyama, Seto Inland Sea (Takeda et al., 2000); Korea - Seongsanpo, Namcheon Dong, and Hae-undae (Kim, 1973); Taiwan; China - Guangdong (Dai & Yang); Gulf of Tongking (Zarenkov, 1990); Philippines - sout of Manila Bay (Serène & Vadon, 1981); Indonesia - Ambon; Australia - Port Jackson (Haswell, 1879b), Port Jackson and South Australian coast (Miers, 1886), Lizard Island (Miers, 1877b), Dampier Archipelago, Flying Foam Passage, Mermaid Strait, Onslow, Peak Island, Port Jackson, Port Denison, and Bowen (Tyndale-Biscoe & George, 1962); New Caledonia - Ilot Maitre (Takeda & Nunomura, 1976); Fiji (Tyndale-Biscoe & George, 1962); 15-80 m.