Paramesotriton guangxiensis (Huang, Tang and Tang, 1983)
Due to its vulnerable habitat and the limited extent of its presently known occurrence this species is listed as endangered (IUCN, 2010). The major threat is habitat loss and degradation due to agriculture. Population trend is decreasing.
Paramesotriton guangxiensis is similar to P. chinensis, notably by its granular skin, but it differs from the latter species by having a flatter body, entirely dark-brown color of the back, short forelimbs, prominent dorsal ridge, and high, compressed tail (Huang et al., 1983).
The mitochondrial DNA sequence data are available in Wu et al. (2010).
Morphologically, Paramesotriton guangxiensis resembles but is nevertheless distinct from P. deloustali, P. yunwuensis and P. fuzhongensis. In P. guangxiensis and P. yunwuensis the extended forelimb does not reach the posterior margin of the eye. In P. deloustali the extended forelimb reaches the midpoint of the eye and in P. fuzhongensis it reaches even further anteriorly to a point midway between the eye and the nostril. Compared to P. yunwuensis, P. guangxiensis is smaller, more gracile (e.g., the trunk is relatively flat in cross-section, versus square or round in P. yunwuensis), and its tail is shorter and deeper.
Moderately small-sized warty newt. Flat, triangular head, longer than wide. Flat and stout body. Snout truncated. Labial fold well developed. Forelimb merely reaches the eye when stretched forward. Digits just meet when forelimbs and hind limbs are adpressed. Skin rugose with small wrinkles, high vertebral ridge extending onto the tail. Warts densely present around neck and dorsum. Tail length shorter than snout-vent length, ending in a thin tip. Cloaca swollen with papillae in the male during reproductive season. Color of upper side dark brown; underside black with large, irregular yellow to orange blotches. Lower tail fin orange, fading towards the tip. Color is lighter in female.
All measurements are from Huang et al. (1983).
Male (9 specimens). Total length: 124.8–139.5 mm; snout-vent length: 67.8–75.5 mm; head length: 20–22.8 mm; head width: 15–17.2 mm; forelimb length: 19.3–23.1 mm; hind-limb length: 19.2–23 mm.
Female (1 specimens). Total length: 134.2 mm; snout-vent length: 71 mm; head length: 21.2 mm; head width: 16.1 mm; forelimb length: 21 mm; hind-limb length: 19.9 mm.
The large head and color pattern give the species the look of a small-sized P. deloustali. Pang et al. (1991) synonymized P. guangxiensis with P. deloustali based on morphological characters. However, mitochondrial phylogeny suggests that P. guangxiensis is more closely related to P. yunwuensis and P. fuzhongensis than to P. deloustali (Wu et al., 2010). Those four species can be distinguished from each other under close examination (see Look Alikes).
It is only known from the type locality, Paiyang shan, Ningming County in Guangxi, China, where it occurs at 470 m altitude (Huang et al., 1983; Zhang & Wen, 2000).
Paramesotriton guangxiensis occurs in low gradient streams around elevations of 500 m. The stream is 1–1.5 m wide, 0.3–0.8 m deep (Pang et al., 1991). Water is clear and slow and full of small rocks and sand. Dense forest and bushes cover the stream. Newts hide under rocks in the stream or in grasses near the stream edge. It is often found on land (0.5–1 m away from the stream) after heavy rains (Fei et al., 2006). This species is mostly nocturnal and preys on small insects and earthworms.
The main reproductive season is from November to February (Fei et al., 2006). The reproductive behavior is similar to that described for P. fuzhongensis and P. deloustali (Rehák, 1984; Sparreboom, 1984abc). The males may be aggressive and appear to defend territories, as in other species of Paramesotriton. When first faced with a female, the male approaches her slowly and nudges her body lightly with his snout. He springs forward rapidly along beside her, turns in front of her head and immediately stops and performs a lateral display. This display consists of fanning movements of the tail, folded against his body. If the female stops and remains stationary, the male continues to perform bouts of tail-fanning. If the female moves forward and nudges the male’s cheek during the lateral display, the male immediately turns away from her and pauses just in front of her snout with his tail S-shaped. When the female nudges his tail with her snout, the male creeps forward, the female following. The male stops and deposits a spermatophore (Arnold, 1972).
Eggs are laid in February-March. With her hind feet the female presses together the leaves of aquatic plants around the eggs as they are laid. Eggs are laid singly, sometimes forming a series, sandwiched between the same leaves. A female may lay about 115 eggs (Romer, 1951). Eggs are larger than in many other salamanders, the jelly capsule measuring 6 x 4.5 mm, and the egg diameter 2.9 mm (Kong & Tong, 1986). Larvae hatch after three to four weeks at a length of 10-14 mm, at different stages of development. Larvae are black, with pink gills, golden iris and a whitish patch on the snout between the nostrils. The belly is black with irregular pale yellow spots. Most larvae reach metamorphosis before the next cold season at a length of 40-44 mm and go on land (Romer, 1951). It takes them three years to reach sexual maturity (Kong & Tong, 1986).