Fragilariopsis atlantica

Forms straight or slightly curved ribbon-shaped colonies. The cells are rectangular in girdle view and two chloroplasts in each cell are located along the girdle. The valves vary in outline according to cell length, larger ones are heteropolar and broadly linear while smaller cells tend to be broadly elliptical. The valves have an eccentric raphe with a central nodule, parallel interstriae and approximately an equal number of striae and fibulae.