IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Description

A moderate to large newt. Fully grown adults can attain more than 170 mm in total length (90 mm in snout-vent length). The total length of most individuals is between 130 and 170 mm. Tail is shorter than the 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 ¦«-shaped manner, converging anteriorly. Transverse gular fold is often obvious on the ventral side. Parotoid region is evident, but the parotoid gland itself is absent (Sauvage 1876). Some specimen exhibits a vertebral groove. Both limbs are short and weak with respect to the robust body. When forelimb and hind limb are pressed towards each other against the flank, digits never meet (Fei et al. 2006). The fingers and toes are short, and their tips are flat and rounded. Webs are present at the base of digits in some animals, whereas others 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, and become laterally compressed for the posterior half. Sexually mature males possess papillae at the cloaca. Juveniles have relatively longer limbs, but otherwise are similar to adults.

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 palish brown on top and ivory brown below (Chang 1936). The size and density of black dots varies intraspecifically. 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.

Pachytriton is a common newt in the commercial pet trade. Novel color patterns are frequently being recognized, providing the basis of classifying new phenotypes. Thiesmeier and Hornberg (1997) described 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 as 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 which 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 normal smooth skin found in Pachytriton, the skin of Pachytriton C is relatively rough. Lastly, Raffaelli and Wallays (pers. comm.) have distinguished a fourth new phenotype called Pachytriton D, which is the largest among all. The extremely wide head and muscular long limbs are diagnostic to congeners. Small diffused dark spots are visible on dark brown to chocolate brown dorsum, and lichen-like yellow markers are present on the ventral side.

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