Class Mammalia Linnaeus, 1758 - mammals
Subclass Theria Parker & Haswell, 1897
Order Artiodactyla Owen, 1848 - even-toed ungulates
see Order Cetartiodactyla Montgelard, Catzeflis & Douzery, 1997
Family Hippopotamidae Gray, 1821 - hippopotamuses
Genus Hexaprotodon Falconer & Cautley, 1836 [monotypic]
Hexaprotodon liberiensis (Morton, 1849) - pygmy hippopotamus
see Choeropsis liberiensis (Morton, 1844)
1 [Hexaprotodon liberiensis liberiensis] Morton, 1849
see Choeropsis liberiensis liberiensis
2 Hexaprotodon liberiensis heslopi Corbet, 1969
see Choeropsis liberiensis heslopi