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Guide to Achnanthidium druartii

Rimet and Couté in Rimet et al. 2010

Achnanthidium Druarti Guide
Credit: Marina Potapova
  1. Valves linear-lanceolate to lanceolate with subrostrate ends
  2. Striae very slightly radiate on both valves
  3. Stria density differs markedly between center valve and ends

Valves are linear-lanceolate to lanceolate with subrostrate ends, 4.1-5.3 μm wide. The raphe valve has a linear axial area, which widens slightly in the middle portion of the valve. The rapheless valve has a narrow, linear axial area widening slightly in the middle. Striae are very slightly radiate throughout both valves, 15-20 in 10 µm in the center valve, 40-50 in 10 µm at the ends of the raphe valve, 25-35 in 10 µm at the ends of the rapheless valve. Very short marginal striae are are often present in the middle portion of the valve.