Mandrills are not baboons

Like all the Old World monkeys, mandrills and drills belong to the Superfamily Cercopithecoidea, which is divisible into two Families; the Colobinae (comprising the African colobus monkeys, Asiatic langurs, leaf monkeys and proboscis monkeys), and the Cercopithecinae (including the guenons, patas monkey, talapoins, macaques, baboons and mangabeys, as well as Mandrillus and several other genera). One tribe of the cercopithecine monkeys, the Papionini, comprises the baboons (Papio), macaques (Macaca), arboreal mangabeys (Lophocebus), semi-terrestrial mangabeys (Cercocebus), the ‘kipunji’ (Rungwecebus) and the gelada (Theropithecus), as well as the genus Mandrillus (Table 2.1 and Figure 2.1).

The adaptive radiation of papionin monkeys in Africa and Asia has resulted in the convergent evolution of a number of primarily terrestrial, large and highly sexually dimorphic monkeys, with impressive canine teeth. Because both species of Mandrillus are large and superficially baboon-like monkeys, they have traditionally been considered as forest baboons and, as such, they were included in the genus Papio (e.g. Stammbach, 1987; Szalay and Delson, 1979). It is only quite recently that these ideas have been challenged and overturned. Similarities between mandrills and baboons are outweighed by many anatomical and genetic differences between the two genera. Comparative studies of mitochondrial DNA (Disotell, 2000; Disotell et al., 1992), as well as of skeletal and other traits (Fleagle and McGraw, 1999, 2002; Groves, 2000) have shown that the genus Mandrillus is more closely related to the semi-terrestrial mangabeys (Cercocebus) than it is to the true baboons.

The arboreal mangabeys (genus Lophocebus) are more closely aligned with members of the genus Papio (e.g. see Guevara and Steiper, 2014) rather than with Cercocebus or Mandrillus. These relationships are made clearer by referring to Figure 2.2.

The phylogenetic position of the ‘kipunji’ (Rungwecebus kipunji) is not shown in Figure 2.2, but this rare and little known species was originally assigned to the arboreal mangabeys (genus Lophocebus), based upon studies of a single specimen (Jones et al., 2005). However, subsequent molecular phylogenetic analyses indicate that the kipunji is probably intermediate between Lophocebus and Papio (Davenport et al., 2006; see also Roberts et al., 2009). As such, it is currently placed in its own genus, Rungwecebus, which was named in honour of Mt. Rungwe in Southern Tanzania, where the kipunji was discovered.