Description
Hynobius vandenburghi, commonly known as the Yamato salamander, is a large Japanese salamander with a snout to vent length range for males of 44 - 67 mm. The species has a large, robust, oval head that is depressed and longer than wide. The round snout projects over the jaw. There is no labial fold. The nostrils are positioned closer to the snout tip than eyes. The moderate eye protrudes, but is inset from the edge of the eye in the dorsal view. The upper eyelid is well developed with a distinct postorbital groove that branches to the angle of the jaw and to the posterior of the distinct parotid glands. Those parotoid glands are positioned from the angle of the jaw to the distinct gular fold. It is typically characterized by having a large body with 13 costal grooves. The forelimbs and hind limbs are short and thick, separated by 1.5 costal grooves when adpressed along the body. They have relative finger lengths of I < IV < III < II and toe lengths of I < V < II < IV < III, with a well developed toe V. The tail is short, starting as a cylindrical shape at the base, but flattening vertically toward the tip, and having a weak dorsal fin. In the lateral view the tail tip is rounded (Matsui et al. 2019).

Hynobius vandenburghi is closely related to H. setouchi and H. setoi. However, H. vandenburghi can be distinguished from H. setouchi, which has larger vomerine teeth. Additionally, H. vandenburghi can be distinguished from H. setoi by H. vandenburghi having a longer tail, larger number of costal grooves, smaller head, more narrow tail, and shorter hindlimbs (Matsui et al. 2019).

Hynobius vandenburghi are typically dark brown without markings in life, with a white colored neck and a lighter colored underside. The throat can have white nuptial coloration. The tail of H. vandenburghi typically has yellow bands on the edges of the tail (Dunn 1923, Matsui et al. 2019).

There was little variation in H. vandenburghi, however, some salamanders appeared to have a spotted dorsum (Matsui et al. 2019).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

Hynobius vandenburghi are found in the Kinki and southern Chubu regions of central Japan at elevations of 40 - 100 m (Matsui et al. 2019, Sakai et al. 2019). This species can be found in the ponds, abandoned paddies, and pools of multiple prefectures on the island of Honshu. They can also be found in bodies of water with very slow currents (Matsui et al. 2019, Dunn 1923).

Life History, Abundance, Activity, and Special Behaviors
This species’ breeding season occurs in the spring, from February to May. After successful breeding, egg sacs are attached to debris or water plants in the bottom of pools, abandoned paddies, ponds, and ditches sometimes with very slow current. In Nagoya, Aichi prefecture, water temperature at the time of breeding is about 4.0 - 15.0°C (Matsui et al. 2019).

Egg sacs are string-like and coiled with an envelope that is thin and wrinkled, but without striations. They range in length from 94 - 185 mm and range in width from 12 - 21 mm, and hold 65 - 113 eggs. Ova are 2.1 - 2.7 mm in diameter and are dark brown with a dark animal pole and lighter colored vegetal pole (Matsui et al. 2019).

Larva
At a completed larval stage of development, H. vandenburghi have an average snout to vent length of 15.8 mm and a total length of 34.8 mm. The larval form is characterized by a shorter snout and a broader and rounder head. The larvae also possess dorsal, ventral, and caudal fins and external gills, indicating an aquatic larval state. Additionally, the larvae lack a strongly pointed tail, claws, and toes, characteristics they develop as they mature into their adult, sexually mature form (Matsui et al. 2019). In life, the dorsum of the larva is light brown with darker markings. The venter is whitish, transparent. There are large black spots dispersed across the flanks and tail and additional golden dots dispersed on the tail fin (Matsui et al. 2019).

Trends and Threats
Hynobius vandenburghi is listed as a “Vulnerable” species by the IUCN Red list because of a small range that is fragmented and threatened by habitat loss to urbanization, water pollution, collection for the pet trade, and predation by invasive species (IUCN 2021). The species is protected in Japan via the Red List of Ministry of the Environment Government of Japan under its previous name, H. nebulosus. Locally, the species is protected by the Prefectural Red List as “Critically Endangered+Endangered” in Osaka, as “Endangered” in Gifu, Aichi, Kyoto, and Nara, as “Vulnerable” in Mie, and as “Near Threatened” in Shiga (Matsui et al. 2019).

Relation to Humans
This species may be collected for the pet trade (IUCN 2021).

Possible reasons for amphibian decline

General habitat alteration and loss
Urbanization
Habitat fragmentation
Local pesticides, fertilizers, and pollutants
Predators (natural or introduced)
Intentional mortality (over-harvesting, pet trade or collecting)

Comments

Phylogenetic relationships

Hynobius vandenburghi was formerly combined with H. nebulosus, but was split by Matsui et al. (2019). Maximum Likelihood and Bayesian analyses of cytb mtDNA found that H. vandenburghi is sister to H. tokyoensis. The next most closely related species is H. setouchi. Molecular clock analysis estimated these splits occurred approximately 2.5 - 6 million years ago (Matsui et al. 2019).

Etymology

The specific name “vandenburghi” is dedicated to John Van Denburgh, who created the reptile and amphibian collection of the California Academy of Sciences (Matsui et al. 2019).

References

Dunn, E. R. (1923). “New species of Hynobius from Japan.” California Academy of Sciences 7, 27-29.

IUCN SSC Amphibian Specialist Group. (2021). "Hynobius vandenburghi." The IUCN Red List of Threatened Species 2021: e.T149668241A149668253. https://dx.doi.org/10.2305/IUCN.UK.2021-1.RLTS.T149668241A149668253.en. Accessed on 20 October 2022.

Matsui, M., Okawa, H., Nishikawa, K., Aoki, G., Eto, K., Yoshikawa, N., Tanabe, S., Misawa, Y., Tominaga, A. (2019). “Systematics of the widely distributed Japanese clouded salamander, Hynobius nebulosus (Amphibia: Caudata: Hynobiidae) and its closest relatives.” Current Herpetology, 38, 32-90. [link]

Sakai, Y., Kusakabe, A., Tsuchida, K., Tsuzuku, Y., Okada, S., Kitamura, T., Tomita, S., Mukai, T., Tagami, M., Takagi, M., Yaoi, Y., Minamoto, T. (2019). “Discovery of an unrecorded population of Yamato salamander (Hynobius vandenburghi) by GIS and eDNA analysis.” Environmental DNA 1, 281-289. [link]

Species Account Citation: AmphibiaWeb 2022 Hynobius vandenburghi: Yamato-sansyou-uwo; Yamato Salamander <https://amphibiaweb.org/species/8974> University of California, Berkeley, CA, USA. Accessed Dec 5, 2023.

Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 5 Dec 2023.

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