Description
Tylototriton anguliceps is a moderately stout newt with a broad, hexagonal head that is longer than wide. Snout-vent length varies between 65.4 – 74.1 mm in females and varies between 61.1 – 62.5 mm in males. In profile, its head is depressed and somewhat oblique and its snout is short, truncated, and somewhat oblique. Its nostrils are very close to its nose tip. The species has a well-defined, narrow, protuberant, and somewhat rough dorsolateral bony ridge on its head that runs from directly over its eye to the anterior portion of its parotoid gland. The dorsolateral bony ridge scrolls proximately, and the extensive middorsal ridge on its head is quite noticeable. Tylototriton anguliceps lacks a labial fold and its dorsolateral crest is steep and narrow. The posterior end of its crest doesn’t reach its exoccipitals. Tylototriton anguliceps’ front squamosal arch is wide and robust. On its upper jaw, T. anguliceps has 98 teeth, and on its lower jaw, it has 112 teeth. It has 66 vomerine teeth in an inverted V-shape formation that converges anteriorly and reaches its choana. Its maxillary bones connect the its quadrate bone and pterygoid bones. Although its oval-shaped tongue is attached to its mouth floor, it can move laterally and posteriorly. Its easily distinguishable parotoid gland projects posteriorly. Tylototriton anguliceps has gular folds but no costal folds. A slight gap separates the middorsal ridge from the prominent, slightly segmented vertebral ridge, which in turn runs from the neck to the base of the tail. Tylototriton anguliceps has rough skin and dense, fine granules on its dorsum; these granules are transversely striated on the mid-ventrum and sparser and smaller on the throat. Its has 15 rib nodules that are distinct and form even rows extending from the axilla to the base of the tail on either side of the body. The size of the nodules slightly increases in size from the most anterior nodule to the fifth nodule, then decrease posteriorly. Its limbs are quite lanky and when adpressed, the tips of the forelimb and hindlimbs greatly overlap. Its fingers lack webbing and relative finger lengths are IV < I < II < III. Its relative toe lengths are V < I < II < IV < III. Tylototriton anguliceps has fourteen trunk vertebrae. Its tail has noticeable lateral compression, and posteriorly, its dorsal fin is more distinct. The ventral edge of its dorsal fin is smooth, and its tail is long and pointed (Le et al. 2015).

Like the adults, larvae also have a trapezoidal head that is depressed and sloping in profile. The larval snout is short and somewhat truncate with a distinct labial fold at the posterior half of the upper jaw. The caudal fin is higher than the head, and the dorsal fin higher than the ventral fin. The dorsal fin emerges intermediately between the insertion of the forelimb and middle of middle of the trunk. The ventral fin has a pointed tail tip and originates from the vent (Le et al. 2015).

Adults have bright orange heads, trunks, limbs, and tail markings that differentiate T. anguliceps from T. daweishanensis, T. taliangensis, T. verrucosus, and members of the subgenus Yaotriton, except for T. panhai. Its orange head and limbs also distinguish T. anguliceps from T. panhai, while the isolated markings on its rib nodules distinguish it from T. kweichowensis, and T. pseudoverrucosus. In addition, T. shanjing, T. shanorum, and T. uyenoi lack the prominent middorsal bony ridge as well as the steep, narrow dorsolateral bony ridges on its head, both of which are characteristic of T. anguliceps. The black ground coloration of T. anguliceps’ body differentiates it from T. pulcherrima, while the orange anterior half of its head differentiates it from T. yangi. Skull morphology is also useful for distinguishing Tylototriton anguliceps from other closely related species. The skull of T. anguliceps features a well-defined crest as well as skeletal connection between the maxillary and pterygoid. Although the maxillary and pterygoid skeletal connection is not characteristic other Tylototritoni, it is also found in Echinotriton, the sister genus of Tylototriton (Le et al. 2015).

Tylototriton anguliceps adults have a dark brown to black dorsal base color. The coloration of the venter is somewhat lighter than that of the dorsum. Bright to dark orange coloration covers the entire head, parotoids, vertebral ridge, rib nodules, limbs, and sections of the ventral trunk, pectoral and public regions, vent, and entire tail. In preservative, the dorsal ground coloration usually fades to light brown, while the orange markings fade to a light cream color (Le et al. 2015).

Dorsally, larvae are light yellowish-brown with a whitish, transparent venter and black spots finely scattered on the dorsal head. These spots form irregular dark splotches on the dorsal trunk, lateral body, and tail fin edge. Larval fingers and toes are yellow. In preservative, dorsal coloration fades to a light cream color (Le et al. 2015).

Although males are smaller than females in general, their limbs are more robust. In males, tails and vent slit lengths are also relatively longer than in females. Specimens often varied in the amount of segmentation between vertebral ridges, and many were more distinctly segmented than the holotype. The length of the vomerine tooth row also varied between specimens. Lastly, markings varied in brightness (Le et al. 2015).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Lao People's Democratic Republic, Thailand, Viet Nam

View distribution map in BerkeleyMapper.

The range of Tylototriton anguliceps includes northwestern Vietnam in Muong Nhe, Dien Bein Province and Thuan Chau, Son La Province, and northern Thailand in Doi Lahnga, Chiang Rai Province in evergreen forests (Le et al. 2015).

Life History, Abundance, Activity, and Special Behaviors
All specimens found in Vietnam were collected between 9:00 am and 11:30 am in evergreen forests with air temperature of 21^oC and humidity at 79% at time of collection. Vietnamese specimens seemed to seek shelter under rotting trees or logs, within leaf litter, or near streams. Scientists collected Thai specimens in May in pools and under rocks. At time of collection, air temperature was 21.2^oC and water temperature was 21.4^oC (Le et al. 2015).

Adults are terrestrial, and gravitate toward rotten logs and leaf litter near breeding bodies of water. After rainfall, they often reside on the forest floor (Le et al. 2015).

Mature eggs range in size from 2.0 to 2.7 mm. In general, the egg is a dark cream color and the animal pole is dark brown. Clutch size is unknown (Le et al. 2015).

Trends and Threats
At the time of this publication there was no information on trends and threats. However, T. anguliceps was long confused with T. shanjing, which has a "Near Threatened" status on the IUCN Redlist (Ohler et al. 2004).

Comments
The species authority is: Le, D.T., Nguyen, T.T., Nishikawa, K., Nguyen, S.L.H., Pham, A.V., Matsui, M., Bernardes, M., Nguyen, T.Q. (2015). ''''A New Species of Tylototriton Anderson, 1871 (Ambphibia: Salamandridae) from Northern Indochina.''.'' Current Herpetology, 34(1), 38-50.

Tylototriton anguliceps is part of the subgenus, Tylototriton, based on a molecular phylogeny using Bayesian analyses of 988 base pair sequences of the partial ND2 mt DNA sequence. In addition, mitochondrial DNA, nuclear DNA, and morphological characteristics indicate that T. anguliceps forms a sister group with T. uyenoi. Nuclear genes sequenced includes proopiomelanocortin (POMC) and Rag1 (recombination activating protein 1; Le et al. 2015, Nishikawa et al. 2013).

In Latin, “angulus” means angular while “ceps” means head, and together they refer to the steep, narrow bony ridges on Tylototriton anguliceps’ head (Le et al. 2015).

Tylototrion anguliceps shares much of its range with T. uyenoi (Le et al. 2015).

Tylototriton anguliceps likely occurs in regions bordering northwestern Vietnam and northern Thailand, such as southern China, western Myanmar, and northern Laos. Tylototrion anguliceps may occur sympatrically with one species of the T. verrucosus-shanjing complex due to overlapping ranges, though this co-occurrence is not yet documented (Le et al. 2015).

References

Le, D.T., Nguyen, T.T., Nishikawa, K., Nguyen, S.L.H., Pham, A.V., Matsui, M., Bernardes, M., Nguyen, T.Q. (2015). ''A new species of Tylototriton Anderson, 1871 (Amphibia: Salamandridae) from northern Indochina.'' Current Herpetology, 34(1), 38-50. [link]

Nishikawa, K., Khonsue, W., Pomchote, P., Matsui, M. (2013). ''Two new species of Tylototriton from Thailand (Amphibia: Urodela: Salamandridae).'' Zootaxa, 3737(3), 261 - 279. [link]

Ohler, A., Shunqing, L., Datong, Y. (2004). Tylototriton shanjing. The IUCN Red List of Threatened Species 2004: e.T59485A11934078. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T59485A11934078.en. Downloaded on 26 April 2016.

Species Account Citation: AmphibiaWeb 2020 Tylototriton anguliceps: Angular-headed newt <https://amphibiaweb.org/species/8316> University of California, Berkeley, CA, USA. Accessed Sep 20, 2024.

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

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