NOTES ON THE AND DISTRIBUTION OF TWO CLOSELY RELATED SPECIES OF GHOST , SINENSIS AND O. CORDIMANUS (, BRACHYURA, )

BY

J.-F. HUANG1), S.-L. YANG2) and P. K. L. NG 3) 1)Department of Aquaculture, National Kaohsiung Institute of Marine Technology, 142 Hai Chuang Road, Nan-Tzu District, Kaohsiung, Taiwan 811, Republic of China 2) Beijing Natural History Museum, Beijing 100050, China 3) Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore

ABSTRACT

The identities of two closely related Indo-West Pacific species of ghost crabs, Ocypode sinensis Dai, Song & Yang, 1985, and O. cordimanus Latreille, 1818, are clarified. These two species are different not only in various external characters, but also in the structure of their gastric mills. The distribution of O. sinensis is now extended to include India, Peninsular Malaysia, Taiwan, Japan, and the Philippines.

RÉSUMÉ

L'identité de deux espèces proches d'Ocypodidae de l'Indo-Ouest Pacifique, Ocypode sinensis Dai, Song & Yang, 1985, et O. cordimanus Latreille, 1818, est clarifiée. Ces deux espèces diffèrent non seulement par différents caractères externes, mais également par la structure de leurs moulins gastriques. La répartition de O. sinensis est ainsi élargie, incluant l'Inde, la péninsule Malaise, Taiwan, le Japon et les Philippines.

INTRODUCTION

Although the ghost genus Oc_ypode is relatively speciose in the Indo-West Pacific, only two species, Ocypode cordimanus Latreille, 1818, and O. sinensis Dai, Song & Yang, 1985, are known to lack a stridulatory ridge on the inner surface of the chela. Although O. cordimanus has been reported from a very wide area from the Indian Ocean to the central Pacific (Sakai & Turkay, 1977a, b; Turkay et al., 1996), O. sinensi.s thus far has been reported only from China (Dai & Yang, 1991 ). 943

In Taiwan, 0. cordimanu.s is the only non-stridulatory species which has been reported and it is a common species throughout the island, especially in the south (Huang et al., 1992). The species is also relatively common in Singapore and Peninsular Malaysia. In mid-1997, the third author noted that the specimens of "O. cordimanus" from Taiwan and Singapore differed in adult size, live colours, and several morphological features, which suggested that two species were in- volved. Recently, the three authors had a chance to make joint comparisons of material of non-stridulatory Ocypode in our individual collections from mainland China, Taiwan, various parts of Southeast Asia, as well as India. This allowed us to reappraise the taxonomy of these two closely related species. Both species are clearly valid taxa, and can be distinguished by a large number of distinct characters. As it turned out, the Taiwanese specimens which had been identified as 0. cordimanus were all 0. sinensis. There was also material of 0. sinensis from Peninsular Malaysia, the Philippines, and India. The present note provides detailed comparisons between these two species, as well as figures of the major differentiating features. Specimens examined are deposited in the Zoological Reference Collection (ZRC), Department of Biological Sciences, National University of Singapore; Institute of Zoology, Academia Sinica (IZAS), Beijing; Beijing Natural History Museum, Beijing; National Kaohsiung Institute of Marine Technology (NKIMT), Taiwan; and the National Museum of Natural History (USNM), Smithsonian Institution, Wash- ington, D.C. Measurements provided are of the carapace widths and lengths, respectively. Abbreviation: G = male pleopod 1.

TAXONOMY

Ocypode sinensis Dai, Song & Yang, 1985 (figs. 1 a; 2a, c, e, g; 3a, c, e, f; 4a, c-e) Ocypode sinensis Dai, Song & Yang, 1985: 377, figs. 8-12; Dai et a]., 1986: 418 (part); Dai & Yang, 1991: 456, fig. 230 (A). Ocypnde cordimanus - Huang et al., 1992: 142, pl. I A fig. 1; Wang & Liu, 1996: 63, figs. 51, 52. (Not Ocypode cordimanus Latreille, 1818.) Ocypode cordimana - Stimpson, 1907: 110, pi. 15 fig. 2; Sakai, 1976: 599, pl. 206 fig. 4; George, 1980: 187, pl. 1. (Not Ocypode cordimanus Latreille, 1818.)

Material examined. - Holotype, male (27.7 by 24.4 mm) (BNHM J97088a), Jinyindao, Xisha Islands, coll. S.-L. Yang, 8 March 1982. Paratypes. - I female (32.3 by 26.7 mm) (BNHM J97088b), same data as holotype; 2 males (26.1 by 22.9 mm, 29.0 by 25.3 mm) (IZAS), Yingehai, Hainan Island, coll. 11April 1957; 1 male (22.8 by 18.4 mm) (IZAS), Sanyan, Hainan Island, coll. 25 March 1958; 6 males (1 juvenile 14.5 by 11.8 mm, largest 25.0 by 22.1 mrn) (IZAS), Sanyan, Hainan Island, coll. 31 March 1958; 1 female (28.0 by 24.3 mm) (TZAS), Haikou, Hainan Island, coll. 3 November 1959; 2 males ( 1 juvenile,