N Geronomensis Guide
Credit: Marina Potapova
  1. Valves linear-lanceolate
  2. Central area asymmetrical
  3. Proximal raphe ends deflected
  4. Striae radiate at the central valve

Valves are linear-lanceolate. The central area is strongly asymmetrical; wedge-shaped on the primary side and semi-lunate on the secondary side. Striae are radiate in the central part of the valve and parallel near the apices. Striae are 9-10 in 10 µm. Proximal raphe ends are deflected toward the primary side.