Higher-level phylogeny of Asian and American coralsnakes, their placement within the Elapidae (Squamata), and the systematic affinities of the enigmatic Asian coralsnake Hemibungarus calligaster (Wiegmann, 1834)

Abstract

1 The snake family Elapidae contains over 60 genera (about 300 species) of highly venomous snakes. About one-third of the alpha-taxonomic diversity of the Elapidae comprises coralsnakes: a major radiation of colourful venomous snakes including six genera distributed in Asia and the Americas. In this study, we examine molecular phylogenetic and descriptive morphological evidence for the placement of the monotypic coralsnake genus Hemibungarus (H. calligaster (Wiegmann)) among the elapids, and clarify the relationships among genera traditionally referred to as 'coralsnakes'. We use two mitochondrial gene fragments (ND4 and cyt-b) and a nuclear gene fragment (c-mos) to estimate relationships among elapids and other colubroid snakes, based on parsimony and likelihood methods, as well as Bayesian phylogenetic methods incorporating complex partitioned models of nucleotide evolution. As different phylogenetic methods provided alternativee results, we include an extensive examination of molecular phylogenetic analyses to facilitate a transparent and thorough exploration of the data. Additionally, we highlight external morphological and hemipenial characters that appear to further support molecular hypotheses for the placement of Hemibungarus, and relationships among the Elapinae. Owing to conflicting descriptions of morpho- logical characters in the literature, and the unavailable of comparative morphological data for certain key species, we include detailed descriptions of the hemipenes of Bungarus caeruleus (Schneider), B. fasciatus (Schneider), Calliophis nigrescens Gunther, Dendroaspis polylepis (Gunther), H. calligaster (Wiegmann), Naja naja (Linnaeus) and Ophiophagus hannah (Cantor). We present evidence that Asian and American coralsnakes (Calliophis, Sinomicrurus, Micruroides, Micrurus and Leptomicrurus) form an exclusive clade, distantly related to Hemibun- garus. Thus, despite long-held beliefs of systematic affinities based on morphology and colour pattern, our results suggest that Hemibungarus is not (phylogenetically) a coralsnake, but instead shares an exclusive common ancestor with Afro-Asian elapine genera (Elapsoidea, Dendroaspis and Ophiophagus). Results of our molecular phylogenetic analyses also support the recognition of two primary clades of elapids corresponding to the subfamilies Elapinae and Hydrophiinae. Additionally, we provide evidence that the Elapinae consists of two main clades: (1) coralsnakes s.s. (Calliophis, Sinomicrurus, Micruroides, Micrurus, Leptomicrurus), and (2) the remaining genera of Afro-Asian species, including cobras, kraits, mambas and Hemibungarus. We suggest a new classification for these two elapine clades: Calliophini for the coralsnakes (Calliophis, Sinomicrurus, Micrurus, Micruroides and Leptomicrurus), and Hemibungarini for the remaining Afro-Asian elapine species, including Hemibungarus. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 151, 809-831.