Abstract
Environmental sampling in Poland and the United States and phylogenetic analyses based on 567 sequences of four genes (155 sequences of nuclear SSU rDNA, 139 of nuclear LSU rDNA, 135 of plastid-encoded SSU rDNA, and 138 of plastid-encoded LSU rDNA) resulted in description of the new genus Flexiglena, which has been erected by accommodating Euglena variabilis, and enriching the Discoplastis and Euglenaformis genera with five new species. Four of them have joined the Discoplastis genus, currently consisting of six representatives: D. adunca, D. angusta (=Euglena angusta), D. constricta (=Lepocinclis constricta), D. excavata (=E. excavata), D. gasterosteus (=E. gasterosteus), and D. spathirhyncha. One of them has enriched the Euglenaformis genus, currently represented by two species: Euf. chlorophoenicea (= E. chlorophoenicea) and Euf. proxima. For most studied species, the diagnostic descriptions have been emended and epitypes were designated. Furthermore, the emending of Discoplastis and Euglenaformis diagnoses was performed.