Pachytriton xanthospilos, Wu, Yunke, Wang, Yuezhao & Hanken, James, 2012

Wu, Yunke, Wang, Yuezhao & Hanken, James, 2012, New species of Pachytriton (Caudata: Salamandridae) from the Nanling Mountain Range, southeastern China, Zootaxa 3388, pp. 1-16 : 8-13

Pachytriton xanthospilos species nov.

( Figs. 4 , 5 )

Holotype: CIB 97902, an adult female from Mangshan National Forest Park, Mt. Mang, 24.93ºN 112.97ºE, elevation 1375 m, near the border between Hunan and Guangdong provinces, P. R. China, collected by Yuhong Guo on July 8, 2009.

Paratypes: CIB 97900–01, 97903–05, same data as the holotype; CIB 21034–35, 21037–38, 21040–41, 21043–45, 21048–55, 21057, 21060–61, from Mt. Mang, Yizhang, Hunan province, collected June 25–27, 1975.

Diagnosis: Pachytriton xanthospilos sp. nov. is assigned to the genus Pachytriton based on its phylogenetic position derived from molecular data and by the following morphological characters: adult total length exceeds 150 mm; skin very smooth; limbs short and do not meet when forelimb and hind limb are adpressed against flank; digits short, flat and with limited webbing; posterior half of tail extremely laterally compressed; dorsal caudal fin conspicuous. The species can be diagnosed from congeners by the following combination of characters: body size large and very robust; dorsal color uniformly brown to light brown in life; large bright-orange spots or blotches extend ribbon-like dorsolaterally in most specimens; orange blotches sometimes present on the head and dorsum.

Description of the holotype: This is a moderately sized newt; SVL equals 82.6 mm. Head is flat and oval to rectangular. Head width measured at the posterior angle of the jaw almost equals width measured at the parotoid gland. Head much longer than wide. Snout truncate, projects slightly beyond mandible. Nostril at snout tip. Eye very small and does not bulge. Labial fold prominent on upper jaw. Tongue pad elliptical, poorly differentiated from the mouth floor. Posterior tip of maxillary bone contacts pterygoid bone; the two bones are arrayed in an apprοximately straight line• vοmerine tοοth patch ٨­shapeđ• Τοοth rοws cοnverge anteriοrly at the anteriοr limit of the internal choanae and extend posteriorly into the oral cavity. Parotoid gland prominent. Gular fold present but inconspicuous. Skin very smooth. Vertebral groove present along the dorsal midline. A few longitudinal wrinkles on throat, and numerous transverse wrinkles on flanks and venter. Limbs very short; digits remain well separated when forelimb and hind limb are adpressed against flank. Four fingers and five toes, with limited webbing at base of digits. Relative length of fingers, 1 <4 <2 <3; relative length of toes, 1 <5 <2 <4 <3. Tail highly laterally compressed. Prominent dorsal caudal fin extends from base of tail to tail tip; ventral caudal fin conspicuous. Tail tip rounded. Cloaca small and not swollen.

Color of the holotype: In preservative, dorsal color uniformly brown, but slightly lighter on head. Upper edge of dorsal caudal fin pale-gold. Pale-gold spots present along dorsolateral flanks, most conspicuous near pectoral and pelvic regions. Venter brown with large, irregular, pale-gold blotches; coloration very light on chin. Cloaca, underside of limbs and tail also pale-gold.

Variation: Linear measurements are summarized in Table 4. Males have larger and slightly swollen cloacae with a few papillae on the cloacal wall. Unlike the poorly differentiated, small adult tongue, the tongue of juveniles is larger, more elevated and with free lateral margins ( Fig. 6 ). This contrast is consistent with the ontogenetic change observed in Pachytriton feii ( Nishikawa et al. 2009) . The pale-gold spots in preserved specimens are bright orange in live salamanders ( Fig. 7 ). The dorsum is also lighter in life. Dorsolateral spots are large and conspicuous in most specimens but can be small or even absent. Orange blotches may be present on the head and dorsum. Ventral coloration varies from a brown ground color with orange blotches to nearly entire orange. Ventral orange blotches have defined margins in smaller animals but are more diffuse in the largest specimens (TTL> 180 mm).

Etymology: The specific epithet xanthospilos is derived from the characteristic orange (xantho-) spots (- spilos) along the dorsolateral side of body. It is used as a noun in apposition to the generic name.

Habitat and distribution: This species occurs in montane streams at elevations above 800 m ( Fig. 7 ). Streams are covered by canopies of lush broad-leaf forest, under which flourish dense bushes and bamboos. Tall grasses grow along the adjacent stream banks. Streams are about 2–3 m wide and 0.5– 1 m in depth; water is cold and clear. Large boulders are scattered in streams or on banks. Stream substrate includes fallen leaves, gravels and sand. Salamanders are usually found in pools (> 2.5 m2 surface area and deeper than 0.5 m) along the stream, where the water current is slow ( Xu et al. 2002). They are most active at night, but can be seen resting at the bottom of pools during the day. Large numbers of tadpoles of Leptobrachium liui co-inhabit the same stream. At night, Trimeresurus stejnegeri are found in bushes and on bamboos along stream banks. The known geographic distribution of P. xanthospilos sp. nov. includes Mt. Mang from the Mangshan National Forest Park. The species very likely occurs in nearby mountains from the Guangdong Nanling National Forest Park. Those mountains are located in the middle-to-eastern section of the Nanling Mountain Range.

Conservation status: Pachytriton xanthospilos sp. nov. has long been collected for the commercial pet trade. Technically, the type locality and nearby mountains are protected from logging and poaching at the national level. Nevertheless, there is frequent illegal collection of salamanders and recent habitat destruction from tourism. In the near future, this species could qualify for a threatened category of the IUCN Red List ver. 3.1 (http:// www.iucnredlist.org). Therefore, we regard P. xanthospilos sp. nov. as Near Threatened.

Taxonomy of Pachytriton : The genus Pachytriton was long understood to contain just two species, P. labiatus and P. brevipes , with the former species comprising two disjunct populations (northeast vs. southwest) separated by several hundred kilometers ( Zhao & Hu 1984; Fei et al. 1999; Fei et al. 2006). Nishikawa et al. (2011a) argue that the lectotype of P. labiatus , which is from the southwest population, is actually a species of the genus Paramesotriton ; they thus designate a new name, Pachytriton inexpectatus , for the former P. labiatus . We adopt this nomenclatural change but do so with caution, because external and x-ray images of the lectotype in Nishikawa et al. (2011a, cf. fig. 2A and 4A) appear to represent different specimens.

Recent phylogenetic analyses reveal that the two populations of P. inexpectatus are remarkably distinct and suggest that the northeast population represents a separate species that is more closely related to P. brevipes ( Wu et al. 2010c; Nishikawa et al. 2011a). Within the geographic range of the northeast population of P. inexpectatus, Chang (1933, 1935 ) described the salamandrid genus Pingia with its monotypic species Pingia granulosa . Based on morphological comparison, Nishikawa et al. (2009) synonymize Pingia granulosa with the northeast population of Pachytriton inexpectatus , which now they treat as Pachytriton granulosus ( Nishikawa et al. 2011a). The holotype of Pingia granulosa was lost during World War II but additional specimens recently identified as Pingia granulosa are available for study ( Hou et al. 2009). No analysis has yet assessed the relationship between Pingia granulosa and the northeast population of Pachytriton inexpectatus in a molecular phylogenetic context. Here we temporarily follow Nishikawa et al. (2011a) in the recognition of Pachytriton granulosus .

Shen et al. (2008) describe the fourth species of Pachytriton named Pachytriton archospotus , which is distinct from congeners in osteological, morphological and genetic characters ( Shen et al. 2008; Wu et al. 2010c; Wu et al. 2012). Recently, two more species, Pachytriton feii and Pachytriton moi, are described based on mitochondrial gene tree and morphological comparisons ( Nishikawa et al. 2011b). The new species described here, Pachytriton xanthospilos sp. nov., represents the seventh species in this genus. It is closely related to Pachytriton feii , Pachytriton brevipes and Pachytriton granulosus .

Figures

FIGURE 4. Pachytriton xanthospilos sp. nov. collected in 2009. A – C: holotype (CIB 97902); D – E: a juvenile paratype (CIB 97905). Scale bar = 2 cm.

FIGURE 5. Pachytriton xanthospilos sp. nov. collected in 1975. A – B: paratype (CIB 21055), showing the dorsolateral blotches; C – D: paratype (CIB 21054); E – F: a juvenile paratype (CIB 21039). Scale bar = 2 cm.

FIGURE 6. Tongue morphology in adult (left, CIB 97900) and juvenile (right, CIB 97905) Pachytriton xanthospilos sp. nov. Red arrow points to the tongue.

FIGURE 7. A: Mt. Mang, near the border between Hunan and Guangdong provinces. B: At the type locality, the stream is covered by canopy. C: Red arrow points to a newt; water depth is about 0.5 m. D – E: ventral and dorsal views of the newt in C, which was released back to the stream. Photography by X. Zhang.