{{Short description|Species of snake}} {{Speciesbox | image = | status = CR | status_system = IUCN3.1 | status_ref = <ref name="iucn" /> | genus = Trimeresurus | species = labialis | authority = [[Franz Steindachner|Steindachner]], 1867 | synonyms = * ''Bothrophis labialis'' <br><small>[[Leopold Fitzinger|Fitzinger]], 1861</small> ''([[nomen nudum]])'' *''Trimeresurus labialis'' <small>Steindachner, 1867</small> *''Trim''[''eresurus'']. ''mutabilis'' <small>[[Ferdinand Stoliczka|Stoliczka]], 1870</small><ref name="McD99">[[:fr:Roy Wallace McDiarmid|McDiarmid RW]], [[Jonathan A. Campbell|Campbell JA]], Touré TA (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1''. Washington, District of Columbia: Herpetologists' League. 511 pp. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref> *''Trimeresurus labialis'' <br><small>— [[Malcolm Arthur Smith|M.A. Smith]], 1943</small> *''Cryptelytrops labialis'' <br><small>— Malhotra & Thorpe, 2004</small> *''Trimeresurus (Trimeresurus) labialis'' <br><small>— David et al., 2011</small><ref>"''Trimeresurus labialis'' ". The Reptile Database. www.reptile-database.org.</ref> }}
'''''Trimeresurus labialis''''', commonly called '''''Nicobar bamboo pit viper''''',<ref name=Gum04>Gumprecht A, Tillack F, [[Nikolai Liutsianovich Orlov|Orlov NL]], [[Ashok Captain|Captain A]], Ryabov S (2004). ''Asian Pitvipers''. First Edition. Berlin: Geitje Books. 368 pp. {{ISBN|3-937975-00-4}}.</ref> is a [[venomous snake|venomous]] [[pit viper]] [[species]] [[Endemism|endemic]] to the [[Nicobar Islands]] of [[India]]. No [[subspecies]] are currently recognized. Based on IUCN assessment in 2021, this viper is classified as [[critically endangered]].<ref name=ITIS>{{ITIS|id=634920|taxon=''Trimeresurus labialis ''|accessdate=27 September 2006}}</ref><ref name="iucn">{{Cite report |url=https://www.iucnredlist.org/species/194061/2295688 |title=Trimeresurus labialis: Mohapatra, P.: The IUCN Red List of Threatened Species 2021: e.T194061A2295688 |last=IUCN |date=2019-09-07 |publisher=International Union for Conservation of Nature |doi=10.2305/iucn.uk.2021-3.rlts.t194061a2295688.en |language=en}}</ref>
==Geographic range== Found only in the [[Nicobar Islands]] of [[India]]. The [[Type locality (biology)|type locality]] given is ''"den Nikobaren"''.<ref name=McD99/>
==Description== Males may attain a total length of {{cvt|42|cm}}, with a tail {{cvt|8|cm}} long; females, total length {{cvt|44|cm}}, tail {{cvt|7|cm}}.
Dorsally, ''T. labialis'' is brown, either light or dark, with or without darker spots or transverse bars. It may have a light streak on each side of the head, beginning at the snout, continuing under the eye, to the neck. Ventrally, it is also brown.
The dorsal scales are smooth, and are usually in 23 rows at midbody. Ventrals: 158-170 in males; 154-174 in females. Subcaudals: 60-65 in males; 46-57 in females. The subcaudals are usually double, but there may be some interspersed singles.<ref>[[Malcolm Arthur Smith|Smith MA]] (1943). ''The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Reptilia and Amphibia. Vol. III.—Serpentes''. London: Secretary of State for India. (Taylor and Francis, Printers). xii + 583 pp. (''Trimeresurus labialis'', pp. 525-526).</ref>
==References== {{Reflist}}
==Further reading== {{refbegin}} *Das I (1999). "Biogeography of the amphibians and reptiles of the Andaman and Nicobar Islands, India". pp. 43–77. '''''In'':''' Ota H (editor) (1999). ''Tropical Island Herpetofauna ...'' Amsterdam: Elsevier. 353 pp. {{ISBN|978-0444501950}}. *[[Franz Steindachner|Steindachner, F]] (1867). "''Reptilien'' ". pp. 1–98. '''''In'':''' [[Bernhard von Wüllerstorf-Urbair|von Wüllerstorf-Urbair B]] (1867) ["1869" on title page]. ''Reise der Österreichischen Fregatte Novara um die Erde in den Jahren 1857, 1858, 1859 unter den Befehlen des Commodore B. von Wüllerstorf-Urbair (Zoologie)'', [Vol. 1, part 3]. Vienna: K. Gerold's Sohn/Kaiserlich-Königl. Hof- und Staatsdruckerei. (''Trimeresurus labialis'', new species, p. 86 + Plate III, figures 1 & 2) (in German). *[[Ferdinand Stoliczka|Stoliczka F]] (1870). "Observations on some Indian and Malayan Amphibia and Reptilia". ''Ann. Mag. Nat. Hist., Fourth Series'' '''6''': 105-109. (''Trimeresurus mutabilis'', new species, p. 108). {{refend}}
==External links== *{{NRDB species|genus=Trimeresurus|species=labialis|date=28 November|year=2012}} {{Trimeresurus}}
{{Taxonbar|from=Q3007690}}
[[Category:Reptiles described in 1867]] [[Category:Endemic fauna of the Nicobar Islands]] [[Category:Snakes of India]] [[Category:Trimeresurus|labialis]] [[Category:Taxa named by Franz Steindachner]]