The Doring River population of Pseudobarbus (Teleostei: Cyprinidae) does not merit formal description

Until the early 2000s, only seven species were recognized within the cyprinid genus Pseudobarbus, based solely on morphology. However, the integration of molecular data, expanded sampling, and reexamination of ichthyological collections revealed eighteen lineages, most of which have since been taxonomically resolved through revalidations or new species descriptions. The application of three core criteria, (i) moderate to deep genetic divergence, (ii) presence of diagnostic morphological differences, and (iii) occurrence in discrete river systems or catchments, has guided these species delimitations and resulted in an increase from seven to 15 valid species over the past decade.

Applying these criteria, this study evaluates the taxonomic status of the Doring River lineage of P. phlegethon in comparison with the topotypic Olifants River lineage. The two lineages show low genetic divergence (1.3%), the lowest recorded in the genus, and complete overlap in all morphological characters examined, precluding a morphological diagnosis. Of the three criteria, only the third, i.e., distinct geographic distributions, is met by the ‘Doring’ and ‘Olifants’ lineages of P. phlegethon; therefore, we adopt a conservative approach, treating them as allopatric populations of the same species.