Stream Brown Frog

The body of this species is relatively robust. The canthus is blunt, and the tympanum is circular. There are 4-5 vomerine teeth. The webbing is well developed, and the tips of the fingers and toes are slightly dilated. The skin on the back of this frog has small granules. The dorsolateral fold is prominent, and is found protruding outwards above the tympanum. The supratympanic fold is also evident. The mean snout to vent length for males is 45 mm (range 38-56), and for females it is 51 mm (range 43-60). There is no vocal sac or opening. Males have nuptial pads that are grayish-yellow or yellow. Breeding males have skin folds on the flanks and the backs of their thighs.R. sakuraii is sometimes sympatric with R. tagoi, but seems completely isolated reproductively by differences in season and site of breeding as well as male calling behavior.

R. sakuraii is found specifically between the Kanta and Kinki Districts of Honshu, in Japan. The species inhabits mountainous forests and lives with the litters on the forests floors.

This species breeds from February to April in mountainous streams. The eggs are light grayish-brown in color with a diameter of 3.1-3.6 mm. The mating calls are uttered under the water, and one call lasts 0.3 sec with 4 notes. There are 5 large and 8 small pairs of chromosomes making 26 in total.

The stream brown frog or Napparagawa frog (Rana sakuraii) is a species of frog in the family Ranidae. It is endemic to Japan.

Its natural habitats are temperate forests and rivers.