In order to evaluate the relative usefulness of the numerous bio-indication methods that use epiphytes as indicators for air pollution, a range of these different methods was applied within the same region (Flanders, Northern Belgium). The study area shows important air pollution gradients and little climatic differentiation. Ninety-one IAP indices were calculated with data collected in the immediate vicinity of SO⊂2 measuring stations on one randomly chosen tree, on ten neighbouring trees and in a sampling grid placed on the tree carrying the largest number of epiphytes. A large majority of indices showed a significant Spearman rank order correlation with mean SO⊂2 winter values over the 5 years 1990-94. Indices based on a selection of 17 lichens gave better results than those based on all lichens. The latter indices showed higher correlation than those using all epiphytes (including bryophytes). Indices using a quantitative estimate of cover or abundance or a combination of these did not result in a higher correlation. Sampling ten trees gave slightly higher correlation than the grid method or sampling of one tree. Taking into account supplementary evaluation criteria (time investment and degree of lichenological knowledge required), sampling of 17 bio-indicator species using a sampling grid is recommended within the study area. Monitoring the presence of all corticolous lichens within a sampling grid is recommended in general.

The subantarctic genus Orceolina is revised and two species are accepted, i.e. Orceolina antarctica Mull. Arg. R. S. Poulsen Søchting comb. nov. and Orceolina kerguelensis (Tuck.) Hertel. Descriptions of the species are provided. In addition the phylogeny of the genus Orceolina and allied taxa was investigated using nucleotide sequences of the LSU rRNA gene. Sequences from these regions of nine agyrialean fungi were aligned to those of four representatives of Pertusariales used as outgroup. The alignment was analysed cladistically using maximum parsimony. The two Orceolina clustered together within the Agyriaceae. The placement in the family is supported by high bootstrap values and the Kishino-Hasegawa test.

The results of an investigation into the lichen vegetation associated with vascular plant communities in the Scottish Highlands are presented. Most lichen species rarely occur in homogeneous stands of vascular plant vegetation, either occurring around the edges of recognized National Vegetation Classification (NVC) communities or in small-scale mosaics with them. However, some lichen species have a high fidelity to the more open NVC communities. The problems associated with applying NVC survey techniques to lichen assemblages are described and discussed.

On the thalline lobes of Pyxine subdnerea there are delimited patches of pruina consisting of bipyramidal prisms, bipyramids and druses of weddellite, i.e. calcium oxalate dehydrate (COD), as revealed by X-ray analysis and SEM observations. The disappearance of the crystals from older thalline areas is preceded by an increase in the frequency of corrosion figures, in the form of etch square pits, and a decrease in the number of crystals occurring on the thalline surface. These features follow a dissolution gradient from the lobe apex towards the proximal edges of the patches. The corrosion figures are linked to the thermodynamic metastability of COD. Partial dissolution of the crystals, performed in water and in EDTA, has confirmed this latter assumption. It is thought that the disappearance of pruina, which interferes with the transmission of light to the algal layer, may allow the formation of soredia in mature thalline portions.

The biological status of Chiodecton epiphyllum (Arthoniales: Roccellaceae), described as a foliicolous lichen from Papua New Guinea, is reassessed, based on additional material from Brazil, Costa Rica, and Papua New Guinea. The species is a lichenicolous fungus growing on the foliicolous lichen Coenogonium flavicans (Gyalectales: Gyalectaceae). Furthermore, its ascomatal anatomy and lichenicolous growth habit suggest placement in the related genus Plectocarpon, instead of Chiodecton. We therefore propose the new combination Plectocarpon epiphyllum [Bas.: Chiodecton epiphyllum]. The species is further lectotypified on its ascomata since parts of the original description which denote vegetative characteristics refer to the sterile thallus of the host lichen.

Thalli of the lichens Buellia frigida and Xanthoria elegans were collected from five different locations each 5-15 km apart in the Vestfold Hills, Princess Elizabeth Land, eastern Antarctica. A further collection was made from Mawson Station, Mac Robertson Land, eastern Antarctica, 660 km away. DNA was extracted from whole thalli and the ribosomal ITS region amplified by PCR using fungal specific primers. Resulting products were sequenced to gain an indication of whether or not variation was present within populations of lichen-forming fungi from continental Antarctica, and therefore of the availability of genetic resources to react to pressures such as climate change. Three genotypes of B. frigida and two of X. elegans were detected in the Vestfold Hill collections. However, these differed by only one nucleotide position suggesting the presence of relatively little genetic variation, if the ITS region is indicative of the overall genome. Buellia frigida collected from Mawson Station had an identical ITS region sequence to the most common Vestfold Hills genotype, indicating that this species may have a low level of genetic variation across much of eastern Antarctica. In contrast, X. elegans collected from Mawson showed considerable genetic variation from the Vestfolds thalli, differing at 14·2% of nucleotide positions and had an identical ITS region sequence to an isolate from maritime Antarctica 4960 km away. Samples from the Vestfold Hills formed a distinct cluster in a phylogenetic analysis of ITS sequences from a worldwide collection of X. elegans isolates.

The first lichen records from the Lakshadweep (Laccadive) Islands are presented.Lithothelium insulare (Pyrenulaceae) is described as new and nine other taxa are reported. The poor lichen flora, dominated by pantropical species, is probably a result of the lack of natural habitats in this area.

The phylogeny of the genus Pertusaria and allied taxa was investigated using nucleotide sequences of the LSU rRNA gene. Sequences from these regions of 15 pertusarialean fungi were aligned to those of three representatives of Agyriales used as outgroup. The alignment was analysed cladistically using maximum parsimony. The Pertusariaceae appear paraphyletic bearing the monophyletic Coccotremataceae on a clade including Ochrolechia and Pertusaria subg. Monomuratae, but monophyly of the family cannot be rejected. The genus Pertusaria is polyphyletic, with the subgenus Monomuratae more closely related to the Coccotremataceae and Ochrolechia than to taxa of the subgenera Pertusaria and Pionospora. Monophyly of the genus Pertusaria is rejected. The monophyly of the subgenera Pertusaria and Pionospora is also rejected. The distribution of selected characters in the Pertusariales is investigated and it is shown that apothecial form and spore wall number have changed in parallel within Pertusaria. The Pertusaria-type ascus is plesiomorphic within the Pertusariaceae and thus cannot be used to circumscribe Pertusaria. The presence of chlorinated xanthones is restricted to Pertusaria s. str

The pH of 192 thin, even-aged twigs from 4 height levels of 12 randomly selected trees within a boreal Picea abies canopy naturally exposed to rainfall with a high pH (>5·2) was measured. The largest variation in bark pH was due to the height above the ground. However, a highly significant horizontal variation between trees was also found, apparently due to small-scale soil variations. The biomass of alectorioid lichens increased with increasing height above die ground to at least 12 m, a height interval with fairly constant pH values. The uppermost twigs had an unusually high pH and an abnormal species composition for P. abies, with dominance of the foliose Melanelia exasperatula. The canopy hosted several cyanobacterial lichens, but these were scattered and had low biomass, restricted to lower branches of the trees with the highest bark pH.

Polycoccum crespoae sp. nov. is described from thalli of Chondropsis semiviridis collected in Australia (Victoria). It has consistently 4-spored asci but differs from known 4-spored species in the size and shape of the ascospores. Attention is also drawn to another undescribed Polycoccum found on another genus of Parmeliaceae, Karoowia adhaerens, from South Africa (Cape Province).

A rapid method to isolate intact functional algae from the lichens Evemia prunastri and Ramalina farinacea has been developed. This method is based on the use of Percoll® gradients after mechanical disruption of lichen thalli. Results obtained show that the algal preparations were virtually free of contamination by fungal hyphae. The purified algal cells were photosynthetically active and without symptoms of photoinhibition, which indicates their functional integrity. This method may be used for the isolation of intact algae from a broad range of lichen species.