Comprehensive DescriptionRead full entry
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.
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.