Nupela Frezelii Guide
Credit: Marina Potapova
  1. Valves lanceolate to linear-elliptic
  2. Raphe absent on one valve
  3. Striae 29-33 in 10 μm
  4. Central area usually asymmetric

Valves are lanceolate to linear-elliptic, with rounded to slightly drawn-out ends. Striae are radiate, 29-33 in 10 μm. Axial area is rhombic-lanceolate. Central area is asymmetric, reaching valve margin on one side of the valve. The raphe is absent on one of the valves.