Molecular phylogenetic estimates of evolutionary affinities and the first reports of phenotypic variation in two secretive, endemic reptiles from the Romblon Island Group, central Philippines

We report on the first molecular estimates of phylogenetic relationships of Brachymeles dalawangdaliri (Scincidae) and Pseudogekko isapa (Gekkonidae), and present new data on phenotypic variation in these two poorly known taxa, endemic to the Romblon Island Group of the central Philippines. Because both species were recently described on the basis of few, relatively older, museum specimens collected in the early 1970s (when preservation of genetic material was not yet standard practice in biodiversity field inventories), neither taxon has ever been included in modern molecular phylogenetic analyses. Likewise, because the original type series for each species consisted of only a few specimens, biologists have been unable to assess standard morphological variation in either taxon, or statistically assess the importance of characters contributing to their diagnoses and identification. Here we ameliorate both historical shortfalls. First, our new genetic data allowed us to perform novel molecular phylogenetic analyses aimed at elucidating the evolutionary relationships of these lineages; secondly, with population level phenotypic data, from the first statistical sample collected for either species, and including adults of both sexes. We reaffirm the distinctiveness of both named taxa as valid species, amend their diagnoses to facilitate the recognition of both, distinguish them from congeners, and consider the biogeographic affinities of both lineages. Our contribution emphasizes the conservation significance of Sibuyan Island’s Mt. Guiting-Guiting Natural Park, the diverse, idiosyncratic biogeographic histories of its variably-assembled, highly endemic reptile fauna, and the critical importance of multiple, repeated, survey–resurvey studies for understanding forest community species composition and the evolutionary history of Philippine biodiversity.