Description
Hynobius yangi has a snout-to-vent length of 42.4 - 62.6mm in males, and 56.8 - 61.4mm in females. The head is generally longer than it is wide, with a length slightly less than a quarter of the snout-to-vent length. It has 12 to 14 costal grooves on each side of its body. The limbs are short, and do not overlap when pressed close to each other. The tail length is approximately three quarters that of the snout-to-vent length. The fifth toe on each foot is generally not well developed (Kim et al. 2003).

Hynobius yangi is most easily confused with another similar species, Hynobius leechii, though there are a few characteristics that distinguish both species. Hynobius yangi has a proportionately longer and higher placed tail, longer distance between adpressed limbs, a coiled egg sac, a light brown back, and is genetically distinct from H. leechii. It can be differentiatiated from H. quelpaertensis from its shorter snout-to-vent length, shorter body, higher number of costal grooves, proportionately longer and higher placed tail, proportionately broader head, higher number of costal grooves, and shorter distance between adpressed limbs. It differs from H. tsuensis by its shorter snout-to-vent length, higher placed tail, and its back is not covered in spots. It differs from H. nebulosus by its shorter snout-to-vent length, smaller number of costal grooves, shorter distance between adpressed limbs, and it does not have light yellow striping by the top or base of the tail. Furthermore, the vomerine teeth of H. yangi is V-shaped, whereas the vomerine teeth in all the other aforementioned species are also V-shaped, but both ends of the V jut out at an angle away from the center (Kim et al. 2003).

In life, H. yangi typically has a smooth, olive green back without distinct markings, though some individuals may have a darker brown back mottled with small, yellow specks. The underside of the salamander has a similar, but lighter, coloration. When preserved in alcohol, the backside of the H. yangi specimen turns gray in color (Kim et al. 2003).

Aside from the aforementioned color variation, there is variation in the relative sizes of body parts. Males have proportionately larger heads than females, though females have proportionately longer bodies than males. Males have proportionately longer and higher placed tails than females (Kim et al. 2003).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Korea, Republic of

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (2 records).

Hynobius yangi is endemic to a restricted portion of the Kori area of Busan in South Korea. It is primarily found in the hilly, forested areas of the Milyang sub-basin of the Kyeongsang Basin. Construction of a nuclear power plant in 2006 has resulted in the translocation of this species and it is said to inhabit only a 20km2 range (Baek et al. 2011, Kim et al. 2003).

Life History, Abundance, Activity, and Special Behaviors
Hynobius yangi is a terrestrial species associated with slow-flowing, freshwater streams within its limited range. There it lays egg sacs and attaches them to water plants or tree branches that have fallen into the water. The breeding season lasts for approximately one month each year from late February to late March. The average clutch size observed is 66 eggs, although one clutch of 86 eggs has been reported. The mean diameter of the eggs ranges from 2.70 - 2.84mm. These eggs are held in a distinctly coil-shaped sac. Eggs hatch as free-living larvae and metamorphose approximately three months later. Males reach sexual maturity around two years of age, while it takes three years in females. It has been proposed that this delayed sexual maturity could explain the larger body size observed in females. The maximum age for both sexes of the salamander is approximately 11 years (Kim et al. 2003, Lee et al. 2010).

Trends and Threats
The population of H. yangi is declining due to habitat destruction and fragmentation. As of 2003, no conservation efforts had yet been taken due to long-time confusion with the widespread H. leechii. This species is especially threatened by the construction of a nuclear power plant (Baek et al. 2010, Kim et al. 2003, Stuart 2008).

Possible reasons for amphibian decline

General habitat alteration and loss
Urbanization
Habitat fragmentation
Local pesticides, fertilizers, and pollutants

Comments
The species authority is: Kim, J. B., Min, M. S., Matsui, M. (2003). "A new species of lentic breeding Korean salamander of the genus Hynobius (Amphibia, Urodela)." Zoological Science, 20(9), 1163-1169.

Hynobius yangi is part of the H. nebulosus species complex, which includes H. nebulosus, H. leechii, H. tsuensis, and H. quelpaertensis. Two monophyletic clades have been identified in the Hynobius species of Korea, with one containing both H. leechii and H. yangi as sister groups. This phylogeny was based on the mtDNA genes, cytochrome b and 12S rRNA, using maximum likelihood estimates and Bayesian interferences (Baek et al. 2011). However, nuclear data (Ldh-1, Ldh-2, Gp-2, Xdh-2, and Aat-2) also supports this species' validity (Kim et al. 2003).

The species epithet yangi is in honor of Dr. Suh-Yung Yang, who has made great contributions to the current knowledge of animals from South Korea (Kim et al. 2003).

The karyotype of Hynobius yangi is 2N = 56. The whole mitochondrial genome has been sequenced, and is 16,403 bp long (Kim et al. 2003, Lee et al. 2011).

References

Baek, H. J., Lee, M. Y., Lee, H., Min, M. S. (2011). ''Mitochondrial DNA Data Unveil Highly Divergent Populations within the Genus Hynobius (Caudata: Hynobiidae) in South Korea.'' Molecules and Cells, 31, 105-112.

Kim, J. B., Min, M. S., Matsui, M. (2003). ''A new species of lentic breeding Korean salamander of the genus Hynobius (Amphibia, Urodela).'' Zoological Science, 20(9), 1163-1169.

Lee, B. H., Kim, J. Y., Song, S., Hur, J. M., Cho, J. Y., Park, Y. C. (2011). ''The complete mitochondrial genome sequence of the Kori salamander Hynobius yangi (Caudata: Hynobiidae).'' Mitochondrial DNA, 22(5-6), 168-170.

Lee, J. H., Min, M. S., Kim, T. H., Bake, H. J., Lee, H., Park, D. (2010). ''Age structure and growth rates of two Korean salamander species (Hynobius yangi and Hynobius quelpaertensis) from field populations.'' Animal Cells and Systems, 14(4), 315-322.

Stuart, S. (2008). Hynobius yangi. The IUCN Red List of Threatened Species. Version 2015.2. www.iucnredlist.org. Downloaded in June 2015.

Species Account Citation: AmphibiaWeb 2015 Hynobius yangi: Kori salamander <https://amphibiaweb.org/species/6217> University of California, Berkeley, CA, USA. Accessed Dec 25, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Dec 2024.

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