Morphological and genetic variation in samango monkeys (Cercopithecus albogularis) in southern Africa

Abstract

My aim was to resolve the taxonomy of the South African forms of Cercopithecus albogularis by exploring morphological and genetic variation in the two samango subspecies described for the region: C. a. erythrarchus and C. a. labiatus. In addition, I estimated their geographic distributions and habitat requirements from the provenance data I collected during my study of museum specimens. My analysis has shown clear morphological differences between C. a. labiatus and C. a. erythrarchus. The two subspecies differ in pelage coloration, but also in cranial shape and tail lengths. Furthermore, C. a. labiatus is slightly smaller, shorter-tailed and stocky compared with the long-tailed slender northern forms of C. albogularis, which may be adaptations to cold environments like montane forest. The northern C. albogularis subspecies are distinguishable from the southern taxa with a high degree of reliability (98.5%), suggesting that C. albogularis consists of more than one species. The most appropriate name for the southern species is C. labiatus. My genetic study did not detect variation among the 10 animals sampled in Hogsback; while it clustered the different taxa, it could not resolve relationships between them, with the exception of the outgroup. The lack of resolution of the deeper nodes could be a result of the fact that our sequence was very short (274 bp). The mt 12S rRNA gene was not an ideal gene for this study, which should have involved a less conserved section of the mtDNA molecule, like the rapidly evolving D-loop. More genetic work is clearly needed to resolve the phylogenetic relationships within the C. mitis supergroup. However, preliminary genetic data indicate that the southern samangos are distinct from the C. mitis of West Africa, while my morphometric study suggests they may also be distinct from C. albogularis in East Africa. Molecular and karyological studies comparing the genomes of Hogsback “C. a. labiatus” with the neighbouring “C. a. erythrarchus” and Zanzibar C. albogularis would be extremely enlightening.