Diatoms of the Tributaries of the Svir River (Northwestern Russia)

Scanning electron microscopy has revealed 297 species and varieties of diatoms from 72 genera in the phytoperiphyton of tributaries of the Svir River, allowing us to obtain the first data on the species composition of Bacillariophyta in a number of tributaries of this watercourse (Yanega, Uslanka, Vazhinka, and Ivina) and expand it for the Oyat and Pasha. Among them, 15 species are new to the flora of Russia, and 59 forms from 19 genera are identified only up to the genus rank. The greatest species richness is recorded in the Yanega (118) and Ivina (148) tributaries, and the highest taxonomic richness is observed among the genera Nitzschia (25), Navicula (26), and Sellaphora (34). A similar number of species and varieties, 208 and 219, respectively, are detected in the left-bank and right-bank tributaries.