Diatoms of North AmericaDiatoms of North America
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Guide to Surirella pinnata

W.Smith 1853

Surirella Pinnata Guide
  1. Keel low, alar wings absent
  2. Valves slightly heteropolar
  3. Valve margins nearly straight
  4. Each 3rd or 4th costa raised
  5. Fibulae extend from the mantle nearly to midline

The valves are slightly heteropolar, with rounded apices. Valve margins are nearly straight, tapering toward the narrower pole (footpole). Fibulae extend from the mantle nearly to the midline, with a density of 9-12 in 10 μm. The costae are dense at 25-32 in 10 µm. Every 3rd or 4th costa is raised.