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.

Phylogenetic relationships of Stereocaulon with emphasis on the crustose taxa were studied based on nuclear ribosomal ITS1–5.8S–ITS2 and partial beta-tubulin sequences. The placement of four of the six crustose species currently included in the genus has previously been confirmed based on molecular data. It has, however, remained unresolved whether the crustose growth form is a plesiomorphic or apomorphic feature within Stereocaulon, due to contradictory placements of the crustose species in earlier studies. The aim of this study was to clarify the position of the crustose species by including additional data, especially of S. nivale and S. plicatile, which have not been included in previous analyses. The inclusion of S. plicatile in the genus is of particular interest as it is the only species in the genus with submurifrom to muriform ascospores. Altogether 37 specimens representing 31 species of the ingroup, including all the crustose Stereocaulon species, were incorporated in the analyses. Conventional, as well as direct optimization parsimony, maximum likelihood and Bayesian analyses were performed. The results show that the crustose species do not form a monophyletic entity and that the crustose growth form is a plesiomorphic feature within Stereocaulon. The crustose S. nivale and S. plicatile are nested within the genus and their inclusion in Stereocaulon is thereby confirmed. The nested position of S. plicatile indicates that the submuriform to muriform spore type has been gained independently within the genus. Here, S. plicatile is also reported for the first time from Scandinavia.

The new species Megaspora rimisorediata Valadbeigi & A. Nordin is described from Iran, where it mainly grows on tree bark but also on calciferous rocks and mosses. It is characterized by a pale ochraceous to bluish grey, cracked and sorediate thallus, very rarely producing ascomata. It appears to be rather commonly distributed in Iran. Its close affinity with Megaspora verrucosa is illustrated in a graph resulting from a phylogenetic network analysis of nuclear rDNA ITS1-5.8S-ITS2 sequences from specimens representing the different genera of Megasporaceae.

Aspicilia fluviatilis and A. granulosa, two arctic and/or (sub)alpine species with elongate ± diverging and ± branching marginal areoles, are described as new and compared with similar species occurring in Fennoscandia. A parsimony analysis based on ITS indicates a close relationship with the mainly coastal A. epiglypta. Aspicilia epiglypta, A. disserpens and A. sublapponica are lectotypified and A. disserpens is reduced to synonymy with A. perradiata. Aspicilia alboradiata and A. circularis are excluded from the Fennoscandian lichen biota. A key to Fennoscandian Aspicilia species with radiating thalli and/or elongate ± diverging and ± branching marginal areoles is also presented.

The new name Aspicilia berntii is proposed to accommodate Lecanora mastoidea Lynge in Aspicilia and a lectotype is designated. Additional characters are added to the species description and a comparison is made with similar species. The species is reported as new to Scandinavia with localities in northern Norway. An assessement of the phylogenetic relationships, based on a split network analysis of ITS sequences, places A. berntii close to A. verrucigera in the A. cinerea group.

Tetramelas phaeophysciae, a new obligately lichenicolous species occurring in Scandinavia, Iceland and Greenland, is described, and the closely related Buellia pulverulenta, together with B. triphragmioides, are transferred to Tetramelas. Phylogenetic reconstructions based on sequence data from nITS1-5.8S-ITS2 rDNA, using Bayesian inference and parsimony analyses, support the segregation of the new species from B. pulverulenta as well as the segregation of Tetramelas and Diplotomma from Buellia s. str.

Three species are added to the recently reintroduced genus Tetramelas, T. chloroleucus comb. nov., T. confusus sp. nov. and T. granulosus comb. nov. Tetramelas confusus was first reported under the name of Buellia papillata but is more similar to T. insignis. Distinguishing characters are given in a Table. Tetramelas poeltii is reduced to synonymy with T. chloroleucus.

Iberian records of Buellia triseptata A. Nordin are presented. This corticolous and lignicolous species was recently described from North America. A description based on the Iberian material is given, together with notes on ecology and distribution. Specimens belonging to B. triseptata were previously reported as B. disciformis, B. lauricassiae, B. pharcidia and B. triphragmia. The main distinguishing features between these taxa and B. triseptata are pointed out, and background to the misapplied names is given. Illustrations of the ascospores of B. triseptata and B. lauricassiae are presented. A distribution map of B. triseptata in the Iberian Peninsula is also provided.