(Fabricius, 1781)
Carapace about 1.6-1.8 times as broad as long, lateral and posterior portions quite expanded, pentagonal in outline and completely hiding ambulatory legs and abdomen. Dorsal surface smooth, median portion elevated and triangular; gastric region depressed, with a granulated crest on each side, obliquely extending postero-laterally; hepatic region depressed. Front produced and triangular, lateral margin slightly convex and indistinctly serrated. Orbit small and rounded. Antero-lateral margin concave behind the hepatic region and with irregular serrations. Posterior and postero-lateral margins continued and arched, cut into several obtuse teeth by shallow fissures.
Chelipeds stout and asymmetrical. Merus flat; its anterior margin crestiform, armed with 3 large teeth and several denticles; its posterior margin convex outwards forming triangular lobes. Carpus small. Palm flat, with 5 acute teeth on the dorsal crest, 2 triangular teeth on the outer and with obtuse teeth on the inner margin. Fingers of major chela obtuse on the inner margin; the minor chela with several blunt denticles. Ambulatory legs slender, decreasing in length from front to rear.
Basal half of the first pleopod of the male stout, distal half tapering; apex fork-shaped. Male abdomen narrow and elongate; third to fifth segments fused together, suture recognizable; sixth segment about twice as broad as long; telson triangular. Carapace length of the male 67.8 mm, breadth 38.5 mm; of the female, length 63.7 mm, breadth 40.5 mm.
Habitat: broken shelly and muddy-sandy bottoms, 25-30 m deep. (Dai & Yang, 1991)
Type locality: Tranquebar, south-eastern India.
Range: Persian Gulf (Alcock, 1895a); India - Palk Strait (Alcock, 1895a); Sri Lanka; Andaman Islands (Alcock, 1895a); Gulf of Martaban; Japan - (de Haan, 1837), Sagami Bay (Ortmann, 1893, Sakai, 1976a); Taiwan - Tingch'ieting (Lin, 1949); China - Hong Kong (Stimpson, 1907), Guangdong including Hainan Island and Fujian (Dai & Yang, 1991); Gulf of Thailand; Malaysia - Kota Baharu, Kelantan (Lanchester, 1902); Singapore (Dana, 1852, Nobili, 1903c); South China Sea - Nansha Islands (Chen & Xu, 1991); Philippines; Indonesia - Makassar and Java Sea (Flipse, 1930); south of New Guinea (Miers, 1886); Australia.