A revision of the Geothelphusa levicervix species group (Crustacea: Decapoda: Brachyura: Potamidae), with descriptions of three new species

Abstract

The taxonomy of the Geothelphusa levicervix species‐group of freshwater crabs (Potamidae), members of which are distributed on five islands in the Ryukyus, Japan, is revised. The present study recognizes five species in the group, three of which are here described as new, and each of which is restricted to its own island. They can be easily distinguished by both carapace and male gonopod characters. On the basis of recent collections, the precise type locality of G. levicervix is here determined to be Tokashiki Island. The five species are diagnosed and a key to the species of the species‐group is provided.

Keywords:

• Freshwater crabs
• Geothelphusa levicervix species‐group
• new species
• Potamidae
• Ryukyu Islands
• taxonomy

Acknowledgements

We are grateful to two anonymous reviewers for reviewing the present manuscript. Thanks are due to Mr Fumiyasu Sato (Kumejima Firefly Museum) for providing specimens and field information of Kume, Tokashiki, and Iheya Islands; to Mr and Mrs Kasai (Kumejima Town) for their help with the field collection at Kume Island; to Dr Takashi Nagai (University of the Ryukyus) for providing field information on Okinawa Island; to Dr Tadashi Aotsuka (Tokyo Metropolitan University) for his support of the field collection at Tokashiki Island; to Mr Sumio Chiba (EAC Co. Ltd) for providing specimens from Iheya Island; to Mr Mitsuru Moriguchi (Sango‐sha Schole) for providing fossil specimens of Okinawa Island; and to Mr Hitoshi Noho (University of the Ryukyus) for teaching the locality names of Iheya Island. This study was partly supported by The Zoshinkai Fund for Protection of Endangered Animals and the 21st Century COE program of the University of the Ryukyus.