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Guide to Aulacoseira valida

(Grunow in Van Heurck) Krammer 1991

Aulacoseira Valida Guide
Credit: Marina Potapova, Jonathan English
  1. Ratio of mantle height to valve diameter 0.8-1.5
  2. Rows of mantle areolae curve to the right
  3. Mantle areolae become smaller from valve face to collum
  4. Spines large, spatula-shaped
  5. Spines originate from two pervalvar costae

Valves have thick walls and are 10-16 µm in diameter, with a mantle height of 7-16 µm. The ratio of the mantle height to valve diameter is 0.8-1.5. The valve face is slightly convex, covered by small areolae. Pervalvar rows of areolae are strongly curved to the right (dextrorse), 12-17 in 10 µm. There are 11-17 areolae in 10 µm along the pervalvar row. The mantle areolae are larger at the valve face and gradually become smaller toward the collum. The spines are large, spatula-shaped and originate from two pervalvar costae.