Description
Rana utsunomiyaorum has a moderately stout body and a triangular head which is as long as it is wide. Its snout is dorsally obtusely pointed and projects beyond the lower jaw. The nostril is much closer to the tip of the snout than to the eye. Its forelimbs are moderately stout and the fingers are unwebbed, with the tips dilated into small discs with circummarginal grooves. The hindlimbs are relatively short, about 2.7 times the length of a forelimb. Its heels overlap when the hindlimbs are held at right angles to the body. When adpressed, the tibiotarsal articulation of the limb reaches between the anterior corner of the eye and the nostril. The toes are rather well webbed with thick, not crenulate, webs. Toe discs are smaller than those of the two outer fingers.

Individuals have a dorsal color ranging from light brown to greenish brown. The dorsum is scattered with numerous tubercles, while the side of the trunk is coarsely granular and the chest and abdomen are smooth. There is a weak, interrupted dorsolateral fold, but there is no supratympanic fold.

This species is the smallest of the R. narina group. Snout to vent length is 40-48 mm in males and 46-58 mm in females. Although R. utsunomiyaorum occupies the same range as R. supranarina, R. utsunomiyaorum is smaller with shorter hind legs. Also, the dark bars on the limbs are usually incomplete and irregular in R. utsunomiyaorum, unlike other frogs of the R. narina group.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Japan

View distribution map in BerkeleyMapper.

R. utsunomiyaorum is found on the two southern islands of Ishigakijima and Iriomotejima, living along brooks in mountain forests. It occurs in the same type of streams as R. supranarina, but always higher up in the mountains. It is not found in the lowlands. Also, where sympatric with R. supranarina, it seems to prefer smaller streams.

Life History, Abundance, Activity, and Special Behaviors
R. utsunomiyaorum breeds from February to April. It lays eggs in the shallows of mountain brooks, attaching them to stones. Clutches are small and contain about 100 eggs. The mean diameter of ova squeezed out of females from Ishigakijima Island range from 3.2 to 4.2 mm. Eggs are yellowish white in color and are laid in a compact, gelatinous mass consisting of three layers.

Males have a pair of vocal sacs and a pair of vocal openings just inside the corners of the mouth. The mating call is said to be a short unpulsed note with moderate frequency modulation.

Possible reasons for amphibian decline

Habitat modification from deforestation, or logging related activities
Predators (natural or introduced)

Comments
The scientific name is in honor of Mrs. Taeko Utsunomiya and her husband, Dr. Yasuaki Utsunomiya.

References

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

Matsui, M. (1994). ''A taxonomic study of the Rana narina complex, with description of three new species (Amphibia: Ranidae).'' Zoological Journal of the Linnean Society, 111(4), 385-415.

Species Account Citation: AmphibiaWeb 2007 Odorrana utsunomiyaorum: Kogata Hanasakigaeru <https://amphibiaweb.org/species/5175> University of California, Berkeley, CA, USA. Accessed Nov 26, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 26 Nov 2024.

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