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Authority

(Perag.) Hust. (Hustedt, 1958: 166, pl. 12, figs 154–156)

Class

Diatomohyceae

Order

Pennales

Family

Bacillariaceae

Synonyms

Nitzschia vanheurckii (Perag.) Hasle (1972a: 115)
?Fragilaria cylindrus f. elongata van Heurck (1909: pl. 3, fig. 43)
See Hasle (1965b) for full synonymy, LM and EM descriptions, distribution and discussion of nomenclatural problems.

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Basionym

Fragilaria vanheurckii Perag. (Peragallo, 1921: 68, pl. 3, fig. 9, as van Heurckii)

Additional References

Hasle (1965b: 30, pl. 12, figs 13–16; pl. 13, figs 7, 8; pl. 15, fig. 8), Hasle & Medlin (1990c: 181, pl. 24.6, figs 13–16; pl. 24.7, fig. 8)

Description

Cells solitary or in ribbon-shaped colonies, linear in valve view, with extremely short broadly rounded poles; apical axis 35–77 µm; transapical axis c. 5 µm. Transapical striae strongly silicified, 10–11 in 10 µm, straight; striae near poles slightly curved or oblique; striae visible in girdle view. A few short apical ribs arising from striae nearest the poles. Interstrial membrane perforations barely visible, comprising 2 rows of minute close-set poroids, 42–51 in 10 µm. Fibulae 7–9 in 10 µm; apertures between fibulae mostly narrow; central aperture larger. Stria adjacent to large central aperture shorter than others. Outer fissure of canal raphe visible in parts of the valve, especially near one pole. Terminal nodules and an interruption of the fissure opposite the large middle aperture. Poroids lacking in the outer canal wall.

Distribution

Southern Ocean, south of Australia; type locality, Argentine Is., Antarctic Peninsula (Peragallo, 1921); BRATEGG sample at 69°12’S 94°06’W, also brownish undersurface of shelf-ice, 78°00’S 38°45’W (Hasle, 1965b); Weddell-Scotia Confluence (Garrison et al., 1987); Lützow-Holm Bay (Tanimura et al., 1990).

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