Description
Tylotriton pasmansi, or Pasman’s Crocodile Newt, was described as two subspecies, T. p. pasmansi and T. p. obsti from eleven males and one female for the former and eleven males for the latter. Combined they have a slender body with a male snout-vent length range of 61.57 - 70.69 mm and the female has a snout-vent length of 76.82 mm. In general , they have a longer than wide head that is slightly wider than the body and somewhat depressed and oblique when viewed from the profile. The snout is wider than long and truncated when viewing it dorsally, angular in the profile and protruding over the lower jaw. The internarial distance is greater than the eye to nares distance. The nostrils are located near the snout tip, and can be slightly seen from above. They have a fold on their lip present as well as a gular fold. Their eyes are widely distanced with a distinct mid-dorsal ridge between them. A pair of moderately protruding dorsolateral bony ridges are found on the head, located above the eye and scrolling medially just anterior to the parotoids. The enlarged parotoids project backwards (Bernardes et al. 2020).

Their dorsal skin hasmore granules than their ventral skin. There are also small round protuberances arranged in transverse stripes on their stomach. The lateral skin between the limbs may be smooth. In their rib area, they have a series of distinct bumps in their skin, or nodules, that range from being more pointy or round. They have 12 - 13 trunk vertebrates. They also have a high, glandular vertebral ridge that extends from the head, but is not connected to the mid-dorsal ridge on the head, to the base of the tail. This vertebral ridge is somewhat rough, segmented, and thinner on the anterior end. When the limbs are adpressed towards each other, the digits either touch or overlap. When adpressed towards the head, the fingers either reach the eye or extend beyond. The thin tail is laterally compressed with an acuminated tip (Bernardes et al. 2020).

DIAGNOSIS:

Tylototriton pasmansi can be distinguished by having a relatively larger interorbital distance apart when compared to T. broadoridgus, T. liuyangensis, T. panhai, and T. wenxianensis. They also have a more distinctly separated rib nodules compared to T. anhuiensis, T. broadoridgus, and Tylotriton liuyangensis, which all have a nodule-like warts that are continuous in the rib area. Their head is longer than it is wide, whereas in many other species, such as T. asperrimus, T. hainanensis, and T. ziegler, have a head that is wider than it is long. The presence of a gular fold distinguishes T. pasmansi from the absence of one in T. broadoridgus, T. vietnamensis, and T. wenxianensis. They also have generally smooth ventral skin with aligned horizontally, wrinkled tubercles as opposed to more rough skin found in T. broadoridgus, T. liuyangensis, and T. wenxianensis. Lastly, T. sparreboomi has a more orange-like color, narrower head, wider distance between the eyes, longer humerus, and more enlarged rib nodules than T. pasmansi (Bernardes et al. 2020).

COLORATION:

In life, they are uniformly colored dark brown-gray both dorsally and ventrally. However, they also contain ventral orange-red coloration in their digits, palms, vent and along their tail. In preservative, they are a faded dark grayish green on the dorsal side. While on the ventral side, the coloration is dark brown with faded yellow in the same areas where it would be orange-red in live specimens (Bernardes et al 2020).

VARIATION:

Variation between paratypes includes an overall stouter body build, more pronounced mid-dorsal ridges, less obvious dorsolateral ridge presence on the head and larger nodules in the rib area. Breeding pads may also be found on the anterior upper arms, which appear as pale yellow in preservative. The two subspecies can be differentiated by geography and by morphology. More specifically, in T. p. obsti has a wider head, longer and narrower snout, less visible nostrils, thinner posterior ends to the dorsolateral ridge of the head, more obvious gular fold, similarly sized, pointy rib nodules throughout their length, shorter limbs, fewer skin warts and granules - including on the lateral surfaces of the skin, and a less robust body (Bernardes et al 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Viet Nam

View distribution map in BerkeleyMapper.

Tylotriton pasmansi inhabit secondary hardwood forests and wetlands in northern Vietnam at an elevation between 720 meter to 1,090 meters. More specifically, T. p. pasmansi can be found in Hoa Binh and Phu Tho Provinces and T. p. obsti can be found in Son La and Thanh Hoa Provinces. These areas have a yearly average precipitation of 1603.5 mm to 1884mm (Bernardes et al. 2020; IUCN 2021).

Life History, Abundance, Activity, and Special Behaviors

They are nocturnal (Hernandez 2016). However, specimens were found between 14:00 and 16:00 h in breeding ponds (Bernardes et al. 2020).

They reproduce through internal fertilization and are oviparous, laying eggs aquatically (Hernandez 2016).

Like all newts, they change from terrestrial to aquatic morphs during their breeding season (Hernandez 2016).

Like other members in the family Salamandridae, they produce potent toxins through the granular skin (Hernandez 2016).

Trends and Threats
Expanding agriculture may be a threat to the species (Sodhi et al. 2010). However, poaching is considered the greatest threat to their population (Bernardes et al. 2020).

Relation to Humans
They are frequently poached for the pet trade and for medicinal purposes (Bernardes et al. 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

PHYLOGENETIC RELATIONSHIPS:

Bayesian, Maximum Likelihood, and Maximum Parsimony analyses on ND2 mtDNA found that the two subspecies of T. pasmansi are members of the T. asperrimus complex, and their closest relative is T. asperrimus (Bernardes et al. 2020).

in a later study, time-calibrated Bayesian and Maximum Likelihood analyses of 12S, 16S, ND1, ND2, COI, Cytb and CR mtDNA supported the relationship between T. pasmansi and T. asperrimus, with the next most closely related species being T. sparreboomi. In the same study, time-calibrated Bayesian and Maximum Likelihood analyses of POMC, RAG1, BDNF and NCX1 nDNA placed T. pasmansi as sister to T. ziegleri, however ,the nuclear sequence phylogenies do not have strong confidence (Dufrensnes and Hernandez 2022).

ETYMOLOGY:

The species epithet, “pasmansi”, is in honor of professor Dr. Frank Pasmans from Ghent University, whose research contributed significantly to the discovery of diseases responsible for amphibian decline (Bernardes et al. 2020).

The subspecies epithet, “obsti”, is in honor of the late professor Fritz-Jürgen Obst, who was a herpetologist and director of the Museum für Tierkunde Dresden, Germany (Bernardes et al. 2020).

References
Bernardes, M., Le, M. D., Nguyen, T. Q., Pham, C. T., Pham, A. V., Nguyen, T. T., Rödder, D., Bonkowski, M., Ziegler, T. (2020). Integrative taxonomy reveals three new taxa within the Tylototriton asperrimus complex (Caudata, Salamandridae) from Vietnam. Zookeys 935: 121–164. [link]

Dufrensnes, C., Hernandez, A. (2022). Towards completing the crocodile newts’ puzzle with all-inclusive phylogeographic resources. Zoological Journal of the Linnean Society 197(3): 620–640. [link]

Hernandez, A. (2016). Crocodile Newts: The Primitive Salamandridae of Asia (Genera Echinotriton and Tylototriton. Chimaira edition, Frankfurt. [link]

IUCN SSC Amphibian Specialist Group. (2021). Tylototriton pasmansi. The IUCN Red List of Threatened Species 2021: e.T179063834A185452241. https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T179063834A185452241.en. Accessed on 23 September 2022.

Sodhi, N.S., Posa, M.R.C., Lee, T.M., Bickford, D., Koh, L.P. Brook, B.W. (2010). The state and conservation of Southeast Asian biodiversity. Biodiversity and Conservation 19: 317-328. [link]

Species Account Citation: AmphibiaWeb 2023 Tylototriton pasmansi: Pasmans Crocodile Newt <https://amphibiaweb.org/species/9191> University of California, Berkeley, CA, USA. Accessed May 28, 2023.

Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 28 May 2023.

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