Takeda & Miyake, 1968
Carapace convex, smooth, ill-defined, thinly covered with fine short hairs mixed with longish tufts of plumose hairs. Antero-lateral border at external orbital angle; first tooth with two or three accessory spinules posteriorly; following two teeth equal to each other, curved forward. Subhepatic region minutely granulated. Chelipeds distinctly unequal; merus short, stout, with terminal and subterminal spines on upper margin; carpus with thick conical granules interspaced with rather scant setae, small carpus with sharper granules and denser setae; larger palm heavy, with conical granules on upper surface and outer proximal portion; smaller palm with sharp granules and setae in some rows. Ambulatory legs thinly covered with setae mixed with scant plumose ones; each merus of first three pairs with five or six small granules on upper margin; each merus and carpus with a terminal spine. (Takeda, 1998)
Description of holotype: The carapace is convex fore and aft, smooth and ill-defined; the surface is thinly covered with fine short hairs mixed with scant longish ones and with some tufts of plumose hairs. The front is declivous and cut into two rounded lobes, each lobe being fringed with spiniform granules and bearing a more prominent lateral spinule. The supraorbital border is minutely spinulated and nearly entire or bears two shallow depressions. The infraorbital border is also spinulated, the inner five or six of those spinules being more prominent. The inner angle of the basal antennal segment is just touched with the ventral prolongation of the front, its outer angle being raised slightly higher than the inner infraorbital angle; the second and third antennal segments are nearly equal in length, but the former is much stouter.
The antero-lateral border is armed with three spine-tipped teeth; the external orbital angle is spine-tipped and provided with one or two accessory spinules behind the main spine; the first is also provided with two or three accessory spinules; the following two are nearly equal and bears no accessory spinules, each spine being curved forward at the tip. The subhepatic region is minutely granulated. The postero-lateral border is longer than the antero-lateral and moderately inclined.
The chelipeds are distinctly unequal, the right one being larger; the merus is short, stout and armed with the terminal and subterminal spines on the upper border; the carpus of the larger cheliped is thickly covered with conical granules interspaced with rather scant setae on the outer surface, its inner angle being armed with a sharp conical granule of good size; the smaller carpus is armed with sharper conical granules and denser setae than in the larger one; the palm of the larger chela is heavy and armed with granules like the larger carpus on the upper surface and the outer proximal portion, the remainder of the surface being glossy; the smaller palm is provided with sharp granules of good size and with setae or longish hairs except for the inner surface, those granules or spinules on the outer surface being distinctly beaded to some longitudinal rows; the fingers of the larger chela are heavy; the cutting edge of the movable finger is bluntly toothed, the inner two teeth being molar-like, and the cutting edge of the immovable one is provided with a larger tooth in the middle and some smaller ones on both sides of the main tooth; the smaller chela is sharply toothed on the cutting edges.
The ambulatory legs are thinly covered with setae or simple longish hairs mixed with scant plumose ones; each merus of the first three pairs bears five or six small granules on the upper border, of which two or three are slightly prominent; the upper border of the last merus is nearly entire; in addition, each merus including the last is armed with a terminal spine; each carpus also bears a terminal spine. (Takeda & Miyake, 1968a)
Type locality: off Ototo-jima, Ogasawara-shoto, Japan.
Range: Japan - Ogasawara-shoto (Takeda & Miyake, 1968a).