北見山脈天塩岳附近及びオホーツク海岸地域の淡水産プラナリアの生態調査報告

抄録

The vertical distribution of freshwater planarians in the Mt. Teshio district in the Kitami Mountains and in the Okhotsk seaboard district in North Hokkaido is reported. The highest peak, Mt. Teshio-dake (1557.6 metres above sea level), is situated at the southern corner of the Kitami Mountains (Lat. 43°57′N. and Long. 142°56′E.). The Okhotsk seaboard district is the flat-surfaced hilly land. The main river systems of the area surveyed are the Teshio, the Ishikari and the Shokotsu. The Shokotsu River discharges into the Okhotsk Sea ; the other two rivers empty into the Sea of Japan. Surveys were made in the summers of 1963,1964 and 1965. In the area surveyed, six species of freshwater planarians, Phagocata vivida (IJIMA et KABURAKI), Polycelis sapporo (IJIMA et KABURAKI), Polycelis akkeshi ICHIKAWA et KAWAKATSU, Polycelis auriculata IJIMA et KABURAKI, Polycelis schmidti (ZABUSOV) and Dendrocoelopsis lacteus ICHIKAWA et OKUGAWA, were found. Ph. vivida and Pol. auriculata were common in the localities in the Rubeshibe River, one of the tributaries of the upper part of the Ishikari River. Ph. vivida was also collected in some localities in the upper part of the Teshio River. Pol. auriculata was also collected in some localities in the upper parts of the Teshio River and the Shokotsu River. Pol. schmidti was collected in the cold-water streams in the upper parts of the Teshio River and the Shokotsu River and in some springs in the Okhotsk seaboard district. Pol. sapporo was most common in the localities of the seashore and mountainous districts. Pol. akkeshi was collected in some localities in the Mt. Teshio district. Pol. akkeshi was, however, the most dominant species in the Okhotsk seaboard district. Den. lacteus was collected only in the localities in the Okhotsk seaboard district. The altitude range of the distribution and inhabitable water temperature range of the above-mentioned species which were found in the Mt. Teshio and the Okhotsk seaboard districts are as follows : Ph. vivida (alt. 280-840 m, 6.3-12.5℃) ; Pol. sapporo (alt. 1-1000 m, 7.9-18.2℃ ; including the data of Pol. akkeshi) ; Pol. auriculata (alt. 280-1000 m, 6.3-12.5℃) ; Pol. schmidti (alt. 4-840 m, 4.8-11.8℃) ; Den. lacteus (alt. 1-90 m, 10.5-14.5℃). The type of vertical distribution in the area surveyed is SVA-VA (the Ishikari River) or S-SVAC (the Teshio River) or SC-SAC (the Shokotsu River and the Okhotsk seaboard districts).