Merrem's hump-nosed viper (Hypnale hypnale)

English: Merrem's hump-nosed viper
Sinhala: කුණකටුවා / පොලොන් තෙලිස්සා [Kunakatuwua/Polon thelissa]
Binomial name: Hypnale hypnale

Hypnale hypnale (Merrem's hump-nosed viper) is a venomous pit viper species found in Sri Lanka and India. 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. hypnale in Sri Lanka has been observed mainly in anthropogenic habitats and no observations have been made in undisturbed forests (Maduwage et al. 2009). At a glance, morphologically all these four species look similar. But with a closer look, H. hypnale can be easily distinguished from its congeners using scalation and with the help of non raised snout tip. This species is more active at night and in the day time they live under the logs, rocks and in the leaf litter. Venom of this genus mainly causes local envenoming, coagulopathy, acute renal failure and death. A research done by Dr. Anjana Silva and others (Silva et al. 2012) to compare the in-vivo toxicity of venoms of this genus reveals that the venom of H. hypnale has the highest toxicity compared to the venom of H. zara and H. nepa, with the LD50 value of 1.6 μg protein/g. Since there are known human bite reports with serious complications, this snake has been placed in the category of ‘Medically important’. 

Ref: 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. 

Maduwage K, Kularatne K, Wazil A, Gawarammana I: Coagulopthy, acute kidney injury and death following Hypnale zara envenoming – The first case report from Sri Lanka. Toxicon 2011, 58:641–643

Lowland Hump-nosed Pit Viper (Hypnale zara)

English: lowland Hump-nosed Pit Viper
Binomial: Hypnale zara
Sinhala: පහතරට මූකලන් තෙලිස්සා

Hypnale zara 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. zara has been restricted to the forests of lowlands and the foothills of the central highlands and no observations have been recorded in anthropogenic habitats (Maduwage et al. 2009). At a glance, morphologically all these four species look similar. But with a closer look, H. zara can be easily distinguished from its congeners using attributes like mentioned in the above named photographs. This species is more active at night and in the day time they live under the logs, rocks and in the leaf litter. 

Venom of this genus mainly causes local envenoming, coagulopathy, acute renal failure and death. A research done by Dr. Anjana Silva and others (Silva et al. 2012) to compare the in-vivo toxicity of venoms of this genus reveals that the venom of H. zara is less toxic compared to the venom of H. hypnale and has a higher LD50 value compared to H. nepa with the LD50 value of 6 μg protein/g. A report authored by Dr. Kalana Maduwage(Maduwage et al. 2011) describes a fatal case of a 47 years old male due to coagulopthy and acute kidney failure followed by envenoming of H. zara. 

Even it is common to seen in lowland forests, deforestations might be the main threat for the species and protecting the remaining fragments of lowland forests will guarantee 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.
• Maduwage K, Kularatne K, Wazil A, Gawarammana I: Coagulopthy, acute kidney injury and death following Hypnale zara envenoming – The first case report from Sri Lanka. Toxicon 2011, 58:641–643.

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

Merrem's Hump-nosed pit viper (Hypnale hypnale)

English : Merrem's hump-nosed pit viper / Hump nosed pit viper
Binomial Name : Hypnale hypnale
Sinhala : කුණකටුවා / පොළොන් තෙලිස්සා [kunakatuwa / Polon thelissa]

H. hypnale is a moderately venomous snake lives in Sri Lanka and India. Lives in wet, intermediate and dry zone. Give birth to live young instead of laying eggs. Responsible for the higherst snake bites of Sri Lanka

Sri Lankan Green Pit Viper (Trimeresurus trigonocephalus)

Engish:     Sri Lankan Green Pit Viper

Scientific: Trimeresurus trigonocephalus

Sinhala:    පලා පොළඟා [Pala Polanga]

T. trigonocephalus is an endemic snake of Sri Lanka. It is moderately venomous and venom mostly consists of hemotoxins that can affect on the bloodstream of it’s pray or enemy. This nocturnal viper has a pair of pit organs on either side of their head that can detect infrared light / heat rays emitted by its pray or enemy. There for Sri Lankan Green Pit Vipers are considered to have a night vision similar to a modern military equipment. Even though they are distributed across most parts of Sri Lanka, Most commonly seen in wet zone rain forest such as Sinharaja and Kanneliya.