Umbilicaria ahtii sp. nov. is described based on morphological and molecular characters. The new species resembles Umbilicaria vellea but the former has larger and submuriform ascospores, a darker lower surface, longer dark brown to black rhizinomorphs, and lacks thalloconidia directly on the lower surface and basal part of the rhizinomorphs. Phylogenetic analyses (ITS, mtLSU and RPB2) confirmed the distinctness of U. ahtii and indicated its sister relationship to U. meizospora. Umbilicaria ahtii is described from Finland and is currently known from several localities in Northern Europe (Svalbard, Norway, Finland, Kola Peninsula in Russia), Asia (Kodar Range, Siberia) and North America (Alaska). Within the U. vellea group, new molecular data confirmed U. koidzumii as a widespread, separate species sister to U. cinereorufescens. Diagnostic traits and variability of species, as well as their distribution patterns and nomenclature, are discussed.

Candelariella ahtii Yakovchenko sp. nov. is described based on phenotypic and ITS nrDNA sequence data. The species, occurring on soil in the crevices and cracks of siliceous rocks, is characterized by its squamulose cushion-forming thallus of imbricate, rounded to weakly incised granules/squamules with a greenish yellow to pale yellow pulverulent upper surface, lecanorine apothecia with a plane to somewhat convex ochre-yellow disc and a permanent thick thalline margin, 8-spored asci and ellipsoid to narrowly ellipsoid ascospores with rounded ends, as well as a distribution in Central and North-East Asia. It is similar to Candelariella citrina but differs in having ascospores without attenuated ends and smaller squamules. Candelariella citrina is excluded from the lichen flora of Russia. A worldwide key to all known Candelariella species with 8-spored asci, including 41 names, is provided.

Three species of the family Teloschistaceae (lichenized Ascomycota) are described as new to science from Southern and Eastern Siberia and the Far East. Corticolous Caloplaca saviczii belongs to the genus Caloplaca s. str.; it has C. cerina-like apothecia and green to grey-green, crateriform soralia with a white rim. Lendemeriella aureopruinosa is a saxicolous taxon with a thin grey thallus and small apothecia 0.3–0.6 mm in diameter, with a dark orange disc usually bearing epipsamma and often with a grey true exciple containing the pigment Cinereorufa-green. Orientophila infirma is a corticolous species with an endophloeodal thallus and small orange apothecia, 0.2–0.3 mm in diameter, usually with an inconspicuous thalline exciple. All new taxa presumably have a boreal north-eastern distribution in Asia.

Umbilicaria orientalis Davydov sp. nov. is described and phylogenetic analysis (ITS, mtLSU and RPB2) confirmed its distinctness and indicated a sister relationship with U. trabeculata within the U. vellea group. The species is morphologically similar to U. vellea but differs by simple, cylindrical or strap-like rhizinomorphs and by thalloconidia, developing both on the lower surface and on rhizinomorphs, that are 1–2 (rarely 4)–celled or in aggregates of up to 5–6 cells. Umbilicaria orientalis is described from the Russian Far East and is currently known from a wide range of localities in East Asia, from the Far East to South Siberia and Mongolia in the north, to Hebei and Tibet in the south. New sequences of U. americana were obtained; the species represents an independent phylogenetic lineage within Umbilicaria subg. Papillophora. Diagnostic traits and variability of different developmental stages of U. orientalis, as well as its East Asian distribution pattern, are discussed.

Phylogenetic reconstructions based on ITS/5.8S and mtSSU DNA sequence data suggest a close relationship between two Lecanora species containing calycin and usnic acid and the Lecanora polytropa group. Lecanora solaris Yakovchenko & Davydov sp. nov. is described from the Altai Mountains in Russia. Its gross morphology resembles that of L. somervellii as both species have an effigurate, citrine-yellow thallus (due to the production of calycin). However, L. solaris is distinguished from L. somervellii by having a small, squamulose to marginally lobate umbilicate thallus and apothecia with a persistent margin, whereas L. somervellii has a large, distinctly placodioid thallus and an apothecial margin that is soon excluded.

Sporastatia crassulata Yakovchenko & Davydov sp. nov. is described and a phylogenetic analysis (mtSSU) is presented, confirming its distinctness and indicating a sister relationship with S. testudinea. The species is unique among Sporastatia species in having a distinctly squamulose, thick, uneven thallus composed of convex, rounded squamules irregularly ascending in the central part of the thallus. The new combination Sporastatia karakorina (Poelt & Obermayer) Davydov & Yakovchenko is proposed. The type specimen of S. subasiatica was examined. A key to the six species of Sporastatia is given. Mountainous Central Asia appears to be the centre of species diversity and endemism for Sporastatia.

Rinodina is a widespread, polyphyletic genus of crustose Physciaceae with c. 300 species worldwide. A major missing link in understanding its global biogeography has been eastern Asia where the genus has never been systematically revised. Here we review specimen and literature records for Rinodina for north-eastern Asia (Russian Far East, Japan and the Korean Peninsula) and recognize 43 species. We describe two species, R. hypobadia and R. orientalis, as new to science. Rinodina hypobadia is distinguished by its pigmented hypothecium, Dirinaria-type ascospores and pannarin in both thallus and epihymenium. Rinodina orientalis is characterized by its erumpent apothecia that remain broadly attached, with discs sometimes becoming convex and excluding the thalline margins, ascospores belonging to the Physcia-type and secondary metabolites absent. Nine other species are reported from the region for the first time. These include R. dolichospora, R. freyi, R. metaboliza, R. sicula, R. subminuta and R. willeyi. Of particular biogeographical interest are three additional new records that have western North American–eastern Asian distributions: the corticolous species R. endospora, R. macrospora and R. megistospora. Six species have the better known eastern North American–eastern Asian distributions: R. ascociscana (syn. R. akagiensis, R. melancholica), R. buckii, R. chrysidiata, R. subminuta, R. tenuis (syn. R. adirondackii) and R. willeyi, and two have eastern North American–eastern Asian–European distributions: R. excrescens and R. moziana (syn. R. destituta, R. vezdae). Our study begins to close one of the largest gaps in our knowledge of circumboreal species distributions in Rinodina and, together with previous studies in North America and Europe, provides new insights into circumboreal crustose lichen biogeography. Rinodina cinereovirens (syn. R. turfacea var. cinereovirens) is also reported as new to North America.

Rhizocarpon smaragdulum Davydov & Yakovchenko sp. nov. is described and a phylogenetic analysis (ITS, mtSSU) is presented, confirming its distinctiveness and indicating a sister relationship with R. suomiense and R. subgeminatum. The species is unique among yellow Rhizocarpon species in having a single hyaline ascospore per ascus. The phylogenetic tree suggests that the number of ascospores per ascus has been reduced in Rhizocarpon more than once during the course of its evolution. Two new distributional records are also reported: Rhizocarpon atroflavescens is new for Siberia and R. norvegicum is new for the Altai Mountains. Rhizocarpon norvegicum in this region grows on rocks and is also lichenicolous on Acarospora bullata.

Candelariella blastidiata Yakovchenko sp. nov. is described. This corticolous species is characterized by biatorine yellow apothecia, a grey squamulose thallus with marginal and lower side blastidia, 8-spored asci, and a northern circumpolar distribution. Candelariella subdeflexa has previously been confused with C. blastidiata, but our analyses of phenotypic and DNA sequence data revealed C. blastidiata should be distinguished from C. subdeflexa. A worldwide key for Candelariella species with grey thalli is provided.

A taxonomic and biogeographic overview of the genus Myrionora is provided. Two species are recognized, M. albidula (Willey) R. C. Harris and M. pseudocyphellariae (Etayo) S. Ekman & Palice comb. nov. The genus is characterized by polysporous asci, the presence of crystals in the hymenium and proper exciple that partly consist of lobaric acid, and a photobiont with large cells (mostly in the range 12–20 µm). Myrionora albidula is currently known from Germany, Norway, Sweden, the Russian Federation (Altayskiy Kray, Chelyabinskaya Oblast', Khabarovskiy Kray and Zabaykal'skiy Kray), and the United States (Alaska, Connecticut, Maine and Massachusetts). It inhabits bark of deciduous trees and shrubs and conifers over a wide range of latitudes. Myrionora pseudocyphellariae is known from Chile and Ecuador, where it has been encountered on lichens and decaying bark. Based on morphological characteristics, we conclude that Myrionora belongs in the Ramalinaceae.