Twenty-three species of epiphytic Caloplaca are recognized in India, of which Caloplaca himalayana Joshi, Y. & Upreti, characterized by thin, continuous, yellowish thallus, numerous ferruginous-red to brownish red, flat to subconvex apothecia with a persistent proper margin and lignicolous habitat, is described here as a new species. Because of the ferruginous coloured apothecial disc, the new species is provisionally placed in the ferruginea group until a taxonomic treatment of the whole group has been carried out. The ferruginea group is characterized by a whitish to grey (rarely yellowish) crustose thallus, a ferruginous to rarely blackish apothecial disc, biatorine to lecanorine exciple, thick-walled spore septa and the chemosyndrome C. The taxonomic affinities of the new taxa with several other taxa, including species of ferruginea group, are discussed. Two new records for India are also recorded: Caloplaca alnetorum Giralt, Nimis & Poelt and C. crocea (Kremp.) Hafellner & Poelt. A key to all the corticolous Caloplaca species occurring in the Indian subcontinent is also provided.

Three species are recognized as additions to the British montane lichen flora: Catillaria gilbertii sp. nov., Halecania bryophila sp. nov., and H. micacea sp. nov. All three have so far been recorded only from the mica-schist mountains of the Central Highlands of Scotland.

Punctelia perreticulata (Räsäanen) G. Wilh. & Ladd is recognized as a distinct species. The only consistent differences between P. perreticulata and P. subrudecta (Nyl.) Krog are the shape and length of conidia. Both species are widespread in the world. In P. perreticulata, there are differences in conidial length among the European, American and Australasian samples studied, but they neither correlate with differences observed in other morphological traits nor with the substratum. An epitype is selected to support the holotype of P. perreticulata, because its identity is uncertain due to the absence of conidia.

Choreospora tibellii P. Const. & R. Sant. gen. & sp. nov., a sporodochial hyphomycete with non-septate, tetraradiate conidia is described from Australia. The fungus grows on a sterile foliicolous lichenized thallus (?Echinoplaca sp.) on leaves of Cordyline.

The following new species of Xanthoparmelia (Parmeliaceae) are described from Western Australia: X. cranfieldii Elix, X. elevata Elix, X. kimberleyensis Elix, X. monadnockensisX. nanoides Elix, X. nortegeta Elix, X. sleei Elix and X. toolbrunupensis Elix. In addition, X. luminosa (Elix) Hale and X. Victoriana Elix & J. Johnst. are reported from Western Australia for the first time.

Abrothallus secedens Wedin & R. Sant. sp. nov., commensalistic on species of Pseudocyphellaria, from Argentina and Kenya and Abrothallus granulatae Wedin sp. nov., parasitic on Pseudocyphellariagranulata, from Argentina (Tierra del Fuego) are described. Vouauxiomycesgranulatae Wedin sp. nov., is regarded as the anamorph of A. granulatae. Sphaerellothecium minutum Hafellner is recorded for the first time from Antarctica and South America, Phaeosporobolus alpinus R. Sant., Alstrup & D. Hawksw. from Antarctica and Argentina, Arthonia epiphyscia Nyl., Dacampia rufescentis (Vouaux) D. Hawksw., Polycoccum pulvinatum (Eitner) R. Sant. And Stigmidium pumilum (Lettau) Matzer & Hafellner from South America and Nesolechia oxyspora (Tul.) Massal. and Pyrenidium actinellum Nyl. from Chile.

An account is given of the lichen genus Phlyctis in India. Phlyctis monosperma, with single spored asci and psoromic acid, and P. subhimalayensis, lacking secondary metabolites, are described here as new to science. A worldwide key to the genus is provided.

The new species Arthothelium desertorum is described from the Namib desert. It is characterized by its saxicolous habit and areolate thallus containing divaricatic acid.

The new species Opegrapha subdictyospora is described from NE Brazil. It is only the third species in the genus with (sub)muriform ascospores and is further characterized by the brown pruinose discs. It was collected at Vale do Catimbau National Park in Pernambuco, which is a Caatinga area, where it is locally common.

Cryptolechia carneolutea is the type species of the genus Cryptolechia, a rare taxon classified as endangered in the UK, now largely confined to ancient Fraxinus trees. The only tree with abundant growth of the species in one of its strongholds, the Slapton Ley National Nature Reserve in Devon, was blown over in a storm in April 2017, making it possible to collect material for molecular studies and transplant specimens to other Fraxinus trees in the area. The results of the phylogenetic analysis revealed C. carneolutea to be nested within the genus Gyalecta (Gyalectaceae). This further supports a broad circumscription of Gyalecta, after also including species previously placed in Belonia and Pachyphiale as proposed in other recent studies. It might be possible to introduce an alternative genus concept in Gyalectaceae, not schematically based on ascoma type and ascospore number, but presently not enough data are available to proceed with such a novel classification. A review of the taxonomic concept of Cryptolechia demonstrates that this name was used inconsistently in the past, and its possible inclusion in Gyalecta was anticipated by other authors. As the majority of species presently classified in Cryptolechia had been placed in Gyalecta before, only five new combinations are required to provide formal inclusion of all taxa in the latter genus: Gyalecta bicellulata (Kalb) D. Hawksw. & Lücking comb. nov., G. caudata (Kalb) D. Hawksw. & Lücking comb. nov., G. pittieriana (Kalb et al.) D. Hawksw. & Lücking comb. nov., G. saxatilis (Vězda) D. Hawksw. & Lücking comb. nov. and G. stellaris (Müll. Arg.) D. Hawksw. & Lücking comb. nov. We also supersede the previous lectotypification of Parmelia carneolutea Turner with the discovery of the holotype specimen in BM.

The two corticolous species Fuscidea lightfootii (Sm.) Coppins & P. James and F. pusilla Tønsberg are morphologically and chemically similar and it has been suggested that they are conspecific. We investigated the interspecific relationship between F. lightfootii and F. pusilla using ITS, LSU and mtSSU rDNA. The combined multigene phylogeny shows that these species are genetically distinct. They are similar in ascocarp anatomy but in thallus morphology and substratum preferences there may be slight differences between them. Moreover, F. pusilla displays a broader ecological range than F. lightfootii. Even though some morphotypes appeared distinct and may be assigned to one of the two species with some degree of certainty, the use of DNA sequencing is recommended for their identification. Epitypes are designated for both species.