Aulacoseira Nivalis Guide
Credit: Jonathan English, Marina Potapova
  1. Ratio of mantle height to valve diameter < 1
  2. Rows of mantle areolae straight, inclined to the right
  3. Valve face flat
  4. Valve face with large areolae
  5. Spines located at the end of each pervalvar costa

Valves are 6-18 µm in diameter, mantle height is 2.5-6 µm. The ratio of the mantle height to valve diameter is less than 1. Rows of pervalvar areolae are straight, slightly inclined to the right, 12-16 in 10 µm, with 2-6 elongated areolae in each row. The valve face is flat, covered by large areolae. The spines originate from every costa. The ringleiste is very shallow. One rimoportula is present on the mantle, near the ringleiste.