A New Species of Long-glanded Coralsnake of the Genus Calliophis (Squamata: Elapidae) from Dinagat Island, with Notes on the Biogeography and Species Diversity of Philippine Calliophis and Hemibungarus

We describe a new species of coralsnake from northern Dinagat Island, southeastern Philippines. The discovery of this new species comes as a surprise because it is phenotypically distinct from all other Philippine coralsnakes and has a close phylogenetic affinity to the blue coralsnakes of the Sunda Shelf. The new species is distinguished from all Philippine and other Southeast Asian taxa by its large body size and ventral scale counts; its black head and neck; an alternating, broadly banded color pattern of black and off-white; and a bright orange tail. We use DNA sequence data to investigate the phylogenetic placement of the new species and that of several other populations of Philippine coralsnakes with respect to other Southeast Asian and Australasian elapids. Our results corroborate the uniqueness of the new species with respect to all other Philippine and Sundaic taxa, including the species most closely related to it: Calliophis bivirgatus, C. bilineatus, C. philippinus, and C. suluensis. We summarize phylogenetic, biogeographic, and phenotypic character data that substantiate the elevation of Philippine species of Calliophis (formerly considered subspecies of C. intestinalis: C. bilineatus, C. philippinus, and C. suluensis) and Hemibungarus (formerly subspecies of H. calligaster: H. calligaster, H. gemianulis, and H. mcclungi) to the level of full species. The allopatric distributions of these taxa emphasize the systematic and biogeographical significance of the newly discovered taxon: a poorly understood and independent colonization of the Philippine Archipelago by elapid snakes.