Taxonomic Revision of Philippine Sun Skinks (Reptilia: Squamata: Scincidae: Eutropis), and Descriptions of Eight New Species

Abstract: Species descriptions of reptiles historically have relied exclusively on the use of morphological data; however, these external, phenotypic data do not always co-vary with lineage divergence. Consequently, it has become increasingly clear that species diversity has been underestimated in many evolutionary radiations. With the use of an integrative approach, we examined the genetic and morphological diversity present in a nearly endemic Philippine radiation of Eutropis. Results demonstrated that current taxonomy does not reflect evolutionary history and that in many cases, morphological divergence has become decoupled from genetic divergence. As a consequence, species diversity is significantly underestimated. Here, we rectify the major taxonomic problems present in Philippine Eutropis by providing formal descriptions for eight new species. Three of the four new species in the E. multicarinata species complex are sympatric with (and have long been confused with) previously described subspecies (which we also elevate to full species here). The fourth species is endemic to the Caroline Islands, clearly derived from a long-distance dispersal event from the Philippines. The new species in the E. indeprensa species complex are allopatrically or parapatrically distributed across the archipelago. In contrast to the last review of Philippine Eutropis, which suggested the endemic radiation was composed of five species (one of which was composed of two subspecies), we demonstrate that this group includes at least 14 distinct evolutionary lineages, with potential for additional diversity to be discovered pending further study.