Hynobius stejnegeri has a snout to vent length of 76-85 mm and a total length of 137-155 mm. Compared to other Japanese Hynobius, this is a large, very robust salamander. Individuals of nearly 200 mm in total length have been reported. It has 13, but sometimes 14, costal grooves. Both its limbs and toes are short. When its limbs are adpressed to the flank, there is a space of 2-3.5 costal grooves between the fore and hind toes. True to its common name, its dorsal surface has an almost translucent blackish brown ground color blotched with bright amber. Its ventral surface is lighter and without blotches.
Since the amber blotches fade in fixative, preserved specimens of H. stejnegeri are easily confused with Hynobius naevius, with which this species is sympatric. In life it can be distinguished by the amber color of its blotches, as compared to the silver or whitish blotches of H. naevius. Also, in H. naevius, the blotches are like dots on the top of the back which become larger on the flanks and tail. In H. stejnegeri, the blotches are generally largish all over the dorsal surfaces (Goris 2004).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Japan
Hynobius stejnegeri is found only in Kyushu, in the mountainous areas of the prefectures of Kumamoto, Miyazaki, and northern Kagoshima. It lives in broad-leaved evergreen or mixed forests (Goris 2004).
Life History, Abundance, Activity, and Special Behaviors
Hynobius stejnegeri breeds near the headwaters of mountain brooks from the end of April to the middle of May. It lays an exceptionally long pair of eggs sacs which are 20-30 cm in length and contain a total of 16-57 eggs. The female remains near the sacs until the eggs hatch. If the female is experimentally removed, the eggs eventually disappear, presumably eaten by freshwater crabs or other animals. The larvae have claws and live in the stream until they metamorphose and emerge in September to October of the year of birth. Many larvae overwinter in the stream and emerge in spring to summer of the following year (Goris 2004).
Trends and Threats
Major threats to Hynobius stejnegeri include the construction of roads, deforestation, erosion and pollution. This species is protected in the Kumamoto Prefecture as a natural monument (IUCN 2006).
Relation to Humans
Hynobius stejnegeri is used for medicine and food (IUCN 2006).
Possible reasons for amphibian decline
General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Local pesticides, fertilizers, and pollutants
Intentional mortality (over-harvesting, pet trade or collecting)
Hynobius stejnegeri is sympatric with H. naevius throughout its range, no intergrades are known, suggesting strong reproductive isolation (Goris 2004).
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.
Written by Nichole Winters (NicholeWinters AT gmail.com), URAP
First submitted 2006-12-07
Edited by Tate Tunstall (2008-02-03)
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