Phylogenetic structure and species boundaries in the mountain pitviper Ovophis monticola (Serpentes: Viperidae: Crotalinae) in Asia

We investigated phylogenetic structure and morphological variation in Asian mountain pitvipers of the genus Ovophis (comprising 3–4 species some of which are considered polytypic) by sequencing four mitochondrial markers (cytochrome b, NADH dehydrogenase subunit 4, 12S and 16S rRNA) from 72 specimens, and analysed them in a Bayesian framework together with another 26 sequences from closely related genera. We reconstructed the region of origin and direction of dispersal of the major clades, and of Ovophis as a whole, using likelihood framework analysis. We also defined morphogroups from 280 specimens from across the range of Ovophis to allow the geographic extent of the major clades to be determined, as well as to allow inclusion of specimens lacking sequence data. Phylogenetic analyses confirmed the monophyly of Ovophis as currently defined, and revealed that it contains two major lineages, eastern (mainly Chinese) and western, with both occurring in southwestern China, central and northern Viet Nam. The most likely origin of the genus, and of individual lineages, coincides with the northeastern boundary of the Indomalayan hotspot. Major diversification in this species group likely corresponded to major climatic changes arising from the uplift of the Tibetan Plateau in the early to mid Miocene. With reference to the defined morphogroups, we suggest that at least five species are present and provide appropriate names. With a few exceptions, the newly defined species boundaries do not correspond to the existing taxonomy.

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► Ovophis is monophyletic but with two main (eastern and western) lineages present.
► The lineages overlap in southwestern China, northern and central Vietnam.
► Five species are defined by a combination of morphological and molecular evidence.
► The newly defined species largely do not correspond with the existing taxonomy.
► Origins of clades occur along the northeastern boundary of the Indomalayan hotspot.