A new Arthothelium species, A. hymeniicola in the apothecia of an unidentified Bacidia sp., is described from Campbell Island, New Zealand. The new species is remarkable, not only by being the first lichenicolous Arthothelium species, but also by being an endohymenial fungus not forming ascomatal structures. Previously, no Arthoniaceae species were reported as parasitic from Bacidia spp. However, both generic and family placements are tentative and the possibility of a placement in the Cookellaceae is also discussed. Differences between Arthoniaceae and Cookellaceae, and the generic delimitations within them, are generally based on the structures of the fruiting bodies, rendering the taxonomic placement of the new species challenging without molecular data; neither fruiting bodies nor molecular data are available for the new species and the Cookellaceae.

The lichen genus Biatora comprises inconspicuous crustose lichens that are typically found on organic substrata such as tree bark, bryophytes and detritus. During the last 20 years many new species have been added to the genus making its delimitation more and more difficult. The infrageneric relationships of the 42 species have never been investigated thoroughly. Using DNA sequences from three gene loci (ITS, RPB2, mrSSU) and 59 OTUs, an attempt was made to reconstruct the phylogenetic relationships of Biatora and its infrageneric groups. Cliostomum appears to be the closest relative of Biatora. The position of Mycobilimbia in the Lecania-clade is confirmed. Phylogenetic relationships within Biatora are poorly supported, but six different species groups that are also phenotypically distinguished are more or less well supported: the vernalis-, meiocarpa-, hertelii-, ocelliformis-, beckhausii- and rufidula- groups. The analysis also confirms the presence of several undescribed taxa. Biatora subduplex as currently circumscribed appears to be heterogeneous, as does B. helvola. Based on the phylogeny, the distributional range of B. alaskana is extended to Japan. The new combinations Biatora ementiens (Nyl.) Printzen and Biatora hemipolia (Nyl.) S. Ekman & Printzen are made and both names are typified.

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.

Lecania chlorotiza and L. falcata, described here as new from Spain/Navarra, the Canary Islands and the Azores, do not belong to Lecania s. str. They belong to a strongly supported clade comprising Bacidia, Bacidina, Scutula and Toninia when examined with maximum parsimony, maximum likelihood and Bayesian inferences using mtSSU, nuLSU and nuITS sequences. This clade represents the Bacidiaceae and is included in the Ramalinaceae s. lat. Most genera included in that family need further work before a new genus can possibly be described for Lecania chlorotiza and L. falcata.

The new species Fellhaneropsis rhododendri is described from living Rhododendron leaves in the Netherlands. It is characterized by pyriform pycnidia with stiff, septate hairs at the mouth. It is doubtlessly due to recent global warming that an obligately foliicolous lichen can be described from a temperate area in Europe.

The preparation of the new edition of The Lichen Flora of the British Isles necessitates the publication of several taxonomic and nomenclatural novelties. The following new species are described: Anisomeridium robustum (Monoblastiaceae), Antennulariella lichenisata (Antennulariellaceae), Fellhanera duplex (Pilocarpaceae), Gyalideopsis crenulata (Gomphillaceae), Micarea farinosa (Pilocarpaceae) and Xerotrema quercicola (Odontotremataceae). Antennulariella lichenisata is the first lichenized member of the order Capnodiales to be described. The following new combinations are proposed: Bacidia squamellosa, Catillaria lobariicola, Collemopsidium arenisedum, C. argilospilum, C. caesium, C. chlorococcum, C. monense, C. subarenisedum, Miriquidica pycnocarpa f. sorediata, Pyrenocarpon thelostomum, Topeliopsis azorica, and Verrucaria nigrescens f. tectorum.

Australian records of Scoliciosporum are reviewed. The new species, Jarmania scoliciosporoides Kantvilas, is described, based on Tasmanian material previously referred to Scoliciosporum pruinosum (P. James) Vězda; the systematic position of these two taxa is considered. Two further species recorded previously, S. compactum Körber and S. umbrinum (Ach.) Arnold, are discussed and all records united under the latter name; S. umbrinum is reported from Tasmania for the first time.

Bacidia coprodes (Körb.) Lettau, until now treated as a synonym of Bacidia trachona (Ach.) Lettau, is resurrected. Morphological, chemical and ecological characteristics place this species close to Toninia in the Ramalinaceae, but we retain it in Bacidia because of uncertainties in the generic taxonomy of this family. Bacidia coprodes is fairly widespread on calcareous and enriched siliceous rock in Europe and eastern North America. In North America the species has also been known under the synonyms Bacidia granosa (Tuck.) Zahlbr. (basionym: Lecidea granosa Tuck.) and Bacidia pammellii (Fink) Zahlbr. (basionym: Bilimbia pammellii Fink). Morphological and chemical features, together with molecular data, suggest that B. trachona does not belong to Bacidia, but rather in the Pilocarpaceae.

Bacidia adastra Sparrius & Aptroot is newly described from the Netherlands, Belgium, England and Germany. It is related to Bacidia arnoldiana s. lat. and differs from Bacidia caligans, B. neosquamulosa and B. viridescens by thallus structure and pigmentation of the excipulum and epithecium. It usually grows on acid or neutral, eutrophicated bark. It is characterized by the remarkable, pale green, thick, leprose thallus, the pale apothecia with aeruginose or dark brown flecks in the epihymenium and excipulum, and the hyaline hymenium and hypothecium.

A new lichen species from the genus Bacidia s. lat., B. brandii, is described from the Netherlands, Belgium, France and Lithuania. It has been found terricolous, on brick, on lignum and on plant debris. The new species belongs to a group sometimes treated in the genus Bacidina Vězda, and shows particular affinities to Bacidia amoldiana, B. chloroticula and B. saxenii.