Pinnularia Streptoraphe Guide
  1. Valves linear
  2. Apices broad, rounded
  3. Central area asymmetric
  4. Raphe undulate
  5. Striae coarse

Valves are linear with parallel margins. The apices are broad and rounded. The central area is asymmetric. The raphe is complex and undulate. Striae are coarse (5 in 10 µm) and mostly parallel throughout.