Detailed morphological investigations and phylogenetic analyses of the ITS/5.8S nrDNA, mtLSU and RPB2 of the Umbilicaria crustulosa–U. spodochroa species complex reveal Umbilicaria hirsuta var. meizospora Harm. to be a separate species. The lectotype has been designated in ANGUC and a new combination Umbilicaria meizospora (Harm.) D. M. Masson & Davydov is proposed. Umbilicaria crustulosa var. badiofusca was recognized as the heterotypic synonym of U. meizospora and the lectotype was designated based on Frey's collection preserved in G. We provide a full description of U. meizospora and outline its distribution and ecology. The species is newly reported from Austria.

To clarify deep relationships among species lineages within Bacidia s. str., and to investigate the robustness of the deeper branches, we combined data from three traditionally used RNA-coding genes (nrITS, nrLSU and mtSSU) with two protein-coding genes (RPB1 and RPB2). The multigene phylogeny contained 48 newly generated sequences from the Russian Far East and all Bacidia s. str. sequences from GenBank (131 sequences). We subjected the alignments for the single and concatenated data sets to Bayesian inference (BI) and two maximum likelihood (ML) analyses (RAxML and IQ-TREE). The topologies of phylogenetic trees recovered from BI and ML analyses were highly concordant. The multilocus phylogeny of Bacidia s. str. was congruent with previous results based on nrITS sequences from the Russian Far East but with considerably higher support values for most of the deeper branches. A correlation between the recovered clades and apothecial pigments in the upper part of the hymenium and lateral exciple was observed. Based on morphological and molecular evidence, Bacidia obtecta is described as new to science. It was recovered as the sister lineage of B. elongata. The two species are alike in having up to four enlarged lumina cells along the exciple edge, but B. obtecta differs in the abundant crystals found in the upper hymenium and lateral exciple, and by having spores with fewer septa.

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.

Three species, Lobothallia brachyloba Paukov & I. V. Frolov, L. epiadelpha Paukov & A. Nordin and L. zogtii Paukov & Davydov, from arid regions of Eurasia (Russia, Kazakhstan, Kyrgyzstan, China and Mongolia) are described as new to science. Lobothallia brachyloba has flat, firmly attached lobes, immersed apothecia lacking a distinct thalline margin, and contains norstictic acid. Both Lobothallia epiadelpha and L. zogtii contain stictic acid and have a brown thallus and sessile apothecia. Lobothallia epiadelpha initially develops on crustose Circinaria spp, has thick lobes loosely attached to the substratum, and brown apothecial discs with constant thalline margins. Lobothallia zogtii is a free-living species with brownish black to jet black apothecial discs surrounded by a receding thalline margin. Lecanora bogdoënsis is synonymized with Lobothallia praeradiosa and Lobothallia helanensis is synonymized with L. subdiffracta. Three new combinations, Lobothallia hedinii (H. Magn.) Paukov, A. Nordin & Sohrabi, L. lacteola (Oxner) Şenkardeşler, Paukov, Davydov & Sohrabi, and L. subdiffracta (H. Magn.) Paukov, are proposed. Phylogenetic analyses of Lobothallia brachyloba, L. epiadelpha and L. subdiffracta (ITS, mtSSU) are presented, showing their relationships within Lobothallia. The lectotype of the name Aspicilia lacteola Oxner is designated. A key to 18 species of Lobothallia is provided.

The Umbilicaria polyphylla aggregate (U. polyphylla (L.) Baumg., U. subpolyphylla Oxner and U. iberica Sancho & Krzewicka) is discussed based on morphological, chemical and molecular data. Umbilicaria iberica is proposed to be a later synonym of U. subpolyphylla. The constructed nrITS + mtLSU phylogeny, which includes specimens with wide geographical ranges, shows that both U. polyphylla and U. subpolyphylla are monophyletic and closely related. Both species have the same type of thalloconidia and identical secondary metabolites. Umbilicaria subpolyphylla has prominent phenotypic differences when compared to U. polyphylla including the monophyllous thallus with a dull upper surface and an elevated, slightly wrinkled centre, often covered with white pruina, and a medulla of the ‘U. havaasii’ type. Phylogenetic evidence for the bipolar distribution of both U. polyphylla and U. subpolyphylla is provided. Sympatric speciation in one region followed by long-distance dispersal seems to be the most plausible phylogeographical explanation for the observed patterns. Umbilicaria subpolyphylla is found in southern temperate-subtropical (Mediterranean) mountains, at least in Europe.

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.

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.

The current view of the geographical ranges of lichens is often distorted by overly narrow or overly broad applications of names and by insufficient survey of most regions of the world. Here we present several cases where species of Teloschistaceae formerly thought to be limited to rather small territories in the western or eastern parts of Eurasia are in fact widespread in northern Eurasia. We support our findings with ITS nrDNA data in several new trees showing relationships in the genera Athallia, Calogaya, Caloplaca, Flavoplaca and Gyalolechia. The widespread species have little in common, except that most of them reproduce both sexually and asexually, and we discuss the possible influence of the combined reproduction on geographical range. Calogaya bryochrysion, Calogaya saxicola, Gyalolechia epiphyta and Gyalolechia ussuriensis are new combinations. Calogaya alaskensis is a younger synonym for C. bryochrysion. The generally arctic-alpine Calogaya bryochrysion also occurs on the bark of solitary trees in dry parts of the Altai Mountains. The Australian Flavoplaca cranfieldii is a younger synonym of F. flavocitrina. Gyalolechia epiphyta has been described numerous times, from different regions and substrata, as Caloplaca juniperi, C. laricina, C. tarani, Gyalolechia arizonica and G. juniperina. The name Gyalolechia xanthostigmoidea has recently been used for G. epiphyta, but it represents a distinct taxon. Gyalolechia ussuriensis is closely related to and morphologically indistinguishable from G. persimilis, but they have a different ecology and distribution and we regard them as distinct species. Caloplaca juniperina Tomin is lectotypified.

It has been suggested that the absence of anthraquinones is not a synapomorphic character, but appears independently in unrelated lineages of Teloschistaceae. We analyzed ITS nrDNA regions in species of the genus Caloplaca and present evidence for five such examples: the Caloplaca cerina group, C. obscurella, the C. servitiana group, the C. xerica group and the C. variabilis group (Pyrenodesmia). In some cases, loss of anthraquinones is observed only in individuals within ordinarily pigmented populations, but sometimes the loss covers whole lineages containing one or more species. Both situations are observed in the C. servitiana group. Loss of anthraquinones is always followed by the synthesis of ‘alternative’ pigments (often Sedifolia-grey). In the specimens with anthraquinone-containing apothecia studied, these pigments are not visible in apothecial sections after dissolving anthraquinones in K. Fully unpigmented apothecia have not been observed.

The Caloplaca xerica group is a newly established, infraspecific grouping of species related to, and similar to, C. xerica. The Caloplaca servitiana group is also newly established and represents an isolated lineage covering two rather different, but related species. Caloplaca neotaurica is described here as a new species with apothecia of two colour variants; orange-red (with anthraquinones) and grey (with Sedifolia-grey).

The genus Huea represents another taxon lacking anthraquinones within Teloschistaceae. The genera Apatoplaca and Cephalophysis, which lack anthraquinones, are tentatively placed in Teloschistaceae, but their phylogenetic identity has not been recognized. Hueidea is reported to have no anthraquinones, but its secondary metabolites should be studied further and its possible placement in Teloschistaceae assessed.

We suggest that Caloplaca abbreviata var. lecideoides and C. celata represent variants of C. stillicidiorum lacking anthraquinones.