Planothidium Harveyi Guide
Credit: Marina Potapova
  1. Valves elliptic-lanceolate, with rostrate apices
  2. Central area large, asymmetric on both valves
  3. Striae 22-25 in 10 μm
  4. Terminal raphe fissures curved to opposite sides

Valves are lanceolate with rostrate apices. Both valves have narrow linear axial areas and large asymmetric central areas, often reaching one or both valve margins. The raphe is straight and the short terminal fissures curve to opposite sides.