Diatoms are highly diverse and widely spread aquatic photosynthetic protists. Studies of regional patterns of diatom diversity are substantial for understanding taxonomy and biogeography of diatoms, as well as for ecological perspectives and applied purposes. DNA barcoding is a modern approach, which can resolve many problems of diatoms identification and can provide valuable information about their diversity in different ecosystems. However, only few studies focused on diatom assemblages of brackish rivers and none of them applied the genetic tools. Herein, we analyzed taxonomic composition and abundance of diatom assemblages in the brackish mixohaline Bolshaya Samoroda River flowing into the Elton Lake (Volgograd region, Russia) using light microscopy and high-throughput sequencing of the V4 region of the 18S rDNA gene amplicons. In total, light microscopy of the samples taken in 2011-2014 and 2018 allowed to distinguish 39 diatom genera, represented by 76 species and infraspecies taxa. Twenty three species of diatoms were recorded in the river for the first time. Next-generation sequencing revealed a larger number of diatom taxa (26 genera and 47 OTUs in two samples vs. 20 genera and 37 species estimated by light microscopy). As a result, sequences of Haslea, Fistulifera, Gedaniella were recorded in the river for the first time. Significant differences in the data obtained with molecular and light microscopy approaches are discussed. Some V4 18S rDNA sequences were characterized by a low similarity with homologues from the reference database. We revealed high spatial-temporal heterogeneity of the diatom assemblages, occurrence of freshwater species together with brackish and marine ones, and predominance of benthic and plankto-benthic species. Thus, investigations of diatoms in brackish rivers based on both morphological and molecular approaches provide a good chance of improving an understanding of diversity, ecology and biogeography of Bacillariophyta.

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For the first time, communities of autotrophic microorganisms in outfalls of seven meso and hypersaline rivers located in the Eltonsky Natural Park were studied. As a result, 132 species, variants, and forms from six divisions were found. The specific composition of taxa in every watercourse was noted. A cor relation between species diversity and salinity levels was not revealed.

In this study we observed 17 additional morphotypes of chrysophycean stomatocysts from the shallow lake Zhurmankol which is located in a protected zone of South Urals steppes (Russia). Including our new records, the number of known chrysophycean stomatocysts from the Lake Zhurmankol increased to 32 morphotypes. Three morphotypes are described as new to science. Their similarity and difference from previously described morphotypes are discussed. While the biological affinity of two new morphotypes remains unknown, the third stomatocyst was produced by a heterotrophic chrysophyte species, Paraphysomonas bandaiensis. Critical analysis of the published micrographs of P. bandaiensis siliceous scales from Russia revealed that they belong to another, yet undescribed, taxon (or taxa). So, our report on P. bandaiensis is the first confirmed record of this species in Russia.

First records of Xanthophyceae for the Vologda and Sverdlovsk regions, and Moscow, Characeae for the Vologda, Orenburg, Tver regions and the Crimea Peninsula, diatoms for the Orenburg Region, aphyllophoroid fungi for the Novgorod and Tyumen regions, agaricoid fungi for the Novosibirsk and Vologda regions, and for the Republic of Altai, lichens for the Arkhangelsk and Murmansk regions, Altai Territory, the Republic of Buryatia and Primorye Territory, mosses for the Kabardino-Balkarian Republic, the Republic of Buryatia, Novaya Zemlya Archipelago and the Kuril Islands, liverwort for the Kurgan Region are presented. The data on their localities, habitats, distribution are provided. The specimens are kept in the herbaria of the Altai State University (ALTB), of the Papanin Institute for Biology of Inland Waters of the Russian Academy of Sciences (IBIW), of the Institute of Problems of Industrial Ecology of the North KSC RAS (INEP), of the Polar-alpine botanical garden-institute KSC RAS (KPABG), of the Komarov Botanical Institute RAS (LE), of the Mire Research Group of the Papanin Institute for Biology of Inland Waters RAS (MIRE), the Central Siberian botanical garden SB RAS (NSK), of the Natural History Museum in Oslo, Norway (O), of the Petrozavodsk State University (PZV), of the Museum of the Institute of Plant and Animal Ecology (SVER), of the Tobolsk complex scientific station of the UB RAS (TOB), of the Institute of General and Experimental Biology SB RAS (UUH) and algological collection in the laboratory of the Algology Group of the Institute for Cellular and Intracellular Symbiosis of the UB RAS.