Saturday, May 19, 2018

Sri Lankan krait (Bungarus ceylonicus)


English: Sri Lankan krait
Sinhala:මුදු කරවලා[Mudu Karawala]
Binomial: Bungarus ceylonicus

Bungarus ceylonicus(Sri Lankan krait ,මුදු කරවලා), is a relatively rare, deadly venomous and endemic elapid snake found mainly in wet and intermediate zones of the island. They live in undisturbed forests, but sometimes in anthropogenic habitats. It has a black, shiny skin crossed with thick white transverse bands that get disappeared with the age. There is a set of other non-venomous snakes in Sri Lanka which belong to the genus Lycodon that mimics the color pattern of Bungarus ceylonicus. But B. ceylonicus can be distinguished by enlarged hexagonal vertebral scales, relatively shiny body scales and undivided subcaudal scales. Also head and the neck are not much distinguishable in kraits when it is compared with the members of genus Licodon. 

The Sri Lankan krait is oviparous and feeds on other reptiles, small mammals like rats and skinks. Even thought the snake is highly venomous, it showed a very timid and non-aggressive behavior in the day time and reluctant to bite. It was also observed that it always tried to escape and hide in covered safe places when threatened or sometimes tried to protect itself by hiding its head under the body loops. But during the night they are said to be become very active and could provide fatal bites for a considerable provocation. Being a relatively rare to find and shy reptile, fatal human bites are rare. But deaths have been reported due to envenomation. 
Venom of B. ceylonicus is mainly powerful neurotoxins that act on nerve endings near the synaptic clefts of neurons. Also, members of the genus Bungarus produce a mix of presynaptic and postsynaptic neurotoxins that need immediate hospitalization and treatments in case of an envenomation. 
A specific anti venom has not been developed so far that work effectively for the bites of B. ceylonicus. Even the B. ceylonicus bites are rare; some clinical studies have been done to study the effect of venom on human. The first fatal case report dates back to 1993 for B. ceylonicus(De Silva et al. 1993) which describes a death of a patient within 90 hours after the bite, followed by a cardio-respiratory arrest even with provided treatments such as anti-venom and mechanical ventilation. 

Also one such recent case study ( Rathnayaka N. et al, 2017) describes a dry bite occurred at day time which was ended without any envenamation symptoms. According to the report, other incident has been taken place at night while the victim was at sleep with signs and symptoms of moderate envenoming such as tightness in the chest and dyspnoea followed by neuromuscular paralysis. Anotether study (Dalugama C. et al, 2017) describes an envenomation by the same snake which caused bilateral partial ptosis, ophthalmoplegia, facial muscle weakness and dysphagia. According to the authors, that patient had been administered polyvalent Indian anti-venom which showed a poor response for the envenomation of B. ceylonicus. Even the snakes are dangerous; they provide an immense support to maintain a proper balance in an eco system. Habitat destruction an unwanted killing have become the main threat for this relatively rare species.

References:
  • A Naturalist's Guide to the Reptiles of Sri Lanka by Anslem de Silva and Kanishka Ukuwela
  • Neurotoxic envenoming by the Sri Lankan krait (Bungarus ceylonicus) complicated by traditional treatment and a reaction to antivenom. Trans. R. Soc. Trop. Med. Hyg. 87, 682e684.De Silva, A., Mendis, S., Warrell, D.A., 1993.
  • Confirmed Ceylon krait (Bungarus ceylonicus) envenoming in Sri Lanka resulting in neuromuscular paralysis: a case report C Dalugama, IB Gawarammana - Journal of medical case reports, 2017
  • Two rare case reports of confirmed Ceylon krait (Bungarus ceylonicus) envenoming in Sri Lanka. Toxicon, 127, 44–48. Namal Rathnayaka, R. M. M. K., Kularatne, S. A. M., Kumarasinghe, K. D. M., Jeganadan, K., & Ranathunga, P. E. A. N. (2017).

Sunday, February 4, 2018

Whistling lizard (Calotes liolepis)

English: Whistling lizard
Sinhala:සිවුරුහඬලන කටුස්සා[Siwuruhandalana katussa]
Binomial: Calotes liolepis

Whistling lizard, සිවුරුහඬලන කටුස්සා (Calotes liolepis) is an endemic species of lizards distributed in wet and intermediate zones from sea level up to 800m. It was given the name ‘Whistling lizard’ due to the high pitched whistling sound they make when disturbed. Since the Calotes liolepis was first described by Bolenger; 1885, it was considered that there is an only one single species distributed throughout the country until further research was done. But now it is said that the liolepis group consists of three distinct species namely, Calotes manamendrai from Knuckles region, Calotes desilvai from Rakwana mountains and the species living in areas like Sinharaja, Galle, Kandy and Ritigala as Calotes liolepis. It falls under ‘Endangered’ category in the IUCN red list and the habitat destruction is the main threat.

Saturday, February 3, 2018

Sri Lanka Tiger Loach(Acanthocobitis urophthalmus)

English:Sri Lanka Tiger Loach
Sinhala: වයිරන් අහිරාවා / පොල් අහිරාවා[Wairan ahirawa/Pol ahirawa]
Binomial: Acanthocobitis urophthalmus

It is an endemic species of freshwater fish found in lowlands of the Western and South-Western wet zones from Kelani to Nilwala river basins.

Saturday, August 5, 2017

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.

Thursday, June 8, 2017

Black ruby barb (Pethia nigrofasciata)

English: Black ruby barb
Binomial: Pethia nigrofasciata
Sinhala: බුලත් හපයා/මනමාලයා

Black ruby barb is an endemic species of freshwater fishes found in lowland wet zone of the Southern and Western region of Sri Lanka. They live in clear and un polluted water streams. It is in the category of 'Least Concern' in the IUCN Red list. But it is a popular species in the aquarium trade and necessary actions have to be taken to save the species in the natural habitats.

Saturday, June 3, 2017

Knuckles Shrub Frog (Pseudophilautus fulvus)



English: Knuckles Shrub Frog
Binomial: Pseudophilautus fulvus
Sinhala: දුම්බර පඳුරු මැඩියා

Pseudophilautus fulvus is an endemic species of shrub frogs restricted to the Knuckles mountain region. It has been observed in closed canopy forests, anthropogenic habitats, secondary forests and cardamom plantations(Meegaskumbura and Manamendra-Arachchi 2005).
Above photographed ones were observed in the adjoining forest of Deanston Conservation Center in the knuckles region. The major threats for the species are habitat destruction and agro-chemical pollution. IUCN Red List status of the frog is ‘Endangered’

References: 
  • Manamendra-Arachchi, K., and Pethiyagoda, R. (2005). ''The Sri Lankan shrub-frogs of the genus Philautus Gistel, 1848 (Ranidae: Rhacophorinae), with description of 27 new species.'' Raffles Bulletin of Zoology, Supplement 12, 163-303.
  • The IUCN Red List of Threatened Species(tm) 2015-4 - http://www.iucnredlist.org
  • Manamendra-Arachchi, K. & R. Pethiyagoda (2006): Sri Lankan amphibians [in Sinhala]. – WHT Publications, Colombo.

Monday, May 1, 2017

Black-lined Golden Rasbora (Rasboroides nigromarginatus)

Male
Female
Male



English: Black-lined Golden Rasbora
Binomial: Rasboroides nigromarginatus
Sinhala: කළු වරල් හල්මල් දණ්ඩියා[Kalu waral halmal dandiya]

Rasboroides nigromarginatus is a relatively rare endemic species of freshwater fish restricted to the Kalu river basin. This species was described for the first time by a Germen biologist named H. Meinken in 1957 after observing a single specimen of the fish among some exported ornamental fresh water fishes from Sri Lanka. Since the exact collected location has not been known, he has mentioned ‘Ceylon’ as the locality. Meanwhile, the species remained in the synonymy of R. vaterifloris for a long time. It has not been observed in the natural environment since then until R. Pethiyagoda & K. Manamendra Arachchi observed some fish from Athwelthota area in 1994 that match with the H. Meinken’s first description. Again in 2010, members of Wildlife Conservation Society, Galle have found and observed the same fish from Athwelthota area and have re-described the fish as a valid species by verifying Meinken’s work(Batuwita S. et al., 2013). 
Above photographed ones were also observed in river Maguru, which is a branch of Kalu river. Observed place was a shady place of the river margin close to the borders of Sinharaja forest. Place was away from human habitats and no activities were observed that cause environmental pollution, which might be the reason to have a healthy living population of this rare fish. Since the population of the fish is restricted to few locations, critical actions need to be taken to protect the species for the future. 

Reference: 
  • Batuwita S., de Silva M. and Edrisinghe U., 2013. A review of the danionine genera Rasboroides and Horadandia (Pisces: Cyprinidae), with description of a new species from Sri Lanka Ichthyol. Exploe. Freshwaters, Vol. 24, No. 2, 121-140 pp.