著者

川勝 正治 堀越 功

出版者

社団法人日本動物学会

雑誌

動物学雑誌 (ISSN:00445118)

巻号頁・発行日

vol.78, no.6, pp.196-203, 1969-06-15

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The vertical distribution of freshwater planarians in the Nikko National Park in the northern part of the Kanto Region, Honshu (Lat. 36°40'N. to Lat. 37°00'N. and Long.139°10'E. to Long. 139°40'E.), is reported in the present paper. The park is characterized by volcanoes of the Nasu Volcanic Zone (Mt. Nantai, Mt. Shirane, etc.) and many volcanic lakes (Lake Chuzenji-ko, Lake Sai-no-umi, Lake Yu-no-umi, Lake Suga-numa, Lake Maru-numa, etc.). The highest peak, Mt. Shirane (2578M above sea level), is located at the central part of the park. The main river systems in the park are the Daiya (the upper tributary of the Kinu River), the Kinu, the Katashina (the upper part of the Tone River) and the Tadami (the upper part of the Aga River). The Oze-ga-hara Moor is situated at the north-western corner of the park (Lake Oze-numa is located at an elevation of 1665M). The survey of the Daiya River system (the altitude range from 530 to 2024M) was made in August-September, 1968. Three species of freshwater planarians, Dugesia japonica Ichikawa et Kawakatsu, Phagocata vivida (Ijima et Kaburaki) and Polycelis auriculata Ijima et Kaburaki, were found in the area surveyed. These three species were also recorded by Kaburaki (1922 a, b, 1936) and Ueno (1934) from the same river system. Kaburaki (op. cit.) recorded Bdellocephala brunnea Ijima et Kaburaki in the vicinity of Nikko City. In the Oze-ga-hara Moor, Ph. vivida was collected by Kawai (in litt. and 1954). As far as our present knowledge goes, the altitude of the upper limit of distribution of D. japonica (J) was about 1460 metres (the vicinity of Yumoto Hot Spring; cf. Kaburaki 1922 a, b). Ph. vivida (V) was recorded in the stations within the altitude range from about 950 to 1460 metres. Pol. auriculata (A) was recorded in the cold-water stations within the altitude range from about 930 to 1660 metres. The type of the vertical distribution in the park is shown as J-JVA-A. This type belongs to the original type J-JV-JVA-VA-A found in North Honshu (cf. Kawakatsu 1965, 1967).