(Sakai, 1938)
The new species here described apparently approaches ceratocarcinus intermedius Zehntner and also somewhat Ceratocarcinus dilatatus A.M. Edwards, so that the comparison of some points of difference among them will suffice to recognize the new species.
1. The elevations of the dorsal surface of carapace almost identical with those of C. dilatatus, i.e., a pair of large obtuse and granulated ones placed on the anterior surface of the gastric region, a pair of very small ones each on metagastric and cardiac region, also a pair of similar ones in front of the said gastric pair, and lastly, a medium-sized one on each branchial region.
2. The rostrum resembles that of C. dilatatus, the median lobes being subtruncate and marked by a median notch; while the outer spines are separated from the former by a distinct notch and pronouncedly project forwards. In the case of Ceratocarcinus intermedius (if the figure of Zehntner be reliable) the rostral lobes are composed of two widely separated spines, the median truncate lobe and the lateral acuminate tooth being confluent and not divided by a notch.
3. The antero-lateral borders much resemble those of Ceratocarcinus intermedius, being composed of three confluent and granulated lobes and one salient lateral spine; the first lobe very small, the second and third lobes subequal but the latter is salient at the posterior angle which is divided from the lateral spine by a very narrow V-shaped sinus. The postero-lateral borders are slightly convex; the posterior border is almost straight.
4. The inferior inner orbital tooth is long and tuberculated, between it and the first lobe of the antero-lateral border is a large elevation which is also granulated. The anterior boundary of the buccal cavern of this species is composed of four granulated lobes, while that of Ceratocarcinus intermedius is almost entirely confluent (if the figure of Zehntner be reliable).
5. Chelipeds are thickly granulated under the lens, the arm, wrist, and palm are roughly sulcated along the upper border. The first ambulatory leg distinctly slenderer and longer than the succeeding ones, which are thick and subequal in length. Merus of all pairs not armed. (Sakai, 1938)
Type locality: Shimoda, Japan.
Range: Japan - Shimoda and Tateyama Bay (Sakai, 1938a), Sagami Bay (Sakai, 1965b), Tokyo Bay, Sagami Bay, Izu Peninsula, Kii Nagashima, Kii Minabe and Tosa Bay (Sakai, 1976a), Hirado, Kushimoto, Hayama, and Izu-Oshima (Chia & Ng, 1998); China - Fujian (Dai et al., 1986).