Sellaphora Alastos Guide
Credit: Loren Bahls
  1. Valves broadly linear
  2. Apices obtusely rounded
  3. Central striae widely spaced
  4. Conopea narrow
  5. Central area rectangular

Sellaphora alastos has large, broadly linear valves with obtusely rounded apices. The central striae are more widely spaced than more distal striae. The narrow axial and rectangular central areas are bordered by narrow conopea.