Hypnale nepa

{{Short description|Species of snake}} {{Speciesbox | image = Hypnale nepa is a venomous pitviper species endemic to Sri Lanka.jpg | status = EN | status_system = IUCN3.1 | status_ref = <ref name="iucn status 18 November 2021">{{cite iucn |author=Ukuwela, K., de Silva, A., Kannishka, S., Pushpamal, V. & Kandambi, D. |date=2021 |title=''Hypnale nepa'' |volume=2021 |article-number=e.T178661A123308135 |url=https://www.iucnredlist.org/species/178661/123308135 |access-date=18 November 2021}}</ref> | genus = Hypnale | species = nepa | authority = ([[Josephus Nicolaus Laurenti|Laurenti]], 1768) | range_map = Hypnale nepa distribution.png | synonyms = * ''Coluber nepa'' Laurenti, 1768 * ''Hypnale nepa'' – [[Albert Günther|Günther]], 1864 * ''Crotalus Hypnale nepa'' – Higgins, 1873 * ''[[Hypnale walli]]'' – [[Howard K. Gloyd|Gloyd.]], 1977 * ''Ancistrodon nepa'' – [[Malcolm Arthur Smith|M.A. Smith]], 1937 * ''Agkistrodon nepa'' – [[Edward Harrison Taylor|Taylor]], 1950 * ''Hypnale nepa'' – [[Howard K. Gloyd|Gloyd]], 1977 | synonyms_ref = <ref name="McD99">McDiarmid RW, [[Jonathan A. Campbell|Campbell JA]], Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref> }}

'''''Hypnale nepa''''', the '''Sri Lankan hump-nosed viper''',<ref name="G&C90">[[Howard K. Gloyd|Gloyd HK]], [[Roger Conant (herpetologist)|Conant R.]] 1990. Snakes of the ''Agkistrodon'' Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp. 52 plates. LCCN 89-50342. {{ISBN|0-916984-20-6}}.</ref> is a [[venomous snake|venomous]] [[Crotalinae|pitviper]] [[species]] [[Endemism|endemic]] to [[Sri Lanka]] where it is known as මූකලන් තෙලිස්සා (mukalan thelissa) in Sinhala. Earlier thought that ''[[Hypnale walli]]'' and ''Hypnale nepa'' were two distinct species, but it is now accepted that it is the same species and ''[[Hypnale walli]]'' is a synonym name. Relatively small, they are distinguished by a strongly upturned snout. No [[subspecies]] are currently recognized.<ref name="ITIS">{{ITIS |id=634894 |taxon=''Hypnale nepa'' |accessdate=8 August 2008}}</ref>

==Description== Adults grow to a total length of {{convert|30|–|35|cm|in|frac=4|abbr=on}}. According to [[Frank Wall (herpetologist)|Wall]] (1921), the maximum recorded lengths are for a male of {{convert|38.7|cm|in|frac=4|abbr=on}} and a female of {{convert|38.1|cm|in|abbr=on}}. According to [[Paules Edward Pieris Deraniyagala|Deraniyagala]] (1955), the largest specimen in the Colombo museum was {{convert|39.2|cm|in|frac=4|abbr=on}} in total length with a tail measuring {{convert|5.9|cm|in|frac=4|abbr=on}}. In general, the tail is 13-18% of total body length. The body is moderately slender, with a head that is conspicuously distinct from the neck.<ref name="G&C90"/>

This species is distinguished from ''[[Hypnale hypnale|H. hypnale]]'' by a snout that has a strongly upturned tip. This is due to an extended [[rostral scale]], which is immediately followed by a raised wart-like hump covered with 7-14 very small scales. Also, the [[Hemipenis|hemipenes]] have clearly visible spines.<ref name="G&C90"/>

The scalation includes 17 rows of [[dorsal scales]] at midbody that are weakly [[Keeled scales|keeled]] or smooth, 124-142 [[ventral scales]], and 33-41 [[subcaudal scales]].<ref name="G&C90"/>

The color pattern consists of a light brown to dark brown to pale olive ground color, flecked and mottled with darker tones. This is overlaid with a series of 17-26 dorsolateral suboval or subtriangular brown blotches that alternate or oppose each other middorsally. These blotches are 3-4 scales wide and extend down to the third scale row. The top of the head is brown, and usually lacks any pattern, except for a black postorbital stripe that extends to the neck.<ref name="G&C90"/>

==Geographic range== ''Hypnale nepa'' is found in [[Sri Lanka]] throughout [[forest]]ed areas, from lowland [[rainforest]] to over {{convert|1,800|m|ft|abbr=on}} altitude. The [[Type locality (biology)|type locality]] given is "Africa." An obvious error, this was amended to "Sri Lanka" by [[:fr:Alphonse Richard Hoge|Hoge]] and Romano-Hoge (1981).<ref name="McD99"/>

==References== {{Reflist}}

==Further reading== * [[Josephus Nicolaus Laurenti|Laurenti, J.N.]] 1768. ''Specimen Medicum, Exhibens Synopsin Reptilium Emendatum Cum Experimentis Circa Venena Et Antidota Reptilium Austriacorum''. "Joan. Thom." Vienna. 214 pp. + Plates I.-V. (''Coluber nepa'', p. 97.)

==External links== * {{NRDB species|genus=Hypnale|species=nepa|date=8 August|year=2008}}

[[Category:Hypnale|nepa]] [[Category:Reptiles of Sri Lanka]] [[Category:Reptiles described in 1768]] [[Category:Taxa named by Josephus Nicolaus Laurenti]]