Grunow, in van Heurck (1880–85: pl. 45, fig. 37)
Lebour (1930: 193, fig. 152), Hendey (1964: 153)
Cells united to form flat ribbon-like colonies; cells and colonies rectangular in girdle view; apical axis 20–50 µm; transapical axis 4–5 µm. Valves narrowly linear to lanceolate, with subacute apices. Transapical striae fine, 22–24 in 10 µm, with a narrow hyaline axial area that is more pronounced in the centre. Areolae poroid, uniseriate. Apical pore field comprising short rows of areolae. Chloroplasts 2 narrow plates lying along the valve.
Plough I. and Ellis Fjord, near Davis Station, East Antarctica; Arctic and Norwegian coasts (Hendey, 1964).
Fragilaria is now regarded as an exclusively freshwater genus (see Williams & Round, 1987; Round et al., 1990). Thus, the Antarctic species listed below (Fragilaria islandica and its varieties) should probably be transferred to a different and possibly new genus. The apical field structure of pores (cf. slits) helps to distinguish Fragilaria from Synedropsis.