The ultrastructure of Gomphonema gautieri (Van Heurck) Lange-Bert. et Metzeltin was studied based on a small population from a small Swedish, slightly acid, eutrophic river. The observations were compared with the holotype slide of G. augur var. gautieri Van Heurck, as the species was originally described in 1885. The valves are characterized in having a typical clavate outline with the largest width near the broadly rounded headpole. The species can be separated from G. augur Ehrenb. by its larger valve dimensions, the presence of broad shoulders on the headpole and the lower number of areolae per stria. Based on these differences, a separation of both taxa is justified.