Abstract: The phylum Cyanophyta (Cyanobacteria; recently renamed to Cyanobacteriota) consists of the classes Cyanophyceae and Vampirovibriophyceae; in terms of the nomenclature of prokaryotes,
they are Oxyphotobacteria and Vampirovibrionia. These taxa correspondingly represent photosynthetic and non-photosynthetic cyanobacteria. The members of former class generally rely on the Mn4CaO5-cluster of PSII (the unique photoenzyme converting molecular water into triplet dioxygen). Global oxygenic photosynthesis is mediated by white light resonating chlorophyll a, which has a long wavelength (ca. 700 nm) absorbance peak. At the same time, a minor group of cyanobacterial strains assimilates, either adaptively or permanently, far-red (> 700 nm) light quanta absorbed by “red-shifted” chlorophylls d and f. Improving the coverage of strains capable to produce such chlorophylls not only helps better evaluate the environmental diversity of cyanobacteria, and enrich their taxonomy; it also provides potential models for in-depth research on the topology and role(s) of red-shifted chlorophylls in oxygenic photosynthetic apparatus. Resulting from present study, in addition to already known 43 cultured strains adaptively expressing chlorophylls d and f under far-red light, 12 new strains were obtained from different loci and environments of Europe and Antarctica. Phylogenomic analysis of these strains allowed us to classify them to the orders Nostocales, Coleofasciculales, Nodosilineales/Oculatellales (provisionally), and Leptolyngbyales. Except furnishing taxonomic descriptions of all these strains, a polyphasic approach applied to some of them allowed us to propose, under the International Code of Nomenclature for algae, fungi, and plants (ICN) provisions, two new species Kovacikia brocelensis sp. nov. and Leptolyngbya fluviusnevae sp. nov. During the course of our work we encountered taxonomic difficulties with “Leptolyngbya-like” strains that forced us to delve into problematic rearrangement of this phylogenetically
heterogeneous group into monophyletic taxa.
