- Rotational symmetry of cell face outline 180 degrees, one end is a reflection of the other
- Raphe absent
In this section
Pennate diatom, elongate to needle-like in valve view, narrow rectangular in girdle view, valves identical, neither possessing a raphe (genus is araphid). Striae in parallel rows, separated along the central axis of the cell at a thickened sternum. Central area lacking striae (or with very faint striae) in the centre of the valve. Similar to Fragilaria but not forming ribbons of cells joined side to side. Cells are often attached to a surface by one end. Chloroplasts golden brown.