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

PeerJ. 2023 May 18:11:e15185. doi: 10.7717/peerj.15185. eCollection 2023.

Abstract

The kukri snakes of the genus Oligodon Fitzinger, 1826 reach the westernmost limits of their distribution in Middle and Southwest Asia (Afghanistan, Iran, and Turkmenistan), and the Palearctic portions of Pakistan. In this article, we review the systematics and distribution of the two species native to this region, Oligodon arnensis (Shaw, 1802) and Oligodon taeniolatus (Jerdon, 1853) based on an integrative approach combining morphological, molecular, and species distribution modeling (SDM) data. Phylogenetic analyses recover O. taeniolatus populations from Iran and Turkmenistan in a clade with the O. arnensis species complex, rendering the former species paraphyletic relative to O. taeniolatus sensu stricto on the Indian subcontinent. To correct this, we resurrect the name Contia transcaspica Nikolsky, 1902 from the synonymy of O. taeniolatus and assign it to populations in Middle-Southwest Asia. So far, Oligodon transcaspicus comb. et stat. nov. is known only from the Köpet-Dag Mountain Range of northeast Iran and southern Turkmenistan, but SDM mapping suggests it may have a wider range. Genetic samples of O. "arnensis" from northern Pakistan are nested in a clade sister to the recently described Oligodon churahensis Mirza, Bhardwaj & Patel, 2021, and are phylogenetically separate from O. arnensis sensu stricto in south India and Sri Lanka. Based on morphological similarity, the Afghanistan and Pakistan populations are assigned to Oligodon russelius (Daudin, 1803) and we synonymize O. churahensis with this species. Our investigation leads us to remove O. taeniolatus from the snake fauna of Afghanistan, Iran, and Turkmenistan, with the consequence that only Oligodon transcaspicus comb. et stat. nov. and O. russelius are present in these countries. Additional studies are needed to resolve the taxonomy of the O. taeniolatus and O. arnensis species complexes on the Indian subcontinent, and an updated key for both groups is provided.

Keywords: Indian subcontinent; Iran; Köpet–Dag Mountain Range; Middle Asia; Oligodon taeniolatus; Oligodon transcaspicus; Taxonomy; Turkmenistan; mtDNA; species distribution modeling.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Afghanistan
  • Animals
  • Cheirogaleidae*
  • Colubridae*
  • Iran
  • Lizards*
  • Phylogeny

Grants and funding

Specimen storage and examination was completed with financial support of Russian Science Foundation (RSF Grant No. 22–14–00037; molecular phylogenetic analysis, specimen examination) to Nikolay A. Poyarkov; with support of the Russian Foundation for Basic Research and Iran National Science Foundation (Grant No. 20–54–56033; specimen collection) to Roman Nazarov; by the grant of the Ministry of Science and Higher Education of the Russian Federation (Grant No. 075-15-2021-1069) and state theme of Zoological Institute RAS 1021051302397-6 (to Nikolai Orlov and Konstantin D. Milto, specimen examination); and by the grant of the Scientific Grant Agency of the Slovak Republic VEGA 1/0242/21 (DNA work, sequencing, SDM modeling, fieldwork, specimen examination) to Daniel Jablonski. The Villanova Scholarship Open Access Reserve (SOAR) Fund provided payment for article processing charges. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.