Allopatric differentiation in the Enteromius anoplus complex in South Africa, with the revalidation of Enteromius cernuus and Enteromius oraniensis, and description of a new species, Enteromius mandelai (Teleostei: Cyprinidae)

Abstract

The chubbyhead barb, Enteromius anoplus, as currently described, is the most widely distributed freshwater fish in South Africa. The species occurs in almost all the major river systems across the country, with the exception of the small coastal drainages on the south coast. The use of a comprehensive data set of mitochondrial (mtDNA) cytochrome b (cyt b) sequences uncovered the presence of four distinct lineages or operational taxonomic units (OTUs) within E. anoplus: (a) the Gouritz lineage endemic to the Gouritz River system, (b) the Olifants lineage endemic to the Olifants‐Doring River system, (c) the Orange lineage endemic to the Orange River system and (d) the Eastern Cape lineage which is distributed across six river systems from the Great Fish to the Buffalo rivers in the Eastern Cape Province of South Africa. The present study provides a new diagnosis for E. anoplus s.s. (the Gouritz lineage), revalidates Enteromius cernuus (the Olifants lineage) and Enteromius oraniensis (the Orange lineage) as distinct species. The study also provides a description for a new species, Enteromius mandelai sp. nov (the Eastern Cape lineage). E. cernuus and E. mandelai differ from both E. anoplus and E. oraniensis by having a complete lateral line (vs. an incomplete lateral line in the latter species). E. cernuus further differs from the other three species by having long maxillary barbels which reach or exceed the vertical through the middle of the eye and the lowest number of circumpendicular scales (10–12 vs. 12–16 for the other three species). E. oraniensis is distinctive from the other three species by having inconspicuous barbels. These findings add to the growing body of literature that shows that the freshwater fishes of the Cape Fold and adjacent freshwater ecoregions have narrow geographic ranges. This has ramifications for conservation planning and management, as well as the understanding of the evolutionary history of the stream fishes in these global endemic hotspots.

How the Freshwater Biodiversity Information System (FBIS) is supporting national freshwater fish conservation decisions in South Africa

“…However, there are additional steps that could improve upon and update the tool, thereby supporting more effective freshwater conservation in the future. Firstly, there is an urgent need to update and resolve the taxonomy of South Africa's freshwater fishes, as there are a number of distinct genetic lineages that await formal description (Chakona et al, 2015(Chakona et al, , 2020bMartin and Chakona, 2019;Bronaugh et al, 2020;Kambikambi et al, 2021;Mazungula and Chakona, 2021;Ramoejane et al, 2021). Once the taxonomy of South Africa's freshwater fishes has been revised, the FBIS and NEST can be updated accordingly.…”

A new species of Parauchenoglanis (Auchenoglanididae: Siluriformes) from the Upper Lualaba River (Upper Congo), with further evidence of hidden species diversity within the genus

“…Preliminary morphological and/or genetic data revealed that all of these species seem to represent species complexes, thus harbouring hidden species diversity. This is consistent with findings from previous studies that have uncovered considerable levels of hidden species diversity within several freshwater fish species that were previously thought to have broad distribution ranges across river basins in southern Africa ( e.g ., Chakona et al ., 2013, 2014, 2018; Chakona & Skelton, 2017; Kambikambi et al ., 2021; Maake et al ., 2014; Mazungula & Chakona, 2021) or major catchments of the Congo Basin ( e.g ., Decru et al ., 2015b, 2019; Katemo Manda et al ., 2018; Mambo Baba et al ., 2020).…”

Functional diversity does not explain the co‐occurrence of non‐native species within a flow‐modified African river system

“…The native ichthyofauna in the Gariep Dam is generally distinct from that of the Great Fish River. Although historical data indicated close affinities in taxa such as Labeo umbratus (A. Smith, 1841) and Enteromius anoplus (Weber, 1897) between the two systems, subsequent research has shown that these also represent distinct lineages and separate species (Ramoejane et al, 2020; Kambikambi et al, 2021).…”

“…This river system is known to host an ichthyofauna assemblage that comprise both native and non‐native species. The native fish assemblage included primary freshwater taxa such as Enteromius mandelai Kambikambi et al, 2021 and the endangered Sandelia bainsii Castelnau, 1861, which were mostly confined to headwater tributaries. In comparison, the mainstem comprised mostly medium‐ to large‐sized species with the upper section comprising two native species, L. umbratus and Anguilla mossambica Peters, 1852, whereas the lower section was characterized by secondary freshwater and estuarine taxa.…”