AmphibiaChina 中国两栖类.

Description
E. andersoni is a stout, flat salamander with a series of 12 to 15 conspicuous knob-like lateral glands. It is uniformly dark brown or black on the dorsal and ventral sides, with only the underside of the tail, cloacal region, and the soles of the feet colored yellow-orange. Vomero-palatine teeth in V-shape, arranged in two longitudinal series, meeting in front (Stejneger 1907). Total length is 13 to 16 cm (Thorn 1969), the tail is usually shorter than the snout-vent length. The body is broad and flattened; the head is broad and triangular in shape. There is no obvious morphological distinction between the sexes (Nussbaum & Brodie Jr 1982; Inger 1947). In both sexes the cloacal opening consists of a longitudinal slit. When slightly opened, the cloaca of the female is smooth on the inside, whereas that of the male is more rugose. When carrying eggs, females have distended abdomens. Levels of genetic variability within island samples are within the intrapopulational range previously reported for other salamandrids (Hayashi et al. 1992).

The genus Echinotriton comprises two species, E. andersoni, endemic on five islands of the Ryukyu archipelago, Japan (Nussbaum & Brodie Jr. 1982; Nussbaum Brodie Jr & Yang 1995) and E. chinhaiensis, occurring in Zhejiang in China (Cai & Fei 1984). Echinotriton is unique among amphibian genera in having an anteriorly curved spine on the posterolateral surface of each quadrate. Echinotriton is most similar to Tylototriton, but differs in a number of significant morphological and life history features. The ribs of Echinotriton are free of muscular attachment distally, sharp-tipped, and often penetrate the skin through the primary warts. Echinotriton has a stockier body than Tylototriton, with shorter limbs, digits and tail (Inger 1947; Nussbaum & Brodie Jr. 1982). The adults are completely terrestrial and deposit their eggs on land, whereas the larvae develop in lentic water bodies.

E. andersoni is closely related and very similar to the Chinese sister species E. chinhaiensis, but differs from that species in that it has rows of secondary warts running on each side of the vertebral crest, between vertebral column and the row of primary warts, supported by the ribs.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan, Taiwan

View distribution map in BerkeleyMapper.

The species is distributed on five islands of the Ryukyu archipelago, including Amami-o-shima and Tokunoshima of the Amami group, and Okinawajima, Sesokojima, and Tokashikijima of the Okinawa group (Hayashi et al. 1992). Reports about its occurrence on Taiwan are based upon three museum specimens and need to be confirmed (Zhao & Adler 1993; Zhao 1999). The species is presently considered extinct on Taiwan (Zhao 1998). On Okinawa, the species is rare and occurs in isolated patches of forest (Hayashi et al. 1992; Kato & Ota 1993). On Tokunoshima the species occurs in and near sugar cane fields, at altitudes of 100 to 200 m, which until the mid sixties of the 20th century were covered by forest. Their occurrence in the remaining patches of forest on that island is doubtful (Utsunomiya et al. 1978).

Life History, Abundance, Activity, and Special Behaviors
The female lays large, single eggs on land, in one or several clutches (Utsunomiya et al. 1978). Eggs are laid in the humus or under rotting leaves in places close to ponds, puddles and springs. Eggs may also be laid when the pond is not yet filled with water. The breeding season extends from early February to late June, with a peak between the middle of March and early April. Both egg-laying and hatching of the larvae appear to be related to rain-fall. The egg capsule measures ca 7 mm in diameter and consists of three layers, the egg proper is 3.0 to 3.2 mm in diameter. It is almost white, lacking brown pigments (Sato 1943). Larvae are flushed out of the terrestrial oviposition sites by rains and are capable of finding their way to water by crawling through the mud and leaping (Utsunomiya et al. 1978). They are without balancers at the time of hatching.

Both males and females of this salamander lead a largely hidden terrestrial life and are difficult to observe outside the breeding season. In the reproductive season, only the females move to the oviposition sites. Males are far less numerous. Mating takes place on land and has only been observed in the laboratory (Utsunomiya 1982). The male approaches the female and deposits several spermatophores on land. The couple makes a circular movement, in the course of which the female is led over the spermatophore. Sperm may be stored in the female cloaca during at least 4 months (Utsunomiya 1982).

Food consists of terrestrial Isopoda and Coleoptera, earthworms and spiders (Sato 1943).

E. andersoni exhibits a stereotyped rigid anti-predator posture, during which the body is flattened and curled up and the hands and tail are raised; The species has elongated, sharp ribs with sharp epipleural processes, capable of piercing through the lateral warts (Brodie Jr et al. 1984).

Trends and Threats
Due to its secretive habits, it is difficult to detect trends in the development of populations. The species is not common and few populations have been followed systematically. Suitable habitats featuring a combination of characteristics such as sufficient cover for the eggs and appropriate water bodies for the development of larvae are becoming rare. It is not possible to determine to what extent the clearing of original forest to make room for sugar cane plantations has a detrimental effect on populations (Utsunomiya et al. 1978). Road construction and deforestation contribute to fragmentation of the scarce habitats and to a decrease in populations and number of individuals (Japan Agency of Environment 2000).

Relation to Humans
Utsunomiya et al. (1978) found dialectal names of localities in Tokunoshima, suggesting a familiarity of the population with this animal, dating to a time when it must have been of more common occurrence. Generally, the animal is not noticed by local inhabitants. The species has been captive-bred on a small scale (Nussbaum and Brodie Jr 1982; Utsunomiya 1982; Snider and Zippel 2000).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Habitat fragmentation

Comments
The author observed this salamander on Okinawa in April 1993, where he was kindly introduced to breeding habitats of this species by Satoshi Tanaka. Mrs. Taeko Utsunomiya provided data on observations of mating behaviour and Hidetoshi Ota was kind enough to translate the relevant paragraphs of Sato (1943) and make available recent Japanese literature. Andy Snider and Kevin Zippel furnished an unpublished account of captive breeding at the Detroit Zoological Institute.

References

Brodie, E.D., Jr, Nussbaum, R.A. and DiGiovanni, M. (1984). ''Antipredator adaptations of Asian salamanders (Salamandridae).'' Herpetologica, 40, 56-68.

Cai, C. M. and Fei, L. (1984). ''Description of neotype of Echinotriton chinhaiensis (Chang) and its ecology and habit (In Chinese, with English abstract).'' Acta Herpetologica Sinica, 3, 71-78.

Hayashi, T., Matsui, M., Utsunomiya, T.,Tanaka, S., and Ota, H. (1992). ''Allozyme variation in the newt Tylototriton andersoni from three islands of the Ryukyu archipelago.'' Herpetologica, 48., 178-184.

Inger, R.F. (1947). ''Preliminary survey of the amphibians of the Riukiu islands.'' Fieldiana: Zoology, 32(5), 296-352.

Japan Agency of Environment (2000). Threatened Wildlife of Japan - Red Data Book. 2nd ed. Reptilia/Amphibia. (in Japanese with English summary). Japan Wildlife Research Center, Tokyo, Japan.

Kato, T. and Ota, H. (1993). Endangered Wildlife of Japan. Hoikusha, Osaka, Japan.

Nussbaum, R. A., Brodie, E. D., Jr., and Datong, Y. (1995). ''A taxonomic review of Tylototriton verrucosus Anderson (Amphibia: Caudata: Salamandridae).'' Herpetologica, 51(3), 257-268.

Nussbaum, R.A. and Brodie, E.D., Jr. (1982). ''Partitioning of the salamandrid genus Tylototriton Anderson (Amphibia: Caudata) with a description of a new genus.'' Herpetologica, 38, 320-332..

Ota, H. (2000). ''Current status of the threatened amphibians and reptiles of Japan.'' Population Ecology, 42, 5-9.

Sato, I. (1943). A Monograph of the Tailed Batrachians of Japan (In Japanese). Nippon Shuppan-Sha, Osaka, Japan.

Snider, A. and Zippel, K. (2000). ''Amphibian conservation at the Detroit Zoological Institute.'' Froglog, 40(2).

Stejneger, L. (1907). Herpetology of Japan and Adjacent Territory. Government Printing Office, Washington. Reprinted 1996, with an introduction by M. Matsui. Society for the Study of Amphibians and Reptiles in cooperation with the Herpetological Society of Japan

Thorn, R. (1969). Les Salamandres d'Europe, d'Asie, et d'Afrique du Nord. Lechevalier, Paris, France.

Utsunomiya, T. (1982). ''Reproductive behavior of male Tylototriton andersoni observed in our laboratory (in Japanese).'' Japanese Journal of Herpetology, 9(126).

Utsunomiya, Y., Utsunomiya, T. and Kawachi, S. (1978). ''Some ecological observations of Tylototriton andersoni, a terrestrial salamander occurring in the Tokunoshima Island.'' Proceedings of the Japan Academy, Series B, 54, 341-346.

Zhao, E. (1998). China Red Data Book of Endangered Animals: Amphibia and Reptilia. Science Press: Endangered Species Scientific Commission, P.R.C., Beijing.

Zhao, E. (1999). ''Distribution patterns of amphibians in temperate East Asia.'' Patterns of Distribution of Amphibians. A Global Perspective. Duellman, W. E., eds., Johns Hopkins University Press, Baltimore, MD, 421-443.

Zhao, E. and Adler, K. (1993). Herpetology of China. Contributions to Herpetology 10. Society for the Study of Amphibians and Reptiles, in cooperation with Chinese Society for the Study of Amphibians and Reptiles, Oxford, Ohio, USA.

Species Account Citation: AmphibiaWeb 2022 Echinotriton andersoni: Anderson’s Spiny Crocodile Newt <https://amphibiaweb.org/species/4248> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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