The article presents new data on ascomycetes (Pezizomycotina) of the Sakhalin Region, including additional information on the species diversity of Sakhalin Island and the adjacent Moneron Island, as well as the islands of the Greater Kuril Ridge (Antsiferov, Iturup, Matua islands) and the Lesser Kuril Ridge (Kunashir and Shikotan islands). Annotated list includes 29 species with data on their habitats and substrates. Some species (Botryosphaeria dothidea, Bulgaria inquinans, Donadinia nigrella, Encoelia furfuracea, Galiella amurensis, Pachycudonia monticola, Perrotia gallica, Pseudoplectania melaena, Sarea difformis, S. resinae, Verpa conica) are published for the first time for the Sakhalin Region. Ascomes of Cistella albidolutea and Parachnopeziza triseptata found in Russia for the first time. Samples of fungi are stored in VLA.

The variability of the composition of secondary metabolites in Hypogymnia vittata and H. subduplicata was studied. Three chemotypes have been identified for H. vittata differing in the composition of the orcinol depsidones of the medulla: I — contains vittatolic acid, 3-hydroxyphysodic and physodic acids; II — contains 3-hydroxyphysodic and physodic acids; III — contains physodic and 2′-O-methylphysodic acids. The chemotype III was shown to be associated with a specific substrate. The composition of secondary metabolites was determined for the first time for H. subduplicata. The species is represented by two chemotypes: I — contains vittatolic acid, 3-hydroxyphysodic and physodic acids; II — contains 3-hydroxyphysodic, physodic acids and lividic acid. The latter was not previously reported for the genus Hypogymnia.

Mediterranean-Atlantic species Waynea adscendens is reported for the first time for Russia from the Krasnodar Territory. This species grows on the trunk of Pistacia atlantica in the sub-Mediterranean xerothermic undisturbed pistacio-juniper community in the Utrish Nature Reserve. Description and key to the Russian species of the genus Waynea (W. adscendens, W. giraltiae, W. hirsuta, W. stoechadiana) are presented. Information on the ecology and distribution of all these species is provided.

The annotated list of 88 species of lichens and three species of lichenicolous fungi, found by the author in the vicinity of Zhelaniya Cape, the northeastern part of the Novaya Zemlya Archipelago, is presented. Altogether 16 species are new for the archipelago, including Pertusaria subobducens new for Europe. The conditions for the growth of lichens and geographical features of the lichen flora are discussed.

Navicula suturata sp. nov. is described on the base of light and scanning electron microscopy observations of a sample, collected from the Niger River at Bamako, Mali. The species resembles four previously described taxa. Navicula suturata is morphologically most similar to N. nielsfogedii, but differs from it by larger valve dimensions and coarser areolae. The new species differs from N. venezuelensis by more convex valve margins, wider central area and higher striae density; from N. babeiensis by absence of external apical grooves, wider valves with coarser striation and finer areolation; from N. delicatilineolata by larger valve dimensions. A new morphological term, rimulae, is introduced for small shallow transapical cracks on the external surface of virgae and axial area.

Corrected anatomical and morphological data on Aspicilia grossheimii Oxner, a little-known crustose lichen species described from the Absheron Peninsula (Azerbaijan) are presented. The species has areolate, 1–5 mm thick, yellowish-white, grayish to greenish thallus, large apothecia up to 4 mm diam., surrounded by a whitish thalline margin, large spheroid spores, 20–34 µm diam., 1–4 per ascus, branching, moniliform paraphyses, and 8–14 µm long pycnoconidia, that characterize it as a representative of the genus Circinaria. According to the phylogenetic tree assembled using nuITS, nuLSU and mtSSU loci, Aspicilia grossheimii does not have close relationships with any known taxon within Circinaria. The species is known from Azerbaijan, Georgia, Russia (Republic of Daghestan and Astrakhan Region), and Romania (Dobrogea). A new combination, Circinaria grossheimii (Oxner) Paukov, Alverdiyeva et Ismailov, is proposed. Aspicilia calcarea var. dobrogensis Vězda is synonymized with Circinaria grossheimii.

The lichen Gyalidea asteriscus is known in Russia from Southern Siberia (Altai, Western and Eastern Sayan, Baikal region, and the Republic of Buryatia). During the study of terricolous lichens collected in the summer 2024 in the vicinity of Sarma village (Baikal region), specimens of G. asteriscus with wide paraphyses, small asci, short and thin ascospores were found and identified as G. asteriscus subsp. gracilispora. After that, we revised all the herbarium material of the Irkutsk State University (IRKU) attributed to this species, and realized that all these specimens also belong to G. asteriscus subsp. gracilispora. Perhaps, all Asian specimens belong to this subspecies, however, additional study of the collections from the western regions of Siberia and Kyrgyzstan is required.

The rare myxomycete Badhamia ovispora was found for the first time in Russia from the Perm Territory and Moscow Region. Morphological features of specimens of this species were studied in detail using light and scanning electron microscopy. The main features are oblong-oval spores that are almost smooth in the light microscope and the triple peridium. It discusses the distinction of B. ovispora from closely related species such as B. goniospora, B. rhytidosperma, B. spinispora, B. verrucospora, Physarum apiculosporum, P. ovisporoides and P. ovisporum. Data on Badhamia ovispora findings in different regions of the world are given.

The rare myxomycete Badhamia ovispora was found for the first time in Russia from the Perm Territory and Moscow Region. Morphological features of specimens of this species were studied in detail using light and scanning electron microscopy. The main features are oblong-oval spores that are almost smooth in the light microscope and the triple peridium. It discusses the distinction of B. ovispora from closely related species such as B. goniospora, B. rhytidosperma, B. spinispora, B. verrucospora, Physarum apiculosporum, P. ovisporoides and P. ovisporum. Data on Badhamia ovispora findings in different regions of the world are given.

The paper provides the data on 148 species of agaricoid basidiomycetes, first recorded in the territory of the Koygorodskiy National Park (Komi Republic, Russia), of which 31 species are new to the republic. New locations of four included in the Red Data Book of the Komi Republic species (Echinoderma echinaceum, Baeospora myriadophylla, Phyllotopsis nidulans, Ripartites tricholoma) are found. Desarmillaria ectypa, a species included in the Red Book of the Russian Federation, is registered for the first time for the region.