The taxonomy of Phacochoerus africanus is very uncertain and in need of revision (Lönnberg 1909; Hollister 1924; Bigourdan 1948; Haltenorth 1963; Ansell 1972; Grubb 1993, 2005; Groves and Grubb 2011). Current taxonomy is based almost entirely on skull size and proportions, of which much geographic variation exists. It may be a monotypic species. Geographic variation appears clinal. Until further study, four subspecies are provisionally recognized (Grubb 1993, 2005): africanus, aeliani, massaicus, and sundevallii. This taxonomy was adopted by Vercammen and Mason (1993), Skinner and Chimimba (2005), Meijaard et al. (2011), and Cumming (2013). Muwanika et al. (2003) found three well-defined mitochondrial haplotype clades within P. africanus: western, eastern, and southern Africa. That more clades might be present is suggested as this study did not sample within the range of P. a. aeliani, and very large areas in the north-west, north, north-east, and south-east of the range of P. africanus were not sampled. Early taxonomy was much confused with that of desert warthog Phacochoerus aethiopicus. See Grubb (1993), Grubb and d'Huart (2010), d'Huart et al. (2013), and Chapter 10 of this book for historic overviews of the taxonomy of Phacochoerus. Synonyms: aeliani, aelianii, barbatus, barkeri, bufo, centralis, fossor, haroia, incisivus, massaicus, sclateri, shortridgei, sundevallii.