They are morphologically well connected, forming a close-knit and cohesive unit. The genus has 12–13 species who are morphologically distinct from the genus Naja and the Afro-elapids according to McDowell (1987). McDowell stated "species diversity is greatest in Africa, but the Asiatic Bungarus and Ophiophagus are each so peculiar in anatomy as to suggest an ancient divergence".[10] Others, including Slowinski, believed that the kraits (Bungarus), are part of a clade that clusters with a group including the king cobra (Ophiophagus hannah) and oddly enough, with the African mambas (Dendroaspis) on the most-parsimonious tree or with Elapsoidea on the maximum-likelihood tree.