This newt species is abundant in its range, yet no detailed work has been devoted to its population dynamics. Local inhabitants collect the animals for consumption and a number of animals is sold in the pet trade (Fei et al., 2006). Pachytriton brevipes populations are threatened when people poison the entire stream to catch fish. Although this species is indirectly protected if it occurs in national parks, there is no regulation of wild exploitation. Although the population trend is decreasing, this species is listed as of least concern by IUCN (2010).
A stout-bodied newt with smooth skin. Epibranchial bones are elongated and curved, wrapped around the neck. Most literature distinguishes P. brevipes from P. labiatus by the presence of numerous small black spots on the entire body, but spotless populations of P. brevipes are common (Wu et al., 2010; Wu, Y. pers. comm.).
2n=24, 1M, 2M, 3M, 4M, 5M, 6SM, 7SM, 8M, 9SM, 10SM, 11SM, 12SM, from Zhang et al. 1984.
M: metacentric; SM: submetacentric; T: telocentric; ST: subtelocentric
The mitochondrial genome has been sequenced by Zhang et al. (2008).
A moderate to large newt. Tail is shorter than snout-vent length. Head is wide and flat, and trunk is stout and fat. Skin is very smooth with mucus. Small nostrils situated at tip of the somewhat flat snout. Eyes are small, and located at or anterior to the jaw angle. Well developed labial folds are present on upper jaw. Two lines of vomerine teeth orient in a Λ-shaped manner, converging anteriorly. Transverse gular fold is often obvious on the ventral side. Paratoid region is evident, but paratoid gland is absent (Sauvage, 1876). Some specimens exhibit a vertebral groove. Limbs are short and weak with respect to the robust body. When forelimb and hind limb are adpressed, toes and digits never meet (Fei et al., 2006). Fingers and toes are short, and their tips are flat and rounded. Webbing is present at the base of digits in some animals, whereas in others digits are nearly half-webbed. The lengths of fingers are 3 > 2 > 4 > 1, and the lengths of toes are 3 > 4 > 2 > 5 > 1. Tail is rounded at the anterior half, becoming laterally compressed at the posterior half. Sexually mature males possess papillae at the cloaca. Juveniles have relatively longer limbs, but otherwise are similar to adults (Yunke Wu, pers. observ.).
Animals are dark brown to light yellow on the dorsal side in life. Ventral color is lighter to even bright orange. Numerous black dots are scattered around the body and tail, and intensify on the dorsum (Fei et al., 2006). When preserved in alcohol, the background color becomes pale brown on top and ivory brown below (Chang, 1936). The size and density of black dots vary among individuals. Some newts lack black dots on the ventral side, and some are entirely spotless (Fei et al., 2006). During the breeding season, males develop a few white spots near the tip of the tail.
All measurements are from Fei et al. (2006).
Male (20 specimens). Total length: 155–193 mm; snout-vent length: 82.5–100.8 mm; head length: 19–23 mm; head width: 14.1–18.4 mm; forelimb length: 15–19.5 mm; hind-limb length: 17.7–21.1 mm.
Female (20 specimens). Total length: 160–185 mm; snout-vent length: 79.5–98 mm; head length: 18.3–21.5 mm; head width: 14.5–17.3 mm; forelimb length: 15.4–18.4 mm; hind-limb length: 17.3–21.5 mm.
Novel color patterns are frequently being recognized in Pachytriton that are sold in the pet trade. Thiesmeier and Hornberg (1997) discussed two potential new species (Pachytriton A and B in their paper) and discussed their difference to the two named species, mainly in the context of coloration. The males of Pachytriton A exhibited ornamental white and blue spots throughout the tail during mating season, making this phenotype most sexually dimorphic. Otherwise the adults are chromatically similar to P. brevipes. However, juveniles of Pachytriton A are spotless (similar to the coloration of P. labiatus) but develop black dots when older. Thus Thiesmeier and Hornberg (2003) considered Pachytriton A was closer to P. labiatus. Correspondingly, Pachytriton B lacks the distinctive dark spots as in P. brevipes, but has small dorsolateral red flecks stretching like ribbon as can be observed in P. labiatus. Yet the animal is brighter and much flatter and stouter than characteristic P. labiatus. Scholz (1998) reported the discovery of Pachytriton C, which is cloudy brown with vague black flecks dorsally and dirty orange underneath. In contrast to the normally smooth skin in Pachytriton, its skin is relatively rough. Lastly but not finally, Raffaelli J. and Wallays H. (pers. comm.) distinguish a fourth new phenotype called Pachytriton D, which is the largest among all. The extremely wide head and muscular long limbs are diagnostic to this form. Small diffused dark spots are visible on a dark brown to chocolate brown dorsum. Lichen-like yellow markers are present on the ventral side.
Recent molecular work suggests that P. brevipes is the sister species to P. archospotus, and the two species together form the sister taxon to P. labiatus (Wu et al., 2010). Pachytriton A is likely a population of P. brevipes (Wu, Y. pers. comm.). Pachytriton B is nested within P. brevipes from northern Guangxi (Wu, Y. unpub.). Pachytriton C is actually a Paramesotriton (Wu et al., 2009). Pachytriton D could be the recently described P. archospotus (Wu, Y. pers. comm.).
Pachytriton brevipes is distributed in Southeastern China (Zhejiang, Jiangxi, Hunan, Fujian, Guangdong, Guangxi Provinces) and Northern Vietnam (Fei et al., 2006). Populations from Zhejiang and Anhui, which were identified as P. labiatus due to morphological similarity, should be included in P. brevipes (Wu et al., 2010).
This species is associated with montane broadleaf and mixed forests. Elevation ranges from 800 to 1,700 m above sea level (Fei et al., 2006). The animals live in various montane streams, which may only be one meter wide and 20 cm deep. Large number of animals can also be found in ponds with slow-running water, more than one meter deep. They are most abundant in rock-bound streams at higher elevation. During daytime, the newts rest at the bottom or hide in the crevices (Fei et al., 2006), where they feed on small prey such as frog tadpoles (Pope, 1931). The animals are much more active and abundant at night (Wu, Y. pers. comm.). When captured or harassed, the animal emanates a strong sulfurate odor (Pope, 1931; Fei et al., 2006). The secreted mucus is at least lethal to other amphibians (Wu, Y. pers. comm.).
The breeding season is from May until August. Males have a swollen cloaca with protruded papillae, and a few whitish spots develop near the tip of the tail. Fertilization is internal through the delivery of spermatophores. Females lay 30 to 60 single eggs attached to the lower surface of rocks in the stream (Fei et al., 2006). Eggs are milky white and form a compact clutch. The ovum is around 4.5 mm in diameter and the egg attains 7.5 mm if jelly capsules are included (Fei et al., 2006). Eggs hatch as free-living larvae. Both females and males are territorial and show aggression towards intruding conspecifics.