Phylogenetic relationships of the five extant Rhinoceros species (Rhinocerotidae, Perissodactyla) based on mitochondrial cytochrome b and 12S rRNA genes

A major question in rhinocerotid phylogenetics concerns the position of the Sumatran rhinoceros (Dicerorhinus sumatrensis) with regard to the other extant Asian (Rhinoceros unicornis and R. sondaicus) and African (Diceros bicornis and Ceratotherium simum) species. We have examined this particular question through the phylogenetic analysis of the complete sequences of the mitochondrial 12S rRNA and cytochrome b genes. Three additional perissodactyls (one tapir and two equids) plus several outgroup cetartiodactyls were included in the analysis. The analysis identified a basal rhinocerotid divergence between the African and the Asian species, with the Sumatran rhinoceros forming the sister group of the genus Rhinoceros. We estimate the Asian and African lineages to have diverged at about 26 million years before present.