Cyclostephanos tazawaensis, sp. nov. Including …—225— Cyclostephanos tazawaensis, sp. nov....
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—225— Cyclostephanos tazawaensis, sp. nov. Including Diatoms from Lake Tazawa Hiroyuki T ANAKA a, * , Noboru KATANO b and Tamotsu NAGUMO c a Maebashi Diatom Institute, 57-3, Kawamagari, Maebashi, 371-0823 JAPAN; b Akita Prefectural University, 241-438, Kaidobata-Nishi, Nakano Shimoshinjo, Akita, 010-0195 JAPAN; c Department of Biology, The Nippon Dental University, 1-9-20, Fujimi, Chiyoda-ku, Tokyo, 102-8159 JAPAN * Corresponding author: [email protected] (Accepted on February 14, 2017) Lake Tazawa in Akita Prefecture is the deepest lake in Japan. In 2011, a core sample was taken from the bottom of the lake and in 2014, another four samples were taken from the shore. All samples produced a total of 114 diatom taxa. The shore samples, in particular, showed mixed assemblages growing in various pH, and it will prove valuable for analysis of the biogeographical and water environment of the lake. One Cyclostephanos taxon found in abundance from the core sample is described as a new species, Cyclostephanos tazawaensis H. Tanaka, Katano & Nagumo. Key words: Bacilariophyceae, Cyclostephanos, Cyclostephanos tazawaensis, diatom, Lake Tazawa, new species. J. Jpn. Bot. 92(4): 225–236 (2017) Lake Tazawa is located in Senboku City, eastern Akita Prefecture, Japan (Fig. 1). The lake is hexagonal in outline, ca. 6 km east to west and ca. 5.8 km north to south. The surface area of the lake is 25.8 km 2 and it lies 249 m above sea level. Its deepest point is 423.4 m, which is the deepest in Japan (Rika Nenpyo 2016). The lake itself is primarily a product of volcanic activity during the Pliocene (Notomi 1937). An aqueduct completed for the purpose of hydroelectric power in 1940 allowed acidic water from the nearby River Tama to flow into Lake Tazawa, but after completion of a neutralization system in 1991, pH of flowing water was around 6 (Katano 2000). Sato (1951) investigated the fauna and flora of the lake, but reported only one diatom taxon, Cyclotella sp. Akita Prefectural Office (1979) reported Melosira sp., Fragilaria sp., Synadra sp., Navicula sp. and Surirella sp. in summer (author unknown). Tanaka (1992) reported topography, water pollution and organisms of Lake Tazawa, that it was an oligotrophic lake, but made no mentioned of the diatoms. A core sample was collected from the bottom of the lake by the Akita Research Center for Public Health and Environment. Four shore samples were collected by one of the author (NK). Taxonomic investigation of all the samples revealed 114 diatom taxa, including one new species, Cyclostephanos tazawaensis. Ecological information regarding the other diatom species found in various degrees of abundance is also included. The present study is the first report on
Transcript of Cyclostephanos tazawaensis, sp. nov. Including …—225— Cyclostephanos tazawaensis, sp. nov....
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Cyclostephanos tazawaensis, sp. nov.Including Diatoms from Lake Tazawa
Hiroyuki Tanakaa,*, Noboru kaTanob and Tamotsu nagumoc
aMaebashi Diatom Institute, 57-3, Kawamagari, Maebashi, 371-0823 JAPAN;bAkita Prefectural University,
241-438, Kaidobata-Nishi, Nakano Shimoshinjo, Akita, 010-0195 JAPAN;cDepartment of Biology, The Nippon Dental University, 1-9-20, Fujimi, Chiyoda-ku, Tokyo, 102-8159 JAPAN
*Corresponding author: [email protected]
(Accepted on February 14, 2017)
Lake Tazawa in Akita Prefecture is the deepest lake in Japan. In 2011, a core sample was taken from the bottom of the lake and in 2014, another four samples were taken from the shore. All samples produced a total of 114 diatom taxa. The shore samples, in particular, showed mixed assemblages growing in various pH, and it will prove valuable for analysis of the biogeographical and water environment of the lake. One Cyclostephanos taxon found in abundance from the core sample is described as a new species, Cyclostephanos tazawaensis H. Tanaka, Katano & Nagumo.
Key words: Bacilariophyceae, Cyclostephanos, Cyclostephanos tazawaensis, diatom, Lake Tazawa, new species.
J. Jpn. Bot. 92(4): 225–236 (2017)
Lake Tazawa is located in Senboku City, eastern Akita Prefecture, Japan (Fig. 1). The lake is hexagonal in outline, ca. 6 km east to west and ca. 5.8 km north to south. The surface area of the lake is 25.8 km2 and it lies 249 m above sea level. Its deepest point is 423.4 m, which is the deepest in Japan (Rika Nenpyo 2016). The lake itself is primarily a product of volcanic activity during the Pliocene (Notomi 1937). An aqueduct completed for the purpose of hydroelectric power in 1940 allowed acidic water from the nearby River Tama to flow into Lake Tazawa, but after completion of a neutralization system in 1991, pH of flowing water was around 6 (Katano 2000).
Sato (1951) investigated the fauna and flora of the lake, but reported only one diatom taxon,
Cyclotella sp. Akita Prefectural Office (1979) reported Melosira sp., Fragilaria sp., Synadra sp., Navicula sp. and Surirella sp. in summer (author unknown). Tanaka (1992) reported topography, water pollution and organisms of Lake Tazawa, that it was an oligotrophic lake, but made no mentioned of the diatoms.
A core sample was collected from the bottom of the lake by the Akita Research Center for Public Health and Environment. Four shore samples were collected by one of the author (NK). Taxonomic investigation of all the samples revealed 114 diatom taxa, including one new species, Cyclostephanos tazawaensis. Ecological information regarding the other diatom species found in various degrees of abundance is also included. The present study is the first report on
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田中宏之 a，片野 登 b，南雲 保 c：新種タザワコタイコトゲケイソウの記載と田沢湖の珪藻植生 秋田県の田沢湖は日本で最も深い湖である．2011年にこの湖底からコア試料，2014年には湖岸から試料を採取し珪藻植生の調査を行った．これらの試料からは 114分類群が見出された．特に湖岸の試料からは多様な酸・アルカリ度に生育する珪藻の出現が認められた．また観察の過程でコア試料から Stephanodiscus属とCyclostephanos属の中間の形態を示す種が見出された．この種についての殻微細構造等の詳細な観察の結果，唇
状突起が所在する間束線が殻端まで到達すること，唇状突起の外管を欠くこと等から Cyclostephanos属に所属する独立した新種とするのが適当と考えられ，タザワコタイコトゲケイソウCyclostephanos tazawaensis H. Tanaka, Katano & Nagumo, sp. nov. として提案する．
（a前橋珪藻研究所，b秋田県立大学生物資源科学部，
c日本歯科大学生命歯学部）
