Diadesmis Pantropica Guide
Credit: Rex Lowe
  1. Valves linear
  2. Axial area narrow
  3. Central area round
  4. Raphe terminates in subapical nodule

Valves linear, slightly swollen in center and at the ends. The axial area narrow, with a round central area. The distal raphe terminates in a subapical nodule.