Delicata Alpestris Guide
  1. Valves lanceolate
  2. Valves weakly dorsiventral
  3. Apices rounded to slightly protracted
  4. Axial area narrow

Valves are lanceolate and weakly dorsiventral. The apices are rounded and straight, but not dorsally recurved. The apices are rounded, or just slightly protracted. Valves are relatively wide, up to 7.5 ┬Ám. The axial and central areas are relatively narrow compared to the nominate variety.