New insights into the molecular phylogeny and taxonomy of mormyrids (Osteoglossiformes, Actinopterygii) in northern East Africa.

Abstract: Based on morphological data and analysis of mitochondrial <italic>cytochrome b</italic> gene and nuclear (<italic>S7 intron 1</italic>) DNA sequences, the phylogenetic relationships of all <italic>Pollimyrus</italic> species known from the Omo‐Turkana enclosed basin and Nile system below the Murchison Falls were solved. A mormyrid “<italic>Pollimyrus</italic>” <italic>petherici</italic> is distantly related to all other studied <italic>Pollimyrus</italic> species and clusters together with <italic>Cyphomyrus</italic> species forming with the later a monophyletic group. Moreover, the West African (but not the Congo River) populations of <italic>Cyphomyrus psittacus</italic>, the type species of the genus, seem to be conspecific to <italic>C. petherici</italic>. That is, the range of the genus <italic>Cyphomyrus</italic> is extended toward the Nile and Omo‐Turkana basins. This genus belongs to the large clade widely distributed in sub‐Saharian Africa and characterized by the presence of a chin appendage. Significance of this character for mormyrid phylogeny is discussed. Two distinct lineages of <italic>Pollimyrus</italic> occurring sympatrically in the White Nile tributaries and previously reported as the light and dark forms of <italic>Pollimyrus isidori</italic> together with five other congeneric species studied form a monophyletic group. The light form apparently represents <italic>P. isidori</italic> distributed in the Nile system downstream of the Murchison Falls and West Africa; the dark‐colored form (designated as <italic>Pollimyrus</italic> “D”) represents a distinct phylogenetic lineage inhabiting both the Omo‐Turkana and the White Nile basin. Morphological and ecological data suggest that this form may be conspecific to East African <italic>Pollimyrus nigricans</italic> or most probably represents a new species. [ABSTRACT FROM AUTHOR]