LAUSR

The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a dataset consisting of 37 mitochondrial cytochrome oxidase subunit I (COI) sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and the Automatic Barcode Gap Discovery (ABGD), a genetic distance method were applied. Both GMYC and bPTP delimited the same Operational Taxonomic Units (OTUs), revealing a higher diversity for the genus in the region than previously recognized, whereas the ABGD failed in delimiting the same candidate species. All methods delimited two species groups and these are supported based on colouration patterning and morphology; the N. multifasciatus and the N. macropterus species groups, and the delimited OTUs were assigned to each. Two putative new species were identified, N. cf. lineostriatus 'Okavango' from the Okavango River and N. cf. lineostriatus 'Kwanza' from the Kwanza River system in Angola. The species N. dageti distribution was confirmed for the Upper Zambezi and extended to the Okavango system, and an identification key for the southern Africa Nannocharax species is provided.