Paramesotriton zhijinensis Li, Tian and Gu, 2008
Until more is known about salamander populations in the neighborhood, the type locality is the only known locality where the species occurs. Population size should be larger because the type locality, an artificial pond, is connected to an underground spring.
Can be distinguished from all other species of Paramesotriton by the following combination of characters: Distinct yellow postocular stripe, two non-continuous, dorsolateral stripes on dorsolateral ridges; warts and glands covering much of dorsal and ventral surfaces; orange-red spots on venter, chin, underside of axillae, cloaca and proximal portion of tail. Neoteny is common with most adult specimens having vestigial gills and gill filaments (Zhao et al., 2008). Zhao et al. (2008) further noted scent glands on snout and considered this is a distinct feature of P. zhijinensis. However, the scent gland is no different from that of other species of Paramesotriton and even of species of Pachytriton.
Mitochondrial DNA data are available from Zhao et al. (2008) and Wu et al. (2010).
Resembles Paramesotriton caudopunctatus and P. longliensis in having two yellow non-continuous dorsolateral strips. Paramesotriton zhijinensis differs from the other two species by the prevalence of neoteny and a distinct yellow postocular stripe located near corner of mouth.
A robust salamander. Head moderately sloping in profile, relatively large and flat; skull broad with maxillaries oriented angular to body axis; head length distinctly longer than head width. Snout short, truncate, extending beyond lower lip. Nostrils located on the tip of the snout. Gular fold present. Eyes are relatively large and round. Upper labial fold well developed. Most adult animals have vestiges of gills or gill filaments. Three tubercular dorsal ridges, one midline and two lateral, extending from behind the head to the tail base. Glands and warts cover much of the dorsal and ventral surfaces. No webbing on fingers and toes. Tail slender, laterally compressed; dorsal tail fin and indistinct ventral tail fin present; posterior end of tail rounded in lateral profile, not pointed. Dorsal color is brown-black. Three tubercular dorsal ridges with non-continuous yellow mottling. Dorsal stripes are variable, sometimes indistinct and with tiny light yellow spots. Large, irregular orange-red spots on venter, chin, underside of axillae, cloaca and tail; some smaller and weak spots interspersed on venter. Orange-red spots diminish in size posteriorly on underside of tail base. Distinct yellow postocular stripe located near corner of mouth.
All measurements are from Li et al. (2008).
Male (10 specimens). Total length: 103–126.9 mm; snout-vent length: 50–73.4 mm; head length: 16–21.6 mm; head width: 12.1–17 mm; forelimb length: 17–21.5 mm; hind-limb length: 17.6–22.3 mm.
Female (10 specimens). Total length: 102.2–125.4 mm; snout-vent length: 54.2–68.3 mm; head length: 17.2–21.7 mm; head width: 12.6–16.4 mm; forelimb length: 17.5–21.6 mm; hind-limb length: 17–24.8 mm.
Paramesotriton caudopunctatus, P. zhijinensis and P. longliensis form a distinct clade within this genus based on mitochondrial evidence (Zhao et al., 2008; Wu et al., 2010). The latter two are sister species yet genetic divergence is only moderate (Wu et al., 2010). More data are needed to assess the phylogenetic relationship between P. zhijinensis and P. longliensis.
All specimens were found in a pool (Shuangyan Pond), fed by an underground spring, in Zhijin County, located on Guizhou Plateau, surrounded by mountains, at an altitude of 1,310 m (Li et al., 2008; Zhao et al., 2008). However, this pond is an artificial pond with concrete walls so the newts likely enter the pond via the underground spring. This suggests a larger population size in this area.
The pond in which the animals have been found has clear water of 16° C year round. In the daytime the animals move to the bottom of the pond, in the evening they move to the littoral region to feed. The pond has large quantities of algae and fish. Li et al. (2008) also reported this newt from slow-flowing, shallow streams at elevations from 1,300 to 1,400 m.
Breeding season from mid April to late June (Li et al., 2008). A larva with well developed gill filaments was collected on May 12, 2007, measuring 61.8 mm in total length. This could be a larva that hatched in the previous year. The larva is uniformly black on the upperside.