Lecanactis rubra is described as new to science. It is characterized by having rounded to irregular or lirellate ascomata, relatively wide 3-septate ascospores and by the production of gyrophoric acid and an anthraquinone. The species is known only from the type locality in the deciduous dry forests in the western part of Madagascar.

Standardized lichen surveys were conducted on 849 trees in 132 ecological long-term observation plots in the Swiss Plateau and Pre-Alps: 262 lichen taxa were identified, 64 (24%) of them sorediate crustose species. Their mean percentage of the flora on individual trees and in individual plots was even higher. The mean percentage of crustose lichen species with vegetative propagules, such as soredia, was per plot significantly higher in the Pre-Alps than in the Plateau, higher in forest than in non-forest areas, and, according to the vegetation belts, lowest in the colline-submontane zone. It was found that the biodiversity of lichens could not be determined without considering the sorediate crustose lichens. Furthermore, by performing standardized surveys of all taxa, the occurrence of the following species in Switzerland was confirmed for the first time: Cliostomum leprosum, Fuscidea arboricola, Fuscidea pusilla, Hypocenomyce leucococca, Hypocenomyce sorophora, Lecanora norvegica, Lepraria eburnea, Lepraria elobata, Lepraria jackii, Lepraria obtusatica, Lepraria rigidula, Pertusaria boreahs and Rinodina griseosoralifera. Seven taxa that displayed distinctive chemistry, could not yet be identified.

A new sorediate species of Rinodina (R. algarvensis sp. nov.) is describedfrom SouthPortugal, where it grows on siliceous rocks. It is mainly characterized by its distinctivechemistry, being the only saxicolous Rinodina species hitherto known to contain stictic, cryptostictic, norstictic and menegazziaic acids in addition to atranorin and zeorin. It is compared with R. aspersa, a morphologically similar saxicolous species, which also occurs in south-west Europe, and with R. stictica, a corticolous, sorediate, North American species that also contains the stictic acid chemosyndrome.

Two species, Cliostomum coppinsii Fryday & Kantvilas sp. nov. from Scotland, and Cliostomum praepallidum (Müll. Arg.) Kantvilas & Fryday comb. nov. from Tasmania and southern South America, are described, illustrated and discussed. Both occupy an unusual position within the genus on account of their atypically wide, ± polarilocular ascospores. Patellaria banksiae Müll. Arg., based on a collection from Australia, is lectotypified and reduced to synonymy with Cliostomum griffithii (Sm.) Coppins.

Xanthoria elegans has a broad ecological amplitude, world-wide distribution and includes morphological variants which differ markedly with respect to colour, form and frequency of apothecia. Distinctive thallus forms are associated with different habitats. Samples from two contrasting habitats were studied on Ellesmere Island in the Canadian High Arctic. Carotenoids, polyphenolic products and isoenzymes were examined to establish whether two thallus types were biochemically distinct. Pigments were comparable in both morphological variants, as were approximately half of the most frequently occurring enzyme forms. Enzymatic similarity between the two resembled that between conspecific populations of other lichens. On the basis of the chemical attributes investigated, the thallus forms did not warrant recognition as fundamentally distinct entities, but were merely variants of an ecologically versatile and extremely plastic species.

Four new species from Cuba are described in the genus Ocellularia, emphasizing the importance of the Caribbean for the diversification of lichen fungi and the level of unrecognized species richness in Ocellularia. Three of the new species belong in the O. bahiana group: O. coronata Lücking & Pérez-Ortega, differing from O. bahiana by the ridged to folded thallus, vertically ridged apothecia, and complex columella largely covering the disc; O. fuscospora Lücking & Pérez-Ortega, differing from O. urceolaris in the immersed to erumpent, columellate apothecia; and O. radiata Lücking, differing from O. bahiana in the complex, radiating columella filling the disc. In contrast, Ocellularia nigririmis Lücking & Pérez-Ortega is a species of the O. papillata morphodeme with immersed apothecia with a small, black-rimmed pore filled by a greyish black columella, and small ascospores. We also clarify the taxonomy and nomenclature of columellate taxa in the O. bahiana group and provide a key to all thelotremoid Graphidaceae with small, brown, (sub-)muriform ascospores. The new combination Ocellularia lunensis (Nagarkar & Hale) Lücking is proposed.

The new genus and species Ducatina umbilicata is described from Îles Crozet and Îles Kerguelen. This lichen is characterized by an umbilicate thallus with a black verrucose lower surface and a greyish to dark olivaceous smooth upper surface having large verrucae, large semi-immersed cephalodia, semi-immersed apothecia with a prominent thalline margin, simple, mainly ellipsoid ascospores of 23–42×12–25 µm and the presence of unknown chemical compounds. Phylogenetic analyses using nuLSU and mtSSU sequences place Ducatina in the Trapeliaceae (Baeomycetales). The new taxon is closely related to Orceolina antarctica and O. kerguelensis, two other lichens endemic to these subantarctic islands, differing by its morphology and the lack of chemical compounds. Ducatina is the only genus in the Trapeliaceae to develop a large umbilicate thallus.

Internal cephalodia of Lobaria pulmonaria were examined in two British locations, one in western Scotland (Isle of Skye) and the other in England (Cumbria, Lake District), sites which were predicted to have contrasting levels of fixed nitrogen deposition. Cephalodia were found to occupy a small proportion of the total biomass averaging (<1%) in both areas. Modelled nitrogen deposition in the sites in Cumbria was 3–6 times higher than in the Skye sites but the cephalodium relative biomass was not significantly different. It is suggested that local climatic and topographic effects might have reduced the estimated rate of nitrogen deposition at the former sites.

Illustrated descriptions are provided for four new lichen species found in The Seychelles: Arthothelium feuereri Aptroot & Seaward, Dimerella straminea Aptroot & Seaward, D. subsquamosa Aptroot & Seaward and Fellhanera silhouettae Aptroot & Seaward.