遊楽部川水系の淡水産ブラナリアの生態調査報告

抄録

KAWAKATSU, Masaharu (Biol, Lab., Fuji women's Coll., Sapporo), YAMADA, Tatsuya (Nayoro City Girls' High School, Nayoro), IWAKI, Sumie (Biol. Lab., Fuji Women's Coll., Sapporo) and TOKUI, Toshinobu (Hokkaido Salmon Hatchery, Sapporo) Report on the ecological survey of freshwater planarians in the Yurappu River system, Hokkaido. Jap. J. Ecol. 18,56-60 (1968). The vertical distribution of freshwater planarians in the Yurappu River system in South Hokkaido (Lat. 42°10′N. to 42°23′N. and Long. 140°00′E. to 140°18′E.) is reported. The Yurappu River system (Yurappu, Sarambe, Otona, Namarikawa, Penkerupeshupe, Towarubetsu and the Seiyobetsu Rivers) is one of the typical rivers in South Hokkaido ; it drains into Funka (Uchiura) Bay, the Pacific Ocean. The area of the Yurappu River system is the lower mountainous land (the highest peak, Mt. Yurappu, is 1275 metres above sea level). Surveys of the majority of the stations were made in August, 1967. In the area surveyed, three species of freshwater planarians, Dugesia japonica ICHIKAWA et KAWAKATSU, Polycelis sapporo (IJIMA et KABURAKI) and Polycelis auriculata IJNDA et KABURAKI, were found. D. japonica was found at the stations in the plain (below the altitude of 10 metres). Pol. sapporo was common at the stations both in the plain and the mountainous district (below the altitude of about 350 metres). Pol. auriculata was rather common at the stations ranging from about 80 to 410 metres in altitude. The inhabitable water temperature ranges of these three species are : D. japonica (18.6〜24.3℃) ; Pol. sapporo (8.6〜20.2℃) ; Pol. auriculata (8.6〜18.9℃). The type of the vertical distribution in the area surveyed is shown as JSA-SA-A (J : D. japonica ; S : Pol. sapporo ; A : Pol. auriculata).