Ehrenb. (Ehrenberg, 1841: 148, pl. 3, fig. 1a–c)
Watanabe (1982), Boden (1985), Hasle & Syvertsen (1997: 107, fig. 6d, e; pl. 18)
Cells solitary, discoid. Valves flat, circular, 30–180 µm diameter. Areolation radial, sometimes indistinctly decussate; areolae 2–9 in 10 µm. Small labiate processes at the points of origin of incomplete striae. Hyaline lines absent. One marginal ring of processes, including 2 slightly larger processes c. 135° apart, these visible by LM as indentations of the valve margin. Smaller processes scarcely visible.
Ross Sea (Watanabe, 1982); Prydz Bay, SIBEX (Boden, 1985); oceanic species with world-wide distribution in temperate seas (Hendey, 1937).
Coscinodiscus radiatus has only occasionally been reported from the Antarctic.