Phylogeny-based species delimitation in Philippine slender skinks (Reptilia: Squamata: Scincidae) II: taxonomic revision of Brachymeles samarensis and description of five new species

With robust new datasets from morphology and DNA sequences, we review the limbed, nonpentadactyl species of the Brachymeles samarensis complex (now known to include B. cebuensis, B. minimus, and B. lukbani), and describe five new species in this highly limb-reduced, endemic Philippine clade of scincid lizards. For more than four decades, B. samarensis has been recognized as a single ‘‘widespread’’ species. This perception of the species’ peculiar geographic range has persisted as a result of weak sampling and similar gross morphology (body sizes, scale pigmentation) among populations. However, previous authors have noted morphological variation between different island populations, and our new data build on these observations and extend them to delimit new proposed species boundaries. Our data indicate that the ‘‘widespread’’ species B. samarensis is actually a complex of six distinct lineages, some of which are not each others’ closest relatives, and each of which is genetically unique. The taxa we define possess allopatric geographic ranges and differ from their congeners by numerous diagnostic characters of external morphology, and therefore should be recognized as full species in accordance with any lineage-based species concept. Species diversity in the genus has doubled in the last 3 yr, with these six taxa increasing the total known number of species of Brachymeles to 30.