Description

Head is longer than broad; rectangular when viewed dorsally, truncated when viewed laterally. Eyes laterally placed. Vomeropalatine teeth extending posteriorly to a point near corners of mouth; run parallel then diverge. Nostrils anteriorly placed, distance from each other is less than their distance from eyes. SVL length is approximately three times distance from anterior point of snout to gular fold. Digits long and without webbing; third finger longest, third and fourth toes nearly equal in length. Fingers and toes slightly contact one another when laterally adpressed. Tail laterally compressed; dorsal and ventral fins are parallel and taper at posterior end. Smooth vertebral ridge from neck to tail, running continuous with dorsal fin ridge. Parotoid gland is large, compressed, and almost continuous with a dorso-lateral glandular ridge, which is cut by transverse grooves into a series of bead-like glands; ventro-lateral glandular ridge also present from axilla to groin. Circular gland also present at the antero-dorsal insertion point of the thigh between the two previously mentioned glandular rows. Males are much more glandular during breeding season. Has rugose skin. Dorsum black, sometimes brownish-black, and may sometimes contain small yellow spots on the back along the dorso-lateral glands (Thorn and Raffaelli 2001). Ventral color is brick red, vermilion, carmine, with variable black mottling. Stejneger (1907) describes specimens collected by Dr. Hugh M. Smith from Kiusiu and Shikoku with a black or blackish green dorsum; blood red with dark green mottling or symmetrical streaks ventrally; and in some specimens back is lighter green and sides of tail steel blue. Although most of the specimens look alike, their variation comes from their ventral patterns (Stejneger 1907).

Sexual dimorphism: Thorn and Raffaelli (2001) describe sexual dimorphism in this species. Males are on average smaller than females. Average length of 20 males of Hiroshima: 86.5 mm, average length of 20 females of Hiroshima: 104 mm. Males contain a “filament” at the end of the tail and skin is less rugose. Blue-purplish coloration can be found on the tail, belly, and other parts of male’s body during the breeding season.

Larvae have limbs with 2 digits and reach a total body length of 45-55 mm (Thorn and Raffaelli 2001) .

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map using BerkeleyMapper.

Japan. Hondo, Shikoku and Kyushu. Found on islands around Japan, see below for subspecies and the different areas in which they occur. Very common and are found in streams, ponds, reservoirs, roadside drains in stagnant, clear water. Occur at altitudes from 0 to 1500 m.

Life History, Abundance, Activity, and Special Behaviors
These salamanders go underground in the summer after the breeding season and return in the autumn. Breeding takes place from April to June. Mating and egg laying behavior are similar to that of Triturus (Thorn and Raffaelli 2001) . Courtship consists of the male nudging the female’s cloacal area or snout, then rhythmically creating caudal movements while the two bodies form an acute angle with one another. Male half-opens his cloaca to expose papillae, which the female nuzzles; thus marking her acceptance of the male. He then continues to walk away while luring her with caudal movements; she continues to make contact with his tail with her snout. The male then stops, raises his tail (while still undulating) and deposits a spermatophore. Female then walks over spermatophore and clasps it with her cloaca. Females lay approximately 200 eggs in one breeding season. The egg diameter is 2 mm. Eggs hatch 20 days after being deposited. Larvae require 10-12 months to metamorphose. Metamorphs emerge onto land from July to September. Sexual maturity is reached in 2 to 3 years and then they return to the water to breed, at which point they may remain aquatic for the rest of their lives.

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

Comments
Kawamura (1956) and Sawada (19611963a 1963b) studied morphological and behavioral variation in C. pyrrhogaster (then called Triturus pyrrhogaster) across different populations in Japan and concluded that there were 6 races/subspecies.

Atsumi Race
This subspecies is found along the Atsumi Peninsula, South of Nagoya, Japan. It differs from its conspecifics in having a smaller body size, red dorsal stripe, and two rows of dorsolateral red dots. Males of this subspecies do not develop the characteristic blue-purplish coloration on the tail as most do, but still maintains the thread which develops at the posterior end of the tail.

Hiroshima Race
This subspecies is found on the islands of Kyushu, Shikoku, Oki, and the Chugoku Region, Japan. Some specimens lack the characteristic dark mottling found along with the bright red coloration ventrally, and instead have solid reddish-orange bellies.

Intermediate Race
Native to Central and Eastern-Central Honshu, Japan. Individuals of this group have a dark brown/black dorsum with reddish-orange bellies mottled with black.

Kanto Race
This subspecies is found in Tokyo, Japan. Can be identified from its other conspecifics in have a more defined blunt tail tip, black rows with solid or broken red dorsolateral stripes, and a large red longitudinal stripe ventrally.

Tamba/Sasayama Race
This subspecies (Cynops pyrrhogaster sasayame) is distributed in the Kinki Region, Japan. Diagnosed by possessing two irregular black lines running down reddish colored bellies, light colored flecking may run along the sides of the abdomen. The bright ventral coloration usually consists of dense, tiny, bright dots on a black background. This characteristic is distinguishable from the typical black and orange/red mottling found in conspecifics. One behavioral difference is that males elevate one hind limb and place it dorsally on the female while simultaneously undulating their tails, perhaps to direct pheromones to her.

Tohuko Race
This subspecies is distributed in Northern Honshu, Japan. It is overall larger in body size, and contains more black blotches and lines ventrally than its other conspecifics.

References

Kawamura, T. (1956). ''Isolating mechanisms in Japanese amphibians.'' Population Genetics. T. Komai and K. Sakai, eds., Baifu-Kan, Tokyo, 143-162.

Sawada, S. (1961). ''A local variation of the mating behavior in the Japanese newt, Triturus pyrrhogaster.'' Zoological Magazine, 70(10), 20-25.

Sawada, S. (1963). ''Studies on the local races of the Japanese newt, Triturus pyrrhogaster Boie. I. Morphological characters.'' Journal of Science, Hiroshima University, B(21), 135-165.

Sawada, S. (1963). ''Studies on the local races of the Japanese newt, Triturus pyrrhogaster Boie. II. Sexual isolation mechanisms.'' Journal of Science, Hiroshima University, B(21), 167-180.

Stejneger, L. H. (1907). Herpetology of Japan and Adjacent Territory, United States National Museum Bulletin 58. Smithsonian Institution, Washington, D. C..

Thorn, R. and Raffaelli, J. (2001). ''Genera Cynops.'' Les Salamandres. Societé Nouvelle des Editions Boubée, Paris, 305-313.

Species Account Citation: AmphibiaWeb 2007 Cynops pyrrhogaster: Japanese Newt <http://amphibiaweb.org/species/4245> University of California, Berkeley, CA, USA. Accessed Mar 18, 2019.

Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Mar 2019.

AmphibiaWeb's policy on data use.