Phylogeny, taxonomy and biogeography of a circum-Indian Ocean clade of leaf-toed geckos (Reptilia: Gekkota), with a description of two new genera
Geckos with a leaf-toed morphology (digits with a single pair of enlarged adhesive pads located terminally) occur on six continents and many islands. Although most leaf-toed gecko genera belong to independently derived lineages, recent studies support the monophyly of a circum-Indian Ocean group including four genera from disparate regions: the southern African genera Afrogecko and Cryptactites, the Malagasy genus Matoatoa, and the Australian genus Christinus. We obtained molecular and/or morphological data for most species in these genera to estimate phylogenetic relationships among constituent species and infer broad historical biogeographic patterns. Our results confirm that Afrogecko is not monophyletic, and that Christinus is embedded among African taxa. Afrogecko is comprised of three lineages, each of which is distinct in external features and osteology. Based on these results, we partition Afrogecko and recognize two new genera. Molecular clock analyses suggest divergences within the circum-Indian Ocean group are too recent for Gondwanan vicariance or hypothesized land bridges (e.g. Kerguelen Plateau) to account for the observed Africa/Madagascar/Australia distributional pattern. Ancestral area analyses support an origin of the clade in mainland Africa or Madagascar, and imply a dispersal event from southern Africa to Australia, similar to those observed in some plant and arthropod taxa, but otherwise unknown among non-volant terrestrial vertebrates. Dispersal was likely via a southern route and may have been facilitated by island hopping using Antarctica or other southern landmasses available in the mid-Cainozoic.