羽状ケイ藻Diatoma vulgare Bory var. grade (W. Smith) Grunowについて

概要

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Samples of the littoral attached diatoms were collected in August 1983, from Lake Ennecy in France and about 500 specimens were analyzed. Valve linear to linear-lanceolate with weakly rostrate to distinctly capitate ends. In the margins of the valve, three types are distinguished, (1) convex, (2) parallel and (3) slightly concave margins. The length of the valve become shorter in (3), (2) and (1), while the breadth become narrower in (1), (2) and (3) in those orders. Length, 28.5-86.0μm ; the mode 40-49μm. Breadth, 4.5-8.0μm; the mode 6.0-6.5μm. Striae, 8-11 in 10μn; the mode 12-13. All these values have no remarkable difference from previously reported data. The valve of Diatoma vulgare var. grande has parallel or slightly concave margins with protruded ends. The type was growing together with the following 3 types. Margins of the valve convex with extremely protruded ends. This type belongs to Diatoma vulgare var. capitulata. Margins of the valve convex with weakly protruded ends. This type belongs to Diatoma vulgare var. linearis. These four types were collected from the same habitat and one type gradually changes to other types and so various intermediate shapes of valve can be recognized. On the basis of these points, three taxa, D. vulgare var. capitulata, D. vulgare var. producta and D. vulgrare var. linearis are considered as synonymus of Diatoma vulgare var. grande.
東京女子体育大学・東京女子体育短期大学の論文