(Ehrenb.) Cleve (1904: 216)
Coscinodiscus labyrinthus Roper (1858: 21, pl. 3, fig. 2)See VanLandingham (1968: 894; 1978: 3994) for further details of synonymy.
Coscinodiscus eccentricus Ehrenb. (Ehrenberg, 1841: 146)
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)
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.
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).
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.