The two-horned chamaeleons of East Africa

There have been numerous attempts to resolve the taxonomy of the two-horned chamaeleons of East Africa. However, the high levels of intraspecific variation and reported sympatry of morphologically distinct taxa indicate that their current classification is unsatisfactory. Tissue samples were collected from specimens from most mountain massifs (excluding the Nguu) where two-horned chamaeleons are known to occur and were used to sequence partial 12S and 16S rRNA, as well as ND2 mtDNA genes. These specimens and further museum material were used to review morphological variation and to define discriminating characters for each taxon. Phylogenetic analyses of gene sequences show clear genetic divergence between allopatric populations, although two lineages occur in sympatry in the East Usambara Mountains, and is supported by divergent morphology. In light of these results a formal revision of the taxonomy of all East African two-horned chamaeleons is proposed and seven species are recognized (Kinyongia boehmei, K. fischeri, K. matschiei, K. multituberculata, K. tavetana, K. uluguruensis and K. vosseleri). These taxa form a monophyletic group except for K. uluguruensis, which seems to be more closely related to one-horned species. Most of these taxa have been previously described and subsequently reduced to synonyms. Two other previously described two-horned taxa are not recognized as valid: Chamaeleo tornieri is considered species inquiriendae, and C. fischeri werneri is placed in synonymy with K. multituberculata. A dichotomous key is provided for the identification of these taxa and some aspects of their conservation, ecology and evolutionary origins are also discussed. (c) 2008 The Linnean Society of London.