Divergent karyotypes of the annual killifish genus Nothobranchius (Cyprinodontiformes, Nothobranchiidae)

Karyotypes of two species of the African annual killifish genus Nothobranchius Peters, 1868, N. brieni Poll, 1938 and Nothobranchius sp. from Kasenga (D. R. Congo) are described. Both species displayed diploid chromosome number 2n = 49/50 for males and females respectively with multiple-sex chromosome system type X1X2Y/X1X1X2X2. The karyotypes of studied species are considerably different from those previously reported for the genus Nothobranchius and similar to the Actinopterygii conservative karyotype.