Paramesotriton caudopunctatus (Liu and Hu in Hu, Zhao and Liu, 1973)
Although reported as a very common species, Paramesotriton caudopunctatus is affected by habitat degradation (e.g., for dam construction and collection of wood) and by harvesting for use in traditional Chinese medicine. There are cases of people being poisoned and dead in 4 hours after eating three cooked newts (Huang et al., 1998). Large numbers of P. caudopunctatus are also exported for the international pet trade (IUCN, 2010). Listed as Near Threatened.
A slender warty newt with a more elongated snout than other species of Paramesotriton and prominent orange dorsal and dorsolateral ridges. Small warts are densely spread on skin. Fingers and toes flattened. Black and conspicuous pink to orange spots in the tail of the male, bordered with black.
Karyotype:
2n=24, 1M, 2M, 3M, 4M, 5M, 6M, 7SM, 8M, 9M, 10SM, 11SM, 12M, from Gu & Gao (1997). M: metacentric; SM: submetacentric
The mitochondrial genome has been sequenced by Zhang et al. (2008).
Slender warty newt, skin smoother and more elongate snout than in other Paramesotriton species. Head flat and longer than wide. Prominent upper lip. Fore legs thinner and longer than hind legs. Toes and fingers short, broad and flattened, tips blunt and rounded. Tail shorter than head and body. Dorsal and ventral tail fins straight. Tail tip blunt and rounded. Skin rough. Prominent dorsal ridge. Dorsal and dorsolateral ridges orange to ochre-colored. Sides of head and body greenish, changing into light ochre towards the tail. Ventral side of chin and throat grey-green, with incidentally a tinge of purple and cream-colored spots. On the sides the color changes from light green to orange-red, with small black spots (Hu et al., 1973; Sparreboom, 1981). The specimens described by Bischoff & Böhme (1980) have an ochre-colored back and a ventral side mottled with green, grey and brown, and a red line running from throat to tail. The male has a light, round or elongate pink spot on each side of the tail end, surrounded with black lines, except on the side of the tail tip. There are some more, smaller and irregular pink spots, arranged in a longitudinal line at the base of the tail, surrounded by black, and a number of small black spots. In the breeding season, these pink spots become more conspicuous and turn into bright purple, surrounded by dark-purple to black linings. The body becomes light ochre-yellow. The female is lacking the spots, but in older females a similar spot at the end of the tail may be vaguely visible. The male, as in most newt species, develops a swollen cloaca in the breeding season, with protruding papillae. Shortly before the female starts laying eggs, her cloaca becomes enlarged and cone-shaped, exceeding the size of the male cloaca (Sparreboom, 1983).
Variation between individual newts is considerable, as is also apparent from the descriptions by Hu et al. (1973) and Bischoff & Böhme (1980). The type description is based on animals from Leishan, in Guizhou, and the specimens described by Bischoff & Böhme (1980) probably come from Guangxi.
All measurements are from Fei et al. (2006).
Male (20 specimens). Total length: 122–145.5 mm; snout-vent length: 66.5–78.5 mm; head length: 16.9–23 mm; head width: 13–16.5 mm; forelimb length: 21.3–25.3 mm; hind-limb length: 21– 23.6mm.
Female (20 specimens). Total length: 131–154 mm; snout-vent length: 69–79 mm; head length: 16–21.5 mm; head width: 12–14.5 mm; forelimb length: 18.7–24 mm; hind-limb length: 21.1–24.9 mm.
The taxonomic position of P. caudopunctatus has been subject of debate (Sparreboom, 1981). In several characteristics P. caudopunctatus differs from all other species of Paramesotriton: Elongate snout, sexual dimorphism, and egg-laying behavior, and was placed in a subgenus of its own (Allomesotriton) by Freytag (1983). Molecular studies based on mitochondrial genes suggest that Paramesotriton may be divided into two clades: one including P. caudopunctatus, P. longliensis and P. zhijinensis, the other the remaining species of Paramesotriton (Zhao et al., 2008; Wu et al., 2010). Chen et al. (2011) show that there is moderate differentiation among populations of P. caudopunctatus from Guizhou and Chongqing.
Southeastern Chongqing, southwestern Hunan, eastern Guizhou, and Fuchuan in eastern Guangxi in central China. Not unlikely also in areas between known sites (IUCN, 2010).
The species inhabits mountain streams or small rivers at elevations from 800 m to 1,800 m (Fei et al., 2006). The stream is covered by dense forest. It prefers pools along the stream, where water is slow. Water depth ranges from 10 cm to 100 cm. The stream is clear and full of small rocks, between which the newts can hide. Paramesotriton caudopunctatus often searches for food near the pool edge, under leaves that fall into the stream. Some animals are also found in grasses, 15 cm away from the pool. They prey on insect larvae, arthropods, snails, frog eggs and earthworms (Fei et al., 2006). In the wild, they are most active from 7 to 9 pm at water temperatures around 17 °C (Wang & Chen, 2000). When water temperature falls to 14 °C in the morning, P. caudopunctatus stays in deeper water and does not move much even when disturbed. Other amphibians, such as Paramesotriton fuzhongensis, Pachytriton labiatus, Quasipaa, Odorrana, Amolops, Megophrys and Vibrissaphora, co-occur with Paramesotriton caudopunctatus.
Reproductive activity has been observed from November to April. The male takes up an alert posture, his fore legs stretched and his tail bent sideward. When he has identified a female he orients in front of her and starts fanning his tail, producing a stream directed to her snout. He keeps his head level with hers. If the female remains standing still, the male continues tail-fanning. When responsive, the female moves forward in the male’s direction. The male turns round, away from the female and moves forward, ahead of the female, making undulating movements with his tail. The female orients to the spot in the tail of the male and follows him. At this stage, the male may raise his tail, stretch it, keeping only the tip bent, the bright-colored spotted tail tip acting as a flag, moving to the left and to the right, thus attracting the female (Sparreboom, 1983). This behavior has not been observed in other Paramesotriton species, which are lacking the bright tail spot, but resembles the luring tail movements of some European newt species. Then the male deposits a spermatophore in front of the female. She moves over it and picks it up in her cloaca. A male may deposit several spermatophores in succession. After egg-laying, females can often be seen staying close to the oviposition site and ‘protecting’ the eggs. This has been observed repeatedly and may represent a form of parental care (Henry Janssen, pers. com.). Larvae and juveniles may be sensitive to stress, and liable to cannibalism, so they should best be kept in separate containers (cf Miller, 2005).