Cocconeis imperatrix A. Schmidt

Cocconeis imperatrix A. Schmidt (Figure 52)

Literature: (Al-Handal and Wulff 2008b, p. 426, figs. 46– 49; Manguin 1960, p. 305, figs. 358, 359; Riaux-Gobin and Romero 2003, p. 28, figs. 29–31, pl. 20, figs. 1–7, pl. 21, figs. 1–8).

Description: Length 38–65 µm, width 25–44 µm, striae (raphe valve) 3–4 in 10 µm.

Remarks: Scott and Thomas (2005) considered Cocconeis imperatrix as a synonym of Cocconeis fasciolata. Studying valve structure of both taxa in Potter Cove revealed noticeable variation between them so that it can be considered to be a separate entity (Al-Handal and Wulff 2008b).

Ecology and distribution: A marine species mostly reported from Antarctica. Common in Potter Cove.

Cocconeis matsii (Al-Handal, Riaux-Gobin et Wulff) Riaux-Gobin, Compère, Romero et Williams (Figure 53) Literature: (Al-Handal et al. 2010, p. 6, figs. 13–18, 25–34 as C. pinnata var. matsii).

Description: Length 10–13 µm, width 5–7 µm, striae (rapheless valve) 7–8 in 10 µm.

Remarks: This species was originally described from Potter Cove as C. pinnata var matsii but was considered a distinct species based on stria and areola density and structure (Riaux-Gobin et al. 2003). These authors, however, did not provide images for specimens but rather established a new combination.

Ecology and distribution: The species has not been reported outside its type locality in Potter Cove. Frequent in the material examined.