Gomphonema Elongatum Guide
Credit: Pat Kociolek
  1. Headpole weakly expaned with protracted apex
  2. Central valve tumid
  3. Valves acuminate-apiculate
  4. 40-105 ┬Ám long

Valves acuminate-apiculate, with the headpole weakly expanded and protracted. The central valve is tumid. Both of the central striae are shortened, and on one side is positioned a single, isolated stigma.