The thesis represents complete original investigation devoted complex study of algae and cyanobacteria from biological soil crusts of some ecosystems of Europe (maritime sand dunes, forests and hypersaline tailing piles of Ukraine and Germany), four vegetation and climatic zones of South America (Chile) and tundra ecosystems of polar regions (Svalbard and Antarctica islands). The investigation was focused on biodiversity, phylogeny and taxonomy of some groups as well as ecological peculiarities and distribution. The main attention was paid to the phylogeny and taxonomy of Klebsormidiophyceae (Streptophyta) as dominating representatives in biocrusts of temperate climatic zone. The thesis was completed using classical and modern molecular-phylogenetic methods (integrative approach) applied for identification of algae and cyanobacteria.
Totally, 313 species of algae and cyanobacteria were found in biocrusts of some regions and ecosystems (Chlorophyta – 160 species, Streptophyta – 30, Ochrophyta – 48 (Xanthophyceae – 26, Eustigmatophyceae – 4 and Bacillariophyceae – 18), Cyanobacteria – 75). Predominance of green algae together with considerable role of cyanobacteria was indicated in biocrusts of sand dunes of Baltic and Black sea coasts; cyanobacteria was the most abandoned in biocrusts of coastal ecosystems of the Sea of Azov; green algae were leading group together with almost complete absence of cyanobacteria in biocrusts of German forests; Ulvophyceae (Chlorophyta) tolerant to saline environment were abandoned in artificial hypersaline ecosystems of Germany; unique taxa of Klebsormidium were dominating in biocrusts of semi-deserts and forests of Chile; Xanthophyceae were numerous and abandoned in polar regions.
It was confirmed based on an integrative approach that Interfilum is a representative of Klebsormidiophyceae (Streptophyta); new genus Streptosarcina was described as well. Thus, general phylogeny of the class which includes algae dominating in the biocrusts of temperate zone was determined. Now the class contains 5 genera: Klebsormidium, Interfilum, Hormidiella, Streptosarcina and Entransia, among them taxa with filamentous as well as packet-like and branched thalli are present. The central phylogenetic lineage of the class was divided on 7 main superclades. The reference strains were proposed for 8 Klebsormidium species; 7 new species and 2 varieties of Klebsormidium from phylogenetic clade G isolated from biocrusts of Europe, Africa, North and South America were described. Prevalent development of superclade G Klebsormidium in terrestrial ecosystems of South hemisphere forces to revision of the genus concept as alga cosmopolitan in distribution. The study of the cell division of Klebsormidiophyceae showed that vegetative cells divide by mechanism close to sporulation. Formation of different morphotypes depends on shape of cells, texture of cell walls, mechanical interactions between cells and the influence of environmental conditions. New phylogenetic lineage among Streptophyta (genus Streptofilum) with unique cell coverage (submicroscopic organic scales of specific piliform shape) was discovered.
Investigation of the strains of rare and interesting algae and cyanobacteria revealed to describe 7 new species (from genera Parietochloris, Tetradesmus, Aliterella, Oculatella, Cyanocohniella), provide emendation and epitypification of 5 species (Crinalium, Actinochloris, Eremochloris, Xerochlorella) and propose 4 taxonomical combinations (Timaviella, Heterochlamydomonas, Xerochlorella).
Investigation of the biocrust biodiversity using molecular phylogenetic methods showed wide, possibly cosmopolitan, distribution within both hemispheres some species of green algae: Bracteacoccus, Watanabea, Elliptochloris, Edaphochlorella, Xerochlorella, Pleurastrosarcina, Interfilum. While distribution of some species of clade G Klebsormidium is realized mostly within South hemisphere.
Totally 2 new genera, 18 species and 2 varieties of algae and cyanobacteria were described, emendation and epitypification were provided for 16 species and 6 taxonomical combinations were proposed.
