This scanning electron microscopy study investigates the morphology of two species of the diatom genus Surirella (S. barrowcliffia, S. didyma) from phytobenthos of the Kilmez River (Udmurtia). Some analyzed quantitative characters (valve length and width, number of costae in 10 μm) manifested greater variability in comparison with the literature data, which allowed us to refine their diagnoses. Analysis of the literature showed that the discovery of S. barrowcliffia in the Kilmez River is the first for the flora of Russia.
Genkal et al. (Sat,) studied this question.