de Haan, 1841
The carapace is slightly longer than broad, but it appears rather broader than it really is owing to the short postocular neck. The upper surface is smooth but it is minutely punctate toward the anterior surface. The front is proportionally broad and thick, its free edge is very obtusely truncate. The junctions of the antero-lateral and postero-lateral borders are somewhat angular, and marked by granules of a larger size than in Leucosia longifrons. The form of the thoracic sinus will be best understood by a reference to text-fig. 26d.
The endopodite and exopodite of the external maxillipeds are distinctly punctate; ischium is not fringed with hairs along the inner border.
Chelipeds are massive, the tubercles found on the arm are somewhat coarser than those of longifrons; its under surface is also beaded with such tubercles. Along the inner border of wrist and palm, there is a row of low tubercles.
The anterior pleopod of male will also serve to distinguish this species from the next species as shown in text-fig. 28.
In a fresh specimen, there are three yellowish spots on either side of the gastric region, the anterior one is smaller and approach each other. There are also two large light yellowish mottles, one on either side of the cardiac region. In the young stage, the yellowish carapace is traversed by a number of longitudinal reddish stripes and the spots or mottles above mentioned are not revealed. (Sakai, 1937)
Type locality: Japan.
Range: India - Coromandel coast (Alcock, 1896), Gulf of Mannar (Laurie, 1906); Sri Lanka (Laurie, 1906); Japan - (de Haan, 1841), Tokyo Bay (Ortmann, 1892), Sagami Bay, Suruga Bay, Omae-zaki, Tanegashima, Bungo Strait, Kii Strait, Ariake Bay, Kagoshima, Tsushima, Goto-retto, and Nagato (Yokoya, 1933), Manazuru (Sakai, 1935), Sagami Bay, Nanki Shirahama and Nagasaki (Sakai, 1937a), Amakusa and Toyama (Miyake et al., 1962), Sagami Bay (Sakai, 1965b), Tsushima Strait (Takeda, 1973c), Tokyo Bay, Sagami Bay, Ise Bay, Wagu, Kii Nagashima, Kii Minabe, Tosa Bay, and Nagasaki (Sakai, 1976a), Shiono-misaki (Takeda, 1979a), Kii Minabe (Miyake, 1983); Korea - Cheju-do (Kim, 1973); East China Sea (Takeda & Miyake, 1970a); Hainan Island (Shen, 1936, 1940b); Gulf of Tongking (Zarenkov, 1990).