(de Haan, 1835)
The carapace is somewhat rhomboidal, its extreme length a little exceeds its breadth excluding spines. The upper surface is covered with minute granules, which are visible to the naked eye. There are seven prominent spines on the margins of the carapace, one at each lateral angle of the branchial region is most prominent, directing obliquely backward at the base and curved forward at the tip. The other five spines are almost equal in size and rather small, one in the median line belongs to the intestinal region and is curved forward at the tip, one on each side of the posterior border and another on each postero-lateral border a little posterior to the middle point. The front markedly produced forward and is truncate, with a distinct median fissure. The subhepatic regions are weakly swollen. The infraorbital lobes and the anterior boundaries of the pterygostomial regions are as in Arcania undecimspinosa. The external maxillipeds have the merus exceedingly short, less than half the length of the ischium measured along the inner border; their exopodite is long and exceeds the tip of the merus.
Chelipeds resemble those of Arcania undecimspinosa but the granules found on the arm are very small, and are mainly confined to the proximal surface. The merus of the ambulatory legs are microscopically granulated, but the remaining segments are smooth, the dactyli are fringed with hairs on both borders. (Sakai, 1937)
Type locality: unknown.
Range: Japan - Inland Sea (de Man, 1907), Fukuura (Sakai, 1935), Sagami Bay, Gobo, Onomichi and Nagasaki (Sakai, 1937a), Amakusa, Sea of Ariake, Tottori, and Toyama (Miyake et al., 1962), Sagami Bay (Sakai, 1965b), Sagami Bay, Kii Minabe, Tosa Bay and Nagasaki (Sakai, 1976a), Amakusa (Yamaguchi et al., 1976), Yamagata Prefecture (Suzuki S., 1979), Tosa Bay (Miyake, 1983); Taiwan - Hsiak'unhsen and Tingch'ieting (Lin, 1949); China - Guangdong including Hainan Island, Zhejiang (Dai & Yang, 1991); Nansha Islands (Yang & Dai, 1994); Singapore; Gulf of Thailand (Rathbun, 1909); Australia - near Moreton Bay, Queensland, and Arnhem Bay, N.T. (Campbell, 1971); 10-150 m.