Gomphonema coronatum

Valves are acuminate-apiculate. A small, acute to blunt protracted headpole is present, while the footpole is rounded. The broadest portion of the valve is near the headpole and/or the central portion of the valve. This feature appears to be population-dependent. Initial valves lack the acuminate structure and appear rounded at the poles and tumid in the middle. The axial area is straight, forming a transverse central area. The striae about the central area are more separate from one another. On one side of the central area there is a shortened stria, on the opposite side the central stria terminates at the stigma. The raphe is lateral and undulate. The punctate striae are radiate about the center, becoming parallel toward the poles returning to radiate at the headpole and strongly radiate towards the footpole.