Tylototriton himalayanus Khatiwada, Wang, Ghimire, Vasudevan, Paudel & Jiang, 2015
|Species Description: Khatiwada JR, Wang B, Ghimire S, Vasudevan K, Paudel S, Jiang J 2015 A new species of the genus Tylototriton (Amphibia: Urodela: Salamandridae) from eastern Himalaya. Asian Herpetological Research 6: 245-256.|
Country distribution from AmphibiaWeb's database: India, Nepal
Author: Axel Hernandez
Tylototriton himalayanus KHATIWADA, WANG, GHIMIRE, VASUDEVAN,
PAUDEL, JIANG 2016
Diagnosis and taxonomyThe holotype (NHMTU17A-0098, an adult male) and two paratypes (NHMTU17A-0098-1, an adult male, and A 2-C002, a female) were collected at Mai Pokhari, Illam District, Mechi, eastern Nepal (27°0'25"N, 87°55'48"E at an elevation of 2,110 m a.s.l.) in 2003 and 2014, respectively. This species is differentiated from other members of its subgenus by the following morphological characters: A moderate TL of 15.3 cm in males and 16.4 cm in females; dorsolateral bony ridges on the head distinct and widely spaced; quadrate spine absent; head broad and flat; snout blunt; and moderately large eyes with granular upper eyelids. The dorsum bears paired dorsolateral rows of 16 dorsolateral glandular warts. The skin on the body and tail is finely granular. The tail is compressed laterally and has a well-developed fin. In life, the dorsal ground color is light brown with darker warts, whereas the ventral faces are cream-colored. Tail, hands and feet are comparatively lighter brown than the body. The ventral sides of the digits are rusty cream, but the palms and soles are of a dull cream color. In preservation, the body color fades to a lighter blackish brown, and the brown color will become lighter (KHATIWADA et al. 2015). A detailed analysis of the morphology (and life history) of Tylototriton spp. from eastern Nepal can also be found in ANDERS et al. (1998). Females tend to be larger than males in various morphometric traits, but do not differ as far as the color pattern is concerned. T. himalayanus is commonly called Pani Kukur, meaning “water dog”, by Nepalese villagers because of a loud noise the animal will generate by snapping its jaws when disturbed, which is very similar to that produced by T. panhai (WONGRATANA 1984, HERNANDEZ 2016b), and "Gorho" by the Gorkha people. A review of the Darjeeling population was provided by DEUTI & HEGDE (2007).
A population that is commonly assigned to T. verrucosus occurs in Manipur, India. Its taxonomic status needs to be clarified, because it is genetically divergent and morphologically different from this taxon. This type is referred to here as T. cf. himalayanus “Manipur”. Other types have also been reported from Bhutan (PALDEN 2003, WANGYAL & GURUNG 2012) and other parts of the eastern Himalayas such as Arunachal Pradesh (MANSUKHANI et al. 1976, SETHY & CHAUHAN 2011). Detailed molecular and morphological studies are therefore essential for identifying the exact distribution ranges of T. himalayanus and similar yet possibly distinct species in the eastern Himalayas, in particular because the distribution of the population in Manipur appears to be patchily distributed with little or no contact; this is particularly apparent in the population in the Senapati District. T. cf. himalayanus “Manipur” is well separated geographically from other populations of Tylototriton in India, although it might well have been connected to one or more southern lineages (Clades A & B) in the past. Another lineage that lives geographically near to T. himalayanus is known from two large populations in Bhutan: T. cf. himalayanus “Bhutan”. While morphologically similar to typical T. himalayanus, this form also deserves in-depth genetic study to clarify not only its taxonomic status but also for conservation purposes. Yet another type commonly attributed to T. verrucosus occurs in the extreme eastern parts of the Himalayas at Gandhigram in the Kamalang Valley, Lohit District, Aranuchal Pradesh, India, and is here treated as T. cf. himalayanus “Arunachal Pradesh” (T. cf verrucosus “Miao” in HERNANDEZ 2016a,b). First mentioned by MANSUKHANI et al. (1976), this poorly studied population is presently known from only five individuals discovered one morning in the early 2000’s in the Namdapha wild tiger national park at between 1126 and 1177 m a.s.l. where tropical rainforest, alpine forest, and temperate forest persist and create a very favorable ambience for these newts. This population might be identical with T. cf. himalayanus “Manipur”, but such a presumption would need support from a genetic analysis. Several other populations have been recorded from along the three main mountain ranges that extend from the Kachin Hills to Sagaing where a lineage of T. verrucosus has been recorded, and from the Chin to the Shan States where a valid species, T. shanorum, exists (HERNANDEZ 2016b,c).
DistributionAside from the type locality at Mai Pokhari in Illam District, Mechi, eastern Nepal, small populations are scattered in the valleys of Shiwalik, Mahabharat, Chulachuli and in the Sagarmatha Mountains (around the city of Kharmi). Old records from Dhankuta District, eastern Nepal, have not been confirmed by more recent surveys. Should T. cf. himalayanus “Bhutan” prove conspecific, this species would also occur in Bhutan from where some isolated populations are known. Identified by FROST in 1985, this form exists in the district of Phunakha (Thinleygang, Khabjisa, Toebisa, Barp, Toep Chubu, Dzomi, Guma, Shengana, Talo, and southeast of Toewang), in the Wangdue Phodrang Valley (Kazhi, Nahi, Thedtsho), and in Sarpang in the northern parts of Galephu City at 800 to 2,000 m a.s.l. Generally speaking, T. cf. himalayanus “Bhutan” occurs at high elevations from 1,255 (Toebrongchu Zam) to 2,679 meters (Lampelri Botanical Park). A small population that was subsequently discovered in Dagana at Lake Thangka suggests that the distribution of the Bhutan type might perhaps be larger than originally supposed and that it might not be threatened at present. Old localities from India that have not been confirmed over the last decades are Nagaland, Tripura, Mizoram and Meghalaya. They were originally ascribed to T. verrucosus, but the continued existence of these populations needs to be confirmed and their taxonomic statuses reassessed. According to SHRUTI SENGUPTA, there is no confirmed population in Tripura and Mizoram and the only record from Shillong, Meghalaya (DAS 1984), is doubtful and should be verified. The form treated here as T. cf. himalayanus “Arunachal Pradesh” lives in the extreme eastern parts of the Himalayas at Gandhigram in the Kamalang Valley, Lohit District, Aranuchal Pradesh, India, and T. cf. himalayanus “Manipur” at Manipur, likewise in India. Thus, we also noticed that Kashmir could harbor new populations according to our bioclimatic studies and some localities need to be verified in the next future (pers. obs.).
Habitat, ethology and ecologyEcological information on this species exists for specimens misidentified as T. verrucosus and mostly from Darjeeling, East Bengal, India. Known localities cover a total of 23,800 km² in this region, span from 1,554 to 2,227 m a.s.l., and between 18 and 101 animals per km² were recorded between 1998 and 2002 (SEGLIE et al. 2003, SEGLIE & ROY 2003). The northeast of India is characterized by a hot and humid climate and heavy rains during the monsoon season from May through September that will create a multitude of water bodies and feed streams as well as rice paddies. The newts inhabit hilly and wet meadows and appear quite capable of adjusting to anthropogenically altered landscapes as long as these will still include temporary pools for breeding. Their prey consists mainly of various beetles (nymphs of Odonata spp.), diving beetles (Dytiscidae), snails and freshwater mollusks (Sphaerium indicum), crustaceans (including terrestrial crabs such as Potamon potamiscus sikkimense), earthworms (Megascolecidae), larvae and cocoons of Diptera, and eggs and tadpoles of frogs. In the lake at Namthing (Darjeeling), they will also consume tadpoles of the toad Bufo himalayanus and the tree frog Polypedates teraiensis (KAUSHIK DEUTI pers. comm. 2015). According to AVINASH BHUJEL (pers. comm.), who is involved in the conservation of this species, the water of the Namthing Pokhari is acidic, with a pH varying from 4.5 to 5, and highest during August when the water level is highest, too. Water temperatures reach their minimum of 11.0 ºC in October and their maximum of 26.0 ºC in June. The highest diel fluctuation is recorded in June (min. 14.0, max. 26.0 ºC) and lowest in August (12.0 and 20.0 ºC, respectively). The value of dissolved oxygen ranges from 7.8 to 9 ppm and will reach its highest concentration in August. The chloride content is 1.1 mg/l, and nitrate and phosphate contents range from 0.03 to 0.04 mg/l and 0.01 to 0.03 mg/l, respectively. During the initial inflow of water in April/May, the sulfate load was measured at 4.02 ppm and gradually increased to 6.01 ppm in October.
AVINASH BHUJEL (pers. comm.) found at Pokhari that these newts hibernate in loose and moist soil up to 20 cm deep under boulders, logs, leaf litter, between roots, or even inside heaps of livestock feed. Hibernating newts were most numerous within 150 m from the lake and ranged in TL from 51 to 168 mm and in weight from 5.6 g to 16.4 g. Nightly surveys revealed that they left their hibernation quarters with the onset of the first rains in April or May and then migrated to the lake. No terrestrial activity could then be observed from mid-June through October, which is when the Pokhari begins to dry up.
Breeding was observed in 2013 at 49 sites at elevations of 1,400 to 2,300 m a.s.l. in Darjeeling. Thirty larvae at different developmental stages were found overwintering in the water at seven sites by NAG & VASUDEVAN (2014). Density can locally reach 100 animals per 100 m².
Data relating to T. cf. himalayanus “Manipur” were provided by various authors. This type occurs in at least six localities at high elevations from 1605 to 2434 m a.s.l. in the Ukhrul and Senapati Districts of Manipur where it is found in temporary pools, permanent ponds, and rice paddies across different habitat types and vegetation structures. The ponds are shallow and murky with moderate to dense vegetation and may be situated near villages as well as in dense forest. Temperatures across the surveyed sites averaged 27.7 ºC and relative humidity 64.5%. Eggs were found at two locations, attached to blades of grass (Scirpus sp.). Local people have noted a gradual decline in the number of newts over the last ten years, thus it is important to identify the causal factors for this trend.
Records from the type locality of T. himalayanus in Nepal reveal that most specimens are encountered in permanent and temporary ponds where their habitats are dominated by subtropical hill forest or scattered vegetation (comp. SHRESTHA 1989, ANDERS et al. 1998, SCHLEICH & KÄSTLE 2002, NAG & VASUDEVAN 2014, KHATIWADA et al. 2015, KHATIWADA et al. 2016).
ReproductionThe newts will arrive at their breeding waters in March, April or May in the wake of the first heavy monsoon showers (SCHLEICH & KÄSTLE 2002, KHATIWADA et al. 2016). These can be permanent or temporary, lie in forests or open areas, and be ponds, large puddles, or man-made structures that hold water and vary greatly in depth. Often, vegetation will have invaded the water. The newts remain in the water until October (DAS 1987). Temperatures during this period range from 6.0 to 27.0 °C. Mating entails an amplexus and follows the pattern also known from related species within the supraspecies. Following an extended courtship of sometimes many hours, the eggs are deposited one by one on aquatic plants such as Acorus calamus and Polygorum spp. Clutch volumes vary from 26 to 60 and egg size from 6 to 10 mm in diameter (NAG & VASUDEVAN 2014, SCHLEICH & KÄSTLE 2002). The fully-grown larva has a tail that will be longer to a little shorter than the SVL and an olive-brownish coloration that is densely with darker pigment (SCHLEICH & KÄSTLE 2002, SPARREBOOM 2013).
Sexual maturity is reached at an age of 2.5 years in males and 3.2 years in females.
Status, threats and conservationWhile the Eastern Himalayan crocodile newt is classified as “Least Concern” by the IUCN (DIJK et al. 2009), several authors have reported a rapid decline of Tylototriton populations in South and East Asia (DASGUPTA 1990, SEGLIE et al. 2003, SEGLIE et al. 2010). Alterations to the natural environment bring about a rapid disappearance of the Himalayan wetlands, which are the major habitat of Tylototriton spp., and have possibly already led to a sharp decline in the population sizes of this group (XIE et al. 2007, KHATIWADA et al. 2016). A conservation project and ex-situ breeding program were launched by the Amphibian Ark initiative of the Chester Zoo (UK) in India in 2000 with the aim of protecting at least some sites (Lake Nakhapani, pool at Algarah, Namthing Pokhri Darjeeling). The Padmaja Naidu Zoo (PNZP) in Darjeeling has since been propagating this newt after the State Wildlife Advisory Board of West Bengal recommended that water bodies be reconverted in surroundings fit for conserving it. Ponds within the PNZP were developed thus and populated with specimens from Maneybhanjyang in 2001 and six more individuals from a pond at Sonada in 2002. As no successful reproduction was observed in these ponds, the PNZP took to constructing an enclosure of 10 x 4 m with a pebbled floor in 2003-4. In 2006, after some changes had been effected to the enclosure design, the first six tadpoles were recorded (JHA 2007), and the species has since been breeding there regularly. In 2008, a conservation breeding program was suggested in which the PNZP was to coordinate respective efforts with the Himalayan Zoological Park and Sikkim and Manipur Zoos, assisted by scientific guidance from the Wildlife Institute of India. In India, these newts are protected as per Schedule II Part 1 of the Wildlife (Protection) Act of 1972 (WPA), also because they were used as specimens at Indian Universities. As it is now quite certain that there are at least two distinct and possibly more species of Tylototriton in India, the conservation status of all of these need to be re- evaluated (SEGLIE et al. 2003, AVINASH BHUJET pers. comm. 2015). For example, the populations in Darjeeling have been well studied and are endangered without a real status (pers. obs.).
Destruction of habitat is the main threat at Bagora on the ridge of Turook-Maldigram, Darjeeling, where an air base has been built. At Nakha Pani (Gopal Dhara Tea Estate), pesticides, herbicides and fertilizers for agriculture caused the demise of many individuals in recent years. Tea plantations are very prominent in this area and the newts are often found nearby (pers. obs.). In addition, pollution and human activities have been affecting many ponds and wetlands that are the breeding habitats of these newts. However, some wetlands have remained favorable to the survival of the species in Darjeeling (Shelpu Hills, Mirik Lake, up Raidhap, wetlands at Pacheng Tea Estate and Margaret Hope) and need to be maintained. A protected area of pine forest surrounding a small lake was established in the shape of the Salamander Wildlife Sanctuary at Jorpokhri in Darjeeling in 1985. There, the species bred in large numbers. Later, to increase its attractiveness to tourists, its main pond was converted into a concrete pool, vegetation was cleared, and swans and ornamental fishes were introduced. This entirely misguided management had an immediate detrimental effect on the newt population, and the species became rare there.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Mar 2023.
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