Gomphonema Ventricosum Guide
Credit: Pat Kociolek
  1. Headpole broadly rounded
  2. Central area irregularly elliptic
  3. Valve broadest at center

Valves are lanceolate-clavate, broadest at the center with a broadly-rounded headpole and rounded footpole. Axial area is narrowly lanceolate forming a distinct, mostly irregularly elliptic central area, with a single stigma. The raphe is weakly undulate and lateral. Striae are punctate, radiate to parallel.