(Stimpson, 1858)
Very closely related to Actumnus squamosus, but the regions of carapace are much less demarcated. The wrist is only sparingly tuberculated near the distal surface; the entire outer surface of palm is covered with distant and pearly granules, but not so thickly as to conceal its proper surface, those on the dorsal proximal surface are covered with tomentum, and those near the fingers are more or less worn out. In the minor cheliped, the immovable finger is armed with about 6 or 7 triangular teeth, the movable finger with about 6 broad and flat teeth; in the case of A. squamosus, these two segments are furnished with very broad and ill-separated lobules. The merus of external maxilliped is much broader than the ischium. (T. Sakai, 1939: 528)
Type locality: Amami-Oshima, Japan.
Range: Japan - Amami-Oshima (Stimpson, 1907), Bingo (Balss, 1922c), Sagami Bay (Sakai, 1965b), Sagami Bay and Nagasaki (Sakai, 1939), Hachijo-jima (Sakai, 1954), Tosa Bay and Ogasawara-shoto (Takeda & Miyake, 1969c), north off Tsushima and Tsushima Strait (Takeda, 1973c), Sagami Bay, Shimoda, Kii Nagashima, Kii Minabe, Tosa Bay, Nagasaki and Yoron-jima (Sakai, 1976a); East China Sea (Takeda & Miyake, 1968c, Takeda, 1975a); South China Sea - near Hong Kong (Garth & Kim, 1983); Philippines - between Burias and Luzon, Balabac Strait, and between Samar and Leyte (Garth & Kim, 1983); Sulu Archipelago - Jolo and Sirum (Garth & Kim, 1983); Indonesia - Buton Strait (Garth & Kim, 1983).