Description
Hynobius abei ranges from 47-71 mm in snout-vent length, and 82-122 mm in total length. It has a short and stout trunk with 11-13 costal grooves, a strongly keeled tail, and fairly short limbs with five toes on the hindlimbs. The color can be red-brown to blackish brown, with occasional flecks of silver or light blue (Goris and Maeda 2004).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

This species is endemic to Japan. It inhabits secondary bamboo forest or deciduous hardwood forest of the northern region of Kyoto and Hyogo Prefectures. It has a fragmented distribution and is known from fewer than 20 sites (Goris and Maeda, 2004)[3684].

Life History, Abundance, Activity, and Special Behaviors
Hynobius abei breeds during November and December, when there is snow. The breeding grounds are in shaded pools formed by small springs or seeps in the forest, where the temperature is relatively stable year-round (neither freezing in the winter nor above 68 degrees in the summer). Adults return to the same pool year after year. During the mating season, the male's jowls swell, which causes the head to appear somewhat triangular. This distinguishes breeding males from the females morphologically (Goris and Maeda 2004).

Females can lay anywhere from 26 to 109 eggs. The eggs are laid in 2 coiled sacs with longitudinal folds, beneath the layer of leaves. After the clutch is deposited, the male remains near the egg sacs for a time. The larvae develop under the snow. They generally mature quickly once the snow melts, though some will overwinter as larvae. Metamorphosis usually occurs in June or July, but occasionally not until August. Juveniles do not disperse far from the breeding pool. (Goris and Maeda 2004).

This species is nocturnal, foraging at night. It is carnivorous, preying on earthworms, spiders, and snails (Goris and Maeda 2004) as well as various insects and aquatic invertebrates (Hutchins et al. 2003).

Trends and Threats
Hynobius abei is endangered. The decline in population is due primarily to loss and fragmentation of habitat because of urbanization (Hutchins et al. 2003). This salamander has a very limited distribution, due in part to its environmental requirements. It needs forested habitat with shade and stable temperatures, and is thus highly susceptible to habitat disturbance (Goris and Maeda 2004).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Urbanization
Habitat fragmentation
Loss of genetic diversity from small population phenomena

Comments
This species is easily confused with H. nebulosus, H. takedai, and H. hidamontanus, which have very similar morphology (Goris and Maeda 2004).

The karyotype of Hynobius abei is 2n = 56, with 9 large, 4 medium, and 15 small pairs. Chromosomal characteristics distinguishing this species include one pair of acrocentric chromosomes in the medium-sized group and 5 pairs of bi-armed chromosomes in the small-sized group. (Seto and Matsui 1984). In addition, H. abei has a very short C-positive/R-negative band in the terminal region of the long arm of chromosome 2, as well as a very short band composed of the entire short arm of chromosome 10 (Izumisawa et al. 1990).

References

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

Izumisawa, Y., Ikebe, C., Kuro-O., M., and Kohno, S. (1990). ''Cytogenetic studies of Hynobiidae (Urodela). IX. Karyological characters of Hynobius abei Sato by means of R- and C-banding.'' Cellular and Molecular Life Sciences, 46(1), 104-106.

Seto, T., and Matsui, M. (1984). ''Karyotype of the Japanese salamander, Hynobius abei.'' Cellular and Molecular Life Sciences, 40(8), 874.

Species Account Citation: AmphibiaWeb 2008 Hynobius abei: Abe's Salamander <https://amphibiaweb.org/species/3878> University of California, Berkeley, CA, USA. Accessed Jan 23, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 23 Jan 2025.

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