Pseudohynobius puxiongensis (Fei & Ye, 2000)
The animal is not easy to find. Data are insufficient to make a statement about its status (IUCN, 2010). Only recently rediscovered, this species is apparently rare. No more than 300 adults were discovered in a three-year survey (Xiong et al., 2011). It is threatened by habitat fragmentation and destruction by grazing.
Vomerine teeth arranged in two short arched series. Premaxillary fontanelle usually small (Peng et al., 2010), but the holotype has no premaxillary fontanelle (Fei & Ye, 2000). No labial folds; no cornified coverings on palms and soles. 13 costal grooves. Upper side uniformly grayish brown, underside dark grey. Inconspicuous dark yellow spots present on dorsal side of tail (Fei & Ye, 2000; Xiong et al., 2011).
Karyotype:
2n=52, 1M, 2ST, 3SM, 4SM, 5M, 6ST, 7M, 8SM, 9SM, 10T, 11SM, 12M, 13M, m (14–26), from Xiong et al. (2011).
The mitochondrial genome has been sequenced by Peng et al. (2010).
Pseudohynobius puxiongensis differs from P. flavomaculatus and P. guizhouensis by having a distinct yellowish line on the dorsal tail and a shorter total length; from P. shuichengensis by having yellow dorsal spots; from P. kuankuoshuiensis by nearly rounded dorsal spots; from P. jinfo by a tail length shorter than snout-vent length (Xiong et al., 2011.
Slender body form; trunk cylindrical, slightly depressed. Head slightly flattened. No labial fold. Vomerine teeth in two short obliquely arched series, almost meeting in midline. Gular fold distinct. The holotype records an internasal bone, which was considered as a primitive character only observed in extinct ancestral amphibians (Fei et al., 2006). However, specimens rediscovered 45 years later show no sign of an internasal bone, and the holotype was considered as a case of rare individual variation (Peng et al., 2010). Similarly, the holotype has no premaxillary fontanelle, which is present in rediscovered specimens (Peng et al., 2010). Tail shorter than snout vent length. 13 costal grooves (Xiong et al., 2011 recorded only 11 costal grooves). Four fingers, five toes. No horny cover on palms and soles. Dorsal fin fold low. Skin smooth (Fei & Ye, 2000). Upper side gray-yellow, mottled with yellowish spots, underside generally grey. A distinct yellowish line presence on the dorsal side of tail (Xiong et al., 2011).
All measurements are from Fei & Ye (2000).
Male (holotyepe). Total length: 133 mm; snout-vent length: 71.4 mm; Head length: 16.8 mm; Head width: 11.3 mm; forelimb length: 19.7 mm; hind-limb length: 20.8 mm.
Pseudohynobius puxiongensis was described as Protohynobius puxiongensis on the basis of a single specimen collected in 1965 (Fei & Ye, 2000). Because the specimen has an internasal bone, it was thought to retain a primitive character lost by a common ancestor of all other hynobiid salamanders, and it was thus considered to be not only a new genus, but also a new subfamily Protohynobiinae (Fei & Ye, 2000). Rediscovery of living individuals of P. puxiongensis near the type locality in 2008-2009 showed that the rediscovered specimens were identical to the original description, except for the presence of the internasal bone and the absence of the premaxillary fontanelle observed in the holotype, which could be just an individual variation. Investigation of the complete mitochondrial genome led to the conclusion that P. puxiongensis was nested within the hynobiid family and was most closely related to the group of Pseudohynobius species. Consequently, Peng et al. (2010) included Protohynobius in the synonymy of the genus Pseudohynobius.
It is only known from the type locality Puxiong and its immediate surroundings, in Yuexi County, Sichuan Province, China (Fei & Ye, 2000; Peng et al., 2010).
This salamander normally lives on land, in and around mountain streams at 2,900 m (Peng et al., 2010). Lush bamboo and shrubs cover the stream (Xiong et al., 2011). The salamanders are always found in the upper parts of small mountain brooks that originate from springs. Batrachuperus pinchonii, Bufo gargarizans and Bombina maxima coexist with this species (Fei & Ye, 2000).
Breeding season likely is from March to the end of April or even longer (Xiong et al., 2011). The pair of egg sacs is coiled in a spiral shape and attached to under surfaces of stones or to a wall of cavities. The eggs are arranged in the egg sac in a single line or interlaced (Peng et al., 2010). Larval coloration in life: dorsal side flaxen, mottled with black brownish spots; ventral side gray; tail fin silver white (Xiong et al., 2011).