Due to Echinotriton andersoni’s 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. 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.
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 and drainage ditch construction and deforestation contribute to fragmentation of the scarce habitats and to a decrease in populations and number of individuals. The species is listed in the Red Data Book as VU (vulnerable) (Japan Agency of Environment, 2000; Ota, 2000) and is classified as rare by Kato & Ota (1993). It is protected by law in Japan, but wild-caught specimens continue to appear in the overseas pet trade.
Echinotriton 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. Levels of genetic variability within island samples are within the intrapopulational range previously reported for other salamandrids (Hayashi et al., 1992).
2n=24, 1M, 2M, 3M, 4M, 5M, 6SM, 7SM, 8M, 9M, 10SM, 11SM, 12ST, from Seto et al. 1982
M: metacentric; SM: submetacentric; T: telocentric; ST: subtelocentric; m: micro-chromosome
The mitochondrial genome has been sequenced by Zhang et al. (2008).
Echinotriton andersoni is a stout, flat salamander with a series of 12 to 15 conspicuous knob-like lateral glands. Vomero-palatine teeth in V-shape, arranged in two longitudinal series, meeting in front (Stejneger, 1907). Body broad and flattened; head broad and triangular in shape. A triangular projection present posterior to the mouth, corresponding to the unique quadrate hook on the skull (Fei et al., 2006). There is no obvious morphological distinction between the sexes (Inger, 1947; Nussbaum & Brodie Jr, 1982). 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. Color 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.
All measurements are from Fei et al. (2006).
Male (4 specimens). Total length: 133–169 mm; snout-vent length: 65–80 mm; head length: 18–22 mm; head width: 19–22 mm; forelimb length: 21–27 mm; hind-limb length: 23–29 mm.
Female (1 specimens). Total length: 142 mm; snout-vent length: 69 mm; head length: 20 mm; head width: 19 mm; forelimb length: 21 mm; hind-limb length: 23 mm.
Based on morphological differences, Nussbaum & Brodie Jr (1982) partitioned the genus Tylototriton and established Echinotriton including two species, E. andersoni and E. chinhaiensis. Zhao & Hu (1988) regarded Echinotriton only as a subgenus of Tylototriton because the morphological characters used by Nussbaum & Brodie Jr (1982) show intraspecific variations. Recent mitochondrial data confirm the validity of Echinotriton as a full genus (Zhang et al., 2008).
Echinotriton chinhaiensis is known only from the type locality and two nearby valleys east of the city of Ningbo (respectively Chengwan, Ruiyansi and Qiushan, district of Beilun, province of Zhejiang, China), where it inhabits a forest area 100-200 m above sea level (Fei et al., 1999). Over the last 20 years, the species has been reported only incidentally from the type locality.
Broad-leaved evergreen forest, secondary forest, grassland and swamp. The species inhabits vegetated areas with constantly humid substrates (IUCN, 2010). Adults live in leaf litter, in rocky crevices, and under rocks and logs. They may even appear in or near cultivated fields (Goris & Maeda, 2005). Both males and females of this salamander lead a largely hidden terrestrial life and are difficult to observe outside the breeding season. Food consists of terrestrial Isopoda and Coleoptera, earthworms and spiders (Sato, 1943).
The reproductive season may start as early as October-November, depending on the rainfall pattern (Goris & Maeda, 2005), but more usually extends from early February to late June, with a peak between the middle of March and early April (Utsunomiya et al., 1978). 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. The male approaches the female and sniffs at her body. The couple makes a circular movement, in the course of which the male excretes a thread of mucous from his cloaca, surrounding the female by a spider-web-like string of mucous attached to the substrate (Utsunomiya, 1982; Utsunomiya & Matsui, 2002). The male then deposits several spermatophores. Sperm pick-up by the female has not yet been observed, but probably the female is led over the spermatophore, in a similar way as in E. chinhaiensis (Sparreboom et al., 2001). Sperm may be stored in the female cloaca during at least 4 months (Utsunomiya, 1982). Both egg-laying and hatching of the larvae appear to be related to rainfall. 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. It takes 55–70 days for eggs to hatch at room temperature (Fei et al., 2006).