Recovering the evolutionary history of Africa’s most diverse viper genus: morphological and molecular phylogeny of Bitis (Reptilia: Squamata: Viperidae)

Assessing evolutionary relationships among wide-ranging species can be particularly beneficial to our understanding of speciation patterns and biogeography of taxa, with broad implications for conservation and applications for human health. Integrative phylogenetic analyses that incorporate multiple independent datasets (e.g., DNA, protein, phenotype) can resolve many problematic issues in systematics such as cryptic diversity and incongruence between datasets. Vipers in the genus Bitis are widely distributed throughout much of sub-Saharan Africa, filling a variety of ecological niches and presenting an important public health problem. However, evolutionary relationships among this medically and ecologically important genus have not been fully resolved due to inadequate taxon sampling and lack of informative characters. Here, we conduct the first phylogenetic study incorporating complete sampling of known species within the genus Bitis. Using morphological, molecular, and combined approaches under multiple criteria, we recovered many of the species groups detected by previous investigators, further validating four currently recognized subgenera. Bitis arietans and Bitis worthingtoni appear to be early-diverging, monotypic lineages, while the “big Bitis” group and the small southern African species form distinct clades. Although our study provides additional information regarding the interspecific relationships within Bitis, the placement of Bitis albanica, Bitis heraldica, and Bitis inornata remains problematic. This study enhances our understanding of the evolutionary history of species within the genus Bitis incorporating a combined evidence approach to phylogenetics.