Status and distribution of a novel redfin lineage, Pseudobarbus sp. ‘burchelli Tradouw’ from the Cape Fold Ecoregion of South Africa

Abstract

Freshwater fish are threatened globally and in addition, knowledge of their diversity is incomplete and species richness is  underestimated. Within the ichthyofauna of the Cape Fold Ecoregion of South Africa, many undescribed lineages exist and for most of  these, information is limited regarding their ecology, distribution and threats. The Tradouw redfin Pseudobarbus sp. ‘burchelli Tradouw’  is a novel and range-restricted lineage within the Breede River redfin Pseudobarbus burchelli. Annual monitoring conducted between  2012 and 2016 investigated spatial and temporal trends in the distribution and population dynamics of this taxon. Results indicated that it  is highly fragmented within its distribution range, likely a result of the combined pressures of invasive fish and poor land use practices.  Short-term monitoring results indicated that invasive fish are established in most of the catchment and that the relative abundance of  redfins remained constant only in the limited section of river where alien fish were absent. Poor land use practices such as water over- abstraction and surface water pollution, are pervasive threats, but the extent to which these affect the redfins requires further  investigation. The long-term survival of this taxon remains uncertain, and short-term and long-term conservation and management  options are explored.