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Ocean Ecosystems/ESRIG, University of Groningen and Arctic Centre, University of Groningen and the RaTS program, British Antarctic Survey.

Authority

(Ehrenb.) Reimann & J.C.Lewin (1964: 289, pl. 124, figs 1–4; pl. 125, figs 1–4)

Class

Diatomophyceae

Order

Pennales

Family

Bacillariaceae

Synonyms

Nitzschia closterium (Ehrenb.) W.Sm. (Smith, 1853: 42, pl. 15, fig. 120), Hasle & Medlin (1990b: 177, pl. 23.1, figs 1–4)
Nitzschiella tenuirostris Mereschk. (Mereschkowsky, 1901: 476, pl. 4, figs 1–3)
See VanLandingham (1978: 3024) for further details of synonymy.

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Basionym

Ceratoneis closterium Ehrenb. (Ehrenberg, 1841: 144, pl. 4, fig. 7)

Additional References

Hasle (1964: 16, pl. 5, fig. 1; pl. 7, figs 1–12; pl. 8, figs 1–8; pl. 9, figs 1–9; pl. 10, figs 1–4), Hasle & Medlin (1990b: 177, pl. 23.1, figs 1–4), Moisan & Fryxell (1993: 493), Hasle & Syvertsen (1997: 294)

Description

[after Hasle (1964) and Hasle & Syvertsen (1997)] Cells solitary, needle-like, straight, sigmoidal or sickle-shaped, with valves sometimes twisted around the apical axis

Distribution

Coastal waters off Davis Station, East Antarctica; near Drygalski Glacier, Ross Sea; Southern Ocean, 57°26’S 112°08’E offshore Wilkes Land; cosmopolitan (Hasle & Medlin, 1990); KERFIX, 50°40’S 68°25’E, Southern Ocean (Kopczyńska et al., 1998); Lützow-Holm Bay (Tanimura et al., 1990); Weddell-Scotia Confluence (Garrison et al., 1987).

Comments

Using only LM observations, it is difficult to distinguish C. closterium from Nitzschia longissima due to their similar size and shape. However, with EM, the raphe of Cylindrotheca is seen to be interrupted in the centre, and the fibulae are narrow, arcuate and fastened to the valve by short cross-bars. In N. longissima the fibulae are also narrow and arcuate, but they join silicified ribs of the same diameter which run parallel to the raphe fissure (see Hasle, 1964, pl. 11, fig. 2). Cylindrotheca is generally broader and is regarded as the more delicate cell.

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