3. Cocconeis clandestina A. Schmidt (Figs 23, 24)

Basionym: Schmidt et al. 1894a, pl. 192, figs 28, 29.

References: Hustedt 1933, p. 331, fig. 784; Witkowski et al. 2000, p. 103, pl. 41, figs 20–25. Description: Valves elliptical to nearly circular, 18–29 μm long, 14–18 μm wide. SV: sternum narrow and linear. Transapical striae biseriate and radiate towards the apices, 5–6 in 10 μm, with 10–12 areolae in 10 μm of stria. No RV observed.

Remarks: This taxon is widespread along the coast of northern Europe (Hustedt 1933, Witkowski et al. 2000) and common in the Baltic Sea (Witkowski et al. 2000). In the Seogwipo coast, very rare from small rock pools; it is herein newly described for South Korea.