Ziegler's Crocodile Newt
Species Description: Nishikawa K, Matsui M, Nguyen TT 2013 A new species of Tylototriton from northern Vietnam (Amphibia: Urodela: Salamandridae). Current Herpetology 32: 34-49.
© 2013 Kanto Nishikawa (1 of 2)
Tylototriton ziegleri is a newt belonging to the genus Tylototriton. This newt has a distinctly rough skin of black coloration with fine granules present along the skin. Granules are dense on the dorsal and ventral side, and are small and scarce around the throat. The body is of medium size and fairly stout. Snout vent length is measured to be 54.4 - 68.3 mm for males and 70.8 mm for females. The head is measured to be wider than it is long (width 17.2 mm, length 16.2 mm in the holotype). The shape of the head is hexagonal and appears somewhat oblique and depressed in profile. The snout is short with a snout length of 7.6 mm. The tip of the snout is broad and squared extending slightly over the lower jaw. Nostrils are located close to the tip of the snout. Eyelid to nostril length is 4.4 mm and internarial distance is 5.9 mm. The eye is quite large measuring 3.0 mm in diameter and distance between the eyes is 7.8 mm. Upper eyelid width was measured to be 2.2 mm and upper eyelid length was 4.5 mm. Bony ridges located dorsolaterally are distinctly present on the head from above the parotoid at the anterior end to above the eye. Another prominent, but shorter ridge, is located middorsally on the head. Labial folds on the head and costal folds on the ribs are both absent. A vertebral ridge is prominent on the dorsum. The ridge is segmented and formed by a row of tubercles beginning at the neck and ending at the base of the tail. The beginning of the ridge is separated from the middorsal ridge on the head by a small gap. Nodules along the rib are prominent and form a row of knob-like warts starting from the axilla region and ending at the base of the tail. Size of the nodules increases from the anterior most nodule to the fourth and then decreases in size the remaining length towards the tail. The limbs are thin and long with the tips of the forelimbs and hindlimbs overlapping greatly when pressed flat against the body. Fingers and toes have no webbing. The tail is compressed laterally (maximum tail height of 7.7 mm) and pointed at the tip. The dorsal fin of the tail is posteriorly distinct and the ventral side of the tail is smooth (Nishikawa et al. 2013).
The head of Tylototriton ziegleri larvae is approximately trapezoidal. In profile, the head is concaved and sloping. The snout is short, slightly flat and squared. A distinct labial fold on the posterior half of the upper jaw is present. The caudal fin is taller than the head. A dorsal fin originates from the middle of the trunk and extends to the tip of the tail, which is rounded. The ventral fin begins at the vent and also extends to the rounded tip of the tail. The ventral fin is shorter than the dorsal fin (Nishikawa et al. 2013).
Tylototriton ziegleri can be differentiated from other species within the same genus based on several characteristics. Tylototriton ziegleri differs from T. asperrimus specifically by having more prominent bony ridges on the head, more dense granules on the body, a defined vertebral ridge on the dorsum, and distinct protruding knob-like rib nodules along the sides of the body. Tylototriton ziegleri also has larger eyes and a thinner, lower tail than T. asperrimusi. Tylototriton ziegleri has a more narrow vertebral ridge than T. broadoridgus along with a thinner, lower tail and longer fore- and hindlimbs. From T. hainanensis, T. ziegleri can be differentiated by having a larger body and comparatively longer trunk, forelimbs, and hindlimbs; but the head is much shorter and narrower. Tylototriton ziegleri differs from T. lizhenchangi by having a longer, wider head, larger eyes, and shorter limbs. Tylototriton ziegleri has a more narrow head and thinner, lower tail than T. notialis and a shorter vent slit and lower, thinner tail than T. vietnamensis. From T. wenxianensis, T. ziegleri differs by having a granules on the ventrum arranged in transverse striations, a wider interorbital distance, larger eyes, and a thinner, lower tail (Nishikawa et al. 2013).
In life, Tylototriton ziegleri is uniformly blackish on the dorsum and the ventrum is slightly lighter than the dorsal side. The ventral side of the tail is a bright orange color. The rib nodules, fingertips, toe tips, and parts of the palms and soles are also bright orange. In preservative, black coloration on the dorsal side of Tylototriton ziegleri fades to a light brown and the orange regions fade to a cream color (Nishikawa et al. 2013).
In life, the dorsal side of Tylototriton ziegleri larvae is a uniform yellow-brown color. The ventral side is transparent and close to white. Finger and toes are yellow. Golden spots cover the dorsal head, dorsal trunk, sides of the body, tail fins, and between the axilla and throat. In preservative, yellow-brown color of dorsum fades to a light brown and golden spots along the body fade to white (Nishikawa et al. 2013).
Females are larger than males and have a comparably longer trunk; but males tend to have limbs that appear more robust than those of females. The tail height of females is smaller than the males and the vent slit is also shorter. Male specimens collected from different collection localities are similar in morphology except for some specimens collected from one location in Ha Giang and two locations in Cao Bang. Specimens from these localities have more sparse granules, rib nodules that are less developed, and a smoother vertebral ridge. Coloration is generally consistent except for the presence, absence, or extent of orange coloration on the palms, soles, and vent (Nishikawa et al. 2013).
Distribution and Habitat
The distribution of Tylototriton ziegleri is not well known, but the species has been seen in Ha Giang, Cao Bang, and Lao Cai provinces of northern Vietnam. Northern Vietnam and regions nearby contain the highest species diversity of the genus Tylototriton, but there is no evidence of this species living in sympatry with other Tylototriton species. The general region is currently being surveyed to better understand species ranges and differences in life history, as well as ecological relationships. Adult Tylototriton ziegleri can be found in permanent ponds, temporal ponds formed from rain, small marshes in level areas, and in certain segments of overflowing streams (Nishikawa et al. 2013).
Life History, Abundance, Activity, and Special Behaviors
Tylototriton ziegleri is mostly a terrestrial species. They are difficult to find and can usually only be found during the breeding season in April and May. The average diameter of mature ova found in the ovaries of a female Tylototriton ziegleri ranged between 2.1 to 3.4 mm. The animal pole of an egg is dark brown and the rest is a dark cream color. Although clutch size has not yet been determined, eggs are known to be formed into masses located on the ground near ponds, usually about 50 - 60 cm from the edge, and are not cared for by adults. On rainy days, hatchlings will crawl to the pond. Larvae mature after July and do not overwinter (Nishikawa et al. 2013).
Trends and Threats
Loss of habitat, especially degradation near breeding ponds, is a major threat to populations of Tylototriton ziegleri. Illegal pet trading is becoming a possible threat to this species as well. Efforts to conserve Tylototriton ziegleri should include regulation of commercial collection and legal protection of habitats (Nishikawa et al. 2013).
Relation to Humans
Species of Tylototriton are popular pets throughout Europe, North America, and Japan despite efforts of legal protection (Nishikawa et al. 2013).
Possible reasons for amphibian decline
General habitat alteration and loss
The species authority is Nishikawa et al. 2013.
Phylogenetic relationships based on a partial sequence of the ND2 region for 37 species showed two major clades in Tylototriton. The first clade contains species with red or orange markings on the body and the second clade contains species with blackish bodies. Tylototriton ziegleri is a part of Clade II and is in one of four subclades, which consists of the species T. hainanensis, T. ziegleri, T. notialis, and T. asperrimus. Tylototriton ziegleri was found to be more closely related to T. notialis and T. asperrimus than to T. haianensis (Nishikawa et al. 2013).
The use of ziegleri as the specific epithet of this species is a dedication to Dr. Thomas Ziegler of Cologne Zoo (located in Germany) for his many contributions to the understanding of the herpetology wildlife in Vietnam (Nishikawa et al. 2013).
Nishikawa, K., Masafumi M., Nguyen, T.T (2013). ''A New Species of Tylototriton from Northern Vietnam (Amphibia: Urodela: Salamandridae).'' Current Herpetology, 32(1), 34-49.
Written by: Athena Dao (2013-11-05)
Edited by: Ann T. Chang (2013-11-10)
Species Account Citation: AmphibiaWeb 2013 Tylototriton ziegleri: Ziegler's Crocodile Newt <https://amphibiaweb.org/species/7972> University of California, Berkeley, CA, USA. Accessed Apr 13, 2021.
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Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 13 Apr 2021.
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