Comprehensive DescriptionRead full entry
The genus Synodontis Cuvier, 1816 ZBK is the most species rich and widespread genus of mochokid catfishes. As currently recognized the genus contains approximately 120 valid species distributed throughout most of the freshwaters of sub-Saharan Africa and the Nile River system. Larger Synodontis ZBK species are important food fishes in many parts of Africa and are commonly known as “squeakers” because they readily produce sounds by stridulating their pectoral spines when handled or disturbed. Furthermore many Synodontis ZBK species are prized ornamental fishes because they have striking pigmentation patterns or display unusual behaviors like an upside down swimming posture.
Poll (1971) last revised the entire genus and noted seven species reported from Gabon based on specimens he examined or previous published accounts and faunal lists: S. angelicus Schilthuis 1891 ZBK , S. albolineatus Pellegrin 1924 ZBK , S. guttatus Guenther 1865 ZBK , S. haugi Pellegrin 1906 ZBK , S. obesus Boulenger 1898 ZBK , S. polyodon Vaillant 1895 ZBK and S. tessmanni Pappenheim 1911 ZBK . Four of these species have well documented type localities within Gabon ( S. albolineatus ZBK , S. haugi ZBK , S. polyodon ZBK and S. tessmanni ZBK ) and appear to be endemics of the Ogôoué or Ntem Rivers and their tributaries.
In contrast, the presences of S. angelicus ZBK , S. guttatus ZBK , and S. obesus ZBK in Gabon are uncertain or possibly erroneous. First, the claim for S. angelicus ZBK is based on the junior synonym S. tholloni Boulenger 1901 ZBK known from a single specimen (MNHN 1890-0030) collected at an unspecified locality possibly within the Ogôoué basin of Gabon. Otherwise, S. angelicus ZBK is known exclusively from the Congo basin. Second, Poll (1971) did not find any specimens of S. guttatus ZBK from Gabon, questioned published records from Gabon by Sauvage (1880, 1884) and concluded that the species is only found in the lower Niger basin. Finally, Boulenger (1898) described S. obesus ZBK based on three syntypes, one from the Opobo River, Nigeria (BMNH 1822.214.171.124) and two from an unspecified locality in Gabon (BMNH 18126.96.36.199-6). Poll (1971) subsequently designated the Nigerian syntype as the lectotype for S. obesus ZBK . Given this type fixation and the uncertain locality data for the paralectotypes, the presence of S. obesus ZBK in Gabon remains ambiguous.
Since Poll’s revision, the first author and others have made many more collections of Gabonese fishes. Review of this material for an upcoming edited book on the freshwater fishes of West Central Africa (Lower Guinea) has revealed the presence of at least eight Synodontis ZBK species in Gabon. These include the previously known endemics ( S. albolineatus ZBK , S. haugi ZBK , S. polyodon ZBK , and S. tessmanni ZBK ), plus four additional species. One of these, S. batesii Boulenger 1907 ZBK , originally described from the Congo basin of Cameroon, is now known from both the Ogôoué and Ntem basins of Gabon. The other newly recorded species are currently under study by several researchers. One of these new species that has unique bony ornamentation and sexual dimorphism is described here.