Phylogeny, taxonomy and biogeography of a circum-Indian Ocean clade of leaf-toed geckos (Reptilia: Gekkota), with a description of two new genera

Abstract

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.

http://zoobank.org/urn:lsid:zoobank.org:pub:7706B624-CD49-45CC-9DA3-FAB370BEE12B).

Key words:

• Afrogecko
• Christinus
• Cryptactites
• dispersal
• Gondwana
• Computed Tomography
• Matoatoa
• molecular clock
• osteology

Acknowledgements

We thank Wulf Haacke (formerly of the Transvaal Museum), Michael Cunningham (University of Pretoria) and Bill Branch (Bayworld, Port Elizabeth) for supplying tissues used in this work. CT scans and 3D rendering were provided by Edward Stanley (American Museum of Natural History), Jessie Maisano and Matthew W. Colbert (University of Texas High-Resolution X-ray CT Facility) and Maureen Kearney (on behalf of the Deep Scaly Project). Anthony P. Russell (University of Calgary) and Kenneth Tighe (United States Natural History Museum, Smithsonian Institution) provided access to X-ray data, and Mark Hutchinson (South Australian Museum) provided access to data from CT scans and dry skeletal preparations. This research was supported by funding from the National Science Foundation of the United States [DEB 084453 and DEB 1019443], the Encyclopedia of Life Rubenstein Fellowship programme, and by the Gerald M. Lemole, M.D. Endowed Chair funds.

Associate Editor: Barry Clarke