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Scanning electron micrograph showing detail of the frustule of this diatom. The larger depressions are called areolae, and perforated region is called the cribrum, within which each perforation is referred to as a cribellum. The same term probably also refers to the perforations in the margins of the areolae. The species is probably C. radiatus. Sample from the water column off Martha's Vineyard. Images by Charley O'Kelly and Shauna Murray.
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This species has a very fine aerolation. It can be distinguished from other species by the central hyaline area and the hyaline lines radiating from it between the areolae. It also has a distinctive shape in girdle view. The valve is very high (often higher than wide) and the valve margin appears to undulate slightly.
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SEM of girdle view. The ligulae which fit in the open girdle bands are weakly visible. Scale bar indicates 100 µm. Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.
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Closeup of the lateral side of the valve. Scale bar indicates 25 µm. Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.
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Valvar View. Scale bar indicates 100 µm. Sample from North Sea near Heligoland (spring diatom bloom). The image was built up using several photomicrographic frames with manual stacking technique. Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.
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Closeup showing hyaline central area. Scale bar indicates 10 µm. Sample from North Sea near Heligoland (spring diatom bloom). Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.
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Closeup showing fine structure of valvar pores. Scale bar indicates 5 µm. Sample from North Sea near Heligoland (spring diatom bloom). Use of SEM equipment courtesy of Lab Dr. Karl-Heinz Schäffner, Solingen, Germany.