A DNA Barcode-Based Evaluation of the Southeast Asian Catfish Genus Hemibagrus Bleeker, 1862 (Teleostei: Siluriformes; Bagridae)

Species of the genus Hemibagrus are large river catfishes found throughout South-east Asia. The complexity of the region’s biogeographical history and the lack of well-defined morphological characters render the taxonomy and phylogenetic reconstruction of Hemibagrus problematical. Early molecular studies of the H. nemurus species group revealed extensive genetic subdivisions, the taxonomic status of which remained unclear. A recent, morphologically-based, revision of the genus provides an opportunity to clarify the taxonomic status of these lineages. We employ a DNA barcode derived from the mitochondrial cytochrome b gene to expand our genetic analyses of the genus and to test the congruence of morphologically and genetically based taxonomies. Secondly, we evaluate phylogenetic relationships among taxa. Thirdly, we describe the phylogeography of Hemibagrus in South-east Asia. The species groups and nominal species proposed in the morphology-based revision generally reflect a hierarchy of monophyletic groups based on phenetic and maximum likelihood reconstructions of mtDNA phylogenies. The most notable exception involves the definition of a morphologically cryptic group from North Borneo. H. nemurus from West Java appears to be a regional population of H. capitulum. The phylogeography of the genus has been principally influenced by the formation of North Borneo and the emergence of the Sunda Islands.