Guide to Aulacoseira nygaardii
Credit: Marina Potapova
- Ratio of mantle height to valve diameter close to or < 1
- Rows of mantle areolae straight
- Valve face appears slightly convex
- Valve face with short radial striae at the periphery
- Spines originate from every second or third costa
Valves are 5-11 µm in diameter, with a mantle height of 4-19 µm. The ratio of the mantle height to valve diameter is close to 1. The valve face appears slightly convex in LM. Rows of pervalvar areolae are straight, 22-31 in 10 µm, with 30-42 areolae in 10 μm. The valve face is plain with short radial striae at the periphery. The spines are anchor-shaped, narrow, and originate from every second or third costa. The ringleiste is shallow and bell-shaped in cross-section.