On the diversity, colonization patterns and status of Hemidactylus spp. (Reptilia: Gekkonidae) from the Western Indian Ocean islands

Hemidactylus geckos are probably the most widespread genus of reptiles, with a world-wide distribution and multiple cases of range expansion and transmarine colonization. With an almost cosmopolitan distribution and many species being morphologically similar it has proved difficult to delimit species diversity and distributions. Using a comprehensive analysis of individuals collected across the Western Indian Ocean islands and some locations along the East African coast, we further assess their diversity and the origin of insular populations. Despite four species of Hemidactylus being widespread across the Western Indian Ocean islands, most of their range in this area may actually be the result of very recent (possibly human-aided) dispersal events. Most probably, all Hemidactylus species occurring in the Comoros and granitic Seychelles archipelagoes are not native. Instances of natural colonization seem to be only the ones of H. mabouia to Madagascar and from there to the coralline archipelago of Aldabra. Surprisingly, Aldabra populations reveal a remarkable diversity and structure. Given the degree of divergence observed we propose that insular (Gulf of Guinea, Comoros, Madagascar, Seychelles) populations of H. mabouia are recognized as H. mercatorius. Cryptic variation is further uncovered in all species in their native range, with H. platycephalus and H. mabouia harbouring several highly divergent lineages, but further taxonomic assignments should await detailed assessments of distribution and molecular variation.