Relative growth rates (RGR) and carbon-based secondary compounds (CBSCs) were quantified in four dominant terricolous arctic-alpine mat-forming lichens with different preferences for snow cover. The aim was to evaluate the effects of snow depth, and thus snow cover duration, on lichen growth and performance. The species, Alectoria ochroleuca, Flavocetraria nivalis, Cladonia mitis and Cetrariella delisei, are associated with increasing snow depth, respectively. They were transplanted for one year at five snow depths (0, 60, 120, 160 and 200 cm measured in early May) along each of four natural ridge to snow bed gradient transects in oceanic-alpine sites (western Norway). Snow slightly thicker than in source habitats caused negative RGR in the ridge top-dependent A. ochroleuca and the co-occurring F. nivalis with somewhat higher snow tolerance. Only C. mitis with the broadest ecological niche had positive RGR along most of the gradients (0–160 cm), even outside its natural range. The most snow-tolerant species, C. delisei, tolerant also to temporal inundation in water, had the lowest RGR. Nevertheless, it performed as well in places with little or no snow as in places where it grows naturally. Snow depth significantly affected total concentrations of CBSCs mainly in A. ochroleuca, which experienced substantial mass loss under snow. There was a highly significant increase in usnic acid concentration with increasing mass loss in A. ochroleuca, probably because usnic acid decays more slowly than other components. In conclusion, snow reduced lichen RGR, but in species-specific ways. Therefore, increasing snow depth per se along spatial and/or temporal scales likely reduces abundance and distribution of dominant mat-forming lichens in the alpine ecosystems of Scandinavia.

We provide an expanded and updated, 2-locus phylogeny (mtSSU, nuLSU) of the lichenized fungal family Trypetheliaceae, with a total of 196 ingroup OTUs, in order to further refine generic delimitations and species concepts in this family. As a result, the following 15 clades are recognized as separate genera, including five newly established genera: Aptrootia, Architrypethelium, Astrothelium (including the bulk of corticate species with astrothelioid ascospores; synonyms: Campylothelium, Cryptothelium, Laurera), Bathelium s. str. (excluding B. degenerans and relatives which fall into Astrothelium), the reinstated Bogoriella (for tropical, lichenized species previously placed in Mycomicrothelia), Constrictolumina gen. nov. (for tropical, lichenized species of Arthopyrenia), Dictyomeridium gen. nov. (for a subgroup of species with muriform ascospores previously placed in Polymeridium), Julella (provisionally, as the type species remains unsequenced), Marcelaria (Laurera purpurina complex), Nigrovothelium gen. nov. (for the Trypethelium tropicum group), Novomicrothelia gen. nov. (for an additional species previously placed in Mycomicrothelia), Polymeridium s. str., Pseudopyrenula, Trypethelium s. str. (T. eluteriae group), and Viridothelium gen. nov. (for the Trypethelium virens group). All recognized genera are phenotypically characterized and a discussion on the evolution of phenotypic features in the family is given. Based on the obtained phylogeny, species delimitations are revised and the importance of characters such as thallus morphology, hymenial inspersion, and secondary chemistry for taxonomic purposes is discussed, resulting in a refined species concept.

Two species of Catinaria with an unusual hepaticolous (i.e. growing on liverworts) lifestyle are described as new to science. Catinaria brodoana is described from species of Cheilolejeunea sect. Leucolejeunea (Lejeuneaceae) growing in south-eastern North America. Catinaria radulae is described from Radula flavifolia (Radulaceae) growing in the Cape Horn Archipelago of southernmost Chile, South America. The species are compared with the type of Catinaria (C. atropurpurea). In addition to occurring on hepatics, C. brodoana is characterized by its cellular exciple, warted ascospores and thallus composed of goniocysts, while C. radulae is characterized by its exciple of radiating hyphae, warted ascospores and absence of a lichenized thallus.

A new cyanolichen, Peltigera islandica sp. nov. in the section Peltigera (‘P. canina group’) is described from Iceland. This species is similar in general appearance to P. rufescens and P. membranacea, but may be recognized by its downturned lobe tips and narrow lobes, respectively. Most thalli are bright emerald green in colour when moist, although a dark khaki green colourmorph is also documented. Monophyly of P. islandica s. lat. (i.e. including P. sp. A sensu O’Brien et al., from Canada) is significantly supported based on ITS sequences and corroborated by molecular synapomorphy (absence of the ITS1 hypervariable region). Analysis of the rbcLX locus indicates the cyanobiont of P. islandica (Nostoc sp.) comprises strains belonging to a pool of Icelandic genotypes, some of which are present in other Peltigera species, including P. “neorufescens”, another taxon new to Iceland collected during this study. Association with photobionts that are shared by other local species suggests P. islandica may be well established in Iceland, but a review of herbarium collections as well as broader field surveys are needed to better characterize its geographical distribution.

A revisionary synopsis is presented for the family Trypetheliaceae, based on a separately published phylogenetic analysis of a large number of species, morpho-anatomical and chemical study of extensive material, and revision of numerous type specimens. A total of 418 species is formally accepted in this synopsis, distributed among 15 genera as follows: Aptrootia (3), Architrypethelium (7), Astrothelium (242), Bathelium (16), Bogoriella (29), Constrictolumina (9), Dictyomeridium (7), Distothelia (3), Marcelaria (3), Nigrovothelium (2), Novomicrothelia (1), Polymeridium (50), Pseudopyrenula (20), Trypethelium (16), and Viridothelium (10). All accepted genera, including new genera described separately in this issue, are keyed out and briefly described and discussed, and keys are provided for all accepted species within each genus. Entries with full synonymy and brief descriptions, and in part also discussions, are provided for all accepted species, except those newly described elsewhere in this issue, which are cross-referenced in the corresponding keys. The description of the newly defined genera takes into account phylogeny in combination with morpho-anatomical features with the result that they are mostly recognizable by a combination of thallus, ascoma and ascospore features. Most species previously assigned to the genera Astrothelium, Campylothelium, Cryptothelium, and Trypethelium, based on a schematic concept of ascoma morphology and ascospore septation, are now included in a single genus, Astrothelium, with highly variable ascoma morphology and ascospore septation but invariably with astrothelioid ascospores (at least when young), that is diamond-shaped lumina, and a well-developed, corticate, usually olive-green thallus that often covers the ascomata. While the genera Aptrootia (large, brown, muriform ascospores), Architrypethelium (large, mostly 3-septate ascospores), and Pseudopyrenula (ecorticate, white thalli and astrothelioid ascospores) are maintained, Trypethelium is redefined to include species with raised, pseudostromatic ascomata and multiseptate ascospores with thin septa. The sister group of Trypethelium is the genus Marcelaria, with brightly coloured pseudostromata and muriform ascospores. Bathelium is now limited to species with strongly raised, fully exposed pseudostromata and septate to muriform ascospores with thin septa. Several genera are recognized for more basal lineages with mostly ecorticate, white thalli and solitary, exposed ascomata previously assigned to Arthopyrenia, Mycomicrothelia and Polymeridium, viz. Bogoriella, Constrictolumina, Dictyomeridium, and Novomicrothelia. In addition, separate genera are accepted for the Trypethelium tropicum (Nigrovothelium) and T. virens (Viridothelium) groups. In addition, a refined species concept resulting from phylogenetic studies is employed which pays particular attention to morphological features of the thallus and ascomata. Of a total of 526 names checked, 107 remain synonyms of accepted names and a further eight are newly excluded from the family. Based on these redispositions, the following 146 new combinations are proposed, including reinstatement of numerous names previously subsumed into synonymy: Architrypethelium columbianum (Nyl.) Aptroot & Lücking comb. nov., A. grande (Kremp.) Aptroot & Lücking comb. nov., Astrothelium aeneum (Eschw.) Aptroot & Lücking comb. nov., A. alboverrucum (Makhija & Patw.) Aptroot & Lücking comb. nov., A. amazonum (R. C. Harris) Aptroot & Lücking comb. nov., A. ambiguum (Malme) Aptroot & Lücking comb. nov., A. andamanicum (Makhija & Patw.) Aptroot comb. nov., A. annulare (Spreng.) Aptroot & Lücking comb. nov., A. aurantiacum (Makhija & Patw) Aptroot & Lücking comb. nov., A. auratum (R. C. Harris) Aptroot & Lücking comb. nov., A. aureomaculatum (Vain.) Aptroot & Lücking comb. nov., A. basilicum (Kremp.) Aptroot & Lücking comb. nov., A. bicolor (Taylor) Aptroot & Lücking comb. nov., A. buckii (R. C. Harris) Aptroot & Lücking comb. nov., A. calosporum (Müll. Arg.) Aptroot & Lücking comb. nov., A. cartilagineum (Fée) Aptroot & Lücking comb. nov., A. cecidiogenum (Aptroot & Lücking) Aptroot & Lücking comb. nov., A. ceratinum (Fée) Aptroot & Lücking comb. nov., A. chapadense (Malme) Aptroot & Lücking comb. nov., A. chrysoglyphum (Vain.) Aptroot & Lücking comb. nov., A. chrysostomum (Vain.) Aptroot & Lücking comb. nov., A. cinereorosellum (Kremp.) Aptroot & Lücking comb. nov., A. cinereum (Müll. Arg.) Aptroot & Lücking comb. et stat. nov., A. confluens (Müll. Arg.) Aptroot & Lücking comb. nov., A. consimile (Müll. Arg.) Aptroot & Lücking comb. nov., A. deforme (Fée) Aptroot & Lücking comb. nov., A. defossum (Müll. Arg.) Aptroot & Lücking comb. nov., A. degenerans (Vain.) Aptroot & Lücking comb. nov., A. dissimilum (Makhija & Patw.) Aptroot & Lücking comb. nov., A. effusum (Aptroot & Sipman) Aptroot & Lücking comb. nov., A. endochryseum (Vain.) Aptroot & Lücking comb. nov., A. exostemmatis (Müll. Arg.) Aptroot & Lücking comb. nov., A. feei (C. F. W. Meissn.) Aptroot & Lücking comb. nov., A. ferrugineum (Müll. Arg.) Aptroot & Lücking comb. nov., A. galligenum (Aptroot) Aptroot & Lücking comb. nov., A. gigantosporum (Müll. Arg.) Aptroot & Lücking comb. nov., A. indicum (Upreti & Ajay Singh) Aptroot & Lücking comb. nov., A. infossum (Nyl.) Aptroot & Lücking comb. nov., A. infuscatulum (Müll. Arg.) Aptroot & Lücking comb. nov., A. irregulare (Müll. Arg.) Aptroot & Lücking comb. nov., A. keralense (Upreti & Ajay Singh) Aptroot & Lücking comb. nov., A. kunzei (Fée) Aptroot & Lücking comb. nov., A. leioplacum (Müll. Arg.) Aptroot & Lücking comb. nov., A. lugescens (Nyl.) Aptroot & Lücking comb. nov., A. luridum (Zahlbr.) Aptroot & Lücking comb. nov., A. macrocarpum (Fée) Aptroot & Lücking comb. nov., A. macrosporum (Makhija & Patw.) Aptroot & Lücking comb. nov., A. marcidum (Fée) Aptroot & Lücking comb. nov., A. megaleium (Kremp.) Aptroot & Lücking comb. nov., A. megalophthalmum (Müll. Arg.) Aptroot & Lücking comb. nov., A. megalostomum (Vain.) Aptroot & Lücking comb. nov., A. megaspermum (Mont.) Aptroot & Lücking comb. nov., A. meiophorum (Nyl.) Aptroot & Lücking comb. nov., A. meristosporoides (P. M. McCarthy & Vongshew.) Aptroot & Lücking comb. nov., A. meristosporum (Mont. & Bosch) Aptroot & Lücking comb. nov., A. neogalbineum (R. C. Harris) Aptroot & Lücking comb. nov., A. nigratum (Müll. Arg.) Aptroot & Lücking comb. et stat. nov., A. nigrorufum (Makhija & Patw.) Aptroot & Lücking comb. nov., A. nitidiusculum (Nyl.) Aptroot & Lücking comb. nov., A. octosporum (Vain.) Aptroot & Lücking comb. nov., A. oligocarpum (Müll. Arg.) Aptroot & Lücking comb. nov., A. olivaceofuscum (Zenker) Aptroot & Lücking comb. nov., A. papillosum (P. M. McCarthy) Aptroot & Lücking comb. nov., A. papulosum (Nyl.) Aptroot & Lücking comb. nov., A. peranceps (Kremp.) Aptroot & Lücking comb. nov., A. phaeothelium (Nyl.) Aptroot & Lücking comb. nov., A. phlyctaenua (Fée) Aptroot & Lücking comb. nov., A. porosum (Ach.) Aptroot & Lücking comb. nov., A. praetervisum (Müll. Arg.) Aptroot & Lücking comb. nov., A. pseudoplatystomum (Makhija & Patw.) Aptroot & Lücking comb. nov., A. pseudovariatum (Upreti & Ajay Singh) Aptroot & Lücking comb. nov., A. puiggarii (Müll. Arg.) Aptroot & Lücking comb. nov., A. pulcherrimum (Fée) Aptroot & Lücking comb. nov., A. pupula (Ach.) Aptroot & Lücking comb. nov., A. purpurascens (Müll. Arg.) Aptroot & Lücking comb. nov., A. pustulatum (Vain.) Aptroot & Lücking comb. nov., A. rufescens (Müll. Arg.) Aptroot & Lücking comb. et stat. nov., A. sanguinarium (Malme) Aptroot & Lücking comb. nov., A. santessonii (Letr.-Gal.) Aptroot & Lücking comb. nov., A. saxicola (Malme) Aptroot & Lücking comb. nov., A. scoria (Fée) Aptroot & Lücking comb. nov., A. scorizum (Müll. Arg.) Aptroot & Lücking comb. nov., A. sierraleonense (C. W. Dodge) Aptroot & Lücking comb. nov., A. sikkimense (Makhija & Patw.) Aptroot & Lücking comb. nov., A. spectabile (Aptroot & Ferraro) Aptroot & Lücking comb. nov., A. sphaerioides (Mont.) Aptroot & Lücking comb. nov., A. stramineum (Malme) Aptroot & Lücking comb. nov., A. straminicolor (Nyl.) Aptroot & Lücking comb. nov., A. subcatervarium (Malme) Aptroot & Lücking comb. nov., A. subdiscretum (Nyl.) Aptroot & Lücking comb. nov., A. subdisjunctum (Müll. Arg.) Aptroot & Lücking comb. nov., A. subdissocians (Nyl. ex Vain.) Aptroot & Lücking comb. et stat. nov., A. superbum (Fr.) Aptroot & Lücking comb. nov., A. tenue (Aptroot) Aptroot & Lücking comb. nov., A. thelotremoides (Nyl.) Aptroot & Lücking comb. nov., A. trypethelizans (Nyl.) Aptroot & Lücking comb. nov., A. tuberculosum (Vain.) Aptroot & Lücking comb. nov., A. ubianense (Vain.) Aptroot & Lücking comb. nov., A. variatum (Nyl.) Aptroot & Lücking comb. nov., A. vezdae (Makhija & Patw.) Aptroot & Lücking comb. nov., Bathelium austroafricanum (Zahlbr.) Aptroot & Lücking comb. nov., B. nigroporum (Makhija & Patw.) Aptroot & Lücking comb. nov., Bogoriella alata (Groenh. ex Aptroot) Aptroot & Lücking comb. nov., B. annonacea (Müll. Arg.) Aptroot & Lücking comb. nov., B. apposita (Nyl.) Aptroot & Lücking comb. nov., B. captiosa (Kremp.) Aptroot & Lücking comb. nov., B. collospora (Vain.) Aptroot & Lücking comb. nov., B. confluens (Müll. Arg.) Aptroot & Lücking comb. nov., B. conothelena (Nyl.) Aptroot & Lücking comb. nov., B. decipiens (Müll. Arg.) Aptroot & Lücking comb. nov., B. exigua (Müll. Arg.) Aptroot & Lücking comb. nov., B. fumosula (Zahlbr.) Aptroot & Lücking comb. nov., B. hemisphaerica (Müll. Arg.) Aptroot & Lücking comb. nov., B. lateralis (Sipman) Aptroot & Lücking comb. nov., B. leuckertii (D. Hawksw. & J. C. David) Aptroot & Lücking comb. nov., B. macrocarpa (Komposch, Aptroot & Hafellner) Aptroot & Lücking comb. nov., B. megaspora (Aptroot & M. Cáceres) Aptroot & Lücking comb. nov., B. miculiformis (Nyl. ex Müll. Arg.) Aptroot & Lücking comb. nov., B. minutula (Zahlbr.) Aptroot & Lücking comb. nov., B. modesta (Müll. Arg.) Aptroot & Lücking comb. nov., B. nonensis (Stirt.) Aptroot & Lücking comb. nov., B. obovata (Stirt.) Aptroot & Lücking comb. nov., B. pachytheca (Sacc. & Syd.) Aptroot & Lücking comb. nov., B. punctata (Aptroot) Aptroot & Lücking comb. nov., B. queenslandica (Müll. Arg.) Aptroot & Lücking comb. nov., B. socialis (Zahlbr.) Aptroot & Lücking comb. nov., B. striguloides (Sérus. & Aptroot) Aptroot & Lücking comb. nov., B. subfallens (Müll. Arg.) Aptroot & Lücking comb. nov., B. thelena (Ach.) Aptroot & Lücking comb. nov., B. triangularis (Aptroot) Aptroot & Lücking comb. nov., B. xanthonica (Komposch, Aptroot & Hafellner) Aptroot & Lücking comb. nov., Constrictolumina esenbeckiana (Fée) Lücking, M. P. Nelsen & Aptroot comb. nov., C. leucostoma (Müll. Arg.) Lücking, M. P. Nelsen & Aptroot comb. nov., C. lyrata (R. C. Harris) Lücking, M. P. Nelsen & Aptroot comb. nov., C. majuscula (Nyl.) Lücking, M. P. Nelsen & Aptroot comb. nov., C. malaccitula (Nyl.) Lücking, M. P. Nelsen & Aptroot comb. nov., C. porospora (Vain.) Lücking, M. P. Nelsen & Aptroot comb. nov., Dictyomeridium amylosporum (Vain.) Aptroot, M. P. Nelsen & Lücking comb. nov., D. campylothelioides (Aptroot & Sipman) Aptroot, M. P. Nelsen & Lücking comb. nov., D. immersum (Aptroot, A. A. Menezes & M. Cáceres) Aptroot, M. P. Nelsen & Lücking comb. nov., D. isohypocrellinum (Xavier-Leite, M. Cáceres & Aptroot) Aptroot, M. P. Nelsen & Lücking comb. nov., D. paraproponens (Aptroot, M. Cáceres & E. L. Lima) Aptroot, M. P. Nelsen & Lücking comb. nov., Distothelia rubrostoma (Aptroot) Aptroot & Lücking comb. nov., Phyllobathelium chlorogastricum (Müll. Arg.) Aptroot & Lücking comb. nov., Pseudopyrenula cubana (Müll. Arg.) Aptroot & Lücking comb. nov., Viridothelium cinereoglaucescens (Vain.) Lücking, M. P. Nelsen & Aptroot comb. nov., V. indutum (Stirt.) Aptroot & Lücking comb. nov., and V. megaspermum (Makhija & Patw.) Aptroot & Lücking comb. nov. In addition, six replacement names are proposed: Astrothelium campylocartilagineum Aptroot & Lücking nom. nov., A. grossoides Aptroot & Lücking nom. nov., A. octosporoides Aptroot & Lücking nom. nov., A. scoriothelium Aptroot & Lücking nom. nov., A. pyrenastrosulphureum Aptroot & Lücking nom. nov., and Bathelium pruinolucens Aptroot & Lücking nom. et stat. nov. Along with this, 57 lectotypes are newly designated. Most species (392 out of 418) are illustrated, with a total of 697 images in 59 plates, including 406 type specimens. Where appropriate, taxa are briefly discussed. New country or continental records are listed for many species in their revised circumscription. A checklist of taxa described or placed in genera belonging in Trypetheliaceae but previously excluded from the family, and their current names, is also provided.

A quantitative prediction of global species richness in the lichenized family Trypetheliaceae employing a grid method previously used in similar approaches for the family Graphidaceae and the genus Cora (Hygrophoraceae) is provided. 421 currently known taxa were used as a base for the calculation and we predict a total of nearly 800 species, corresponding to an increase of almost 100%. Most of the unrecognized taxa are predicted to occur in the Neotropics, which have the highest known species richness. The Palaeotropics are less diverse. In contrast to Graphidaceae, which are mostly confined to rainforests, Trypetheliaceae show substantial species richness in dry forest and savannah ecosystems, and future collection efforts should take well-preserved areas representing such ecosystems into consideration.

The genus Rinodina (Physciaceae), with approximately 300 species, has been subject to few phylogenetic studies. Consequently taxonomic hypotheses in Rinodina are largely reliant on phenotypic data, while hypotheses incorporating DNA dependent methods remain to be tested. Here we investigate Rinodina degeliana/R. subparieta and the Rinodina mniaraea group, which previously have not been subjected to comprehensive molecular and phenotypic studies. We conducted detailed morphological, anatomical, chemical, molecular phylogenetic and species delimitation studies including 24 newly sequenced specimens. We propose that Rinodina degeliana and R. subparieta are conspecific and that chemical morphs within the R. mniaraea group should be recognized as distinct species. We also propose the placement of the recently described genus Oxnerella in Physciaceae.

Three new species of Diploicia are described from the Galapagos Islands and a fourth, D. glebosa, is transferred from Pyxine; all four are considered endemic to the archipelago. In order to accommodate these species, the generic concept of Diploicia has been emended. Two of the species are sterile; D. leproidica is placodioid-leproid, where the thalli derive from pseudocorticate granules aggregating into small, placodioid rosettes with distinctly lobate margins. The second sterile species, D. squamulosa, forms scattered squamules that eventually aggregate into small, placodioid rosettes. The two fertile species, D. glebosa, with an olivaceous to beige, smooth, epruinose upper surface, and D. neotropica, with a white to grey-white, roughened, pruinose upper surface, form larger thalli typical of Diploicia, have apothecia that are initially lecideine, but are soon engulfed and hidden by a thick thalline margin. Anatomically the proper exciple remains visible for a considerable part of the ontogeny, although it eventually becomes almost completely reduced to a few pigmented or almost hyaline hyphae. This transition from lecideine to lecanorine apothecia is similar to the physciaeformis-type ontogeny observed in some Pyxine species. Several species currently accommodated in Buellia s. lat. with diploicin and effigurate thalli that lack distinctly lobate margins are discussed and the Socotran endemic Physcia endopyxinea is transferred into Diploicia.