The diatom Nitzschia acidoclinata is a widespread eurybiontic alga. There is little information on its life cycle properties and cardinal points. To fill this gap, we analyzed six N. acidoclinata clones from a range of habitats in Asiatic Russia regarding their genetic diversity, morphology, morphometry, geography, and ecology. A comparison of 15 N. acidoclinata rbcL sequences sampled across its relatively wide distribution area and contrasting habitats revealed no distinct genotypes in the species. We demonstrated that the valve morphology, their length, and the sexual activity of the investigated clones varied depending on the phase of their life cycle. In this species, abrupt size reduction was observed. It was revealed that N. acidoclinata reproduced by pedogamy, and its auxosporulation was season-dependent and observed in spring and autumn only. The mating activity in our clones was detected only when the cell size was reduced to 9–22 µm in length. The available data on sexual reproduction in the genus Nitzschia suggest that neither clades nor subclades comprise pedogamous or anisogamous taxa at the same time. However, isogamy could occur in the same clade with either pedogamy or anisogamy. These data provide a fundamental basis for the development of N. acidoclinata mass cultivation and long-term maintenance in culture technologies.

The diatom Nitzschia palea is a widespread eurybiontic alga that inhabits the benthos of freshwater ponds and watercourses, soils and caves. This species has a potential for biotechnological applications; therefore, knowledge on its biology is important. Although the species has been studied quite extensively, comprehensive information on its life cycle properties, including cardinal points, is still lacking. In this contribution, based on our own observations and literature data, we supplement and summarize the available information on the species’ life cycle, including data on morphology, morphometry, teratological structures of valves and cardinal points. We also revealed a uniparental inheritance of the mitochondrial gene cox1 in N. palea. The data obtained will be important for phylogeography studies of the species, as well as provide fundamental basis for the technology of long-term maintenance of N. palea in culture.

A new coccoid cyanobacterium Aliterella vladivostokensis sp. nov. was described from an urban aerophytic habitat in a temperate monsoon climate (Vladivostok, Russia) using a polyphasic approach. Phylogenetic analyses based on the 16S rRNA gene sequences confirmed that our isolate was a member of the Aliterella genus clade. Aliterella species are hardly distinguishable from each other morphologically and were described from highly contrasting natural and artificial environments with only a few records from several continents. Despite high similarity of morphometric data for A. vladivostokensis and A. antarctica cells and a compensatory base change in the D1–D1′ helix shared by these species; high percent of dissimilarity (11.6±1.3) between their 16S–23S internal transcribed spacer sequences with at least 5 autapomorphic mutations in the D1–D1′ and Box-B helices, and distinct folding patterns of the Box-B helix allowed us to erect a new species.

Diatoms inhabit different aquatic and non-aquatic environments, including soils. The naviculoid genus Luticola is widespread in various habitats and accounts for 264 species that are only based on morphological and morphometric characteristics. These parameters can greatly vary during the life cycle, making the species very similar to each other and complicating their unambiguous identification. During a study on soil algal diversity in the Russian Far East (Jewish Autonomous Region), we isolated a strain of naviculoid diatom and examined it using an integrative approach (phylogenetic, morphological, ultrastructural data, and life cycle). Phylogenetic analyses, based on chloroplast rbcL gene data, showed affinity of the new strain with the genus Luticola. Our alga shares morphological features typical of the genus members but differs from them by having valves with a larger width and hook-shaped external proximal raphe ends deflected to the side opposite the stigma. It was revealed that the strain reproduces via two types of sexual reproduction—isogamy and cis-anisogamy. Based on these phenotypic traits, we described the new isolate as Luticola tenera sp. nov.

Volcanic activity has a significant influence on the development of terrestrial ecosystems, including the Kamchatka Peninsula. We aimed to study the terrestrial algoflora of the Mutnovsky and Gorely volcanoes based on the use of clonal cultures of algae and cyanobacteria, and phenotypic and molecular genetic analyses. A total of 48 taxa were identified: 9 cyanobacteria, 32 Chlorophyta (11 Chlorophyceae, 21 Trebouxiophyceae), 3 Ochrophyta, and 4 Charophyta. In soils of the Mutnovsky volcano, 30 taxa were found, and in soils of the Gorely volcano, 24 were observed. In the studied area, small coccoid or mucilage-producing algae, which belong to cosmopolitan species, were identified, including representatives of the genera Bracteacoccus, Chlorococcum, Coccomyxa, Coelastrella, Klebsormidium, Neocystis, and Vischeria. Certain taxa were detected for the first time in the studied region, including Bracteacoccus bullatus, Chlorococcum hypnosporum, Chlorococcum lobatum, Coccomyxa subellipsoidea, Klebsormidium nitens, Leptosira obovata, Lobosphaera incisa, Parietochloris pseudoalveolaris, Stenomitos tremulus, and Vischeria magna. Our analysis of the algal communities at different altitudes reveals expansion in species richness with increasing distance from the tops of the volcanoes. The obtained data allowed us to estimate the real biodiversity of terrestrial algae and cyanobacteria of Kamchatkan volcanic soils, as well as the ecologies of these microorganisms.