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Authority

(Ehrenb.) Cleve (1904: 216)

Class

Diatomophyceae

Order

Centrales

Family

Thalassiosiraceae

Synonyms

Coscinodiscus labyrinthus Roper (1858: 21, pl. 3, fig. 2)
See VanLandingham (1968: 894; 1978: 3994) for further details of synonymy.

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Basionym

Coscinodiscus eccentricus Ehrenb. (Ehrenberg, 1841: 146)

Additional References

Ehrenberg (1843: 371, pl. 1/3, fig. 20; pl. 3/7, fig. 5, as excentricus), Hendey (1937: 242, as excentricus), Cupp (1943: 52, fig. 14), Fryxell & Hasle (1972: 300, figs 1–18), Hasle & Syvertsen (1997: 62, pl. 6, tab. 8)

Description

Cells chain-forming, discoid; pervalvar axis from one-sixth to longer than cell diameter. Valves flat, circular, 15–110 µm diameter (40–140 µm fide Hendey, 1937); mantle low and rounded. Areolation coarse but finer towards the margin, tangential or in 6–8 ill-defined sectors of curved and somewhat parallel rows; areolae hexagonal, 5–11 in 10 µm; central areolae usually larger than marginal ones. Strutted processes in 2 marginal rings; processes 2–5 in 10 µm, each with a short external extension. One ring of short pointed spines further from valve margin. Labiate process solitary, near the margin.

Distribution

Ross Sea (Watanabe, 1982; Andreoli et al., 1995); Atlantic Ocean (Hustedt, 1958; Makarova, 1978); Prydz Bay, East Antarctica (Boden, 1985); Southern Ocean, south of Australia (Wood, 1960).

Comments

The marginal ring of spines is a distinctive feature of this species. Hasle & Syvertsen (1997) noted the distribution of T. eccentrica as “cosmopolitan, exclusive [of] polar regions”. Although we have not found this species, we include it because of the Antarctic records mentioned above.

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