Description

Bufo japonicus has a robust body and a triangular head with a pointed snout and short and thick limbs. Body color varies from dark green, yellow-brown to dark-brown depending on locality. Numerous round tubercles can be seen on the limbs, back, and lateral side of the trunk. Warts and parotoid glands above the tympanum secrete venom when attacked by a predator. In the breeding season, males and females have smoother skin, and the male's body color tends to become more yellowish.

The snout-vent length ranges from 43-162 mm for B.j.formosus and 80-176 mm for B.j.japonicus. Females' body length is usually larger than males. Bufo japonicus living in warmer regions, on average, have greater snout-vent length. The tympanum is elliptical, and the eye-tympanum distance is about equal length to the long axis of tympanum. The fore-limb, with four fingers, is about half the length of the hind-limb; the third finger is the longest and the second is shortest. Hind-limb is nearly twice as long as the body; the fourth toe longest and the first toe shortest of all five toes. Webbing is poorly developed with deep incisions.