Description
Hynobius tsuensis has a snout to vent length of 58-75 mm and a total length of 109-142 mm. It normally has 13 costal grooves. Its limbs are relatively short and when they are adpressed to the flank, there is a gap of 1-3 costal grooves between the fore and hind toes. Its hindfeet have 5 toes. There is sexual dimorphism in color. Females are flecked with dark brown spots on a yellowish background. Males are flecked with purplish spots on a blackish background. The vent of both sexes is lighter in color, and both sexes have an orange stripe on the upper and lower edges of the tail. The stripe tends to be wider in females (Goris and Maeda 2004).

Hynobius nebulosus also has a bright stripe on both edges of its tail, but its flecks of color are very tiny compared to those of H. tsuensis, and the ranges of the two are completely separate (Goris and Maeda 2004).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

Hynobius tsuensis is found throughout the island of Tsushima only, both in the mountains and in lowlands (Goris and Maeda 2004). [3684]

Life History, Abundance, Activity, and Special Behaviors

Hynobius tsuensis belongs to the family Hynobiidae, which is one of only two salamander families exhibiting external fertilization of eggs. H. tsuensis breeds in running water, attaching its egg sacs to the undersides of rocks or other places in brooks. The egg sacs are banana-shaped and contain a small number of relatively large (ca. 3 mm) eggs. The total clutch contains 27-75 eggs, of which as many as 50% may be unfertilized. Some larvae metamorphose before autumn, but a large proportion of them overwinter as larvae. There is little information available on the natural history of H. tsuensis outside the breeding season. Larvae that leave the water before autumn do not disperse far from the stream of birth until the following year. From collection data it is surmised that adults return to the vicinity of the breeding sites in late autumn and early winter, where they overwinter in preparation for the next breeding season (Goris and Maeda 2004). [3684]

References

Goris, R.C. and Maeda, N. (2004). Guide to the Amphibians and Reptiles of Japan. Krieger Publishing Company, Malabar, Florida.

Species Account Citation: AmphibiaWeb 2007 Hynobius tsuensis: Tsushima Sansho-uo <https://amphibiaweb.org/species/3900> University of California, Berkeley, CA, USA. Accessed Jan 26, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Jan 2025.

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