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Guide to Asterionella formosa

Hassall 1850

Asterionella Formosa Guide
Credit: Sarah Spaulding
  1. Valves heteropolar
  2. Sternum narrow
  3. Rimoportula present
  4. Marginal spines present
  5. Apical porefield present

Valves are elongate, narrow, with capitate apices. Valves are distinctly heteropolar. The central sternum is very narrow and may not be distinguishable. The striae are slightly off-set from one another at the central sternum. Irregular marginal spines may, or may not, be present. A single rimoportula is present at the footpole. A small apical porefield is present.