On the occurrence and distribution of Synodontis nigrita and Synodontis violaceus (Siluriformes: Mochokidae) in the Nilo-Sudan, and Upper and Lower Guinea ichthyofaunal provinces.

Examination of the holotype of Synodontis nigrita, the type specimens of both its (potential) junior synonyms, Synodontis fascipinna and Synodontis ornatus, and an additional 306 specimens, previously identified as S. nigrita, confirmed that the interorbital width is the most important diagnostic character to distinguish S. nigrita from its Nilo-Sudanic (N-S), and Upper and Lower Guinea ichthyofaunal province congeners.