 The Black dwarf hornbill is typically classified in the genus "Tockus" but in this study, is a sister species to the White-crested hornbill.If these two species are classified in congeneric, "Tropicranus" becomes a junior synonym of "Horizocerus", as that was one of the old names used for the Black dwarf hornbill.This clade also includes one Southeast Asian species, the White-crowned hornbill.