(Sakai, 1965)
The new species is related to Parthenope nummifera, but the entire body is smooth and the carapace less markedly granulated. The carapace is as long as broad, but it looks rather oblong, because of its hepatic and orbitofrontal portions markedly convergent anteriorly. On the dorsal surface, the gastric region is moderately convex and mounted with a tubercle, the cardiac region is ill-defined and depressed, while the intestinal region is strikingly convex and conical, also mounted with an obtuse tubercle. The front is well produced forwards and obliquely downwards, its distal portion obtusely triangular in shape, and its dorsal surface sulcated.
The antero-lateral borders are moderately convex; the hepatic margin is unarmed and smooth, and the branchial margin armed with nine teeth, all similar in shape and their tips obtuse. Below the hepatic border can be seen a series of tubercles, which grow on the ridge extending from the antero-external angle of the buccal cavern towards the subbranchial area.
The postero-lateral borders are rather convex, and a prominent process is found growing close to the postero-lateral angle of the carapace. The dorsal branchial carina ends at the base of this process, and an interval is formed between this process and the last antero-lateral tooth; two or three additional tubercles may be seen between this process and the lateral angle of the posterior border.
The chelipeds are strikingly long - more than three times the length of the carapace; the merus bears 20 or so teeth along the anterior border, which are alternately different in size; its posterior border bears 6 or 7 teeth near its proximal half; and the propodus bears 5 or 6 prominent processes on the outer border, and 2 or 3 on the inner border.
The ambulatory legs are extremely slender and rather depressed; the borders, both anterior and posterior of the merus, and the anterior border of the carpus are elegantly denticulated; in the last pair, the anterior border of the propodus is also denticulated.
The segments of the sternum, the abdominal tergum, and the external maxillipeds are all closely and evenly granulated. (T. Sakai, 1965: 94)
Type locality: Amadaiba, off Hayama, Sagami Bay, Japan, 65 m.
Range: Japan - Sagami Bay (Sakai, 1965b, 1976), Shiono-misaki (Takeda, 1979a); South China Sea (Dai & Yang, 1991).