(Bréb.) Ralfs, in Pritchard (1861: 783, pl. 4, fig. 23)
Ceratoneis longissima Bréb., in Kützing (1849: 891)
van Heurck (1880–85: 185, pl. 70, figs 1–4), Peragallo (1897–1908: 293, pl. 74, figs 16–20), Cupp (1943: 200, fig. 154), Proschkina-Lavrenko (1955b: 200, fig. 95), Hasle (1964: 20, pl. 1, fig. 2; pl. 5, fig. 6; pl. 10, figs 5–7; pl. 11, figs 1–4), Hasle & Syvertsen (1997: 329, pl. 74)
Cells solitary; median part narrowly lanceolate in valve view, with slightly rostrate ends; apical axis 125–450 µm; transapical axis 6–7 µm. Transapical striae 52–60 in 10 µm (Hasle, 1964). Fibulae 6–14(?) in 10 µm, narrow and arcuate, adjoining silicified ribs of the same diameter which run parallel to the raphe fissure (see Hasle, 1964, pl. 11, fig. 2). Central nodule present.
Southern Ocean, south of Australia; Indian Ocean sector of the Antarctic (Kopczyńska et al., 1986).
See notes under Cylindrotheca closterium .
Using only LM observations, it is difficult to distinguish Nitzschia longissima from C. closterium due to their similar size and shape. Cylindrotheca is generally broader and is regarded as the more delicate cell.
In N. longissima the raphe fibulae are narrow and arcuate, and joined to silicified ribs of the same diameter that run parallel to the raphe fissure (see Hasle, 1964, pl. 11, fig. 2). By comparison, the raphe fibulae of Cylindrotheca are narrow and arcuate, and fastened to the valve by short cross-bars.