Zoological Studies

Vol. 56, 2017

(update: 2017.8.9)

East Asian Cymonomid Crabs (Crustacea: Brachyura)

Shane T. Ahyong1,* and Peter K.L. Ng2


1Australian Museum, 1 William St., Sydney, NSW 2010, Australia, and School of Biological, Earth & Environmental Sciences, University of New South Wales, Kensington, NSW 2052, Australia
2Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore, 2 Conservatory Drive, Singapore 117377, Republic of Singapore. E-mail:

(Received 14 June 2017; Accepted 9 August 2017; Communicated by Benny K.K. Chan)

Shane T. Ahyong and Peter K.L. Ng (2017) Cymonomid crabs are small cryptic deep-water brachyurans occurring worldwide. Six species have been reported from East Asia: one from both Taiwan and Japan (C. andamanicus Alcock, 1905) and five from Japan only (C. curvirostris Sakai, 1965, C. japonicus Balss, 1922, C. sagamiensis Sakai, 1983, C. soela Ahyong and Brown, 2003, C. umitakae Takeda, 1981). Cymonomus curvirostris, C. japonicus, C. sagamiensis and C. umitakae were described from Japanese waters, but C. andamanicus and C. soela have much more distant type localities - the Andaman Sea and southeastern Australia, respectively. We review all previous records of Cymonomus from East Asia, describe two new species, and clarify the status of records of C. andamanicus and C. soela from the region. Records of C. andamanicus and C. soela from East Asia are referrable to two new species occurring in both Taiwan and Japan. The identities of C. japonicus and C. sagamiensis are fixed by neotype selection; C. sagamiensis is made a junior objective synonym of C. umitakae. Six species of Cymonomus are now recorded from Japan, of which two also occur off Taiwan. We also report on cymonomids collected by Taiwanese research vessels in the South China Sea (Dongsha and Macclesfield Bank) of which four species were collected, including C. hakuhoae Takeda and Moosa, 1990, not previously found in Japan or Taiwan. A key to the species of Cymonomus from East Asia and the South China Sea is included.

Key words: Crustacea, Cymonomus, Crab, Taiwan, Japan, South China Sea, Seamount.

Correspondence: E-mail: shane.ahyong@austmus.gov.au

Citation: Ahyong ST, Ng PKL. 2017. East Asian cymonomid crabs (Crustacea: Brachyura). Zool Stud 56:24. doi:10.6620/ZS.2017.56-24.