Examination of specimens of Peltigera didactyla, from Africa, Asia, Europe and North America revealed that this sorediate species includes three entities that can be separated on morphological characters. A new species, P. lambinonii, is described from East Africa, and a new combination P. didactyla var. extenuata, is proposed to accommodate morphs from mesic forest habitats in Asia, Europe and North America. Despite this taxonomic reduction, P. didactyla var. didactyla remains a ubiquitous taxon. The former two taxa often produce methyl gyrophorate, which can co-occur with traces of gyrophoric acid. These tridepsides were only rarely detected in var. didactyla; their occasional presence seems to be best explained by hybridization. The taxonomic and ecological significance of these substances is discussed.

The new lichen genus Sergipea M. Cáceres, Ertz & Aptroot is described in the Roccellaceae, based on the new species Sergipea aurata M. Cáceres, Ertz & Aptroot from NE Brazil. The species was found in a remnant of Atlantic transition forest in Sergipe. It is similar in many respects to species of the genus Enterographa, but it is characterized by bright orange stromata, due to the presence of an anthraquinone, and a thallus with a somewhat byssoid hypothallus. Phylogenetically it is close to the genera Dichosporidium and Erythrodecton. The phylogenetic position of the generic type of Dichosporidium confirms the close relationship of the genus to Erythrodecton in the basal branch of the Roccellaceae. A new species of Enterographa is also described from NE Brazil. Enterographa rotundata E. L. Lima, M. Cáceres & Aptroot has solitary, round apothecia, which is unusual in this genus with mainly elongated apothecia or punctiform apothecia arranged in lines. It was found in Caatinga forest in Pernambuco.

Five new species and one new record of Astrothelium (Trypetheliaceae) are reported from Thailand. Phylogenetic analysis of four DNA loci (ITS, nuLSU, mtSSU rDNA and RPB1) demonstrated the placement of the new species within Astrothelium, as well as their distinction from similar or related taxa. The new species are: A. flavocoronatum, with a yellow pigment surrounding the ostiole, and 3-septate ascospores 22–28×8·0–9·5 µm; A. macrostiolatum, with large whitish ostiolar area, a hamathecium inspersed with small oil droplets, and 9–11-septate ascospores 80–100×17–19 µm; A. neglectum, with lichexanthone on the thallus and pseudostromata, a non-inspersed hamathecium and 3–5-septate ascospores 21–25×7·5–9·5 µm; A. neovariolosum, with inspersed hamathecium and 3-septate ascospores 17–23×6–7 µm; and A. siamense, with inspersed hamathecium and 4–7-septate ascospores 30–50×10·5–12·0 µm. Astrothelium aenascens is reported from Thailand for the first time.

Tremella cetrariicola is shown to be heterogeneous and to represent two phylogenetic sister species, which are shown here to be distinct in the morphology of the galls, basidia and basidiospores, and in their host selection. Tremella cetrariicola s. str. is confined to Tuckermannopsis, whilst the material on Cetrariella delisei is described here as the new Tremella cetrariellae. The new species is known from Finland, Greenland, Norway, Russia, Svalbard, and Sweden.

The Tasmanian species of the family Thelotremataceae with thin-walled ascospores and exfoliating, chroodiscoid apothecia are studied in detail. Problems in the delimitation of genera are discussed, and characters such as the morphology of the apothecia, structure and form of the exciple, presence of periphyses, ascus structure, ascospore morphology and thallus chemistry are evaluated. The concept of the typically foliicolous genus Chroodiscus (Müll. Arg.) Müll. Arg. is expanded to include corticolous and terricolous species, and the new taxa C. asteliae Kantvilas & Vězda, C. australis Kantvilas & Vězda, C. australis subsp. tasmanicus Kantvilas & Vězda, C. lamelliferus Kantvilas & Vězda and C. minor Kantvilas & Vězda are described and illustrated. The related Australasian species, C. megalophthalmus (Müll. Arg.) Vězda & Kantvilas is also treated. Two new genera are also described. Pseudoramonia Kantvilas & Vězda, based on the Venezuelan species, P. stipitata (Vězda & Hertel) Kantvilas & Vězda, is introduced to accommodate P. richeae Kantvilas & Vězda; Topeliopsis Kantvilas & Vězda is described to include the Tasmanian taxa, T. muscicola Kantvilas & Vězda and T. rugosa Kantvilas & Vězda, and the North American species T. toensbergii Vězda & Kantvilas.

The use of ascoma ontogeny in the systematics of lichenized ascomycetes is reviewed briefly. Two recently studied examples are discussed to illustrate the use of ontogenetic studies to discover phylogenetic relationships. As one example, the Agyriaceae was mainly circumscribed by the ascus type and included diverse genera. Xylographa is characterized by lirelliform apothecia. However, the ascoma development shares the ontogenetic pattern observed in Trapelia and its placement in the family was confirmed. In contrast, Anamylopsora exhibited a substantially different apothecial development and was separated as a family of its own. As a second example, the Candelariaceae is based on chemical characters. With the detection of pulvinic acid derivatives also in the genus Lecanora, the distinction of the Candelariaceae and Lecanoraceae became doubtful. Therefore, the ascoma ontogeny was employed to evaluate this classification and is illustrated here in detail for Candelaria fibrosa. The substantial similarity of the ascoma development found in both families suggests that both might be better united. Finally, a general discussion of the significance of ontogenetic characters in lichen taxonomy is included.

A cyclic exchange between communities of mosses and the lichen Baeomyces rufus is described. The cushions of different mosses are supplanted by the lichen. After a lifespan of about 3 years the lichen dies off and the location is repossessed by mosses. The vegetative reproduction of the lichen is adapted to this ecological cycle.

The new taxa Cliostomum subtenerum, Dactylospora suburceolata, Fuscidea oceanica, Lecania granulata, Lecidea herteliana, and Ropalospora lugubris f. sorediata are described from collections made from Scotland and Wales. Outside the British Isles, D. suburceolata is also known from Switzerland, L. herteliana from NE North America and R. lugubris f. sorediata from Sweden and NE North America. In addition, Lecidea luteoatra Nyl. belongs to the Lecanora marginata group and the name Lecanora viridiatra (Stenh.) Nyl. is taken up for this species, Peterjamesia sorediata is transferred to Roccellographa, and Ropalospora atroumbrina is included in the synonymy of R. lugubris f. sorediata.

The new genus Vahliella is recognized as a genus since molecular studies have shown that the subgenus Micropannaria of Fuscopannaria differs so much from this genus that it cannot even be placed in the Pannariaceae. While its family position remains unclear, it is certainly best established as a genus, as it is recognizable also on morphological and chemical characters. Unlike the mainly warm-temperate genus Fuscopannaria, it is restricted to cold-temperate regions. Presently it is known to contain eight species, a key to which is given. The following new combinations are introduced: Vahliella adnata (P. M. Jørg. & Upreti), Vahliella atlantica (P. M. Jørg. & P. W. James), Vahliella californica (Tuck.), Vahliella globuligera (Fryday & P. M. Jørg.), Vahliella hookerioides (P. M. Jørg.), Vahliella labrata (P. M. Jørg.), Vahliella leucophaea (Vahl), Vahliella saubinetii (Mont.).

Tyrosinases are a widespread family of multicopper oxidase enzymes. In our earlier work, we identified the presence of tyrosinases in lichenized Ascomycetes based on their substratum specificity, sensitivity to inhibitors and molecular mass. Here, we present a more detailed characterization of a tyrosinase from the lichen Lobaria pulmonaria. We also compare tyrosinase activity with the activities of laccases and peroxidases, the other redox enzymes present in this species. The importance of tyrosinases in lichen biology was studied by testing their role in melanin synthesis. Laboratory experiments clearly showed that tyrosinases from L. pulmonaria resemble those from other lichens and in free-living fungi. While the tyrosinases can metabolize the melanin precursor L-DOPA, L-DOPA can also be metabolized by peroxidases and laccases. A field experiment showed that exposing shade-adapted L. pulmonaria to normal solar radiation induces L-DOPA melanin synthesis. Synthesis occurred when lichens were exposed to either direct sunlight, or placed under a wavelength-neutral filter that slightly reduced overall light. In lichens receiving unfiltered sunlight, melanin synthesis was accompanied by increased laccase activity; by contrast, no changes in enzyme activity occurred in lichens placed under the wavelength-neutral filter. Melanization was reduced by placing lichens under filters that removed UV-B, and prevented by filters that removed both UV-A and UV-B. Removing UV-B had no effect on enzyme activity, whereas removing both UV-A and UV-B increased tyrosinase activity. Results from this study indicate that under some conditions laccases may be involved in melanin synthesis, but they provide no evidence for a role for tyrosinases in melanization. Although high tyrosinase activities are widespread in lichens, many questions on the role of this enzyme in lichen biology remain to be answered.

The new species Cryptothecia fabispora and C. lichexanthonica are described from NE Brazil. The first has domed asci with two large, reniform ascospores and the thallus contains psoromic acid. The second contains lichexanthone and has globose asci. Cryptothecia fabispora was found at the Serra de Itabaiana National Park which represents one of the few rainforest remnants in the state, and is a transitional area with Mata Atlantica influence and also open vegetation spots like Caatinga. It was also found in Caxiuaná in Amazonian Para and may well occur elsewhere. Cryptothecia lichexanthonica was collected at Vale do Catimbau National Park in Pernambuco, which is in a Caatinga area.

The phylogeny of the Micareaceae and the genus Micarea Fr. was studied using 39 nuclear small subunit ribosomal DNA sequences. Phylogenetic analyses were carried out using maximum parsimony, maximum likelihood, and Bayesian inference. A confidence set of trees was estimated using expected likelihood weights to investigate a series of hypotheses of monophyly. Tree topologies were very similar between methods and differed only in the placement of a few poorly supported branches. The results indicate that the Micareaceae in its current circumscription belongs in the Lecanorales, but that it is not monophyletic. Psilolechia, Micarea with a ‘non-micareoid’ photobiont, Micarea sensu stricto and Byssoloma form a paraphyletic grade in this study. Micarea sensu stricto and Byssoloma (Pilocarpaceae) form a strongly supported monophyletic group, which constitutes the sister group to the Bacidiaceae. Scoliciosporum A. Massal has sometimes been considered close to Micarea, but no support was found for that hypothesis.

Verrucaria nodosa sp. nov. and V. rosula sp. nov. each have a thallus composed of initially discrete units which coalesce and overlap with age, forming an uneven crust. They are related species and similar in appearance, but the thallus units are coarser in Verrucaria nodosa, and the involucrellum is typically more regularly thickened than in V. rosula. Verrucaria placida sp. nov. has a smooth, subgelatinous thallus; it is related to V. hydrophila sp. nov. but differs in the larger ascospores and perithecia. It is not closely related to V. andesiatica but is morphologically similar, differing mainly in the narrower ascospores. Verrucaria hydrophila has been widely known as V. hydrela auct., non Ach. or V. denudata Zsch. nom. illeg. Verrucaria laevata Ach. is considered to be a nomen dubium.

Topelia nimisiana Tretiach & Vězda is described from old Quercus pedunculata bark in Castelporziano, near Rome (Italy). It is characterized by a hymenium inspersed by numerous oil droplets, by immersed, perithecioid ascomata and by a continuous, dark green thallus.

Bacidina flavoleprosa is described as a new species from the Czech Republic. Its position within the genus is supported by phylogenetic inferences of ITS rDNA sequences from its holotype and many other representatives of Bacidia s. lat., including newly sequenced Bacidina sulphurella, B. adastra and B. neosquamulosa, as well as additional sequences of B. arnoldiana. ITS data also support the recent delimitation of B. arnoldiana and B. sulphurella based on the shape of conidia and ecological preferences.

The species assigned to the genus Catillochroma are reassessed. The two characters used to characterize Catillochroma, exciple anatomy and thalline chemistry, are shown to be variable and contradictory with a number of intermediates. Consequently, Catillochroma is reduced to synonymy with Megalaria, and the species previously placed in Catillochroma transferred, or returned, to Megalaria. As such, the following new combinations are proposed: Megalaria anaglyptica, M. endochroma, M. intermiscens and M. leptocheila. The genus Lopezaria is also shown to be related to Megalaria and to be closely related to the type species of Catillochroma, C. endochroma, and so is also reduced to synonymy with Megalaria. A number of species found to have been misplaced in Catillaria are also transferred to Megalaria: M. leucochlora, M. melanopotamica, M. obludens, M. pannosa and M. phaeolomiza. Megalaria imshaugii is reduced to synonymy with M. obludens, Megalaria pannosa is reported for the first time from North America and Lopezaria isidiza is reported for the first time from outside Asia from Jamaica.

In North America the names Punctelia subrudecta and P. perreticulata have variously been applied to corticolous sorediate Punctelia specimens with lecanoric acid and a pale lower surface. ITS1, 5.8S, and ITS2 sequence data were generated from a geographically and morphologically broad sampling from within these specimens, and a molecular phylogeny was inferred. A combined approach using morphology, geography, and phylogeny was used to circumscribe three distinct species in North America, one of which is described as new to science (P. caseana), one of which is finally confirmed for the continent (P. jeckeri), and one whose original circumscription is validated (P. perreticulata). The phylogeny inferred from ITS sequence data supports the taxonomic value of the following morphological characters for distinguishing species in this group: presence/absence of pruina; conidium type and length (although see discussion of P. jeckeri), and presence/absence of scrobiculae on the upper surface. A key to the North American species of Punctelia is provided.