Abstract
Adult frogs of the Rana nigromaculata group were collected at eleven localities in Iwate Prefecture, and the mid-dorsal line, dorsal black spots, and hindlimb length were compared among populations. The characteristics of Rana brevipoda porosa were seen in the populations from the paddy fields along the River Kitakami from the southern to the central part of Iwate Prefecture. Frogs with the characteristics of Rana nigromaculata were predominant in the populations from the northern part of this prefecture. Frogs of the Rana nigromaculata group were not found in the eastern part of Iwate Prefecture.
