Red-tailed Knobby Newt
© 2005 Henk Wallays (1 of 33)
Author: Axel Hernandez
Tylototriton kweichowensis FANG & CHANG 1932
Diagnosis and taxonomyThe holotype (CIB 4664) and ten paratypes were collected at Kungchishan, Dahtinghsien (actually Dading County) in western Kweichow (=Guizhou) Province, China, at an elevation of about 2,000 m a.s.l. in 1930. Its taxon name refers to his distribution: Kweichow is Guizhou Province. Another ten specimens were collected at Shihfangin and four at Shihmenkan, Guizhou, in 1934. All these latter specimens are now in the United States National Museum collection (LIU 1950). My phylogenetic study indicates that the red-tailed crocodile newt is clustered with the northern species (Clade C). It exhibits a high level of genetic variation between its populations with 28 haplotypes being known from 14 analyzed populations from the Yunnan-Guizhou plateau (ZHANG et al. 2013). The latter authors also suggested that this species experienced a post-Pleistocene population expansion. T. kweichowensis is a large and robust crocodile newt whose adult males measure up to 19.5 cm and females 21.0 cm in maximum TL (FEI et al. 2006). This species is characterized by a triangular and relatively flat head with a depressed crown in the frontal and interorbital areas. The areas just above and behind the eyes on the sides of the head are elevated. The parotoid glands are large. The nostrils are small and located near the snout, separated by ½ of the interorbital distance. The snout is rounded. Two long, slanted rows of vomerine teeth form a /, meeting near the inner nasal bone. The body is robust, covered with finely granular skin and large glandular warts on the dorsum, with these tubercles being more densely packed along three evenly spaced strips, running from head to tail dorsally and on either side dorsolaterally. The venter is less granular. The limbs are stubby and short, with toes touching when the fore- and hindlimbs are adpressed to the flank. There are four unwebbed toes on each forelimb and five unwebbed toes on each hindlimb; the tips of the toes are rounded. The tail is round in cross-section near the body, but mostly compressed laterally as the tail stretches out. A tailfin is apparent, reaching its tallest point near the middle of the tail. Males are more slender and will have a protruding cloaca during the breeding period.
According to LIU (1950), two color morphs can be distinguished, one is blackish brown on the head, body, limbs and a small part of the sides of the base of the tail and orange otherwise, and the other group has three or five, wide, clay-colored stripes down the dorsum and this color also covers nearly the whole tail and is present on the lower eyelids, the corners of the mouth, the posterior ends of the cranial ridge, most of the parotoids, the sides of the neck, the anterior portions of the bases of the arms and legs, all fingers and toes, and the region around the vent, too. The dorsal stripes, the color of the tail and the parotoids are constant, whereas the other markings will be variable. Specimens with yellow-orange flanks and a black back were noted in the terrarium animal trade in 2014.
DistributionBesides from the type locality at Kungchishan, Dading County, in Guizhou Province, China, this species has so far also been recorded from Bijie, Dafang, Hezhang, Nayong, Shuicheng, Weining and Zhijin in western Guizhou Province, and from Yiliang and Yongshan in northeastern Yunnan (ZHAO 1998, ZHANG et al. 2013, RAFFAËLLI 2013, SPARREBOOM 2014).
Habitat, ethology and ecologyThis fossorial species occurs in grassland from about 1,400 to 2,400 meters near to large ephemeral water points. It is a predominantly terrestrial newt that will take to water only during the breeding season. Its reproduction plays out in ponds with a significant depth of about 1 meter that are vegetated with algae and aquatic plants (SPARREBOOM 2014). It is most active in the morning hours and at night, and feeds on beetles, centipedes, snails, earthworms and small frogs. During the winter period, temperatures in Northern Guizhou province are cold (around 2 °C) and adults are hidden up to 30-40 cm underground in burrows (pers. obs.).
ReproductionIn general, the breeding season begins in the first ten days of May and will continue until early July. An average clutch comprises 121.5 ± 7.81 eggs that hatch after 21.6 days at a rate of 44.33% (TIAN et al. 1997). There is a positive correlation between clutch size and the snout-vent length of the female. The sex ratio in the breeding ponds varies with the month, with males usually outnumbering females, especially in June and July. In Guizhou Province, T. kweichowensis was observed breeding in large ponds with water with a pH of 6 - 6.5 and 13.5 - 15.0 °C in temperature (GU & SHANG 1994, HU et al. 1996, TIAN et al. 1997). At one site near Bijie, HU et al. (1996) reported the snout-vent length of reproducing males to range from 77 to 91 mm with a minimum of 70 mm and that of reproductive females 89-98 mm (min. 80 mm). Courtship was observed by FLECK (1992) in captivity and TIAN et al. (1997) in the field. According to FLECK (1992, 2010) who has been propagating this species in Europe for years, mating is initiated by the male wagging his tail in a manner similar to Triturus spp. Actual mating then happens in the course of a roundabout dancing ritual during which the partners keep their heads more or less in contact in the center of the circle so that the cloacae of the two newts move along a fairly accurate radius. It is during this dance that the male may deposit several spermatophores and the female will pick one up with her cloaca for internal fertilization. There is no direct body contact in the form of an amplexus as would be the case in T. verrucosus. However, some other reports described an amplexus in which the male would grab the female from below by hooking his front legs into those of the female and maintaining this position for up to two days (TIAN et al. 1997). Eggs are laid one to three days after mating, singly, or two to three at a time, and scattered on the bottom of the pond. Some may also be deposited on land, in moist soil under stones near the pond. The egg diameter is 2.3 - 3.4 mm and 5.5 to 6.2 mm including the jelly. At water temperatures of 16.0 to 22.0 °C, the larvae will hatch after 21 days. Hatching rates are higher in June than in May as a result of increased rainfall and rising air temperatures. Hatchling larvae measure 12 mm in total length and will have remains of yolk left at this point of time. They will grow to ca. 62 mm before the orange color of the vertebral stripe and tail appears and metamorphose after about 105 days (TIAN et al. 1997, SPARREBOOM 2014). The morphological features of the juveniles change distinctly day by day initially. Sexual maturity is usually reached at an age of between 3 and 4 years and its longevity is estimated at 15 years (FRANÇOIS MAILLET pers. com. 2014), but some captive specimens have lived to 23 to 25 years (FLECK 1992, 2010, SPARREBOOM 2014). Indeed, this species was imported in large numbers into Europe in 1990-1995, but only a few keepers managed to maintain colonies of this species in the long run. An instance of mass-mortality of imported Red-tailed crocodile newts occurred in Belgium and the Netherlands in 2004. In addition to massive infections with Rhabdias tokyoensis, Ranavirus was isolated from some perished specimens that were subjected to post-mortems. Apart from the possibility of exposure to a non-sensitive host, this mortality episode might have been related to stress resulting from the transport of the newts while they were in breeding condition, a presumption that is supported by the presence of degenerating egg-follicles in the females (PASMANS et al. 2008). A few wild-caught specimens were imported into France in 2004, but most of these were afflicted with skin necrosis and those that were not ended up dying of exhaustion or later turned out having been contaminated by the others. Captive- bred specimens are usually healthy and robust, but very susceptible to disease (pers. obs.).
Status, threats and conservationThis species inhabits an area of 34,329 km² in which their habitats are threatened by industrial activities, intensive mining, agriculture, urbanization, and habitat destruction. This species is also illegally collected for traditional Chinese medicine and sale in the pet trade. It was imported in large numbers in the past although many specimens arrived dead and/or infected with ranaviruses (PASMANS et al. 2008). Its IUCN status is “Vulnerable”, and various authors have critically discussed this classification, because its populations are continually declining. Establishing both in and ex situ breeding programs has been suggested (ZHANG et al. 2013).
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Citation: AmphibiaWeb. 2021. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 15 Jan 2021.
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