Uéno’s Crocodile Newt, Chiang Mai Crocodile Newt
Species Description: Nishikawa K, Khonsue W, Pomchote P, Matsui M. 2013. Two new species of Tylototriton from Thailand (Amphibia: Urodela.Salamandridae). Zootaxa 3737: 261-179.
© 2015 Axel Hernandez (1 of 11)
Author: Axel Hernandez, updated October 2020
Tylototriton uyenoi NISHIKAWA, KHONSUE, POMCHOTE, & MATSUI 2013
Original descriptionNISHIKAWA K, KHONSUE W, POMCHOTE P, MATSUI M. 2013. Two new species of Tylototriton from Thailand (Amphibia: Urodela. Salamandridae). Zootaxa 3737: 261-179.
Taxonomic statusThe holotype (KUHE 19147) is an adult male collected at the Phuping Rajanives Palace in Doi Suthep, Chiang Mai Province, Thailand at 1,436 m a.s.l. together with some paratypes in August of 1994. The species name is in honor of Shun-ichi Uéno who collected some of the paratypes. According to a recent phylogeny, T. uyenoi is clustered with T. anguliceps and T. phukhaensis (Pomchote et al. 2020b).
DiagnosisT. uyenoi is robust crocodile newt characterized by a large size. Females can grow to 175 and males to 150 mm in TL (Nishikawa et al. 2013). Males have more robust limbs, a relatively longer tail, and a rounded and longer cloacal slit than females. Male specimens show a brighter orange coloration on dorsolateral glandular warts, parotoids, vertebral ridge, limbs, tips of fingers and tail than females (Hernandez 2016b). The species has a rough skin with fine granules, the dorsolateral bony ridges on the head are prominent although narrow, the vertebral ridge is distinct and slightly segmented, the 13-15 dorsolateral glandular warts are prominent and distinct, the limbs long and thin, and the tips of the fingers and toes overlap substantially when the limbs are adpressed along the body. The tail is thin. The dorsal side of the head, upper and lower lips, vertebral ridge, dorsolateral glandular warts, limbs, cloacal region, and the entire tail are orange to reddish brown while the ground color is dark brown. Its skull bones and the parotoid glands are much less pronounced than in Yaotriton (Raffaëlli 2013). Also, its head is wider and longer and the tail higher. More generally, females are often darker in coloration and have a more robust body than males (pers. obs.). Males have more robust limbs and a relatively longer tail (Nishikawa et al. 2013). According to Dowwiangkan et al. (2018), the cloacae of male adult newts are longer than those of females. In females, the cloacae are round and swollen. The SVL, TL, TTL, HW and body weight values of female adult newts were higher than those of males (P < 0.001).
Differential DiagnosisTylototriton uyenoi differs morphologically from all known congeners by having the combination of orange to reddish brown markings, narrow and sharply protruding dorsolateral bony ridges on head, weakly segmented vertebral ridge, and long and high tail (Nishikawa et al. 2013).
Status of subspecies and morphological variationNo subspecies are recognized to this date. However, polymorphism is known in T. uyenoi. A wide morphological variety within this taxon was observed in populations native to northern Thailand and the adjacent mountains in Myanmar. An in-depth study should investigate these and some isolated populations that might warrant taxonomic divisions and the northeastern 'group B' of T. uyenoi from Hernandez (2016b) is now regarded as a new valid species, T. phukhaensis (Pomchote et al. 2020b).
DistributionThe type locality is: Phuping Rajanives Palace, Doi Suthep, Chiang Mai province, Thailand. shows the widest range of distribution from the Daen Lao Hills to the Thanon Thong Chai Range up to the Dawna Range including: Doi (= Mountain in Thai language) Ang Khang, Doi Chang Kien, Doi Chiang Dao, Doi Inthanon, Doi Pui, Doi Suthep in Chiang Mai province; Namtok Mae Surin in Mae Hong Son province and, Doi Mon Jong, Doi Soi Malai, Mae Tueng Wildlife Sanctuary, Lan Sang, Umphang Wildlife Sanctuary in Tak province, northern Thailand at moderate (1,200 m a.s.l.) to high elevations (1,900 m a.s.l.) (Taylor 1962, Nabhitabhata and Chan-ard 2005, Pomchote et al. 2008, Gerlach 2012, Nishikawa et al. 2013, Hernandez 2016a,b, 2017, Hernandez et al. 2019, Dowwiangkan et al. 2018, Pomchote et al. 2020a,b). The northeasternmost population previously classified as T. cf. uyenoi 'Group B' by Hernandez (2016a,b) was recently described as Tylototriton phukhaensis (Pomchote et al. 2020b). T. uyenoi stricto sensu (being now restricted to the 'Group A' of Hernandez (2016b) in the northern and northwestern regions) is likely to occur in neighbouring Myanmar, as the Daen Lao Hills have a network of mountains that extend to the southern Shan states and Karen Hills (Kayah and Kayin States bordering Mae Hong Son province) in Myanmar, and are connected to the northwestern mountains of Thailand (Dawna-Tenasserim hills) where this species occurs as well (Hernandez 2016a,b, 2017). Recently, Hernandez and Pomchote (2020) reported T. uyenoifrom 15.05° N at 1,507 m a.s.l. in Kanchanaburi province near the Myanmar border. This is the southernmost locality for the whole genus Tylototriton but, also, for salamanders in Asia.
Habitat and ecologyAdult individuals inhabit subtropical moist, broad-leaf, dry dipterocarp, mixed deciduous and hill evergreen forests near bodies of water (Hernandez 2016b). Water temperatures here range from 13.0 to 22.0 °C all year round (Pomchote et al. 2008). Adults are mainly terrestrial and show secretive habits, with a peak of activity patterns at night (Hernandez 2016a,b). Most of the mature specimens are found under leaf litter outside the breeding season (Dowwiangkan et al. 2018). The species is also found in natural, artificial ponds or dams and slow-flowing streams during the breeding season, with an average water depth of 38.2 cm (range 9 – 120 cm). According to Michaels (2015), adults and a single larva of T. uyenoiwere recorded from the Chiang Dao Wildlife Sanctuary at 1,200 m a.s.l.) in a pond in bamboo scrub at the edge of a forest at night, and under wads of cut grass during the day, in the vicinity of the Khun Huay Mae Kok Guard Station. This pond was shallow and sparsely vegetated with a deep substrate of reddish silt, and water values were pH 6.4, GH 3°d, KH 3°d, NO2- 0 mg/l, and NO3- 0 mg/l. The adult specimens were similar in size to those reported by Pomchote et al. (2008) and Nishikawa et al. (2013), and matched in appearance those pictured by Gerlach (2012). Dowwiangkan et al. (2018) studied in details the population in Maesa-Kogma Biosphere Reserve in Chiang Mai province at 1,332 m a.s.l. from March to December 2017. The population included 360 individuals, the total density was 0.089 newts/100 m2 and the highest density was 12.178 newts/100 m2 in the permanent pond during the breeding season (June to August). Ovipositional areas showed a tendency towards having a dissolved oxygen level of 5.77 mg/L and water temperature of 20.5°C. Larvae were found under leaf litter in the permanent pond, temporal rainfall pond and slow-flowing stream, in water with an average DO of 5.77 ± 0.57 mg/L, temperature of 20.50 ± 0.09°C, CD of 25.19 ± 3.56 US and pH of 5.94 ± 0.26.
DietThe species has an unspecialized diet and can be regarded as a generalist predator. It mainly feed on various beetles (nymphs of Odonata spp.), diving beetles (Dytiscidae), snails and freshwater mollusks, crustaceans, earthworms (Megascolecidae), larvae and cocoons of Diptera, and eggs and tadpoles of frogs but also Hymenoptera (ants), Dermaptera (earwigs), Orthoptera (crickets), and Oligochaeta (earthworms). Reproduction in natural habitat Breeding season begins in May in the wake of the first heavy monsoon showers. Mating takes place in water with a temperature of 18 °C. A male addressed by a female will respond by wagging his tail in the manner known from Triturus spp. prior to amplecting her by taking hold of one of the female’s front legs with its own (Hernandez 2016a,b). In general, oviposition follows a mating event after two to three weeks. Each females lay 15-31 eggs which are deposited in a singly manner near a body of water on the roots of shrubs, trunks of banana trees, or grass, moist leaves, gravel and mosses (Dowwiangkan et al. 2018, Hernandez et al. 2019). During the breeding season, adult males use a greater variety of habitats than did adult females. Eggs are 2.5 ± 0.4 mm in diameter (n = 42) and the adult sex ratio is 2.25:1 in Doi Suthep, Chiang Mai province (Dowwiangkan et al. 2018). Sixteen individual eggs were seen hanging from a branch at a pond in Doi Pui on 26 August 2014 (Hernandez 2016b). Some larvae of 55 mm in total length (TL) were observed in artificial ponds at Doi Pui around the end of August 2014. Larval cannibalism is known. Larvae are found in the water bodies from August to December (Nishikawa et al. 2013). Conservation status Several authors have reported a rapid decline of Tylototriton populations in Southeastern Asia (Nishikawa et al. 2013, Raffaëlli 2013, Le et al. 2015, Phimmachak et al. 2015). Deforestation and alterations to the natural environment bring about a rapid disappearance of the wetlands and forests, which are the major habitats of Tylototriton spp., and have possibly already led to a sharp decline in the population sizes of this group (Hernandez 2016a,b). Other threats are environmental disturbances and susceptibility to the emerging infectious chytrid fungal pathogen, Batrachytrium salamandrivorans, the international pet trade and climate change, which affects the life cycle of pond-breeding species, in particular the aquatic larvae that metamorphose into terrestrial adults (Hernandez 2016b, Dowwiangkan et al. 2018). T. uyenoi is not protected by the Wild Animal Reservation and Protection Act B.E. 2535 (Anonymous 2017) and its international conservation status has not been evaluated by the IUCN due to changes in its taxonomy (Dowwiangkan et al. 2018). However, most of the localities known are located within protected areas (Hernandez 2016a,b). Therefore, the population of Tylototriton species in Thailand should be evaluated to enable the formulation of effective conservation and management strategies (Dowwiangkan et al. 2018, Pomchote et al. 2020a,b).
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