The genus Usnea is a conspicuous component of the macrolichen vegetation in Macaronesia. Ten species are recognized in the Azorean archipelago: Usnea cornuta Körb., U. esperantiana P. Clerc, U. flammea Stirt., U. geissleriana P. Clerc sp. nov., U. krogiana P. Clerc sp. nov., U. macaronesica P. Clerc sp. nov., U. rubicunda Stirt., U. silesiaca Motyka, U. subflammea P. Clerc sp. nov., and U. subscabrosa Motyka. All these species occur in the Canary Islands as well. Descriptive, chemical, ecological and distributional data for each species are provided. Species that have been recorded once for the Azores but not seen, or that are doubtful or excluded in this work, are briefly discussed.

The Caloplaca citrina group in the Nordic countries, except Iceland, is analysed with regard to morphology, anatomy, ecology, and chemistry. Their genetic relationship is also analysed using the ITS ribosomal DNA gene. The results show that there are at least five species within what has been called C. citrina, of which four are closely related to one another and to several non-sorediate species. Three of these, C. citrina, C. flavocitrina and C. arcis have previously been recognized at specific or varietal level some time during the last two centuries, whereas the fourth species, C. dichroa, is described as new. The fifth species, C. phlogina, is not related to the other species but shows a close relationship to the Xanthoria candelaria group. The species are described and illustrated in colour. Distribution maps are given for the study area and a key to sorediate, yellow to orange species occurring in the Nordic countries, except Iceland, is also provided.

Current knowledge about the non-lichenized genus Chaenothecopsis in Switzerland is reviewed. A characterization of the genus and a key to all accepted European taxa are presented, excluding the little known resinicolous species. The distribution of the 15 Chaenothecopsis species recorded in Switzerland is briefly summarized. Specimens in the herbaria belong mainly to C. pusilla, C. rubescens and C. viridialba; recent collections include rarer species such as C. hospitans, C. ochroleuca, C. retinens and C. tasmanica. It seems that many taxa occur predominantly in montane to subalpine forests in the Northern Prealps, although distributional data are still scarce.

“Quality and Quantity: maintaining biological diversity in space and time”—Session II of the 5th Symposium of the International Association for Lichenology, Tartu, Estonia, 16–21 August 2004. As naturalists and especially as lichenologists, we would all agree that lichen diversity is desirable for its own sake. A species-poor forest looks ‘wrong’ to an experienced outdoors-person, and, conversely, a lichen-rich forest is a delight, even if the viewer knows nothing about lichens per se. This is why many people, not just lichen-lovers, agonize over the loss of lichen diversity in our natural landscape.

Caloplaca sorediella Arup is described as a new species. It is so far known only from extreme maritime situations on seashore rocks in western England, Scotland and Wales.

Lithographa serpentina Coppins & Fryday is newly described from Campbell Island (New Zealand), and is unique within its genus and order for having submuriform ascospores. Also newly described are Lithographa opegraphoides Coppins & Fryday from the Falkland Isles, Rimularia actinostoma Coppins & Fryday from Canada (British Columbia), and Rimularia austrolimborina Coppins & Fryday from southern Chile. The new combination Lithographa graphidioides (Cromb.) Imshaug ex Coppins & Fryday is made to accommodate the previously misunderstood Stigmatidium graphidioides Cromb. and the more recently described Lithographa subantarctica Hertel & Rambold. A key to all described species of Lithographa is provided.

The new species Lepraria santosii Argüello & Crespo is described from the Canary Islands. It is characterized by a crustose to subsquamulose thallus with slightly raised rim and the presence of atranorin and the stictic acid chemosyndrome. It is currently known from Tenerife (Canary Islands), where it grows on soil over basaltic rocks in the laurel forest. Twelve new sequences of the ITS region from this species and L. isidiata were obtained and analysed with sequences downloaded from GenBank. Maximum parsimony and Bayesian analyses suggest that Lepraria santosii is closely related to L. isidiata. The latter name is here lectotypified and the characters for the distinction of the two species from similar taxa are discussed.

The lichen genus Lepraria in Poland, comprising 17 species, is reviewed: for each taxon, remarks on the chemistry, distribution and habitat preferences are provided. Distribution maps are also presented, together with a key for determination of the Polish species. Lepraria diffusa var. chrysodetoides is reduced to a synonym of L. diffusa s. str., a new chemotype with a new substance is reported for L. neglecta, and rangiformic acid is reported for the first time for chemotype III of L. caesioalba. Lepraria borealis is reported for the first time from Africa (Canary Islands) and L. nigrocincta from Nepal.

The new species, Polysporina frigida Kantvilas & Seppelt is described and illustrated. It is the first record of this genus from the Antarctic continent.

Arthopyrenia tuscanensis Coppins & S. Ravera and A. coppinsii S. Ravera are described as new to science. They share the characteristic tadpole-shaped ascospores with a conical lower cell, but are otherwise comparable to A. salicis A. Massal.

Bacidia pycnidiata sp. nov. (Ramalinaceae) is described from Poland and the Czech Republic. It is the first species within Bacidia s. lat., referable to the Bacidina group, known to have sessile, long-necked, lageniform pycnidia bearing straight macroconidia. It has been found growing on saxicolous as well as on corticolous bryophytes and directly on bark of deciduous trees within young, hardly changed woodlands or in the vicinity of human settlements.

Three new species of Lepraria, L. celata, L. humida, and L. sylvicola, are described from Europe. They each possess a finely granular unstratified thallus containing fatty acids and atranorin, but can be distinguished from each other by the type of fatty acids present and by their ecology. Anthraquinones are present in subthalline hyphae of L. humida and L. sylvicola, and are also reported for L. atlantica. Toensbergianic acid can be produced by L. jackii as a minor compound. A key is presented to species of Lepraria containing fatty acids and atranorin as major substances.

The distribution of lichen species in upland regions of Aberdeenshire, Scotland, is investigated along a landuse gradient from natural forest to intensive agriculture. Quantitative data on lichen communities on saxicolous, epiphytic and terricolous substrata were collected from 16 hectares in one km2 in each landuse type. Multivariate analyses, NMDS and Cluster analysis were used to identify lichen communities associated with environmental factors including landuse, substratum type and age. The epiphytic community of native pinewoods was distinguished from all others by the highest species richness, the presence of indicators of ecological continuity and the absence of nitrophytes, while the epiphytic communities of farmland were distinguished by absence of acidophytes and a high contribution of nitrophytes. Plantations of conifers were distinguished by low species richness and an increase in tolerant species. Saxicolous communities were frequent on walls in all sites except native pinewood, where saxicolous substrata were rare. Intensively farmed sites were distinguished by an increase in percentage contribution of nitrophytes. The high acidophyte contribution in all sites suggests that crustose species of acid rocks may not respond rapidly to an increase in applied nitrogen. In landscapes where tree cover is sparse or non-existent combined assessment of habitat diversity and nitrophyte indicator species can be used to assess changes associated with agricultural intensification.

The new genus and species Nyungwea pallida is characterized by a thin thallus lichenized with Trentepohlia and pale stipes producing goniocysts. Its taxonomic position is uncertain. It is named after the large pristine montane forest of Nyungwe in Rwanda (East Africa) where it was first found; it is also known from the Mabira forest in Uganda.

Caloplaca badioreagens is a new endolithic species of subgenus Pyrenodesmia characterized by a greyish brown, K+ reddish brown epithecium, and simple, non-capitate paraphyses. It is readily distinguishable from other endolithic Pyrenodesmias (C. agardhiana, C. alociza, C. erodens) by the presence of an unknown lichen substance in the excipulum and the subhymenium, forming large, rectangular crystal plates in GAW and GE. The new species was collected on hard limestone in three localities of central and southern Italy.

The new lichenicolous fungus, Gelatinopsis leptogii, is described from Belgium and Germany, where it grows on Leptogium byssinum. It differs from G. ericetorum, which grows on Dibaeis, in the shorter and broader ascospores and different ascomatal pigments, and from G. roccellae, which grows on Roccella, in the shorter ascospores and larger ascomata.

Bactrospora perspiralis, B. subdryina, Enterographa mesomela, Graphidastra laii and Lecanographa atropunctata (Roccellaceae) are described as new to science based on specimens collected in the wet subtropical lowlands of northern Thailand and Vietnam. The new Graphidastra is the third species in the genus and was also found in Taiwan.

Two new Pertusaria species with brown ascospores are described from southern California and Baja California, Mexico. Pertusaria islandica sp. nov. is characterized by pertusariate to pseudolecanorate ascomata, ellipsoid ascospores, 8-spored asci, a strongly K+ violet reacting epithecium, and the presence of the 2′-O-methylperlatolic acid chemosyndrome, while P. occidentalis sp. nov. has pertusariate ascomata, globose to subglobose ascospores, 8-spored asci, and contains the arthothelin chemosyndrome. Pertusaria ochracea Kremp. is reduced to synonymy with P. melanospora Nyl.

Porina pilifera Neuwirth sp. nov. is described from Costa Rica. It is similar to P. palmicola, but differs in having smaller ascospores 27–36×3–4 μm. Porina pilifera is only known from the type locality in tropical Central America, where it grows on the leaves of palm trees.

Topeliopsis darlingtonii A. Frisch & Kalb and Topeliopsis elixii A. Frisch & Kalb from Australia and Topeliopsis meridensis Kalb & A. Frisch from Venezuela are described as new species. Thelotrema decorticans Müll. Arg. and Ocellularia subdenticulata Zahlbr. are transferred to Topeliopsis and are the correct names for T. corticola Kalb and T. vezdae Kalb, respectively. A revised key of the genus Topeliopsis is presented. Ascoconidia, produced in old ascospores of T. elixii, are described for the first time for the Thelotremataceae.