Labyrinthula diatomea n. sp.-A Labyrinthulid Associated with Marine Diatoms.

Labyrinthulomycetes are mostly fungus-like heterotrophic protists that absorb nutrients in an osmotrophic or phagotrophic manner. Members of order Labyrinthulida produce unique membrane-bound ectoplasmic networks for movement and feeding. Among the various types of labyrinthulids' food substrates, diatoms play an important role due to their ubiquitous distribution and abundant biomass. We isolated and cultivated new diatom consuming Labyrinthulida strains from shallow coastal marine sediments. We described Labyrinthula diatomea n. sp. that differs from all known labyrinthulids in both molecular and morphological features. We provided strain delimitation within the genus Labyrinthula based on ITS sequences via haplotype network construction and compared it with previous phylogenetic surveys.

Insight into picophytoplankton diversity of the subarctic White Sea-The first recording of Pedinophyceae in environmental DNA.

Operational taxonomic units 94%-95% similar to the known Pedinophyceae were found as a result of high-through sequencing of 18S rDNA V4 amplicons of environmental DNA from the summer picophytoplankton samples from the White Sea. Partial sequence of a ribosomal operon (the 5,298 bp includes partial 18S and 28S rDNA, complete 5.8S rDNA, ITS1, and ITS2 sequences) and a partial 2,112 bp chloroplast 23S rDNA sequence White Sea Pedinophyceae was amplified from metagenomic DNA by specific primers and sequenced. A new phylotype was designated as uncultured Pedinophyceae WS. On Chlorophyta phylogenetic trees the discovered phylotype occupies a basal position in the Marsupiomonadales clade. The synapomorphic base substitutions in rRNA hairpins confirm the relationship of Pedinophyceae WS to Marsupiomonadales and its difference from known genera of the order. The obtained results extend knowledge of picophytoplankton diversity in subarctic waters.