Heteromormyrus Steindachner, 1866, a genus of Mormyridae (Teleostei: Osteoglossomorpha), has been monotypic since the description of Heteromormyrus pauciradiatus (Steindacher, 1866) from a single specimen. No type locality other than Angola was given and almost no specimens have been subsequently identified to this species. In order to investigate the relationship of this taxon to fresh specimens collected in Angola and elsewhere, whole genome paired-end sequencing of DNA extracted from the holotype specimen of Heteromormyrus pauciradiatus was performed and a nearly complete mitogenome assembled from the sequences obtained. Comparison of cytochrome oxidase I and cytochrome b sequences from this mitogenome to sequences from recently collected material reveal that Heteromormyrus pauciradiatus is closely related to specimens identified as Hippopotamyrus ansorgii (Boulenger, 1905), Hippopotamyrus szaboi Kramer, van der Bank & Wink, 2004, Hippopotamyrus longilateralis Kramer & Swartz, 2010, as well as to several undescribed forms from subequatorial Africa collectively referred to in the literature as the Hippopotamyrus ansorgii species complex and colloquially known as slender stonebashers. Previous molecular phylogenetic work has shown that these species are not close relatives of Hippopotamyrus castor Pappenheim, 1906, the type species of genus Hippopotamyrus Pappenheim, 1906 from Cameroon, and are thus misclassified. Hippopotamyrus ansorgii species complex taxa and another species shown to have been misclassified, Paramormyrops tavernei (Poll, 1972), are placed in genus Heteromormyrus and one genetic lineage from the Kwanza and Lucala rivers of Angola are identified as conspecific Heteromormyrus pauciradiatus. Three additional new combinations and a synonymy in Mormyridae are introduced. The morphological characteristics and geographical distribution of the genus Heteromormyrus are reviewed. The electric organ discharges (EODs) of Heteromormyrus species are to be treated in a separate study.