Warthogs without incisors were described from the Cape of Good Hope as Phacochoerus aethiopicus and warthogs possessing incisors were first found in Senegal and later named Phacochoerus africanus. During the second half of the 18^th century and the whole of the 19^th century, the majority of workers recognised these two taxa as distinct. Twentieth century palaeontologists working in Africa also recognised the two species of warthogs in the Pleistocene and Holocene fossil records and were aware of the differences between the two Recent species. But in the same period, most zoologists considered all warthogs to belong to a single polytypic species. Re-examination of the literature and inspection of recent material confirm distinctive differences corresponding with geographic distribution of two species of warthogs: the widespread common warthog Phacochoerus africanus and the Cape warthog P. aethiopicus. Whereas the Cape warthog, P. aethiopicus aethiopicus, became extinct in South Africa in the 1870s, it survives in Kenya, Ethiopia and Somalia as a geographically isolated subspecies, P. aethiopicus delamerei. This discontinuous distribution has been noted in the literature, as are the criteria which distinguish P. aethiopicus from P. africanus.