Navigating taxonomic confusion: three novel freshwater crabs (Brachyura: Potamonautidae: Potamonautes) nested within a species complex in the Drakensberg Mountains, South Africa

During the present study species boundaries we examined in the freshwater crab species complex (comprising Potamonautes clarus Gouws, Stewart & Coke, 2000 and P. depressus Krauss, 1843). DNA sequence data from three mitochondrial loci and one nuclear locus were used for additional specimens sampled along the Drakensberg Mountains, KwaZulu-Natal Province, South Africa. Phylogenetic analyses using Bayesian Inference and Maximum Likelihood platforms incorporating additional sample localities using a total evidence DNA sequence dataset revealed the presence of a monophyletic Drakensberg Mountain group comprised of four main clades. Clade A comprised specimens from Impendle, Karkloof Nature Reserve, Injisuthi and Dargle Forest sister to clade B. The latter clade comprised specimens from Ngome Forest sister to P. clarus (from Oliviershoek Pass, and Gudu Falls) sister to Paardeplaats Nature Reserve. Clade (B) was sister to P. baziya Daniels, Marais, Barnes & Gouws, 2021 (clade C) that was sister to the remainder of clade D that comprised specimens from Himeville, Bushmans Nek, Rougham, Vergelegen Nature Reserve, Coleford Nature Reserve, Sani Pass and Garden Castle Nature Reserve. Clade A was collected closest to the type locality in the near eastern Drakensberg Mountains and is here designated P. depressus s.s., whereas specimens from Ngome Forest and Paardeplaats Nature Reserve are designated as P. ngomiensis sp. nov. and P. paardeplaatsie sp. nov. respectively, whereas the clade from the southern Drakensberg Mountains (clade D) is here designated as P. drakensbergie sp. nov. and sister to P. baziya. Divergence time estimation revealed Pliocene-Pleistocene cladogenesis. Climatic ameliorations are recognised as the main driver of speciation in the species complex. The three new potamonautid freshwater crab species are herein described and a neotype is designated for P. depressus s.s. to stabilise the taxonomy of the species. ZooBank: urn:lsid:zoobank.org:pub:954D6BEA-075F-4DAA-8D27-CCBEAC459FE3.