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

Abstract

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cinereus sensu lato broadly overlap and supposed differences in hemipenial morphology between the two taxa are due to outdated terminologies used to describe the organ.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.

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

“…Our mtDNAbased genealogy for the genus Oligodon (Fig. 2) correlates well with the set of phylogenetic relationships obtained from previous phy logenies (Nguyen et al 2020;Qian et al 2021;Mirza et al 2021;Das et al 2022;Yushchenko and Lee et al 2023) and confirms the inferring of five major clades within the genus, along with the suggested presence of one addition al clade (see Fig. 2).…”

“…Abbrevia tions for characters can be found in the materials and methods. Data for other species are based on the following literature sources: Pope (1935), Smith (1943), Wagner (1975Wagner ( , 1976, David et al (2008aDavid et al ( , 2008bDavid et al ( , 2011David et al ( , 2012, Orlov et al (2010), Vassilieva et al (2013, Pham et al (2014), Vassilieva (2015, Nguyen et al (2016Nguyen et al ( , 2017Nguyen et al ( , 2022, Nguyen et al (2020), Lalbiakzuala and Lalremsanga (2020), Lee (2022), Yushchenko and Lee et al (2023). hemipenial morphology, only select members of the O. cyclurus-taeniatus species grouphave bilobed hemipenes without spinous calyces or myoectaces (papillae).…”

“…The kukri snakes of the genus Oligodon Fitzinger, 1826 are a speciesrich group of colubrids comprised of 89 rec ognized species (Nguyen et al 2022;Uetz et al 2022;Yushchenko and Lee et al 2023). Although the genus is taxonomically diverse, most members are infrequently collected in the field and are known from only a few spec imens or their namebearing types (Supsup and Carestia 2020;Lee et al 2021).…”

“…Of these, eight are considered endemic, and ten have been described in the last decade (David et al 2008a(David et al , 2008b(David et al , 2012Vassilieva et al 2013;Vassilieva 2015;Nguyen et al , 2017Nguyen et al , 2022Nguyen et al 2020). Yushchenko and Lee et al (2023) recently reassessed the taxonomy of one newly described Vietnamese species, Oligodon cattienensis Vassilieva et al, 2013, resulting in its syn onymziation with the more wideranging and morpholog ically variable Oligodon cinereus Günther, 1864. In addi tion, Nguyen et al (2022) described another new species, Oligodon tuani Nguyen et al, 2022 from the Langbian Plateau of southern Vietnam. These studies indicate our knowledge of Oligodon in this country is far from com plete, and taxonomic revisions are still needed to under stand the species boundaries of many of its members.…”

Kukri snakes Oligodon Fitzinger, 1826 of the Western Palearctic with the resurrection of Contia transcaspica Nikolsky, 1902 (Reptilia, Squamata, Colubridae)

“…tillacki herein (see Discussion). For outgroup taxa, we chose one sample each of Oreocryptophis porphyraceus ( Cantor, 1839 ) (subfamily Colubrinae) and Hebius vibakari ( Boie, 1826 ) (subfamily Natricinae) due to their use in previous phylogenies of Oligodon published in the literature ( Nguyen et al, 2020 ; Yushchenko et al, 2023a , 2023b ). One specimen (ZMMU Re-16687) will be transferred to the International Center for Science, High Technology and Environmental Sciences Herpetological Collection (ICSTZM) in order to meet the obligations of fieldwork permissions.…”