Luang Phabang Crocodile Newt
Species Description: Phimmachak S, Aowphol A, Stuart BL 2015 Morphological and molecular variation in Tylototriton (Caudata: Salamandridae) in Laos, with description of a new species. Zootaxa 4006: 285-310.
Hatchlings have a total length about 12.7 mm and are a yellow-brown color with dark brown spots on their heads, gills, and tail fins. At hatching, larvae lack legs but have three pairs of gills. After a month, most larvae grow to have a total body length of 24.3 mm and develop four legs. They retain their three pairs of gills. At about five months after hatching, the few larvae that remain in ponds have a total body length of about 35.9 mm. Newly emerged terrestrial juveniles had total body lengths of about 55.4 mm and weigh about 0.7 g. (Phimmachak and Stuart et al. 2015).
Tylotrotiton podichthys is distinct due to its mitochondrial DNA haplotypes and because of the glandular skin on its head and body, its body and limb coloration, and the shape of its rib nodules. Tylotrotiton podichthys has an indistinct glandular ridge on the midline of its crown, round rib nodules with diameters equal to or greater than the eye, parotoid parallel to the body’s lateral axis, a thick, glandular, vertebral tubercular ridge, rough, glandular skin on its cranial crest, even orange coloration on the ventral surfaces of its limbs, and darkly colored digit tips (Phimmachak and Aowphol et al. 2015).
Tylototriton podichthys varies from the closely related T. anguliceps by the former’s indistinct glandular ridge on the midline of its crown and because the males of T. anguliceps are distinctly slimmer than those of T. podichthys. Tylotrotriton podichthys differs from T. kweichowensis and T. psedoverrucosus because of the separated orange markings on its rib nodules. It differs from T. shanjing due to the indistinct glandular ridge on the midline of its crown, lack of distinct contrast between its orange crown and black nape, the dark coloring of the ventral surfaces of its limbs, and dark fingertips. Tylotrotiton podichthys differs from T. shanorum because of the former’s conspicuous, rounded rib nodules and its thick, glandular vertebral tubercular ridge. It differs from T. taliangensis due to the presence of its rib nodules and the orange coloration of its body. The species is distinct from T. uyenoi because of the heads of male T. podichthys are comparatively much narrower, because of T. podichthys’ indistinct glandular ridge on the midline of the crown, and because its parotoid is oriented parallel to the body axis in lateral view. It differs from T. verrucosus because of T. podichthys’ distinctly contrasting coloration between body and cranial crest, parotoids, vertebral ridge, and ridge nodules, its indistinct glandular ridge of the midline of its crown, the rough, glandular skin on its cranial crest, and the orientation of its paotoid parallel to the body axis in lateral view. Tylotrotiton podichthys differs from T. yangi due to its uniformly orange cranial crest and parotoids (Phimmachak and Aowphol et al. 2015).
In life, Tylototriton podichthys is black on its nape, lores, and on the dorsal surface of its body. The ventral surfaces of its throat, chest, belly, and limb are also black with sparse, sporadic orange mottling. The remainder of the coloring on its head, parotoids, vertebral ridge, rib nodules, ventral margin of the lower jaw, dorsal surface of limbs, ventral surfaces of hands and feet, cloaca, and tail is orange, with the brightest orange on its parotoids, vertebral ridge and rib nodules. The tips of its digits are dark brown. Its eyes have brown irises and black pupils. In preservative, Tylototriton podichthys’ bright orange coloration fades to beige or brown (Phimmachak and Aowphol et al. 2015).
The coloration of some paratypes is much darker orange in life and in preservative. Some paratypes also have dorsolateral rows of rib nodules that extend only to the base of the tail. Individuals sometimes have truncated snouts in dorsal view. Females are often heavier with a longer, more robust body and shorter vent slits. Some tail tips appear acuminate rather than rounded in profile (Phimmachak and Aowphol et al. 2015).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Lao People's Democratic Republic
There is not much data on the genus Tylototriton’s distribution in Laos, as it was only recently documented in the country. Several voucher species have been collected from Laos. They are known to occur in Laos specifically at northern latitudes greater than or equal to 17°38’N and at elevations over 980 meters (Phimmachak and Aowphol et al. 2015, Phimmachak and Stuart et al. 2015).
Life History, Abundance, Activity, and Special Behaviors
The breeding cycle of Tylototriton podichthys lasts roughly between June and July. Both males and females travel to dried streams during rainy days and nights at this time of year to breed. Female newts oviposit 4 - 12 eggs per night where they adhere in groups of 1 - 3 to thick grasses, leaf litter, and dead branches. Early in development, eggs measure about 2.9 mm in diameter and appear sticky, round, and a dark cream color. Later in development, they grow to about 5 mm, and a clear capsule containing a dark brown pole appears enclosed within the egg. Although we are unsure how long it takes larvae of T. podichthys to hatch, the closely related T. shanjing hatches after 15 - 40 days (Phimmachak and Stuart et al. 2015).
By early July, a few hatchings were found. This coincided with beginning of the streams filling, which allowing larvae to live near the bottoms of these grassy pools. By August, eggs are no longer present in streams, but larvae are abundant. Most larvae metamorphosed and left ponds by December. Terrestrial juveniles were present during all sampling periods (June, July, August, and December). Juveniles were smallest during December, as they had just recently emerged. Mature characteristics typically don’t occur until about 2 years of age (Phimmachak and Stuart et al. 2015).
Tylototriton podichthys subsists on a diet consisting of terrestrial arthropods. They eat primarily woodlice, earthworms, and pillbugs, but they also eat other various insects such as centipedes and millipedes. Juvenile newts ate mostly woodlice. No significant differences in body size were found between newts with differing diets (Phimmachak and Stuart et al. 2015).
Trends and Threats
The IUCN Red List of Threatened Species lists Laotriton laoensisk (a similar newt species whose range overlaps with that of T. podichthys) as endangered largely due to over-harvesting. Likewise several species of newts have gone extinct in neighboring Vietnam for the same reason. Therefore, Tylototriton podychthys populations are susceptible, but there is inadequate data to claim definitively whether they are endangered (Phimmachak and Stuart et al. 2015).
Relation to Humans
Possible reasons for amphibian decline
Intentional mortality (over-harvesting, pet trade or collecting)
Usually, newly described species fall under the genus Tylotrotiton based on mitochondrial DNA sequence divergence, in-life coloration, or variation in size and/or shape. For example, T. verrucosus and T. shanjing are two widespread species in the genus that have shared mitochondrial genomes (Phimmachak and Aowphol et al. 2015).
DNA analysis of aligned datasets containing 3121 characters strongly suggests that Tylototriton is its own monophyletic group. Its sister clade is Echinotriton. Within Tylototriton, there are two major clades, the first of which contains the subgenus Tylototriton taliangensis, T. kweichowensis, T. shanorum, T. yangi, T. uyenoi, T. verrucosis, and T. shanjing. The second clade contains the subgenus Yaotriton, which in turn contains two subclades with the species Tylototriton lizhenchangi, T. liuyangensis, T. wenxianensis in the first subclade and T. dabienicus, T. broadorigus, T. cf. wenxianensis, T. vietnamesis, T. panhai, T. asperrimus, T. hainanesis, T. notialis, T. cf. asperriums, and T. ziegleri in the second subclade (Phimmachak and Aowphol et al. 2015).
Species delimiting in the genus Tylototriton is difficult because there are only slight differences in size, shape, skin texture, and coloration between species. Even in non-contentious species, DNA divergences are low (Phimmachak and Aowphol et al. 2015).
Based on Bayesian analysis of 3,121 aligned characters of mitochondrial DNA, within the subgenus Tylototriton, Tylototriton podichthys is most closely related to the clades consisting of the species T. verrucosusi and T. shanjing (Phimmachak and Aowphol et al. 2015).
Both T. podichythys and T. anguliceps reside in northern Laos, but in distinct localities, but due to lack of data it is unknown if they come into contact (Phimmachak and Aowphol et al. 2015).
A study in 2015, which extended through Thailand, Vietnam, and Laos, documented four species of Tylototriton in Laos, and it’s currently believed that T. podichthys may be endemic to northern Laos (Phimmachak and Aowphol et al. 2015, Phimmachak and Stuart et al. 2015).
The species name, podichthys, has Greek roots, as pod means foot and ichthys fish. Therefore, podichthys suggests a fish with feet, which is a reference to the Lao term for the species (pa theen), which translates to “fish with feet” (Phimmachak and Aowphol et al. 2015).
Phimmachak, S., Aowphol, A., Stuart, B.L. (2015). ''Morphological and molecular variation in Tylototriton (Caudata: Salamandridae) in Laos, with description of a new species.'' Zootaxa, 4006(2), 285-310.
Phimmachak, S., Stuart, B. L., Aowphol, A. (2015). ''Ecology and natural history of the knobby newt Tylototriton podichthys (Caudata: Salamandridae) in Laos.'' Raffles Bulletin of Zoology, 63, 389-400.
Originally submitted by: Nicole Duong (first posted 2016-02-16)
Edited by: Ann T. Chang (2016-02-18)
Species Account Citation: AmphibiaWeb 2016 Tylototriton podichthys: Luang Phabang Crocodile Newt <https://amphibiaweb.org/species/8374> University of California, Berkeley, CA, USA. Accessed Apr 16, 2021.
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Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 16 Apr 2021.
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