Evolutionary convergence in body shape obscures taxonomic diversity in species of the African Labeo forskalii group: Case study of L. parvus Boulenger 1902 and L. ogunensis Boulenger 1910

Labeo is the third most diverse genus of African cyprinids and is widely distributed across the continent. Labeo parvus, a small species originally described from the Congo basin, has been considered the only species of the L. forskalii group distributed across five African ichthyofaunal provinces (Nilo-Sudan, Congo, Cuanza, and Upper and Lower Guinea). However, morphological similarity between L. parvus and numerous congeners remains a central cause of taxonomic confusion within the genus. Here we employed a phylogenetic comparative approach to assess phenotypic convergence among species of the L. forskalii group, investigate the taxonomic status of L. parvus sensu lato (sl) in west Africa, and reevaluate the composition and distribution of L. parvus sensu stricto (ss). Our phylogenetic analysis provides no support for a sister relationship between L. parvus ss and any of the west African Labeo parvus-like species. Geometric morphometric and molecular phylogenetic data indicate that L. parvus ss is a Congo basin endemic, and seemingly ecologically equivalent species found in west Africa are L. ogunensis, L. obscurus and other undescribed or previously synonymized species. We discuss our findings in terms of convergent evolution using phylomorphospace and tests for phylogenetic signal.