Sunday, August 25, 2019

Dumbara corrugated frog (Lankanectes pera)

English: Dumbara corrugated frog
Sinhala: දුම්බර වකරැලි මැඩියා [Dumbara wakareli madiya]
Binomial: Lankanectes pera
For more than 150 years, it was believed that the genus Lankanectes is monotypic and the genus consists of a one species named, Lankanectes corrugatus. But later, a group of researchers observed an amphibian in Knuckles mountains that was very similar to previously known L. corrugatus, but having some morphological differences. 
Finally in 2018, they have described the Lankanectes population resides in the knuckles mountain range as a new species by giving the name, Lankanectes pera. Species was named after University of Peradeniya and the name 'Pera' is a short form of the name for University of Peradeniya which is being used by many university students. 
Genetic studies have also been carried out to compare genetic differences between L. corrugatus and the knuckles population of Lankanectes. Results from DNA barcoding and phylogenetic analyses have shown that L. pera differs from L. corrugates by 3.5−3.7% uncorrected genetic distances for 16S rRNA, which is adequate to name the knuckles population as a separate species. Based on the study, they have concluded that the new species defers from L. corrugates in external morphology, genetics and climatic niche. 
Distribution of L. pera is very limited and they have been restricted to higher altitude streams flowing through the montane forests in the Knuckles region where elevation is about 1100m above the sea level. Also, the environments they live have already been threatened by human activities. Hence, some immediate conservation actions must be taken to protect this rare frog.
Referance:
Senevirathne, Gayani & Samarawickrama, Pradeep & Wijayathilaka, Nayana & Manameendraarchchi, Kelum & Samarawikrama, DRNS & Meegaskumbura, Madhava. (2018). A new frog species from rapidly dwindling cloud forest streams of Sri Lanka—Lankanectes pera (Anura, Nyctibatrachidae). Zootaxa. 4461. 519-538. 10.11646/zootaxa.4461.4.4.

Sunday, June 9, 2019

Mihintale Red Narrow-mouthed Frog (Microhyla mihintalei)

English: Mihintale Red Narrow-mouthed Frog
Sinhala: මිහින්තලය රතු මුව පටු මැඩියා [Mihinthalaya rathu muwa-patu madiya]
Binomial: Microhyla mihintalei

Mihintale Red Narrow-mouthed Frog(Microhyla mihintalei) is an endemic frog and it was described recently (2016) with the help of specimens collected from dry zone of Sri Lanka including Mihinthale. The species was named after Mihintale which is one of the world’s earliest documented sanctuaries. It is also known as the place where King Dewanampiya Tissa met Mihindu thero who came from India in 246 BC.
But the ancestors of Microhyla mihintalei have found their way to Sri Lankan lowlands from India few million years ago via the land bridge created between Sri Lanka and India which was caused by earlier ice ages followed by excessive ice deposits in poles. But later, rise in the sea level caused land mass between India and Sri Lanka to disappear by creating an oceanic barrier and that resulted closing the land connection between two lands.
In India, Still lives a frog named Microhyla rubra, who is considered to be a descendent of the common ancestor of Microhyla mihintalei. As a result of thousands of years of separation due to the oceanic barrier between two land masses, Sri Lankan population of this common frog has been evolved as the new species we call, Microhyla mihintalei.
Studies have suggested significant genetic distance, morphology and differences in vocalization to distinguish Microhyla mihintalei from its common Indian ancestral species, Microhyla rubra.

Reference:
Meegaskumbura, Madhava; Biju, S. D.; Karunarathna, Nuwan; Senevirathne, Gayani; Garg, Sonali; Wijayathilaka, Nayana (2016). "A new species of Microhyla (Anura: Microhylidae) from Sri Lanka: an integrative taxonomic approach". Zootaxa. 4066 (3): 331–342. doi:10.11646/zootaxa.4066.3.9

Sunday, May 26, 2019

Rough-horn lizard(Ceratophora aspera)

English: Rough-horn lizard
Sinhala:රළු අංකටුස්සා[Ralu Ankatussa]
Binomial: Ceratophora aspera

Ceratophora aspera, an edemic horn bearing lizard was first described by Albert Günther in 1864.Several theories have been suggested to describe the evolutionary purpose of the horn of these agamid lizards.One such hypothesis suggests that it is used for the purpose of communication within the species. Also it is said that more larger and prominent horns in males are used in attracting females for reproduction. Another theory describes that rough, brown colored horn like structure has provided an evolutionary advantage by providing a form of camouflage by letting them to blend with the leaf litter filled environment. Studies carried out using mitochondrial DNA reveals that the diversification of C. aspera has been taken place from its common ancestor about 12.6 million years ago in the Miocene(Schulte et al. 2002).


Reference:
Schulte, James A, J.Robert Macey, Rohan Pethiyagoda, and Allan Larson 2002 Rostral Horn Evolution among Agamid Lizards of the Genus Ceratophora Endemic to Sri Lanka. Molecular Phylogenetics and Evolution 22(1): 111–117.

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.