A revision of the West African Hepsetus (Characiformes: Hepsetidae) with a description of Hepsetus akawo sp. nov. and a redescription of Hepsetus odoe (Bloch, 1794)

Abstract

Within the genus Hepsetus, a new species from the eastern part of West Africa is described. Hepsetus akawo sp. nov. is mainly distinguished from Hepsetus odoe by a smaller number of lateral line scales [43–51 vs 50–60 (exceptionally 49)] and a shallower head depth [38.0–45.6 (mean 42.0) % head length vs 41.4–49.0 (44.6) % head length] (positively allometric). Hepsetus akawo sp. nov. differs mainly from the recently rehabilitated Hepsetus cuvieri by: a higher number of gill rakers (17–23 vs 8–13); and a lower number of scales between the dorsal fin and the lateral line (7½–9½ vs 10½–11½). Within West Africa, the distribution area of the new species is restricted to the Sassandra River (Ivory Coast) in the west up to the Cross River (Cameroon) in the east. The species is entirely allopatric with H. odoe, which has a far more restricted distribution than previously thought and occurs from the Senegal River (Senegal) in the west to the Cavally River (Ivory Coast) in the east.

Keywords:

• Hepsetus odoe
• Hepsetus akawo sp. nov.
• West Africa
• revision
• new species

Acknowledgements

We are grateful to Alain Reygel (RMCA) for the drawings of both species, to Tobias Musschoot (RMCA-FishBase) for the distribution map of both species, to Gert Boden (RMCA-FishBase) for the database of examined specimens, and to Miguel Parrent (RMCA) for managing and registering the collection material. We would like to acknowledge James Maclaine from the BMNH (London) and Patrice Pruvost from the MNHN (Paris) for the loan of specimens under their care. We are also very grateful to Rainer Sonnenberg (ZMFK) and Dr Peter Bartsch (ZMB) for examining and re-examining the holotype of H. odoe.