Ceratoplax truncatifrons Rathbun, 1914

Arzivian, Arteen, Alrubaie, Ahmad, Yang, Jessica, Lin, Huiyu, Zhang, Eva & Leong, Rupert, 2022, Crabs (Crustacea, Decapoda) from the Seas of East and Southeast Asia Collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 4. South China Sea, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (4), pp. 147-191 : 172-173

Ceratoplax truncatifrons Rathbun, 1914

( Fig. 12 )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 42, 1 8 (CB 5.3×CL 3.3 mm), NSMT-Cr 30934.

Remarks. The genus Ceratoplax is comprised of nine species ( Ng et al., 2008; Ng and Clark, 2015), each of which is superficially similar with smooth and glabrous carapace surfaces. Ng and Clark (2015) finely depicted the specific characters among C. truncatifrons Rathbun, 1914 , C. fulgida Rathbun, 1914 , and a new species named C. margarita , with many photographs and illustrations including the type specimens of Rathbun`s two species. According to Ng and Clark (2015), in C. marginata , the carapace posterolateral margin is more distinctly converging towards the carapace posterior margin, and the third maxilliped merus is auriculiform at its antero-external angle similar to that of C. fulgida , but different from the prominently elongated antero-external angle of the merus in C. truncata . It is impossible at present to apply the sex-associated characters with the female at hand, and the differences of the carapace shape may be subtle for the species identification as shown at the photographic angles ( Fig. 12A–B ). In the present female, however, the antero-external corner of the third maxilliped merus is sharply developed as in the figure given by Ng and Clark (2015, fig. 4C).

Distribution. Ng and Clark (2015) overlooked Takeda (1989) who recorded this species with fine drawings from the Oshima Passage in Amami-Oshima Island, the northern Ryukyu Islands, at the depth of 45 m. This species is otherwise recorded from the type locality (Badian Island, off western Samar, the Philippines, 58 m depth) by Rathbun (1914), the Sula Islands (east of Sulawesi, Indonesia, 22 m depth) by Tesch (1918), and the Nansha Islands (South China Sea, 97–206 m depth) by Chen (1998b). The specimens from Indonesia collected by the Siboga Expedition were re-examined and photographed by Ng and Clark (2015).

Figures

Fig. 12. Ceratoplax truncatifrons Rathbun, 8 (NSMT-Cr 30934; CB 5.3×CL 3.3mm) from sta. 42.