Achnanthes lanceolata f. minor Schulz-Danzig Achnanthes lanceolata f. minor Schulz-Danzig1is basionym for Planothidium frequentissimum var. minus (Schulz-Danzig) Lange-Bert. in Iconogr. Diatomol. 6: 276. 199921. Author abbreviation not checked., 2. (Basionym:) fig. 42