Nitzschia sigma (Kützing) W. Smith (Figure 100)

Literature: (Hendey 1964, p. 281, 282, pl. 42, fig. 1; Witkowski et al. 2000, p. 404, pl. 206, figs. 1–10).

Description: Length 82–105 µm, width 14–18 µm, striae 32– 34 in 10 µm, fibulae 5–6 in 10 µm.

Remarks: A species with a wide variation in valve outline, striae and fibulae density. The observed specimens bear coarser and less dense fibulae, Krammer and Lange-Bertalot (1988) reported 7–12 fibula in 10 µm while Hendey (1964) reported eight in 10 µm.

Ecology and distribution: A widely distributed marine and brackish-water species. reported from the Arctic as sea-ice diatoms (Wiktor et al. 1998). Not found previously in Potter Cove. Rare in the material examined.