Leptogium imbricatum P.M. Jorg. sp. nov. and L. intermedium (Arnold)Arnold are established as the correct names for two fairly widespread, small species:L. imbricatum has an arctic–alpine distribution. Leptogium intermedium was previously mostly named L. minutissimum (Florke) Fr., the type of which is L. subtile (Schrader) Torss., a distinct species usually growing on rotting wood or debris. Leptogium magnussonii Degel. & P.M. Jorg, mainly from maritime rock outcrops in Norway and Sweden, is described as new. The species complexes of L. plicatile (Ach.) Leighton and L. schraderi (Bernh.) Nyl. are discussed. The differences between L. byssinum (Hoffm.) Nyl. and L. biatorinum (Nyl.) Leighton are given, and L. aquale (Arnold) P.M. Jørg. comb, nov., a taxon related to the latter, is considered to be a distinct species growing in mountain brooks in Central Europe. Leptogium rivale Tuck, is recorded as new to Europe, from Romania. Leptogium bellopratense Hy is shown to be a synonym of L. brebissonii Mont. New records for L. coralloideum (Meyen & Flotow) Vainio, L. massiliense Nyl. and L. rivulare (Ach.) Mont, are given.A preliminary key to the small European species (north of the Alps) is appended. The following names have been lecto– or neotypified: Collema byssinum Hoffm., Collema pulvinatum Hoffm., Leptogium bellopratense Hy., Leptogium crenulatum Watson, Leptogium massiliense Nyl., Leptogium minutissimum var. intermedium Arnold, Leptogium minutissimum f. plumbeum Zwackh ex Arnold, Leptogium pusillum var. aquale Arnold, Leptogium rivulare var. crenatulum Nyl., Leptogium scotinum var. crenatum Nyl., Lichen byssinus Hoffm., Lichen minutissimus Flöurke, Lichen schraderi Bernh., Lichen subtilis Schrader and Parmelia scotina var. lophaea Ach.

A description is given for Cetraria obtusata (Schaerer) v. d. Boom & Sipman, comb, et stat. nov., known so far only from the central Alps, and characterized by a pale yellow, C+ yellowish orange medulla and raised pseudocyphellae often surrounded by projections. It contains the rare lichen substance secalonic acid C and two unidentified substances.

The morphology, anatomy, chemistry, ecology and distribution of ‘Buelli’ lindingeri and Rinodina anomala, R. biloculata, R. euskadiensis, R. kalbiiR. madeirensis are treated.Rinodina kalbii from Corsica and Sardinia is described as new. A key to the species is provided.

The lichenicolous fungi Arthrorhaphis aeruginosa R. Sant. & Tønsb. On Cladonia spp. and Arthrorhaphis olivaceae R. Sant. & Tonsb. on Melanelia olivacea are described as new from Norway, Scotland and western North America, and from Sweden, respectively.

Biatora meiocarpa (Nyl.) Arnold (Lecanorales, lichenized Ascomycotina) is described and compared with some of its relatives, particularly B. helvola Körber ex Hellbom (syn. Lecideahelvola), a species with which it has often been confused. Biatora meiocarpa and B. helvola differ in (1) width of the paraphysis tops, (2) hymenium height, (3) apothecium width, (4) gelatinization of the paraphyses, (5) composition of the excipulum (hyphae with ellipsoid or shortly rectangular lumina in B. meiocarpa, narrowly linear lumina in B. helvola), (6) chemistry (1-2 triterpenoids or no substances in B. meiocarpa, gyrophoric acid plus 1-2 triterpenoids in B. helvola), and (7) length and shape of conidia. The variation in the first three characters overlaps but one–way analysis of variance (ANOVA) shows that B. meiocarpa and B. helvola differ significantly in each of these characters. Three further characters were subjected to ANOVA: spore length, spore width and length/width ratio of the spores. No statistically significant differences were observed in these characters.Biatora meiocarpa generally occurs on smooth bark of broad–leaved trees and shrubs. It is known from northern Sweden, Finland, and northwestern Russia

A description is given of the corticolous, sciaphilous lichen associations Ramonio-Stiguletum mediterraneae Bricaud & Roux ass. nov. and Striguletum affinis Bricaud & Roux ass. nov. These associations occur mainly in mesomediterranean Quercus ilex forests and less usually in mesomediterranean or supramediterranean Quercus pubescens forests. The former usually grow on the more or less decayed rhytidome of Quercus ilex, the latter exclusively on Hedera helix trunks.

Gyalidea cylindrical is described as new, living on pleurocarpic epiphytic mosses in shaded situations.Gyalidea phyllophila is recorded for the first time in Europe. Both of them have been collected in the French Atlantic Pyrénées.

The new combination Amandinea petermannii (Hue) Matzer, Mayrh. & Scheidegger; is proposed. The taxonomy, morphology, anatomy, chemistry, ecology and distribution of this lichen are discussed. Rinodina convoluta D. C. Lindsay is synonym of A. petermannii.

Changes in foliicolous lichen populations of the shrub Wilkiea macrophylla in rainforest at Mt Glorious (south-east Queensland) were observed in the field for 3 years. Leaves successively distal from the twig apices were treated as a chronosequence for lichen successional studies. Five species of lichen each colonized more than 50° 0 of the leaves, and leaves successively distal from the apex showed increasing mean species number. Lichen cover rose until the seventh most distal leaf from the first colonized leaf along a twig, reaching 52%. More distal (older) leaves had apparently lower cover. Different lichen species show different instantaneous colonization rates that vary with time. The sequence of lichen colonization and subsequent community composition is best described by a ‘Tolerance’ model of succession if a single leaf is selected as the unit or with a ‘Chronic Disturbance’ model if a leaf population is considered.

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.

Phoma evemiae sp.nov. on Evemia prunastri and Polycoccum slaptoniense sp.nov. (on Xanthoria parietind) are described as new to science. Three further species are reported from the British Isles for the first time: Dactylospora microspore Etayo,Monodictys anaptychiae (Lindau) D. Hawksw., and Sphaerellothecium araneosum (Arnold) Zopf. Notes are also presented on Bispora lichenumDiederich, Opegrapha physciaria (Nyl.) D. Hawksw. & Coppins, Polycoccum kerneri Steiner, Pronectria xanthoriae Lowen & Diederich, Stigmidium degelii R. Sant., and S. hagenii(Rehm) Hafellner.

Two new species are described: .Megalospora occidentalis Kantvilas from Western Australia, with solitary muriform ascospores; M. pulverata Kantvilas from Tasmania, with typically two-spored asci and bicellular ascospores. The new combination M. melanodermia var. galactocarpa (Zahlbr.) Kantvilas is proposed. Megalospora taylori Dodge, described from Tasmania, is a synonym of M. gompholoma subsp. fuscolineata Sipman. New records are reported for Megaloblastenia flavidoatra(Nyl.) Sipman (from Tasmania), .Megalospora disjuncta Sipman (from New South Wales and Queensland), and M. subtuberculosa (Knight) Sipman (from New South Wales). Additional data for Austroblastenia pupa Sipman, M. gompholomasubsp. fuscolineata Sipman and M. lopadioides Sipman, and a key for the family in Australia are presented. M. disjuncta Sipman is lectotypified. Biogeographical and ecological patterns are discussed briefly.

The distribution of epiphytic lichens on branches of a stand of Picea abies has been mapped, and patterns of succession and community structure are described. Many crustose species are of particular interest since little is known about their ecological requirements (e.g. Fuscidea pusilla Tønsb., Japewia subaurifera Muhr & Tønsb. and Gyalideopsis alnicola Noble & Vězda). Numerical treatment (correspondence analysis and canonical correspondence analysis) of the species data was used to study the lichen distribution in relation to measured environmental variables. Tree age, tree height and branch height above ground are shown to be the most important variables to explain the species distribution. No significant relationship was found between branch compass point and the distribution of lichens. The species composition and cover changed from young to old trees. The largest variation in the lichen vegetation was found on the branches of young trees. A more homogeneous and stable lichen community appears on branches of mature trees. A clear zonation of the epiphytic vegetation develops as the branches grow, resulting in the occurrence of typical ‘branch-tip’ and ‘branch-base’ species. The highest number of species was recorded on the outermost part of branches before lichen cover reached the maximum. Hyperepiphytic thalli were mainly located in specific areas with high lichen cover on the branches. Lichens with reduced vitality were most common at the base of branches.

The pinkish galls on Usnea, often called Biatoropsis usnearum are shown to represent basidiomata of a previously unrecognized genus of heterobasidiomycetes with transversely septate basidia, to which the generic name Biatoropsis can be applied. The new genus is tentatively included in the Platygloeales. The hyphomycetous anamorph strongly resembles the genus Hormomyces. Biatoropsis usnearum is very frequent and widely distributed on Usnea, but has also been collected on Protousnea; the galls have been found parasitized by Abrothallus usneae and three species of Lichenoconium. Two other heterobasidiomycetes growing on Usnea are described: Tremella santessonii Diederich sp. nov. from Africa has transversally 1- septate basidia; T. stevensiana Diederich sp. nov. from Australia has longitudinally 1-3-septate basidia and a type of hyphomycetous anamorph poorly known in other species of Tremellales. Several other Tremella–like or gall-forming fungi on Usnea are briefly discussed.

All species of Antarctic Acarosporaceae (s. lat., including Biatorellaceae) with yellow thalli are revised. Four genera, Acarospora, Biatorella, Biatorellopsis, Eklundia, and ten species, all of them endemic, were previously reported from Antarctica. Our results indicate that in Antarctica Acarospora subgen. Xanthothallia s. str. includes only two species, A. gwynnii Dodge and A. flavocordia sp. nov.; Biatorella does not occur in Antarctica, the species described by Dodge belonging instead in Candelariella; the genus Eklundia is a synonym of Candelariella; Biatorellopsis does not occur in Continental Antarctica, and the genus is a synonym of Pleopsidium; Pleopsidium is represented in Antarctica by one species, P. chlorophanum, which was treated under very different generic and specific names by earlier authors. Altogether, the number of species of yellow Acarosporaceae known from Antarctica is reduced from ten to three, distributed in two genera: Acarospora and Pleopsidium. The two Acarospora species, A. gwynnii and A. flavocordiaare apparently endemic to Antarctica, whereas P. chlorophanum is a widespread bipolar lichen. A comprehensive list of synonyms and a key are provided.

Twelve species of Sticta are recorded from southern South America,(Argentina and Chile including Juan Fernandez) south of latitude 30°S, viz., S ainoae, S. caulescens, S. fuliginosa, S. gaudichaldia, S. hypochra, S. hypopsila, S lineariloba, S. limbata, S. longipes, S. sublimbata and S. weigelii, and S. santessonii D Galloway is newly described. A key is provided, and details of anatomy, morphology, distribution, ecology and taxonomy are discussed.

Nylon mesh litter–bags markedly reduced the rate of weight loss of lichen litter, as compared to unconfined (free) lichens, suggesting that herbivores and detritivores larger than the mesh size make a significant contribution to the disappearance of lichen litter. The half–life of free lichen litter was 1·5 months for Alectoria sarmentosa, 2·5 months for Hypogymnia inactiva, 3·5 months for Platismatia glauca, and 7 months for Lobaria oregana. The half–lives were 2·9 times longer for the same species in litter–bags. Because A. sarmentosa showed the greatest difference between free litter and litter–bags, we conclude that, of the four species studied, it had the highest rate of consumption by larger herbivores and detritivores.

This bibliographic review includes 316 works specifically devoted to lichens and biodeterioration of stonework and covers the time-span from 1825 to 1992. The list is accompanied by an analytical index in which the number of the articles is referred to under the appropriate topic category.

Saxicolous and terricolous lichen communities associated with the Blair Atholl limestone are described by reference to two main sites—the Meall Breac area and Tulach Hill (including Creag Odhar). Several rare arctic-alpine lichens occur in the Meall Breac area, including the first population of Cetraria nivalis to be found outside acidic lichen-moss heaths in Great Britain. Tulach Hill and Creag Odhar, in contrast, are at relatively low altitudes and more sheltered, supporting a range of species not normally seen in the Highlands. These communities, most of which lie in the anthropogenic zone that was formerly covered by woodland, are compared with those of major montane calcareous sites in Scotland that have always been above the tree line.