Taxon-rich phylogeny and taxonomy of the genus Phacus (Euglenida) based on morphological and molecular data

Biodiversity of autotrophic euglenids based on the group specific DNA metabarcoding approach

This study reports a comprehensive analysis of photoautotrophic euglenids' distribution and biodiversity in 16 small water bodies of various types (including fish ponds, field ponds, rural ponds and park ponds) located in three regions of Poland: Masovia, Masuria and Pomerania during a period of three years. By employing a euglenid specific barcode marker and a curated database of V2 18S rDNA sequences it was possible to identify 97.7 % of euglenid reads at species level. A total of 152 species classified in 13 genera were identified. The number of euglenid species found in one pond varied from 40 to 102. The most common species were Euglena agilis and Euglenaria caudata, found in every analysed waterbody. The highest number of observed species belonged to Trachelomonas and Phacus. Certain species exhibited a tendency to coexist, suggesting the presence of distinct species assemblages. Among them, the most distinctive cluster was associated with water bodies located in the Masuria region, characterized also by the greatest species richness, including many very rare species: Euglenaformis chlorophoenicea, Lepocinclis autumnalis, L. marssonii, Trachelomonas eurystoma, T. manschurica, T. mucosa, T. zuberi, T. zuberi var. nepos.

Discovery of a new photosynthetic euglenoid in Poland: Euglena mazurica sp. nov. (Euglenales, Euglenaceae)

Herein we describe a new photosynthetic euglenoid species found in Poland - Euglena mazurica. A large population exists in a small, eutrophic body of water located in a pasture near Mikołajki town inside the Masurian Landscape Park (covering a part of the Masurian Lake District in Poland). The unique cell shape (corkscrew-like) discerns it well from other previously described euglenoid species with metabolic cells. The new species possesses two plate-like chloroplasts each with a pyrenoid accompanied by two paramylon caps placed on either side of it (diplopyrenoids). On the phylogenetic tree, the new species is situated within the Euglena clade. Though it is a sister branch to three clades - one representing the similar Euglena agilis, characterized by its fusiform cells and two chloroplasts with diplopyrenoids, the two species are clearly morphologically and molecularly distinct.

Description of Flexiglena gen. nov. and new members of Discoplastis and Euglenaformis (Euglenida)

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.

Evaluation of V2 18S rDNA barcode marker and assessment of sample collection and DNA extraction methods for metabarcoding of autotrophic euglenids

Even though the interest in metabarcoding in environmental studies is growing, euglenids are still underrepresented in both sea and freshwater bodies researches. The reason for this situation could be the unsuitability of universal eukaryotic DNA barcodes and primers as well as the lack of a verified protocol, suitable to assess euglenid diversity. In this study, using specific primers for the V2 hypervariable region of 18S rDNA for metabarcoding resulted in obtaining a high fraction (85%) of euglenid reads and species‐level identification of almost 90% of them. Fifty species were detected by the metabarcoding method, including almost all species observed using a light microscope. We investigated three biomass harvesting methods (filtering, centrifugation and scraping the side of a collection vessel) and determined that centrifugation and filtration outperformed scrapes, but the choice between them is not crucial for the reliability of the analysis. In addition, eight DNA extraction methods were evaluated. We compared five commercially available DNA isolation kits, two CTAB‐based protocols and a chelating resin. For this purpose, the efficiency of extraction, quality of obtained DNA, preparation time and generated costs were taken into consideration. After examination of the aforementioned criteria, we chose the GeneMATRIX Soil DNA Purification Kit as the most suitable for DNA isolation.