Gomphoneis Minuta Guide
Credit: Pat Kociolek
  1. Valves linear-clavate
  2. Margins convex but not tumid at the center
  3. Longitudinal lines half-way between the axial area and margin

Valves are linear-clavate, with convex margins. The margins do not become tumid at the center valve. Longitudinal lines are present, located about half-way between the axial area and margin.