Sellaphora smirnovii (Bacillariophyta, Sellaphoraceae), a new small-celled species from Lake Glubokoe, European Russia, together with transfer of Navicula pseudoventralis to the genus Sellaphora

A new small-celled species of the genus Sellaphora is described from Lake Glubokoe (Moscow Region, European Russia). For another taxon (also small-celled), a new combination in the same genus is proposed. Both species were studied with light and scanning electron microscopy. Analysis of valve morphology supported assignment to the genus Sellaphora. Sellaphora smirnovii sp. nov. is morphologically most similar to S. pulchra, however it differs from the latter in shape of valve apices, striation pattern and absence of a marginal fold. This taxon is also compared to other morphologically similar species. Navicula pseudoventralis is transferred to the genus Sellaphora as Sellaphora pseudoventralis comb. nov. Observations on S. pseudoventralis showed the presence of biseriate striae, similar to those found in S. seminulum and S. barae.