Tiannan Crocodile Newt
Species Description: Hou M, Li P, Lu S 2012 Morphological research development of genus Tylototriton and primary confirmation of the status of four cryptic species (in Chinese). J Huangshan Univ 14:61-65. (authors of name: Hou, Zhang, Zhou, Li and Lu).
© 2017 Henk Wallays (1 of 25)
Author: Axel Hernandez
Tylototriton yangi HOU, ZHANG ZHOU, LI & LÜ 2012
Diagnosis and taxonomyThe holotype (SYNY HM20070801-NT001) and three paratypes were collected in Gejiu, Yunnan, China, in 2007. According to recent phylogenetic studies, T. yangi is close to T. uyenoi and forms a separated clade (LE et al. 2015, this study). This species exhibits morphological characters that are intermediate between T. shanjing and T. kweichowensis and shares with the latter species the black head (partially yellow in other species). The females are larger and more massive than the males, growing to 17.2 cm max. TL, whereas males will measure only up to 15.8 cm (FEI et al. 2012). The snout is rounded, with pronounced cephalic edges (similar to T. kweichowensis), the vertebral line is prominent, the 15 - 16 dorsolateral glandular warts are distinct, and the skin is distinctly warty. Both the upper and lower parts are black, and orange-yellow pigment is found on the parotoids from where a wide dorsal stripe continues to the tail, on the glandular warts, tips of fingers and toes, the cloaca, and the lateral and ventral parts of the tail.
T. yangi has the taxon Tylototriton daweishanensis from Mount Dawei Pingbian County, Honghe (Yunnan, China) in its synonymy (NISHIKAWA et al. 2015). Both taxa are genetically identical and very similar morphologically, except that some individuals from Daweishan have the yellow to orange pigmentation limited to the lower sides of the fingers and toes, the cloacal region, and the ventral caudal keel. Dorsolateral glandular warts are more distinct and less prominent. A new population with morphological characteristics similar to T. yangi was discovered on the Lao border by the author.
DistributionNext to the type locality Gejiu, Honghe County, Honghe Hani and Yi Autonomous Prefecture in southwestern Yunnan Province, China, other localities known are distributed in Honghe and Wenshan Counties, including Daweishan National Forest Park; Mengzi, Hekou and Wenshan National Nature Reserve, Laojunshan Mountains. This last locality is at the easternmost distribution limits of this species.
Habitat, ethology and ecologyT. yangi inhabits the Karst Mountains between fields of mainly tomato, pepper and cabbage that are surrounded by tall grass and sport small ponds at relatively high elevations of 1,600 to 1,800 m a.s.l.. Here, it shelters in leaf litter near the pools where humidity levels are very high (70 to 90%). Its natural diet consists of insects and mollusks. My field observations in Mengzhi County in 2015 entailed ten adults that were found at 1750 m at night in small ponds with grassy embankments next to crop fields where the air temperature was 20.9 - 22.4 °C at a relative humidity of 87%. A total of 13 larvae were observed in six small ponds fed by slow-flowing streams and co-harboring mollusks, tadpoles and crabs, with the latter of which being potential predators. The temperature of the water was 19.6 °C on average, the pools had depths of 20 to 30 cm, and their pH was 7.6. During the winter (November through February), temperatures will not exceed 8.0 °C at Gejiu.
ReproductionAccording to RAFFAËLLI (2013), reproduction begins in May-June in small livestock waterholes next to forest remnants. Reproducing this species in a captive setting is possible when a large aquatic section with water 15 cm deep is made available to adult specimens. Following copious misting, the newts will take to the water when temperatures are raised in late spring and humidity starts hovering around 90% after a three-month dry winter period at 5 - 10.0 °C. The males are the first to take to the water and will wait for several days until the females follow, entering and exiting the water repeatedly and eating little. The males will be particularly active in the morning hours and may now develop rugose nuptial pads on their forelimbs as in Pleurodeles spp. (pers. obs.). The females will initially venture into the water only for short stints and swim around quickly, pursued by the males. A receptive female is courted by the male rubbing his head and parotoid glands on the female’s flanks and legs. After several such attempts over several days, the male will grab the female by his front legs and facilitate an amplexus in a manner similar to that known from Pleurodeles spp. The male will then deposit cone-shaped spermatophores for the female to recover with her cloaca. Two to three days later, the female will deposit 60 - 80 eggs. These eggs do not possess an adhesive outer layer whereas those of others species as T. shanjing are adhesive and attached to the aquatic plants.
Captive propagation was first achieved by ALEX TSUKANOV (Russia) who used a large terrarium with a moisture-saturated climate and emulated heavy rains during the month of July in 2011. The eggs of two subsequent clutches were deposited between embankment stones and plants following replacements of the water, in a manner similar to T. kweichowensis and, to a lesser extent, shanjing. The eggs proved susceptible to fungal infection and must not be touched with bare hands. Once the embryos are visibly ready to hatch, the eggs can be moved to a small aquarium with well-oxygenated water and Java moss. A few dead leaves of oak or Indian almond tree (Terminalia catappa) will have an antifungal action and lower the pH at the same time. Raising the larvae is similar to other species of the genus. They grow up in stagnant water in the wild, but this will render them susceptible to fungi (Saprolegnia spp.) in a captive environment. They require daily feeding with Daphnia, Tubifex and mosquito larvae and will usually metamorphose after two months at 20.0 °C when they have grown to 4 - 5 cm. Sexual maturity is reached at 3.5 to 4 years of age. This species is hard to successfully propagate every year. Hybrids between T. shanjing and T. yangi produced by ALEX TSUKANOV (Russia) were noteworthy for their exclusively aquatic ecology.
Status, threats and conservationThis species is highly threatened by excessive collecting for the terrarium animal trade. A year after its discovery in 2012, specimens were exported to Europe and the United States in numbers, decimating the wild populations to a major extent. The destruction through mining operations and pollution of their habitats with agrochemicals also pose substantial threats. A visit to these habitats in 2015 showed them to be highly degraded. T. yangi has furthermore been collected for traditional medicinal purposes for many years. Its current status is “Vulnerable” as per IUCN criteria due to its small distribution range and ongoing exploitation, but should actually be upgraded to “Endangered”.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Aug 2019.
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