Wenxian Knobby Newt
|Taxonomic Notes: Fei, Ye & Jiang 2012 Colored atlas of Chinese amphibians place this species Yaotriton, consider a subgenus by others.|
Species Description: Chen X.H., Wang X.W., Tao J. 2010. (in Chinese) A new subspecies of genus Tylototriton from China (Caudata, Salamandridae). Acta Zootaxonomica Sinica/Dong wu fen lei xue bao. Beijing 35: 666–670
© 2008 Henk Wallays (1 of 16)
Author: Axel Hernandez
Tylototriton wenxianensis FEI, YE, & YANG 1984
Diagnosis and taxonomyTylototriton wenxianensis was first described as a subspecies of T. asperrimus (FEI et al. 1984) after a male holotype (CIB 638164) and six paratypes from Longnan Prefecture, Wenxian County, southern Gansu Province, China, collected in May of 1963 at 946 meters above sea level. The Wenxian crocodile newt is phylogenetically clustered with T. dabienicus and broadoridgus (this study). FEI et al. (1990) distinguished T. wenxianensis from T. asperrimus by the dorsolateral glandular warts being separated in wenxianensis vs. connected in asperrimus and elevated it to full species rank. Molecular phylogenies show these two species to be sister taxa at a moderate genetic divergence (ZHANG et al. 2008, STUART et al. 2010). T. wenxianensis is the morphologically most readily recognized species of the subgenus Yaotriton, standing out by its lack of dorsolateral glandular warts. It is nevertheless often confused with asperrimus, which differs from it by its more massive body, indistinctly separated dorsolateral glandular warts that form dorsolateral ridges, ventral warts that are as large as the dorsal ones, and a cloacal region that will be black in most specimens (FEI et al. 2006). Topotypic T. wenxianensis have a moderate TL of up to 13.3 cm in males and 14 cm in females. According to RAFFAËLLI (2013) and SPARREBOOM (2014), T. wenxianensis is characterized by having a flat and oval head (width equals its length) with prominent bony ridges, a rounded snout, no labial fold, and a conspicuous gular fold. When the forelimb is stretched forward, the digits will reach the nostril. When front- and hind limbs are adpressed to the body, their digits will touch or slightly overlap. The vertebral ridge is distinct. The dorsolateral glandular warts connect to the dorsolateral ridge, and the boundaries between individual warts are indistinct. The skin is rough, with the sizes of the warts being nearly uniform on both dorsum and venter. The tail is compressed laterally and ends in a pointed tip, and shorter than the snout-vent length. The dorsal color is black throughout, and the ventral sides are brownish black, orange to reddish only on the tips of the digits and underside of the tail. The cloacal region is black in most specimens; only a few have yellow cloacal lips (FEI et al. 2006). Some specimens have an orange tint on the vertebral and cephalic ridges (GONG et al. 2008).
The taxon pingwuensis DENG & YU 1984 has been placed in the synonymy of T. wenxianensis by ZHAO et al. (1988) and YE et al. (1993). It was described as a subspecies of asperrimus on the basis of an adult male (CIB 75005) collected on the Gaozhuang Tree Farm, Pingwu County, Sichuan, at 1400 m, in June of 1974, one adult female from Duiwoliang, Pingwu County (CIB 74074), and numerous paratopotypes. It was morphologically differentiated from T. asperrimus by the following characteristics: (1) warts on the flank irregular with no distinct demarcations between each; (2) distance between the nostrils shorter than from the snout to the eye; (3) periphery of the anus blackish brown; and (4) ventral surface rough with numerous warts.
Morphologically differentiated forms were noted in Guizhou, Hunan, Hubei and Henan Provinces, but their statuses have not been resolved to date. Another population in southern Guizhou and on the Anhui to Henan border is likely to refer to T. broadoridgus. Several populations in Hunan were previously referred to this species, but have meanwhile been re- identified as T. lizhenchangi (Mt. Mangshan), T. broadoridgus (northwestern Hunan), and T. liuyangensis (northeastern Hunan), respectively.
DistributionOver and above the type locality in Longnan Prefecture, Wenxian County, southern Gansu Province, China, other localities are located in five more counties, and three major, geographically isolated populations are identifiable:
Habitat, ethology and ecologyT. wenxianensis has secretive and nocturnal habits even though this species may be active during the day in the breeding season. It is found from 640 to 2,500 m a.s.l. (mainly 940 - 1,400 m a.s.l.) near ponds and slow-flowing streams in wet bamboo forests, open areas surrounded by pine forest, and even near plantations in Sichuan (LI et al. 2008). According to FEI et al. (2012), adults are mainly terrestrial and hide in thick bush vegetation near fields and plantations in Guizhou, in decaying wood trunks (pers. obs.), under wet rocks and in burrows covered with dead leaves (MU & GONG 2006). In the rainy season, the newts have a lighter coloring. Their main predators include water snakes, but many other predators reject these newts due to their toxic skin excretions. Feigning death is a common self-defense means.
A large population of 186 individuals (170 males and 16 females) located in Qingchuan in northeastern Sichuan was monitored for a full year by GONG & MU (2006) at three rainwater-fed ponds measuring 10 m² with a water depth of 50 cm surrounded by dense vegetation on ground covered with dead leaves.
In the Baishuijiang National Nature Reserve, specimens were found from 950 to 1,280 m, in sympatry with Andrias davidianus and Batrachuperus tibetanus that occurred in the same streams, but at higher elevations (pers. obs.).
ReproductionForest ponds and small pools with shallow water, fine vegetation, and mud bottoms are favorable breeding sites (LI et al. 2008). Males will release pheromones when the first rains arrive between early April and late May and circle females while rubbing their chin on the body during a courtship dance that will last 5 - 6 hours on average. A few days after the female has recovered a spermatophore, she will deposit her eggs in the litter and grass near or in the water. The eggs incubate for 20 - 32 days. Larvae were observed by the author in 2012, in several pools in stands of bamboo where a wide variety of micro-invertebrates were present on the decaying bamboo leaves lining the bottom of the ponds.
Status, threats and conservationThis species is categorized as “Vulnerable” by the IUCN (2010). The major threats are habitat loss and degradation due to the development of montane green tea plantations in place of old-growth forest (LI et al. 2008) that increase in coverage by about 3% per annum. For drying the tealeaves, firewood is collected in large quantities, which obviously leads to damage to the forest structure. Some breeding ponds have dried out as a result. Another consequential threat is population fragmentation. This species is also threatened by illegal collecting for the pet trade, as it has been sold (under the name Tylototriton asperrimus) in large numbers in the United States and Europe since the 1990’. The estimated population density was estimated at around 16 newts per square kilometer and the total population size at some 30,000 specimens (LI et al. 2008), but populations have shrunk by more than half by 2015 (XIE FENG pers. com. 2015).
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Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 14 May 2021.
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