Between an ocean and a high place: coastal drainage isolation generates endemic cryptic species in the Cape Kurper Sandelia capensis (Anabantiformes: Anabantidae), Cape Region, South Africa

This study investigated the range-wide phylogenetics and biogeography of the Cape Kurper Sandelia capensis, a primary freshwater fish endemic to, and widespread within, the Cape Floristic Region (CFR) of South Africa. Maximum likelihood, Bayesian phylogenetic, and haplotype network analyses, based on two mitochondrial and two nuclear genes, revealed the existence of three reciprocally monophyletic, deeply divergent and allopatric clades that likely represent cryptic species. The West Coast Clade is largely confined to the Langvlei, Verlorenvlei, Berg, and Diep rivers, the Klein River Clade is endemic to the Klein River, and the South Coast Clade is found everywhere else in the range of S. capensis sensu lato. It was hypothesized that divergences within S. capensis sensu lato likely occurred because of (1) isolation of coastal drainages by persistent drainage divides and/or (2) vicariance of current tributaries by the drowning of their confluences by high sea levels. The current distri...