Phylogenetic relationships of mormyrid electric fishes (Mormyridae; Teleostei) inferred from cytochrome b sequences

The Mormyridae are African osteoglossomorph freshwater fishes of great inte rest because of their electric organs, They have become an important model in studies of electrophysiology and behavior but their phylogenetic relatio nships are poorly known. Phylogenetic relationships among mormyrids were de termined by comparing cytochrome b sequences (588 bp) of 27 species belongi ng to 15 genera, Results showed that the Petrocephalus species (subfamily P etrocephalinae) are the sister-group of all other mormyrids (subfamily Morm yrinae), The monophyly of the Mormyrinae was supported, as well as three or iginal intraMormyrinae clades, Three genera, Marcusenius, Pollimyrus, and B rienomyrus, were found to be polyphyletic with high support. Some of these polyphylies are tentatively explained. The results confirmed that the later al ethmoid bone was lost several times within the Mormyrinae. These finding s emphasize the necessity of systematic studies and taxonomic revision of t he Mormyridae, The tree obtained from the mitochondrial data showed a singl e rise of each electrocyte type except for electrocyte with penetrating sta lk ("Pa"), Constraining the single occurrence of electrocyte type Pa did no t require an excessive number of extra steps (1.86%). (C) 2000 Academic Pre ss.