Various freshwater habitats, some slightly under brackish water influence, have been investigated from Vaigach Island, Mestnyi Island, Matveev Island and the Yugorsky Peninsula in north - west Siberia. In only 17 samples with obviously different water quality conditions 490 taxa or "Sippen" (i.e. morphodemes currently having no formal taxonomic rank), were found in this very small area of the Arctic. Evaluating the 490 taxa from taxonomical and phytogeographical points of view the following results have been obtained: - 345 taxa (ca. 70%) occur in Central Europe. They therefore represent either cosmopolitan or floral elements with a wider distribution in theholarctic kingdom - 159 taxa (ca. 30%) or taxonomically undefined but probable species were found in the studied region, but are not in the checklist (LANGE-BERTALOT 1996) of Central Europe - 42 (from 159) are described here as new species (subspecies) - 14 other ones are transferred from their original taxonomic position as nov. comb. or nov. stat. - 6 taxa are recognised as obvious new species but will formally be described by KRAMMER later in connection with a comprehensive revision of the genera CYMBELLA (sensu lato) and DIPLONEIS - 25 are very probably new species, they are marked in table 2 as "(?nov.) spec.weiterlesen