A new species of kukri snake (Squamata: Colubridae: Oligodon Fitzinger, 1826) from Con Dao Islands, southern Vietnam

NA. The taxonomic status of the kukri snake Oligodon arenarius Vassilieva, 2015 with a redescription of Oligodon macrurus (Angel, 1927) (Squamata, Serpentes, Colubridae)

We investigated the taxonomic status of the recently described kukri snake Oligodon arenarius Vassilieva, 2015 and the morphologically similar Oligodon macrurus (Angel, 1927), two species endemic to the southern coast of Vietnam. Based on phylogenetic analyses using three mitochondrial genes (12S–16S rRNA, cytochrome b), we recovered O. arenarius and O. macrurus in a clade within the O. cyclurus-taeniatus species group, agreeing with previous intrageneric classifications. Genetic distances between O. arenarius and O. macrurus are extremely low (less than 0.5% based on 12S–16S) and render O. arenarius paraphyletic. All preserved specimens of O. arenarius and O. macrurus convey little to no differences in color pattern, hemipenial morphology and osteological features; the latter of which is based on three dimensional micro computer tomography (µCT) scans of one specimen per species. Contrasting these results, univariate and multivariate analyses revealed significant differences in relative tail length, and the number of ventral and subcaudal scales between both species. Although the molecular and morphological datasets present conflicting results, integrating the evidence leads us to synonymize O. arenarius with O. macrurus. We provide a formal redescription of O. macrurus, designate a neotype specimen to avoid future taxonomic confusion, and provide the first detailed osteological description of this species. Oligodon macrurus sensu stricto is endemic to coastal dunefields and adjacent forest habitats in southern Vietnam, where ongoing human development, tourism and road mortality pose significant threats to its conservation. Consequently, we suggest that O. macrurus should be listed as “Vulnerable” based on the assessment criteria of the International Union for Conservation of Nature (IUCN).

A taxonomic re-assessment of Oligodon cinereus (Günther, 1864) (Squamata, Serpentes, Colubridae) populations from southern Indochina

The ashy kukri snake Oligodon cinereus (Günther, 1864) is a widely distributed and morphologically variable species found throughout mainland Southeast Asia. In this paper, we re-assessed the taxonomic status of O. cinereus populations found in southern Indochina (southern Vietnam, Cambodia, and southern Laos), including the recently described Cat Tien kukri snake Oligodon cattienensisVassilieva et al., 2013, which was previously confused with this species. Phylogenetic analyses using mitochondrial DNA from the 12S–16S ribosomal subunit and cytochrome b gene revealed that O. cattienensis is embedded in a mixed clade containing samples of the subspecies O. cinereus pallidocinctus, which bears a dorsal color pattern with white crossbars and black edges. This clade forms a strongly supported sister group with a topotypic sample of O. cinereus cinereus, representing populations bearing a uniform dorsal color pattern and slight reticulate markings, however the genetic divergence between the two clades is very low. The morphological characters used to distinguish O. cattienensis from O. cinereus sensu lato broadly overlap and supposed differences in hemipenial morphology between the two taxa are due to outdated terminologies used to describe the organ. We relegate both O. cattienensis and O. cinereus pallidocinctus to the junior synonymy of O. cinereus and consider all color patterns of this species found near the type locality in Cambodia, southern Laos, and southern Vietnam to represent O. cinereus sensu stricto. Future integrative investigations across the range of O. cinereus sensu lato are needed to resolve the status of the remaining subspecies and synonyms associated with this taxon. Problems associated with hemipenial morphology and Oligodon systematics are also discussed.

A new species of Oligodon Fitzinger, 1826 from the Langbian Plateau, southern Vietnam, with additional information on Oligodon annamensis Leviton, 1953 (Squamata: Colubridae)

We describe a new species of Oligodon from the highlands of the Langbian Plateau, southern Truong Son Mountains, Vietnam, based on morphological and molecular phylogenetic analyses. The new species, Oligodon rostralissp. nov is distinguished from its congeners by the following morphological characters: medium size in adults (male TL = 582 mm); small and broad head with long protruding snout; dorsal scale row formula 15-15-13; 167 ventrals, 47 subcaudals; single preocular, single postocular; loreal and presubocular absent; six supralabials, third and fourth entering orbit; six infralabials, anterior four contacting first pair of chin shields; internasals separate from prefrontals; nasal divided; single anterior and two posterior temporals; cloacal plate undivided; hemipenes short, bilobed, bifurcating in anterior one third of their length, extending to 8th subcaudal, lacking spines and papillae, with a prominent transverse flounces and distal calyces; six maxillary teeth, the posterior three enlarged; dorsal pattern consisting of 14+4 large dark-brown blotches and a bright-orange vertebral stripe on tail and dorsum; and ventral surfaces in life cream laterally with dark quadrangular spots; dark temporal streak present, edged with white. We also provide additional information on O. annamensis, including a morphological dataset of all specimens known from natural history collections and confirmation of an earlier record of O. annamensis from Cambodia. We also provide the first record of O. annamensis for Dak Lak Province. Phylogenetic analyses of mtDNA genes (3,131 bp of 12S rRNA, 16S rRNA and cyt b) suggest sister relationships of Oligodon rostralissp. nov. and O. annamensis and place them in one clade with the O. cyclurus and O. taeniatus species groups, which is concordant with previous studies on the phylogenetic relationships of Oligodon. Our study demonstrates high level of herpetofaunal diversity and endemism of Langbian Plateau and further supports the importance of this area for conservation herpetofaunal diversity in Indochina.