Twenty-six species of lichenicolous fungi and fifteen lichen species are newly reported from Kolguev Island. These include Arthonia pannariae, A. peltigerea, Cercidospora punctillata, C. stenotropae, Didymocyrtis consimilis, Endococcus propinquus, Geltingia associata, Knufia peltigerae, Muellerella hospitans, M. lichenicola, Niesslia cladoniicola, Peltigera extenuata, Polyblastia gothica, Polycoccum peltigerae, and Stigmidium peltideae first reported for the Nenets Autonomous Area of Russia. A species of Sphaerellothecium growing on Psoroma hypnorum is briefly described, illustrated, and compared with Sphaerellothecium pannariacearum. The distribution of the taxa listed is discussed. A total of 95 lichen species and 27 species of lichenicolous fungi are known for Kolguev Island to date.

The study presents information about 28 new findings of lichen species from the territory of the Pinezhsky Nature Reserve. Arthopyrenia cerasi, Verrucaria elaeomelaena, and V. murina are new for Northwest Russia, other 14 species are new for the Arkhangelsk Region, 11 — new for its mainland part. The findings were confirmed by specimens stored in the herbaria of Petrozavodsk State University (PZV) and the University of Helsinki (H).

The subfamily Teloschistoideae (Teloschistaceae) is mainly distributed in the Southern Hemisphere. Just a few its species were recorded in eastern Asia, and only Teloschistes flavicans has been known in the Russian Far East. Here, we report the discovery of Tayloriellina microphyllina in the Primorye Territory on the eastern shore of Lake Khanka where it is abundant in xerothermic conditions of Quercus mongolica–Pinus × funebris forest. This corticolous Teloschistoideae species has been previously known in the temperate regions from the southern Canada to central Mexico in North America. Our finding is confirmed by molecular data (nrITS). Morphology and chemistry as well as long distance dispersal vs. relict origin of the Far Eastern population of T. microphyllina are shortly discussed.

Several small-sized centric diatom Pantocsekiella species were identified during a study of phytoplankton in the Krasnoyarsk Reservoir (Krasnoyarsk Territory, Russia) with the use of scanning electron microscopy. One of them, Pantocsekiella minuscula, is new for Russia. This species was previously known only from Europe (North Macedonia) and North America (USA, Canada). Comparison of such features as the diameter of the valve and its central area and the density of marginal fultoportulae is revealed differences from the original description of this species. Variability in the presence/absence and location of granules on the valve face was also shown, all of which enabled us to amend the species description. The new data on the occurrence of P. minuscula allowed us to expand the species distribution.

Kurzia and Lepidozia are revised for the Russian Far East. The identification keys, morphological descriptions, line drawings and lifetime photographs of species, ecological conditions and the clarified distribution within the region are provided. In general, the Russian Far East seems too cold region for high taxonomic diversity of the members of the family; nevertheless, the taxonomic diversity of Lepidoziaceae here is higher than in other regions of Russia.

During field work in the Murmansk Region, a new species for the North-West of Russia Timmia norvegica was found, and the location of rare species, T. bavarica, has been confirmed since its first discovery in the region almost 90 years ago. Identification of the specimens was confirmed by molecular genetic data — nuclear ribosomal 26S region and trnL-F cpDNA. Four species of the genus Timmia are currently known in the Murmansk Region (T. austriaca, T. bavarica, T. comata, and T. norvegica). Their regional distribution is regarded.

An annotated list of liverworts collected in the basin of Unya River, a left tributary of Pechora River, is presented for the first time. The list includes 85 species, one subspecies and three varieties belonging to 50 genera, 32 families. For each taxon, the data on geographical locations, substrates, habitats, and structures associated with reproduction are provided. The new locations of rare liverworts of the Komi Republic (Frullania oakesiana, Reboulia hemisphaerica, Radula lindenbergiana) and of eight species protected in the Komi Republic (Arnellia fennica, Lophozia ascendens, Metzgeria furcata, Nardia breidleri, Odontoschisma elongatum, Porella platyphylla, Scapania apiculata, S. nemorea) are described. The studied forest habitats and rock outcrops are characterized by the highest taxonomic diversity: 49 and 37 species, respectively. The spruce-fir forests dominate in number of species (31) among the forest formations. Revealed liverworts prefer to grow on rocky substrates and disturbed soil. About 45% of the identified species form reproductive structures.

Two rare species, Chlamydomonas proteus and Xerochlorella minuta, were isolated from snow samples in sites of “algal blooms” in the Subpolar Urals and Western Sayan. As a result of the study of strains using light microscopy and molecular genetic methods (the nucleotide sequence analysis of 18S and ITS2 rDNA), new data on morphology, ecology and distribution of these species were obtained. The data expanded the species’ diagnostic characteristics. Chlamydomonas proteus is the first record on Russian territory supported by molecular studies.

A new species, Mallomonas doanii sp. nov, is described from Vietnam based on the morphology of silica scales and bristles observed using transmission electron microscopy (TEM). Scales of M. doanii were found in six localities in four provinces of Vietnam. The species belongs to the section Ouradiotae. The scales of the new species are small in size and broadly oval in shape, without a dome, with scattered papillae on the shield and one or two rows of papillae on the anterior flange, a V-rib with a broadly oval base, shifted to the center and continuous with the anterior submarginal ribs. The bristles of M. doanii have a wide and flattened base and a bifurcated distal end with a wide, rounded middle part. A comparison with species similar in morphological structure (M. ouradion, M. cronbergiae, M. acidophila and M. korshikovii) and data on the distribution and ecological conditions of the new species are provided.

Based on SEM examination of the phytobenthos samples collected in the tributaries of the Svir River (Leningrad Region), a diatom species Fragilaria pararumpens, rare for Russia, was found. As no previous detailed studies of this species using SEM were performed, we provide a description of its morphology, as well as a comparison of our data with the results of previous studies. Also we provide a comparison of specimens of F. pararumpens from the Svir River with similar Fragilaria taxa.