AmphibiaChina 中国两栖类.

Description
Pachytriton inexpectatus is a stout-bodied, smooth-skinned salamander in which males have a snout-vent length range in adult males of 68.6 - 99.1 mm and adult females are 75.9 - 108.6 mm. Total lengths of males range from 128.2 - 196.9 mm and females from 144.1 - 206.6 mm. The head is flat, and longer than it is wide. The eyes are small, and the parotoid glands are pronounced. Another gland behind the parotid gland can also be observed. There are 11 costal grooves. The species has short, stubby limbs and digits. When the limbs are adpressed along the body towards each other they are separated by about 3.5 costal grooves. They have strong, paddle-like tails that are rounded at the tip. The tail also contains a caudal fin on the last two-thirds, with a low keel running the length of the underside of the tail (Nishikawa et al. 2011).

DIAGNOSIS:

Pachytriton inexpectatus is also found at higher elevations than the species it was formerly mistaken for Paramesotriton labiatus. A larger, more robust body and wider head differentiates P. inexpectatus from the similar P. granulosus. Additionally, they are separated by a large geographic distance (Nishikawa et al. 2011). Geographic range also separates P. inexpectatus from the similar species, P. archospotus, P. brevipes, P. feii and P. xanthospilos (Wu et al. 2013).

COLORATION:

In life, P. inexpectatus have a dark to pale brown dorsum and lateral surfaces. The background color of the ventrum is lighter than the dorsum and has reddish-orange marks that are arranged in two longitudinal lines. There are also reddish orange markings on the throat and ventral surface of the limbs. Orange markings along the ventral side appear vivid in juveniles and then dull over time into adulthood. When preserved, the colors fade with the dorsum becoming light brown and the ventrum becoming pale cream (Nishikawa et al. 2011).

VARIATION:

Morphological variation among individuals is minimal, with the most variation seen due to age and sex. Juveniles exhibit brightly colored orange ventral spots, which diffuse in adults. An orange spot can be observed at the base of each of the limbs in juveniles. This species exhibits sexual dimorphism, with males having proportionately longer limbs and larger heads. The webbing between digits is variable in individuals (Nishikawa et al. 2011).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: China

View distribution map in BerkeleyMapper.

Pachytriton inexpectatus is found within a wide range in southern China. This includes the northern and eastern parts of the Guangxi Province, the southwestern part of the Hunan Province, the western part of Guizhou Province and the northwestern part of the Guangdong Province (Nishikawa et al. 2011). These habitats can range from 300 meters to 2000 meters in elevation. Pachytriton inexpectatus is primarily found in temperate forests within montane streams (IUCN 2022).

Life History, Abundance, Activity, and Special Behaviors
Pachytriton inexpectatus is mainly aquatic as adults. They can be found under rocks throughout most of the day and become active at night. This species utilizes flowing water and their suction feeding mechanism to forage. Small juveniles are likely terrestrial as they are rarely found in streams (Nishikawa et al. 2011).

Most likely because of its presence in montane stream habitats, P. inexpectatus exhibits smooth skin optimal for cutaneous respiration, a broad, paddle-like tail good for propelling through the water, and a tongue for suction feeding (Nishikawa et al. 2011).

Their diet mainly consists of various species of annelids, molluscs, and insects, both aquatic and terrestrial (Nishikawa et al. 2011).

Breeding take place between April to late July in rocky moving streams. Both male and female exhibit aggressive behavior toward any animals that are coming within sight, of or near their nesting site (Nishikawa et al. 2011). However, specific breeding behavior is unknown (Nishikawa et al. 2011; IUCN 2022.)

Eggs and larvae are not commonly found, but ova found in the ovaries of females had a mean diameter range of 3.4 - 4.7 mm. Both the vegetal and animal poles of mature ova were beige while immature ova were cream colored. Clutches ranged from 32 - 89 eggs (Nishikawa et al. 2011).

Trends and Threats
Pachytriton inexpectatus populations are stable, and the species has the IUCN Red List status as “Least Concern”. Factors that may play a role in their population decline include habitat destruction, over-harvesting locally and nationally for traditional Chinese traditional medicine, and the international pet trade. Pachytriton inexpectatus has been observed within protected areas, however these protected areas have not been specified (IUCN 2022).

Relation to Humans
Pachytriton inexpectatus are harvested for both traditional Chinese traditional medicine nationally, and the pet trade internationally (Sparreboom 2014).

Possible reasons for amphibian decline

General habitat alteration and loss
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

PHYLOGENETIC RELATIONSHIPS:

Based on Bayesian Inference and Maximum Likelihood analyses on ~1200 base pair DNA fragments of both mitochondrial and nuclear DNA, P. inexpectatus is the sister taxon to the clade composed of P. archospotus, P. brevipes, P. feii, P. granulosus, and P. xanthospilos (Wu et al. 2013). However this analysis did not include P. moi, which a 2012 study using Bayesian Inference and Maximum Likelihood analyses on the same mtDNA fragment did. Those results largely supported the 2013 results, but found that P. inexpectatus is sister to P. moi with the next most closely related clade consisting of P. archospotus, P. brevipes, P. feii, P. granulosus, and P. xanthospilos (Wu 2012).

Pachytriton inexpectatus was previously mistaken for Parmesotriton labiatus (Nishikawa et al. 2011).

ETYMOLOGY:

The species epithet, “inexpectatus”, is Latin for “unexpected”. It refers to the unexpected determination of P. inexpectatus as a new species despite being common in the pet trade (Nishikawa et al. 2011).

References

IUCN SSC Amphibian Specialist Group. (2020). "Pachytriton inexpectatus." The IUCN Red List of Threatened Species 2020: e.T88384145A122177550. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T88384145A122177550.en. Accessed on 22 February 2022.

Nishikawa K, Jiang J-P, Matsui M, Mo Y-M (2011). "Unmasking Pachytriton labiatus (Amphibia: Urodela: Salamandridae), with Description of a New Species of Pachytriton from Guangxi, China." Zoological Science, 28(6), 453-461. [link]

Sparreboom, M. (2014). "Pachytriton inexpectatus." Salamanders of the Old World. KNNV Publishing, The Netherlands, 279–81.

Wu, Y., Wang, Y., Hanken, J. (2012). “New species of Pachytriton (Caudata: Salamandridae) from the Nanling Mountain Range, southeastern China.” ZooTaxa, 3388(1), 1-16. [link]

Wu, Y., Wang, Y., Jiang, K., Hanken, J. (2013). “Significance of pre-Quaternary climate change for montane species diversity: Insights from Asian salamanders (Salamandridae: Pachytriton)”, Molecular Phylogenetics and Evolution, 66(1), 380-390. [link]

Species Account Citation: AmphibiaWeb 2022 Pachytriton inexpectatus: Yaoshan Stout Newt; Pachytriton de Guangxi <https://amphibiaweb.org/species/7661> University of California, Berkeley, CA, USA. Accessed Apr 20, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Apr 2024.

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