Tylototriton broadoridgus Shen, Jiang & Mo, 2012
Sangzhi Crocodile Newt
|Species Description: Shen Y, Jiang J, Mo X 2012 A new species of the genus Tylototriton (Amphibia, Salamandridae) from Hunan, China. Asian Herpetological Research 3: 21-30.|
Taxonomic Notes: Fei, Ye & Jiang 2012 Colored atlas of Chinese amphibians place this species in what others consider subgenus Yaotriton.
© 2015 Axel Hernandez (1 of 2)
Author: Axel Hernandez
Tylototriton broadoridgus SHEN, JIANG, MO 2012
Diagnosis and taxonomyThe original description of Tylototriton broadoridgus is based on an adult male holotype (HNUL 840513527) and 38 paratopotypes collected at Liaoyewan, Tianping Mountains (29°49’N, 110°9’E) in Sangzhi County, Hunan Province, China, in May of 1984. Its specific epithet makes reference to its broad spinal ridge. T. broadoridgus is genetically close to T. wenxianensis and T. dabienicus and they are in the same clade. Females can reach a size of up to 16.3 cm TL. They are generally thickset and bear buds on the cloaca, which are absent in males. Males do not exceed 14 cm TL, have a labial fold and a more elongated body. This species resembles T. wenxianensis morphologically, but differs from the latter taxon by a very broad dorsal ridge. The head is wide with an elongated snout and short, rounded cephalic edges, the skin is warty skin, and the dorsolateral glandular warts are indistinct and separated by transverse striations reminiscent of the other members of its supraspecies. The species features a black dress, with orange pigment being limited to the lower caudal keel, cloaca, and undersides of the fingers and toes. The upper caudal keel is more developed and the head larger than in T. asperrimus and T. wenxianensis. The tail is shorter than snout-vent length, and tail height is smaller than tail width at the base. The tail is notably compressed laterally with relatively strong tail muscles. Its dorsal fin starts from the base and is conspicuously thin and high, whereas the ventral fin begins only at some point posterior to the cloaca, is thick and short.
DistributionThe type locality in Sangzhi County, Hunan Province, forms part of a mountain range whose peak, Badagongshan, lies in the neighboring province of Hubei, and the species is distributed throughout this range. A second population was recently discovered in central Hunan Province, but results are not available at this stage.
Habitat, ethology and ecologyThe Badagong Mountain National Nature Reserve in which the Tianping Mts. are located is characterized by two types of forests: humid subtropical forest and mixed forest of deciduous hardwoods. These mountains are home to many endemic animal species and relict plants. T. broadoridgus lives between 1,000 and 1,600 m a.s.l. in wetland habitats or where the canopy is dense, mainly vegetated by Fagaceae spp., Ericaceae spp., Lauraceae spp., Theaceae spp., Cyclobalanopsis multinervis, Fagus lucida, Rhododendron stamineum, Litsea enlongata, Eurya brevistyla, and Symplocos anomala. The species is terrestrial and lives in the thick of the leaf litter on the ground that is slowly turned into humus by a rich micro-invertebrate fauna. The climate in these mountains is variable and temperature may decrease to 5.0 °C above 1,600 m in winter, while reaching maxima of about 23.0 °C in summer. T. broadoridgus become aquatic in May to breed for a period of several months. Young males are particularly aquatic and will be the first to enter the water; they may stay in the water for as long as from May through November. Their breeding ponds are fed by monsoon rainwater, have a muddy bottom, and sport layers of dead leaves of Cyclobalanopsis multinervis in particular, branches and other plant debris. These ponds are widely scattered in the Tianping Mountains with one or two being found in several square kilometers, very small with just a few square meters in dimension, and have a depth of only about 30 cm. The water is relatively acidic. Humidity ranges around 80 - 90% from May through November. After mating, the adults will crawl through the leaf litter on land in search of food, but return to rest at the ponds (YOUHUI CHEN pers. comm. 2015).
ReproductionReproduction begins in May when temperatures reach about 19.0 °C in the breeding ponds and continues for several months until the end of the monsoon season. The larvae hatch about 1 to 1.5 months after the eggs have been deposited in or next to the water. They measure 3.4 cm at hatching and will grow to 5.8 cm before they metamorphose before the onset of winter. Some may overwinter aquatically, though, as is evident from several larvae that were collected in submerged leaf litter or under tree branches lying in the water in late March (SHEN et al. 2012).
Status, threats and conservationsThe Tianping Mountains have several protected reserves where the species seems to still exist. Ongoing destruction of the forest and ponds could endanger it, though. It was considered vulnerable by FEI et al. (2012). According to YOUHUI CHEN (pers. comm.), T. broadoridgus has a very limited range, and its population could decline quickly in the near future. I therefore recommend reviewing this species’ conservation status.
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