Species account

Description
Fairly large but slender salamander. Head flat and large, longer than wide, snout truncated, conspicuous labial folds. Eyes rather small. Paratoid glands prominent, another gland behind the paratoid gland. Distinct gular fold. No vertebral ridge, but a slight vertebral groove on the trunk. Tail strong, same length as snout-vent length, round at the base and compressed at the end with a rounded tip. Caudal fin on upper side of last two third part of the tail and a low keel on underpart of the entire tail. Fore and hind legs short, not touching when adpressed to the body. Fingers and digits short and stubby. Skin smooth with vertical wrinkles on the sides of the body and cross-wrinkles on the vent.

Sexual dimorphism not pronounced. Cloacal region not much different in the sexes, slightly swollen in the breeding male. Villi 2 mm long protruding from cloaca of breeding male. Breeding males develop one or several bluish-white spots on the distal part of the tail.

Colour of back and sides mostly uniform chocolate or dark brown; often dorso-lateral red spots or lines, running from head to tail. Ventral side coloured vivid red and black, without dark spotting. Red and black ratio can differ greatly, from nearly completely red to almost entirely black (Thiesmeier, 1997).

Total length 15 to 19 cm (Ye et al., 1993), or a little smaller (Thiesmeier, 1997).

Diagnosis
Large-bodied newt with smooth skin. Colour of the back uniform brown, sometimes with red spots or dorso-lateral orange stripes. No small black spots on body, head and tail, as in P. brevipes. Distinct red and black colouration of the belly. Generally more slender and less muscular phenotype than P. brevipes. Ratio head-width to snout-vent length provides an index to distinguish the two taxa (Thiesmeier, 1997). Digits and toes shorter than in P. brevipes (Novarini, 1998).

Eggs and larvae
Egg deposition in captivity was reported by Thiesmeier & Hornberg (1998, 2000): In two consecutive years a female laid a clutch of 42 eggs on the ceiling of the hiding place, where she normally sat. Watertemperature 9.5° C. Eggs were large, diameter of the embryo varying between 4.7 and 5.3 mm. Length of hatching larva 15.1 to 17.6 mm, at a stage when yolk was still present and legs were not yet formed. Embryonic development took c. 57 days in water with an average temperature of 13.5° C. Metamorphosis after c. three months, watertemp. 16-17° C. Metamorphosed newts are small, around 35-42 mm, and have a granulated skin. Juveniles are thought to live on land for the first few years of life, before reaching sexual maturity and returning to water.

Distribution
Central and southern China in Guizhou, Anhui, Zhejiang, Hunan, Guangxi and Guangdong Provinces, from 50 to 1,800 m altitude (IUCN, Conservation International, and NatureServe, 2006). The map shows a disjunct distribution. The exact range is poorly known.

Habitat
Pachytriton labiatus inhabits low-gradient hill streams of varying sizes, where it lives mainly an aquatic life (IUCN, Conservation International, and NatureServe, 2006).

Behaviour
Pachytriton labiatus has a gape and suck eating habit specialized for foraging in streaming water. Its diet includes species of annelids, molluscs and insects (Xu et al., 2002).

Little is known about ecology and natural history. In Guangdong the breeding season is in September-October (Xue et al., 2002). Reports on captive specimens form the basis of the following information on reproductive behaviour. Both sexes are aggressive and fiercely attack animals coming within sight or near their hiding place, especially during the reproductive season. The female exerts a form of parental care: Eggs are deposited in assemblages on the lower surface of stones or in hollows. The female sits under the eggs and does not leave this place during development of the eggs. She fends off other animals by biting. She may eat some of her eggs, possibly the mouldy or unfertilized ones (Thiesmeier & Hornberg, 1998; Sparreboom & Thiesmeier, 1999).

The courtship of Pachytriton resembles that of other tail-fanning, aquatic salamandrids that lack amplexus (Cynops, Paramesotriton). The male folds back his tail and makes fanning movements with the distal part of his tail, fanning roughly in the direction of the female’s snout. If the female is responsive and moves forward to the male, the male turns round and starts creeping ahead of the female. The female probably orients to the bright spots in the male’s undulating tail and touches his tail with her snout. After a number of such tail-touches, the male deposits a spermatophore and creeps on, the female following him. The female moves over the spermatophore and picks up the spermcap in her cloaca (Sparreboom & Thiesmeier, 1999).

Tail-fanning is not always associated with courtship. Any form of excitement, such as disturbance or the approach of a conspecific newt, may release bouts of tail-fanning in both male and female.

Threats and conservation
The species is collected for use as traditional Chinese medicine and exported for the international pet market. Habitat destruction and degradation also pose a threat, but the species is relatively common and presently not listed as endangered (IUCN, Conservation International, and NatureServe, 2006).

Observations in captivity
Aquariums for Pachytriton must be spacious and should have flowing water. Due to this species’ extremely aggressive behaviour, a tank can accommodate only one or two animals and should contain many hiding places where animals can sit in isolation (Thiesmeier & Hornberg, 1997, 1998, 2000; Miller, 2005; Reilley, 2005).

Comments
Besides P. brevipes and P. labiatus, at least three other phenotypes have been recognized among animals imported through the pet trade (Thiesmeier & Hornberg, 1997, 2000; Scholz, 1998). See under Pachytriton brevipes. Field observations and work on specimens with known collecting localities are needed to clarify the systematic relationships in the genus.

Pachytriton labiatus
© 1997 Burkhard Thiesmeier

 
© 2006 IUCN, Conservation International and NatureServe. (click on map to enlarge)