Highland Hump-nosed Pit Viper (Hypnale nepa)

English: Highland Hump-nosed Pit Viper
Binomial: Hypnale nepa 
Sinhala: කදුකර මූකලන් තෙලිස්සා

Hypnale nepa is a venomous pitviper species endemic to Sri Lanka. Based on the taxonomic revisions done so far, have stated that there are four species that belong to the genus Hypnale which live in Sri Lanka (Including possibly new species Hypnale sp. ‘amal’). Among them, population of H. nepa has been restricted to the highlands. At a glance, morphologically all these four species look similar. But with a closer look, H. nepa can be easily distinguished from its congeners using attributes like mentioned in the above named photograph.

This species is more active at night and they mostly live under the logs, rocks and in the leaf litter. Also they have been observed both in disturbed and undisturbed forests. It has been found that this species feeds on other snakes(Aspidura sp.), skinks, soft-shelled eggs and frogs (Maduwage et al. 2009).

Venom of this genus mainly causes local envenoming, coagulopathy and acute renal failure. H. nepa has the least toxicity among the studied three species of Hypnale with the LD50 value of 9.5 μg protein/g. Currently it is in the category of ‘Mildly venomous’ and so far no deaths have been reported due to envenomation (Silva et al. 2012).

Above photographed specimen was found at Dothalugala area in the Knuckles region. Observed place was an undisturbed montane forest. Elevation above the sea level of that location was about 1282m and that falls in the same elevation range (1250-1850m) of H. nepa’ s distribution mentioned in the research paper published by Dr. Kalana Maduwage and others (Maduwage et al. 2009). In the IUCN Red List it is in the category of ‘Least concern’. But necessary actions have to taken to make sure the future existence of the species.

References:

• Silva, Anjana, Panduka Gunawardena, Danister Weilgama, Kalana Maduwage, and Indika Gawarammana 2012 Comparative in-Vivo Toxicity of Venoms from South Asian Hump-Nosed Pit Vipers (Viperidae: Crotalinae: Hypnale). BMC Research Notes 5(1): 471.
• Maduwage, Kalana, Anjana Silva, Kelum Manamendra-Arachchi, and Rohan Pethiyagoda 2009 A Taxonomic Revision of the South Asian Hump-Nosed Pit Vipers (Squamata: Viperidae: Hypnale). Zootaxa 2232: 1–28.
• The IUCN Red List of Threatened Species(tm) 2015-4 - http://www.iucnredlist.org