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Authority

(G.Karst.) Hust. (Hustedt, 1958: 109, pl. 3, figs 4–7)

Class

Diatomophyceae

Order

Centrales

Family

Thalassiosiraceae

Synonyms

Coscinodiscus minimus G.Karst. (Karsten, 1905: 78, pl. 4, fig. 8)

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Basionym

Coscinodiscus gracilis G.Karst. (Karsten, 1905: 78, pl. 3, fig. 4)

Additional References

Johansen & Fryxell (1985: 168, figs 8, 58, 59), Fryxell & Johansen (1990: 99, pl. 11.8, fig. 4), Moisan & Fryxell (1993: 293), Hasle & Syvertsen (1997: 82, pl. 12)

Description

Cells solitary or chain-forming, discoid, heavily silicified, with a thin chitinous strand from the central strutted process; pervalvar axis 3.5–9.5 µm. Valves flat, circular, 5–28 µm diameter. Areolation coarse; areolae 8–12 in 10 µm in the centre, 16–20 in 10 µm towards the margin, loculate, opening externally via a simple foramen and internally via a finely pored velum (Fig. d). Strutted process solitary in valve centre or off-centre, a single ring of processes at the margin, 3–4 in 10 µm; processes with internal extensions, operculate. Labiate process solitary, located c. one-third of the distance from margin to valve centre (Fig. b–d).

Distribution

Antarctic sectors of the Atlantic, Indian and Pacific Oceans (Johansen & Fryxell, 1985); Ross Sea (Watanabe, 1982; Andreoli et al., 1995); Lützow-Holm Bay (Tanimura et al., 1990); sub-Antarctic (Hustedt, 1958); subtropics (Fryxell & Hasle, 1979a); KERFIX, 50°40’S 68°25’E, Southern Ocean (Kopczyńska et al., 1998).

Comments

N/A

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