Gomphonema Duplipunctatum Guide
  1. Valves rhombic-lanceolate
  2. Apices narrowly rounded
  3. Two isolated stigmoids
  4. Valves up to 35 ┬Ám in length

Valves are small and rhombic-lanceolate. The apices are narrowly rounded and not protracted. Two isolated stigmoids are present on one side of the central area at the ends of shortened striae.