Taxonomy of the Rhampholeon boulengeri Complex (Sauria: Chamaeleonidae): Five New Species from Central Africa’s Albertine Rift

Abstract

In a recent molecular study, the pygmy chameleon Rhampholeon boulengeri Steindachner, 1911 was shown to contain six genetically distinct, but phenotypically cryptic lineages. Phylogenetic analyses of genetic data demonstrated that several well-supported clades occurred in non-overlapping elevational ranges across the Albertine Rift in Central Africa. In order to resolve the taxonomy of the R. boulengeri complex, we examined the morphology of specimens representing all six genetic lineages, including the type specimens. Results supported the notion that the current taxonomy does not reflect species diversity and further uncovered the extent to which morphological differences were dissociated from genetic divergence in this complex. We formally describe five new species of Albertine Rift Rhampholeon, which reflects the species diversity more accurately within the region. All of the species are morphologically conserved and seem to exhibit a pattern of cryptic speciation similar to that observed in the genus and in other chameleon genera. Several of the new species are distributed in adjacent habitats, but occur in parapatry where they are separated by elevation, while species that overlap in elevation are allopatric. At least one of the new species exhibited bone fluorescence from its facial tubercles when examined under ultraviolet light, which is the first published account for the genus. Our results highlight the importance of investigating cryptic diversity using an integrative framework, especially for widespread species that look similar, and the description of these new species reinforces the Albertine Rift as one of the world's richest biodiversity hotspots.