Systematic review of Pseudobarbus burchelli (Teleostei, Cyprinidae), with revalidation of P. vulneratus and description of a new species

Pseudobarbus burchelli (Smith, 1841) was previously considered to have a relatively wide distribution range spanning four isolated river systems in the Cape Fold Ecoregion of South Africa: the Breede, Duiwenhoks, Goukou, and Heuningnes. Extensive exploration and the application of molecular data led to the discovery and description of a new species, Pseudobarbus skeltoni, from the Breede River system, and the identification of three distinct lineages within P. burchelli.

These lineages were provisionally named P. burchelli ‘ Tradouw’ from the Tradouw catchment in the Breede River system, P. burchelli ‘ Breede’, distributed across the Breede, Duiwenhoks, and Goukou river systems, and P. burchelli ‘ Heuningnes’, distributed in the Heuningnes River system. Additionally, recent surveys found a new redfin population in the upper Klein River, genetically linked to the Heuningnes lineage. This study used an integrative approach to assess the taxonomic status of these three lineages.

Detailed morphological examination identified a combination of characters that consistently separate the lineages, supporting their recognition as distinct species. Based on both genetic and morphological distinctiveness, we redescribe P. burchelli s. s. for the P. burchelli ‘ Tradouw’ lineage, revalidate Pseudobarbus vulneratus (Castelnau, 1861) for the P. burchelli ‘ Breede’ lineage, and describe the P. burchelli ‘ Heuningnes’ lineage as a new species, Pseudobarbus agulhas sp. nov.

These three species differ in circumpeduncular scale count, head and snout proportions, and the number of teeth in the outer pharyngeal tooth row. The biogeographic history, key threats, and conservation needs of these three species are discussed.