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Guide to Pinnularia spinifera

Potapova, Kersey and Aycock 2023

Pinnularia spinifera guide
  1. Valves linear, with straight, slightly concave, or triundulate margins
  2. Apices broadly rounded, slightly off-set
  3. Axial area 1/3–1/5 valve width
  4. Longitudinal line crosses striae mid-way
  5. Valve/mantle junction with short spines

Valves are linear, with straight or very slightly concave or triundulate margins. The apices are broadly rounded, slightly off-set. A longitudinal line crosses the striae approximately mid-way between the axial area and margin. Short spines are located on the valve face–mantle junction, on both sides of the valve, randomly placed on some virgae, with 2–5 virgae in between.