Two new species of freshwater crabs from Mount Elgon, East Africa (Brachyura: Potamoidea: Potamonautidae) and a re-diagnosis of Potamonautes niloticus (H. Milne Edwards, 1837) with notes on their natural history and onchocerciasis

Abstract

Two new species of potamonautid freshwater crabs from eastern Uganda, Africa are described, and Potamonautes niloticus (H. Milne Edwards, 1837) is re-diagnosed with key characters illustrated photographically. A total of four species of crabs are now known to occur on Mount Elgon, which borders both Kenya and Uganda. Two of these species are endemic to the mountain and the distribution patterns of all four species indicate a distinct altitudinal preference. All taxa are compared with similar species and their distributions and natural history are reviewed. Furthermore, three of the crabs recorded from Mount Elgon have been implicated in the transmission of onchocerciasis in East Africa.

Keywords:

• Potamoidea
• Potamonautidae
• Potamonautes elgonensis sp. nov
• Potamonautes williamsi sp. nov
• Potamonautes niloticus
• Potamonautes loveni
• freshwater crab
• onchocerciasis
• Mount Elgon
• Kenya
• Uganda
• East Africa

Acknowledgements

Trefor R. Williams (retired, formerly of the University of Liverpool, UK) is thanked for donating to NHM and NMU the specimens described here, and for many thoughtful discussions with the first author. Miranda Lowe (NHM) is thanked for loaning specimens and Dr Rafael Lemaitre and Marilyn Schotte (USNM) are thanked for their support during work by the first author on the USNM collection. Furthermore, Ardis Johnson (MCZ) is thanked for their assistance and kind hospitality during visits by the first author to these museums. The Peter White Scholar Award (NMU) is acknowledged for its support for the first author, and we are grateful to Phil Crabb (NHM Photography Unit) for taking the photographs reproduced in figures 1, 4 and 7.