Description of holotype: Carapace strongly vaulted fore and aft, and divided into areolae by wide and deep furrows, being entirely covered with more or less spongy tomentum; tomentum composed of stiff, erect, rather sparse brush-like setae, and more prominent on areolae than in furrows; each areola provided with several, or more, setae of various length; on denudation, areolae moderately convex, without granules. Detailed accounts of areolae are as follows. Frontal region not convex, with three long setae arranged transversely. Epigastric region moderately convex fore and aft as a whole, with a long and some longish setae. Protogastric region large, with ten, or more, setae of various length, being shallowly and incompletely subdivided into two for its about half by a median wide, longitudinal furrow or depression. Median gastric region barely subdivided into three, which are indicated by a tuft of some long or longish setae at each part; a longitudinal furrow from behind distinctly observable through a tomentum. Cardiac region transversely quadrilateral and not convex, with a tuft of some setae near each anterior angle, being surrounded by a deep furrow. Hepatic region convex as a whole, with a prominent tuft of longish setae, and isolated from protogastric and branchial regions and supraorbital and antero-lateral borders. Branchial region subdivided into three by oblique furrows, but last one just lateral of cardiac region not distinct; the first prominent and deeply separated from last antero-lateral tooth; posterior outer part of branchial region deeply concave dorsally for reception of last ambulatory leg.
Front declivous and cut into two lobes by a median narrow and deep notch; each lobe weakly arched laterally, being fringed with a long and some longish setae. Eyestalk covered with a tomentum and terminally provided with some longish setae. Supraorbital border also fringed with prominent setae, by which two deep notches are entirely disguised. Infraorbital border bears a small, but distinct notch near external orbital angle, being fringed with fine setae; its inner angle raised, but neither sharp nor convex ventrally. Inner angle of antennal basal segment just touched with ventral prolongation of front, orbital hiatus being thus occupied by second segment. Surfaces of pterygostomial region and third maxilliped nearly smooth only with sparse short fine hairs.
External orbital angle and three antero-lateral teeth more or less tuberculated, each with a spinule at its tip; no accessory granules or spinules on slopes.
Chelipeds heavy and unequal as usual. Merus hidden under carapace, only with setae on upper and distal borders; a subdistal and a distal spinule on upper border in smaller cheliped, but not in the larger. Outer surfaces of carpus and palm covered with a spongy tomentum implanted by stiff setae of various length; inner angle of carpus armed with a spiniform tubercle, and a smaller one at about distal one-third of inner upper border and a similar one at antero-inner part of outer surface. Outer surface of palm also tomentose, with long stiff setae, for its proximal and distal upper parts; four equidistant, spiniform tubercles on upper border, and three smaller ones in a row outside of upper border; otherwise, outer surface entirely covered with conical granules of good size. Immovable finger short, with two median large and some proximal small teeth, its lower border weakly concave in outer view; a tuft of setae at median part of outer surface in larger chela, and an additional small one in smaller chela.
Ambulatory legs comparatively stout and prominently hairy like carapace and chelipeds except for upper surfaces of meri of first three pairs. Carpus with a longitudinal furrow on its upper surface. (Takeda, 1977a)
Type locality: Ogasawara-shoto, Japan.
Range: Japan - Ogasawara-shoto (Takeda, 1977a).