抄録
Distribution of BL (bluish body color type) and DA (dark body-color type) populations of the Japanese freshwater crab Geothelphusa dehaani (White) was investigated in a basin of the Sagami River in the central part of Kanagawa Prefecture. These populations were identified on the basis of the body-color type and length of hairs on walking legs of large individuals. As a whole, DA populations were distributed in the upper reaches and BL populations in the lower reaches as in the Kaname (Hanamizu) and Sakawa Rivers in Kanagawa Prefecture. The boundaries between BL and DA populations were situated in Hinata (lsehara City), Nanasawa, Kamifurusawa and Shimofuruswa (Atsugi City), Tana (Sgamihara City) and Aihara (Machida City, Tokyo). Mixed populations were recorded at Hinata and Nanasawa.
