Abstract
In order to determine diagnostic characters which differentiate the Japanese pond frogs, Rana nigromaculata and three forms of R. brevipoda, four characters, each divided into three character states, were chosen according to the shape and distribution of temporal dark spots, and variations in these characters were statistically analysed within and among the four forms. Among the four characters selected, the shape of the dark spot (s) behind the dark band on the supratympanic fold and the distance between these two markings were most stable within forms and most different between nigromaculata and forms of brevipoda, which suggests that they are of value in differentiating these two species.
