A Alpestre Guide Copy
Credit: Marina Potapova
  1. Valves linear-lanceolate with blunt, subrostrate ends
  2. Stria density high, 25-32 at valve center

Valves linear-lanceolate with subrostrate ends. The striae are parallel or very slightly radiate throughout both valves. The striae are very dense, up to 28-32 in 10 μm in the valve center. The axial area is narrow and only slightly widened in the valve center.