Abstract
Distribution of BL (blue body-color type) and DA (dark body-color type) populations of the Japanese freshwater crab Geothelphusa dehaani (White) was investigated in the water system of Ayuzawa-gawa and the upper part of the water system of Kise-gawa in the western part of Kanagawa and the eastern part of Sizuoka Prefectures. We classified local populations using the color of carapace and hair index (mean length of longer hairs on propodus of a second ambulatory leg/ length of propodus of a second ambulatory leg). Body color was examined for individuals with carapace of 20mm and larger in width, and hair index was determined for all collected individuals. Distribution of BL and DA populations classified by the both methods were nearly coincided. BL populations were distributed in the water system of Kise-gawa and apart of the water system of Ayuzawa-gawa. DA populations were distributed in Ayuzawa-gawa, but not in Kise-gawa. Mixed populations were found at several places in tributaries of Ayuzawa-gawa near the border of Oyama-cho and Gotenba-shi, and in one tributary of Kise-gawa, the tributary which is thought to have been a tributary of Ayuzawa-gawa. BL and DA populations in the study area were different in the population genetic structures as found by Aotsuka et al. (1995).
