Enteromiuspallidus was described by Smith in 1841 without a designated type specimen for the species. Herein, we designate a specimen from the Baakens River system as a neotype for E.pallidus and provide a thorough description for this species to facilitate ongoing taxonomic revisions of southern African Enteromius. Enteromiuspallidus can be distinguished from the other minnows in the "goldie barb group" by having an incomplete lateral line, lack of distinct chevron or tubular markings around lateral line pores, absence of a distinct lateral stripe, absence of wavy parallel lines along scale rows and lack of black pigmentation around the borders of the scales. We provide mtDNA COI sequences for the neotype and an additional specimen from the Baakens River as DNA barcodes of types and topotypes are a fundamental requirement for further taxonomic studies.
The chubbyhead barbs, a distinct group of fishes endemic to southern Africa, currently include eight valid species. Historically, Enteromius anoplus was the most widespread freshwater fish in South Africa due to synonymizations in the 1960s. It occurred in nearly every river system except coastal systems in the Cape Fold Ecoregion and the lower Orange River. However, a recent revision utilizing molecular and morphological analyses has led to significant taxonomic updates. Enteromius anoplus is restricted to the Gouritz River system, whereas Enteromius cernuus and Enteromius oraniensis have been revalidated and respectively confined to the Olifants and Orange River systems. Additionally, a new species Enteromius mandelai was described, with its range currently considered to encompass several river systems in the Eastern Cape. Despite these advances, the taxonomic status of fish previously assigned to E. anoplus from KwaZulu-Natal remained uncertain. In this study, an integrative approach, combining genetic analysis, morphological characteristics, and geographic data, was employed to resurrect Enteromius karkensis as a distinct species from E. anoplus. Enteromius karkensis is deeply genetically differentiated (3.99%-8.07% p-distance) from its congeners within the chubbyhead group. Morphologically, E. karkensis is easily distinguishable from its counterparts due to possession of a terminal mouth (vs. inferior in E. amatolicus), one pair of maxillary barbels (vs. two conspicuous pairs in E. motebensis, E. treurensis, and E. gurneyi), and a complete lateral line (vs. incomplete in E. anoplus and E. oraniensis). Furthermore, E. karkensis is differentiated from E. mandelai and E. cernuus by its long maxillary barbels that extend beyond the midpoint of the orbit. These findings highlight a consistent pattern from previous studies that show many freshwater fishes in South Africa have narrow geographic ranges. This emphasizes the importance of targeted conservation and management efforts, and our understanding of the biogeographic and evolutionary history of freshwater fishes in southern Africa.