Planothidium Abbreviatum Guide
Credit: Marina Potapova
  1. Valves elliptic-lanceolate with subrostrate apices
  2. Raphe valve with transversely rectangular to elliptic central area
  3. Rapheless valve with rhomboid axial area
  4. Rapheless valve with cavum
  5. Striae radiate

Valves are elliptic-lanceolate with subrostrate apices. The raphe valve has a transversely rectangular to elliptic central area. The rapheless valve has a rhomboid axial area and asymmetric central area with a cavum on the internal valve surface. The striae are radiate.