Phylogenetic Analyses of Cyprinid Species from the Rokel River Basin of Sierra Leone, West Africa: Taxonomic, Biogeographic, and Conservation Implications

The Rokel River (RR) basin is one of the most neglected ichthyofaunal basins, despite the potential for undetected diversity and high levels of endemism. Data on the molecular phylogeny of freshwater fish from this river are rare. Morphological features alone are inadequate for precise species identification. Here, a phylogenetic analysis performed based on the mtDNA Cytb gene for eleven cyprinid fish from the RR basin recovered eleven distinct lineages. The same was also observed for two of our species delineation analyses, of which four are identical to six morphospecies, one is of taxonomic uncertainty, and the rest are currently unrecognized. The disjunct distribution found here in some cyprinid species from the RR basin and their sister species suggests that this river had a past complex historical inter-basin connection exchange with the nearby river basins of the Zaire and lower Guinean ecoregions. The unrecognized diversity observed from cyprinid species of this area may have significant implications for the conservation of biodiversity.