Karyotype of a Nigerian population of Hyperopisus bebe (Osteoglossiformes: Mormyridae) revealed another evolutionary lineage in the monospecific genus: Hyperopisus

This study provides data on the gross chromosome morphology, including centromeric and silver nitrate banding of a Nigerian population of Hyperopisus bebe, sampled from Asejire Reservoir, Osun River basin. The chromosomes of the fish samples were extracted using the Giemsa staining technique, and the centromeric and silver nitrate bandings were analyzed based on standard cytogenetic methods. The H. bebe population had a chromosome number of 2n = 40 and a karyotype formula of 2n = 40 (24m+6sm+10st/a), FN = 70. C-bands were restricted to the centromeric regions, suggesting that Robertsonian events are the major mechanism in the karyotype evolution in the population. Currently, H. bebe represents the only species in the genus Hyperopisus. The karyomorph data from this study suggest that the fish sample belongs to another species. However, other systematic approaches are needed to establish its taxonomic status.