Tylototriton uyenoi Nishikawa, Khonsue, Pomchote & Matsui, 2013
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.|
© 2017 Axel Hernandez (1 of 11)
Tylototriton uyenoi is a rough-skinned crocodile newt with a somewhat stout body. The snout-vent length ranges from 63.9 - 74.9 for males and two female specimens were 69.3, 78.3 mm. The hexagonal-shaped head has a width greater than the length. In profile, the head is concave and somewhat oblique. The dorsolateral crests are tall. The middorsal crest on the head is pronounced. The snout is short and extends beyond the lower jaw a bit. The nostrils are near the snout tip. It has narrow, pronounced, and somewhat rough dorsolateral bony ridges on its head that extend from above the eye to above the parotoid’s anterior end. The posterior end of the dorsolateral ridges are curved on the proximal side. It has a short middorsal ridge on the head that is not very prominent. It lacks a labial fold but has the gular fold (Nishikawa et al. 2013).
The vertebral ridge is pronounced and somewhat segmented, extending from the neck to the tail’s base. There is a small space between the middorsal ridge on the head and the vertebral ridge. The 12 - 16 rib nodules are prominent, small, and resemble rounded warts. The rib nodules increase in size from anterior end to the middle and decrease from the middle to the posterior end, with the fourth nodule as the largest and the most anterior and posterior nodules as the smallest. Tylototrtiton uyenoi lacks costal folds. There are 14 trunk vertebrae. The forelimb and hindlimb tips overlap when they are placed along the body. None of the digits have webbing. The tail is fairly flat. The dorsal fin protrudes more in the posterior side. It has a smooth ventral edge and a pointed tip (Nishikawa et al. 2013).
A late-stage larval specimen is 66.1 mm in length. The gills are beginning to shrink. The larva has a rounded triangular head, which in profile is concave and slanted. The snout is round and short. The labial fold is prominent in the upper jaw’s posterior side. It is close to completely absorbing its caudal and dorsal fins. It has a round tip of the tail.
Tylototriton uyenoi can be differentiated from T. daweishanensis, T. taliangensis, and T. verrucosus verrucosus by its head, trunk, limbs, and tail markings that range from orange to reddish-brown in color in T. uyenoi. Tylototriton uyenoi is distinguished from T. kweichowensis and T. pseudoverrucosus by T. uyenoi’s separated markings on the rib nodules that range from orange to reddish-brown in color. Tylototriton uyenoi is distinct from T. shanjing by the former’s darker markings, somewhat wider head, greater tail length and height, and vomerine teeth series that have greater width and length. Tylototriton uyenoi is differentiated from T. panhai by T. uyenoi’s limbs and tail ranging from orange to reddish-brown and T. uyenoi’s slim dorsolateral ridges on the head. Tylototriton uyenoi is distinguished from T. v. pulcherrima by T. uyenoi’s black ground color of its body. Tylototriton uyenoi is distinct from T. yangi by the orange color of the former’s anterior side of the head (Nishikawa et al. 2013).
Tylototriton uyenoi can be distinguished from T. phukhaensis by T. uyenoi’s larger size, head width, internarial distance, interorbital distance, orbit length, medial tail width and height, basal tail height, maximum tail height, forelimb length, and hindlimb length. Tylototriton uyenoihas a smaller axilla-groin distance, trunk length, and basal tail width. Tylototriton uyenoi has a rounder snout, wider dorsolateral bony ridges, which are less prominently curved medially at the posterior side. Tylototriton uyenoi’s sagittal ridge is wider and not as defined. Tylototriton uyenoi’s vertebral ridge is wider and more segmented than T. phukhaensis. Tylototriton uyenoi has 12 - 16 rib nodules while T. phukhaensis has 14 - 15. And lastly, the skin of T. uyenoi has bigger and more dense granules (Pomchote et al. 2020).
Tylototriton uyenoi is distinct from T. anguliceps by the former’s larger size. Tylototriton uyenoi has darker orange markings and T. anguliceps has darker ground color in the head and body. Tylototriton uyenoi has weaker and less dense dorsal granules. On the skull, T. anguliceps has a more protruding middorsal crest and much steeper dorsolateral crests compared to T. uyenoi (Le et al. 2015).
In life, the dorsal ground color ranges from dark brown to black. The venter is moderately lighter than the dorsum. The region that ranges from orange to reddish-brown includes the anterior half of the head, parotoids, vertebral ridge, rib nodules, limbs, vent region, and the entire tail. In preservative, the dorsum is faded to a light brown. The regions that ranged from orange to brown fade to a cream color (Nishikawa et al. 2013).
In preservative, larvae have a dorsum color that is a yellow-brown color. The venter is more pale, and the anterior head, parotoids, vertebral ridge, rib nodules, limbs, and tail are all yellow (Nishikawa et al. 2013).
There is some sexual dimorphism. Adult females were bigger and weighed more than the adult males. Males and females differ in cloacae shape (Dowwiangkan et al. 2018). The tail and vent slit are longer in males than females. The limbs of adult males are more sturdy than those of females (Nishikawa et al. 2013). Among male specimens there were differences in the amount of separation between vertebral ridges, size in rib nodules, and the roughness of the dorsolateral bony ridges on the head. All specimens had 14 trunk vertebrae. There was some variation in the coloration of markings of different specimens, ranging from orange to reddish brown (Nishikawa et al. 2013).
Distribution and Habitat
The range of T. uyenoi includes Doi Ang Khang, Doi Chang Kien, Doi Inthanon, Doi Pui, and Doi Suthep (Nishikawa et al. 2013), and Doi Mon Jong of the Chiang Mai Province, and in Doi Soi Malai and Umphang of the Tak Province (Hernandez et al. 2019). The species is found in artificial and man-made pools, streams, and ditches (NIshikawa et al. 2013).
Life History, Abundance, Activity, and Special Behaviors
Terrestrial immature newts were most commonly seen beneath leaf litter on land. Adult newts used several microhabitats during the breeding season, but outside of breeding season they were most frequently found in permanent ponds beneath leaf litter, followed by those found on land beneath leaf litter, then those in slow-flowing streams, on land beneath logs, and lastly in the temporal and rainfall ponds (Dowwiangkan et al. 2018).
During the breeding season from May to July, the species is found in natural and artificial pools, ditches near farms, and streams with slow water flow. The average depth of the water they are found in is 38.2 cm. Adults are found in water in months outside of breeding season so they are likely semi-aquatic (Nishikawa et al. 2013).
The mating process occurs in 18oC water. First, the female catches the male’s attention and the male swings his tail in response to the female. The male uses his front legs to grasp onto the female’s front legs and they embrace. The female lays the eggs two to three weeks after mating (Hernandez pers. comm.)
Ripe ova found in the ovaries had a mean diameter ranging from 1.9 - 2.8 mm. It has a dark brown animal pole and the rest of the area is a dark cream color (Nishikawa et al. 2013). Tylototriton uyenoi females lay their eggs underwater (Hernandez et al. 2019). The eggs were laid on damp leaves, gravel, and mosses close to water during nighttime from June through August. The number of eggs laid by each female for one night ranged from 15 - 31. The eggs had a diameter of 2.5 ± 0.4 mm (Dowwiangkan et al. 2018).
Larvae were found from March to December beneath leaf litter in permanent and temporary ponds, and slow streams. Some were in clear water while others were in muddy water. The water body floor was covered in debris and leaf litter. Where the larvae were found, the average amount of dissolved oxygen was 5.77 ± 0.57 mg/L, the average temperature was 20.50 ± 0.09°C, the average conductivity was 25.19 ± 3.56 US, and the average pH was 5.94 ± 0.26. (Dowwiangkan et al. 2018).
Tylototriton uyenoi eats various beetles, including diving beetles, as well as snails, freshwater mollusks, crustaceans, the Megascolecidae family of earthworms, Diptera larvae and cocoons, frog eggs and tadpoles, ants, earwigs, and crickets (Hernandez pers. comm.)
Trends and Threats
Tylototriton uyenoi has permeable skin so it is more vulnerable to ecological disturbances and the chytrid pathogen Batrachochytrium salamandrivorans. Excessive deforestation threatens T. uyenoi. Climate change impacts aquatic larvae. Collection for the international pet trade is also a major concern (Dowwiangkan et al. 2018).
Relation to Humans
Tylototriton uyenoi has been collected for the international pet trade (Dowwiangkan et al. 2018).
Possible reasons for amphibian decline
General habitat alteration and loss
Nishikawa et al. (2013) categorized six lineages of the T. shanjing complex. After phylogenetic analyses, T. shanjing Lineage 4 was classified as a distinct species, T. uyenoi, and T. shanjing Lineage 6 was classified as a distinct species as well, T. panhai. Maximum Likelihood and Bayesian Inference on the NADH dehydrogenase subunit 2 region (ND2) of mtDNA were used to determine the relationship among the 19 Tylototriton specimens and Echinotriton andersoni, E. chinhaiensis, Pleurodeles waltl, and Notophthalmus viridescens. Additionally, a Neighbor-joining tree was created using the nuclear DNA genes proopiomelanocortin and Rag1 for 13 samples. These phylogenetic analysis methods found that T. uyenoi belongs in a clade with T. kweichowensis, T. shanjing Lineages 1 – 5 (which included T. uyenoi), T. taliangensis, T. v. verrucosus, T. v. pulcherrima, and T. yangi. Tylototriton panhai is not closely related to T. uyenoi. Instead, T. uyenoi is most closely related to T. shanjing Lineage 5, followed by the clade composed of T. v. pulcherrima, T. yangi, and T. shanjing Lineages 1 - 3, which the authors considered all to be T. shanjing (Nishikawa et al. 2013). Tylototriton shanjing Lineage 5 is now known as T. anguliceps (Le et al. 2015).
Another analysis by Le et al. (2015) using Maximum likelihood and Bayesian reference on the partial ND2 mtDNA region on 22 specimens supported that T. anguliceps, T. uyenoi, the verrucosus-shanjing complex, and T. yangi form a clade (Le et al. 2015).
A further Maximum Likelihood and Bayesian Inference analyses on partial ND2 mtDNA gene sequences were used to determine the relationship among various Tylototriton species. The results found that T. uyenoi is a sister species to T. anguliceps and T. phukhaensis. However, the analysis was not robust enough to accurately define the relationships further (Pomchote et al. 2020).
The species epithet “uyenoi”, comes from Dr. Shun-ichi Uéno, who obtained some of the paratypes of T. uyenoi (Nishikawa et al. 2013).
Please see the account of this species by Hernandez (alternative tab). Since the Hernandez account was written, the population of this species from northeastern Thailand has been described as a new species, Tylototriton phukaensis, which becomes the fifth species salamander from Thailand. Hernandez and Pomchote (2020 Bull Soc Herp. France) report T. uyenoi from 15.05° N at 1,507, near the Myanmar border. This is the southernmost locality for salamanders in Asia.
Dowwiangkan, T., Ponpituk, Y., Chuaynkern, C., Chuaynkern, Y., Duengkae, P. (2018). ''Population and habitat selection of the Tylototriton uyenoi in the Maesa-Kogma Biosphere Reserve, Chiang Mai Province, northern Thailand.'' Alytes, 36(1-4), 300-313. [link]
Hernandez, A and Pomchote P (2020). ''New southernmost record for the genus Tylototriton in Asia: Tylototriton uyenoi Nishikawa, Khonsue, Pomchote & Matsui 2013, discovered in Khao Laem National Park, Kanchanaburi province, western Thailand.'' Bulletin de la Société Herpétologique de France, 174, 64-67.
Hernandez, A., Escoriza, D., Pomchote, P., Hou, M. (2019). ''New localities for Tylototriton uyenoi, T. panhai and T. anguliceps in Thailand.'' The Herpetological Bulletin, 147, 15-18. [link]
Le, D.T., Nguyen, T.T., Nishikawa, K., Nguyen, S.L.H., Pham, A.V., Matsui, M., Bernardes, M., Nguyen, T.Q. (2015). ''A new species of Tylototriton Anderson, 1871 (Amphibia: Salamandridae) from northern Indochina.'' Current Herpetology, 34(1), 38-50. [link]
Nishikawa, K., Khonsue, W., Pomchote, P., Matsui, M. (2013). ''Two new species of Tylototriton from Thailand (Amphibia: Urodela: Salamandridae).'' Zootaxa, 3737(3), 261 - 279. [link]
Pomchote, P., Khonsue, W., Thammachoti, P., Hernandez, A., Peerachidacho, P., Suwannapoom, C., Onishi, Y., Nishikawa, K. (2020). ''A new species of Tylototriton (Urodela: Salamandridae) from Nan Province, northern Thailand.'' Tropical Natural History, 20(2), 144-161. [link]
Originally submitted by: Kira Wiesinger (first posted 2020-09-07)
Edited by: AmphibiaWeb, Ann T. Chang (2020-10-29)
Species Account Citation: AmphibiaWeb 2020 Tylototriton uyenoi: Uéno’s Crocodile Newt <https://amphibiaweb.org/species/8093> University of California, Berkeley, CA, USA. Accessed Nov 29, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 29 Nov 2022.
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