(Stimpson, 1858)
Closely resembles Actumnus setifer, but the lobules of carapace are more convex and well demarcated; 3M is distinctly divided by a median groove and a groove found immediately behind 1P is deeper than in setifer. Antero-lateral borders are cut into four acuminate teeth and the two frontal lobes much like those of setifer. Chelipeds are markedly unequal than in setifer, wrist bears fewer granules beneath the tomentum, palm also covered with fewer granules on the outer surface, where the tomentum extends from the entire proximal surface obliquely toward the distal upper surface, the remainder of the surface is quite naked. Ambulatory legs are rather more slender, each segment being only sparingly fringed with hairs; the propodus of the anterior three pairs has a longitudinal row of hairs on the dorsal surface, but this character was not mentioned by the original author. (T. Sakai, 1939: 529)
Type locality: Hong Kong.
Range: Japan - Sagami Bay and Nagasaki (Sakai, 1939, 1976), Sagami Bay (Sakai, 1965b), off Fukuma, Fukuoka Pref., Nagasaki and Amakusa-shoto (Takeda & Miyake, 1969c), north off Tsushima and Genkai-nada (Takeda, 1973c), Kii Minabe and Ishigaki-jima (Sakai, 1983), Oshima Passage, Amami-Oshima (Takeda, 1989), Manazuru, Hatsushima, and Tosa Bay (Muraoka, 1998); Hong Kong (Stimpson, 1907); Philippines - Manila Bay, eastern Palawan and S. Fernando Pt. (Garth & Kim, 1983); Borneo - Sandakan Light (Garth & Kim, 1983); Indonesia - Buton Strait (Garth & Kim, 1983).