Cosmonotus grayii Adams, 1847

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 : 151-153

Cosmonotus grayii Adams , in Belcher, 1847

( Fig. 2A–B )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 45, 1 8 (CB 5.1×CL 6.1 mm), NSMT-Cr 30903.

Remarks. In describing the third species of the genus Cosmonotus , C. mclaughlinae, Tavares (2006) suggested that C. grayii recorded by Takeda and Miyake (1970) from Japanese waters may be referable to an unknown species different from both of C. grayii Adams , in Belcher, 1847, and C. genkaiae Takeda and Miyake, 1970 . This suggestion stemmed mainly from the fact that the supraorbital border of C. grayii was illustrated as having only one notch by Takeda and Miyake (1970: fig. 1A) for a specimen from off the Tsushima Islands, north of Kyushu. During this study, we could not re-examine the specimen reported by Takeda and Miyake (1970) and Takeda (1973b), but examined several additional Japanese specimens as follows: — Shimoda, Sagami Bay (1 8, NSMT-Cr 7913); Suruga Bay (1Ə, 1Ə infested by a Sacculina , NSMT-Cr 12054); Kushimoto, Kii Peninsula (2ƏƏ, 1 8, NSMT-Cr 6388); Tosa Bay (1Ə, NSMT-Cr 12772); West of Goto Islands (1Ə, NSMT-Cr 9789); Tsushima Islands (4 ƏƏ, 1 8, NSMT-Cr 979, 980, 982, 983). All of them proved to be referable to C. mclaughlinae , agreeing well with the accounts by Tavares (2006) and the subsequent record by Seo et al. (2018); the main part of the carapace dorsal surface is smooth, but the anterolateral portion is distinctly roughened with minute granules of irregular size, and the carapace midline is rather thickened and ridged for much of its length, somewhat like a lbackbone.z

Cosmonotus genkaiae is distinguished from two congeneric species by the characteristic dorsal sculpture of the carapace, and is currently known only from the male holotype from the Tsushima Islands and the paratype female from the East China Sea. Takeda and Miyake (1970) mentioned that one male specimen recorded by Yokoya (1933) as C. grayii is referable to C. genkaiae . The species was said to be in poor condition, but reliably identified based on the dorsal carapace sculpture. The locality is the S.S. Sôyô-Maru station 465 (north of the Goto Islands, west of Hirato, 106 m) is not far from the type locality of C. genkaiae , off the Tsushima Islands (114 m depth). Otherwise, Nagai (1991: pl. 1, fig. 4) recorded a female from off Shionomisaki, Kii Peninsula, 150 m depth, as the second record of C. genkaiae since the original description. The photograph is not clear, but the diagnostic dorsal sculpture is distinguishable. During this study, we examined a male from the East China Sea, 182– 167 m depth (NSMT-Cr 13917, Fig. 1C–D ) preserved in the Tsukuba Research Departments, National Museum of Nature and Science, Tokyo. In this specimen, the carapace dorsal surface is much more strongly striated than in the holotype, with the longer and deeper striae closely set together, and the carapace dorsal midline is weakly ridged throughout the whole length; the frontal median sinus is provided with a small tubercle ventrally, as mentioned in the original description, and the supraorbital margin is interrupted only by one notch.

The present specimen from the South China Sea is identified as C. grayii owing to the carapace dorsal sculpture being wholly and uniformly covered with small pits, the absence of the distinct median ridge on the carapace dorsal surface, and the presence of two notches on the supraorbital border, without median tubercle at the bottom of the frontal median sinus. Chen and Xu (1991) recorded C. grayii from the South China Sea, 50–138 m in depth; their figures seem to agree with the figures given by Takeda and Miyake (1970, figs. 1A, 2G–I, 3C–D). Chen and Sun (2002) also recorded C. grayii from the East and South China Seas, without definite locality of the figured specimen in the East China Sea or South China Sea, but their figures (fig. 79) are reproduced from Chen and Xu (1991).

The authorship and publication year of the genus Cosmonotus and the species, C. grayii , were clarified by Clark and Presswell (2001). The description of C. grayii appeared in two papers of same title and content, lShort descriptions of new or little-known decapod Crustacea,z published in l Proceedings of the Zoological Society of London, 15 (1847) and l The Annals and Magazine of Natural History, including Zoology, Botany, and Geology, ser. 2, vol. 2 (1848),z but their actual dates of publication were indicated by them as 29 March and October in 1848, respectively. According to Low et al. (2020), however, the brief explanations of the genus and species by Adams (1847) in Narrative of the Voyage of H.M.S. Samarang are available for the original definition and description of a new genus and a new species, Cosmonotus grayii .

Distribution. Takeda and Miyake (1970) provided the synonymy list of C. grayii known to date including the literature recording the specimens from Japanese waters ( Yokoya, 1933; Sakai, 1937, 1965). The type locality is Borneo, with a wide geographical range in the Indo-West Pacific from the West Pacific to Western Australia and to the east coast of Africa and the Red Sea, with a bathymetric range of 30– 212 m. There may be some misidentifications with C. mclaughlinae from the West Pacific, and therefore the specimens from Taiwan, the Philippines, and the South China Sea should be re-examined to determine whether both species are sympatric, parapatric or allopatric in their distributional patterns.

Figures

Fig. 2. A–B: Cosmonotus grayii White, 8 (NSMT-Cr 30903; CB 5.1×CL 6.1mm) from sta. 45. C–D: Cosmonotus genkaiae Takeda and Miyake, Ə (NSMT-Cr 13917; CB 14.2×CL 19.4mm) from the East China Sea, 182–167m depth.

Fig. 1. A: Mclaydromia colini Guinot and Tavares, 8 (NSMT-Cr 30898; CB 13.1×CL 15.0mm including pseudorostral teeth) from sta. 45. B: Mursia australiensis Campbell, juv. (NSMT-Cr 30905; CB 8.2mm excluding lateral tubercles, CL 7.4 mm) from sta. 52. C: Podophthalmus nacreus Alcock, 8 (NSMT-Cr 30925; CB 11.0×CL 7.1mm) from sta. 45. D: Lissocarcinus arkati Kemp, 8 (NSMT-Cr 30921; CB 9.8×CL 8.7mm) from sta. 45. E–F: Parilia pattersoni Ng, Devi and Kumar, juv. (NSMT-Cr 30906; CB 5.6×CL 6.6mm including posterior median tubercle) from sta. 42.