Species delineation within the yellowfish and chiselmouth genus Labeobarbus (Cypriniformes: Cyprinidae) in southern Africa: is DNA barcoding an effective tool?

Species-level identification in Labeobarbus Rüppell, 1835, is often challenging. This is due to considerable phenotypic variation in traditionally considered taxonomically informative traits, such as mouth morphotype, primary dorsal spine or ray nature, and overall body form within and among species. Consequently, numerous nominal species have been described and later synonymised. This study assessed the effectiveness of DNA (COI) barcoding in delineating the yellowfish and chiselmouth genus Labeobarbus. The primary objective was to evaluate the extent to which DNA barcoding differentiates morphologically delineated southern African Labeobarbus species. Specimens representing 10 of the 11 valid species were collected from their respective type locality or type basin and included in this study. A secondary objective explored whether COI barcoding could differentiate distinct mouth morphotypes within conspecific specimens, using the Limpopo River basin (type basin) L. marequensis as a case study. Ten independent lineages (K2P genetic distance 0.72–7.26%) were delimited, consistent with the ten identified species included. No distinct haplogroups were recovered based on Labeobarbus-, Varicorhinus-, and intermediate-mouth morphotypes in the L. marequensis case study. These findings support the use of COI for species delineation of Labeobarbus but also suggest that the intraspecific morphological variation in L. marequensis might point to hybridisation.