Hynobius hidamontanus has a snout vent length of 44-58 mm and a total length of 76-105 mm. It has 12, or rarely 13, costal grooves. Its limbs are fairly short, such that when its limbs are adpressed to the flank, there is a space of 0.5-3 costal grooves between the toes. Its hind feet have only 4 toes. Its dorsal ground color is purplish brown, flecked with light yellow spots and its tail usually has a lichen-like pattern. H. hidamontanus is most similar to Hynobius lichenatus, but it can be distinguished from H. lichenatus by its relatively short and high tail, long trunk, and short limbs (Goris 2004).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Japan
Hynobius hidamontanus is so far known only from the eastern slopes of the Hida Mountains in Nagano Prefecture. It lives in cold swamps at the edge of the forest. Juveniles and adults can be found deep in the swamp, under fallen logs and rocks at the swamp edge, and beneath the roots of plants (Goris 2004). 
Life History, Abundance, Activity, and Special Behaviors
Hynobius hidamontanus breeds from the middle of April to the beginning of May, the time of the spring thaw, in very slow-moving water. It lays two transparent, banana-shaped, unstriated egg sacs which contain a total of 30-76 eggs. After oviposition the female leaves the water, but the male remains in the vicinity of the egg sacs. The eggs hatch in June. Most larvae metamorphose in September to November, but a few overwinter and metamorphose the following July. The larvae feed on aquatic insects, crustaceans, tubifex worms, and other invertebrates. They are also cannibalistic (Goris 2004). 
Trends and Threats
Populations are declining due to the rapid construction of villas, which destroy the habitat around Hakuba village. Other threats include shrinkage and drying of wetlands, pollution, discarding of waste, and the pet trade (IUCN 2006). 
Relation to Humans
Hynobius hidamontanus is in the pet trade (IUCN 2006). 
Possible reasons for amphibian decline
General habitat alteration and loss
Drainage of habitat
Local pesticides, fertilizers, and pollutants
Intentional mortality (over-harvesting, pet trade or collecting)
The vernacular name comes from Mt. Hakuba of the Hida Mountains, a subdivision of the northern Japanese Alps (Goris 2004).  Hynobius tenuis is now included in this taxon.
Goris, R.C. and Maeda, N. (2004). Guide to the Amphibians and Reptiles of Japan. Krieger Publishing Company, Malabar, Florida.
IUCN, Conservation International, and NatureServe. 2006. Global Amphibian Assessment. < www.globalamphibians.org >. Accessed on 28 November 2006.
Originally submitted by: Nichole Winters (first posted 2006-12-07)
Edited by: Tate Tunstall (2007-05-11)
Species Account Citation: AmphibiaWeb 2007 Hynobius hidamontanus: Hakuba Salamander <https://amphibiaweb.org/species/3884> University of California, Berkeley, CA, USA. Accessed Oct 22, 2021.
Feedback or comments about this page.
Citation: AmphibiaWeb. 2021. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Oct 2021.
AmphibiaWeb's policy on data use.