Primers are presented to amplify an intron-containing portion of the actin type I locus from Asterochloris algae. The amount of variation and phylogenetic resolution provided by the ITS rDNA are compared with that from the actin locus. The number of variable and parsimony-informative sites within the actin locus was drastically higher than that of the ITS. Phylogenetic analyses of the ITS resulted in poorly resolved trees with low support values. In contrast, phylogenetic analyses of the actin locus yielded trees with better support and resolution. It is concluded that the actin type I introns will be useful for studies investigating species concepts and population genetics.

Observations have been made on the effects of different storage treatments, either 100°0 or 0°0 r.h., 12 h light:12h dark or 24 h dark for 2 days, on the ultrastructure of the phycobionts of Lobaria amplissima and Lasallia pustulata. After storage, Myrmecia, in the more desiccation-sensitive lichen L. amplissima, showed an increased number of cytoplasmic storage bodies which had more frequently dark contents and a half-moon-like appearance.Trebouxia, from the desiccation-resistant L. pustulata, showed major cellular disorganization when stored at 100°0 r.h. in the light:dark regime, whereas, in the dark, reorganization of thylakoids into a parallel arrangement occurred. Treatment at 0°0 r.h. in the light:dark regime induced an accumulation of starch around the pyrenoid of Trebouxia and, in the light:dark and dark regimes, a peripheral location of pyrenoglobuli without a decrease in the total volume of lipid material. The results are discussed in terms of the utilization and mobilization of reserve substances and the habitat preferences of the two lichens.

The effect of a copper-smelting plant on populations of Hypogymnia physodes and Tuckermanopsis sepincola was studied in the Middle Urals. A different population response was found between the two lichen species due to different life strategies. The pollution appears to decrease growth and developmental rate of H. physodes (a vegetatively reproducing strongly competitive species), resulting in a shift of population structure towards smaller, esorediate to low sorediate thalli. The background population of the sexually reproducing Tuckermanopsis sepincola consisted mainly of young, small thalli of a low fertility as a result of strong inter-species competition with H. physodes. At the polluted site, the sharp decrease in the abundance of H. physodes led to a shift in structure of the T. sepincola population towards larger and more fertile thalli. It may be concluded that T. sepincola benefits from air pollution by an indirect effect of the removal of a strong competitor, i.e. H. physodes.

The anatomy of Xanthomaculna convolute shows adaptation to a vagrant life form and to the moisture conditions of its habitat. The differential swelling of the irregularly thickened upper cortex and the medulla, in addition to the rigid medullary structure, due to the deposition of calcium oxalate, allow orderly hygroscopic thalline movements. The architecture of the medulla appears to be closely related to masonry-like arches where the material is only stressed by compression and the stresses are distributed at the hinges. The possible role of crystalline medullary deposition as a radiation reflector is also suggested.

Zeorin-containing red-fruited Cladonia species, the so-called C. coccifera group, are widespread terrestrial lichens which share most of their secondary substances but differ morphologically. The main objective of this study was to explore whether the current delimitation of these species is supported by molecular data. A total of 52 European and North American specimens of C. coccifera, C. deformis, C. diversa, and C. pleurota were examined. The internal transcribed spacer regions of the nuclear ribosomal DNA and the β-tubulin gene loci were sequenced for phylogenetic analyses. Traditional morphological species circumscriptions in zeorin-containing members of the C. coccifera group are not supported by molecular data. Cladonia coccifera, C. deformis, and C. pleurota were recovered as polyphyletic in both gene topologies; C. diversa formed a lineage in the ITS phylogeny but this was not statistically supported. We detected chemical patterns of the presence/absence of porphyrilic and/or isousnic acid which may help to characterize two lineages. Our results also show incongruence between the two molecular markers studied. Therefore, we focused on possible explanations of this phenomenon. Five major evolutionary mechanisms can potentially result in phylogenetic discordance between genes: presence of pseudogenes, horizontal gene transfer, gene paralogy, incomplete lineage sorting, and hybridization. These mechanisms are briefly discussed. We consider incomplete lineage sorting and/or hybridization to best explain the incongruence.

Field measurements of CO2 exchange by lichens are difficult because these poikilohydric organisms rely on direct hydration by rain, dew or fog. Continuous enclosure of thalli in conditioned, measurement cuvettes is, therefore, not experimentally reasonable. Porometric instruments with brief enclosure times, have proved useful for studies of lichen gas exchange but allow only spot measurements and recording is not easily possible for extended time periods. We describe a newly developed, automatically operating cuvette that allows long-term monitoring of lichen photosynthetic and respiratory CO2 exchange in the field. Samples, e.g. flat stone slabs covered with epilithic lichens, are positioned on the base of the cuvette where, when the cuvette is open, they are exposed to the same environmental conditions as naturally growing thalli. At regular intervals (typically 30 min), an upper lid automatically encloses the lichen for c. 3 min in a stirred cuvette; CO2 exchange is measured using IRGA techniques and microclimate data arc recorded. The successful operation of the cuvette is illustrated by means of diel time courses of CO2 exchange for selected, very different weather conditions.

Epiphytic lichen communities on trunks of Pinus sylvestris and Picea abieswere studied on a west–to–east gradient through the central pan of Finland with special reference to macrolichens. Comparisons were made between the two conifer species, the coast of the Gulf of Bothnia and the more continental inland area, open commercial and denser natural forests differing in their local climate, and tree bases (0·0–0·7m) and upper trunks (0·7–2·0m). Differences were found not in species composition but in relative species abundance, the main distinction being between the two tree species. There were also noticeable geographical, vertical and habitatdependent differences. In addition to climatic factors, the importance of bark properties for the epiphytes is briefly discussed.

ITSl and ITS2 regions were sequenced from a number of Parmeliopsis ambigua and P. hyperopta specimens from Uppland, Sweden. The data were analysed cladistically and the ITS region was found to contain enough variation to support the hypothesis that the taxa should be regarded as species rather than chemotypes.

The nature of elm bark as a lichen substratum is considered; a method of bark pH measurement is described and examples show the effects of the environment on bark pH. A summary of elm taxonomy includes a field key to the identification of elms. An estimation of the degree of restriction of 97 lichen species found on elms is given together with distribution maps of the most restricted species, and a list of lichens recorded on elm. The spread and control of Dutch Elm Disease is discussed. The future of elms and the consequences for the more highly restricted lichen species are reviewed. Bacidia incompta, Collema fragrans, Gyalecta flotowii, G. ulmi, and particularly Caloplaca luteoalba and Cryptolechia carneolutea, are most at risk from the widespread loss of elms.

Members of the Cladonia gracilis group of lichen fungi are common terrestrial lichens where morphological features are more similar between members of the C. gracilis species complex and allied species outside the complex than they are between subspecies within the complex. The objectives of this study were to examine whether the Cladonia gracilis species complex is monophyletic, to determine whether morphological similarity is supported by genetic variation, and to examine the utility of the polyketide synthase (PKS) gene for phylogenetic studies among closely related species. Two loci, the ketosynthase region of the PKS gene and the internal transcribed spacer (ITS) region of nuclear ribosomal DNA, were sequenced and analysed by Maximum Parsimony, Bayesian and haplotype network analyses. Functional differences were also inferred through ITS2 RNA secondary structures and non-synonymous changes in translated PKS amino acid sequences. The monophyly of the C. gracilis complex is supported by 71% bootstrap in the ITS phylogeny, and 92% bootstrap with greater than 95% posterior probability in the PKS phylogeny. Morphological similarity is not always supported by genetic similarity. The PKS gene is less variable than the ITS but the PKS supports species hypotheses that are reflected in the ITS2 RNA model. We conclude that monophyly of the C. gracilis complex can be supported if C. cornuta, C. coniocraea and C. ochrochlora are included in the complex. In addition, C. maxima, C. phyllophora and C. subchordalis are supported as monophyletic species outside the C. gracilis complex. Cladonia maxima may form a separate species and variation among podetial morphology may be explained by convergent evolution.

The Antarctic endemics Umbilicariakappenii and U. antarctica are morphologically close, but mainly distinguished by their reproductive strategies. Umbilicaria antarctica propagates by means of thalloconidia. Umbilicaria kappenii lacks thalloconidia, but exhibits a variety of asexual propagules: soredia, adventive lobes and thallyles. We have now employed molecular data from three gene regions to examine the phylogenetic relationships of these two morphotypes. The phylogeny of ten samples and four outgroup taxa (Umbilicaria decussata, U. krascheninnikovii, U. nylanderiana, U. umbilicarioides) was reconstructed using Bayesian and maximum parsimony analyses of a combined data set of nuclear ITS, nuclear LSU rDNA and mitochondrial LSU rDNA sequences. Forty two new partial sequences of 14 specimens were generated. Our results indicate that all samples morphologically referred to U. antarctica and U. kappenii form a monophyletic group. A topology separating the two morphotypes as phylogenetic species is significantly rejected with the data set. It is proposed to place U. kappenii into synonymy with U. antarctica.

The epilithic lichen flora on the Beacon sandstone formation in Victoria Land consists of seven species: Acarospora gwynniiDodge & Rudolph, Buellia grisea Dodge & Baker, B. pallida Dodge & Baker, Carbonea capsulata (Dodge & Baker) Hale comb, nov., Lecanora fuscobrunnea Dodge & Baker, Leaded cancriformis Dodge & Baker, and L. siplei Dodge & Baker. The typification of the species is given along with descriptions and distribution in Antarctica.

The xanthorioid taxa Xanthomendoza borealis and Xanthoria mawsonii are revised using morphological, anatomical, secondary chemical, and molecular characters. We conclude that most specimens determined as X. mawsonii from the Antarctic are conspecific with specimens labelled X. borealis from the Northern Hemisphere. Some specimens named X. mawsonii from the Antarctic are wrongly determined specimens of Xanthoria candelaria (L.) Th. Fr, including the holotype of Xanthoria mawsonii C. W. Dodge. Accordingly, Xanthoria mawsonii C. W. Dodge is a synonym to Xanthoria candelaria (L.) Th. Fr. The only available correct name for the bipolar species, which comprises material previously determined as X. borealis and X. mawsonii, and is distinct from the more widespread taxon X. candelaria, is Xanthomendoza borealis (R. Sant. & Poelt) Søchting, Kärnefelt & S. Kondratyuk.

The term ‘cladoniiform lichens’ is applied to a group of lichen-forming discomycetes which either produce a ‘dimorphous’ thallus (differentiated into vertical and horizontal structures) or which resemble such lichens in having somewhat similar fruticose thalli and related phenolic chemistry. Seventeen genera comprising the families Cladoniaceae, Heterodeaceae, Cladiaceae, Baeomycetaceae and Siphulaceae are included in the group. A podetium is defined as a lichenized, stem-like portion (stipe) bearing the hymenial discs, and sometimes conidiomata, in a fruticose, simple or compound apothecium. The terminal structures commonly called apothecia on podetia or other ascomatal stipes in lichens are not whole apothecia but separate hymenial discs of a polydiscoid ascoma. In spite of superficial similarity in gross morphology and phenolic composition, the cladoniiform lichens are a life-form group rather than a taxonomic entity.

The different views on the taxonomic use of chemical characters in lichenology are reviewed using the opposing opinions of W. L. Culberson and Rogers and the somewhat intermediate position of Hawksworth as examples. The differing significance of secondary metabolites is illustrated with two examples in the genus Lecanora. In L. campestris and similar species, the chemistry has been useful to differentiate morphologically similar species, which subsequently were found to differ in minute anatomical differences as well. However, in L. caesiorubella, a remarkable chemical variation can be observed that is not correlated with other differences and is thus interpreted as intraspecific variation. An a posteriori valuation of the taxonomic significance of metabolic data is preferred.

Lobes of Xanthoria elegans are shown to be engulfed by more rapidly growing neighbouring lobes, thereafter ceasing to grow, and the rate of lobe engulfment increases with thallus age. Similarly, growth can cease when lobes of adjacent thalli meet. Mature central areas of eroded thalli may regenerate lobes and resume growth. In Buellia coniops, B. russa and Caloplaca cirrochrooides, peripheral concentric zonation does not always correspond to a single year's growth, and one zonation effect is correlated with an unusually severe winter.

The epiphytic lichen Evernia prunastri is sensitive to air pollution and reacted by total retreat to the worsening of air quality during the peak of SO2 pollution in Central Europe (1950s–1990). Since 1990, after a significant decrease in air pollution, epiphytic lichens recolonized previously polluted areas, including E. prunastri. We investigated the physiological status of E. prunastri, transplanted for six months in 34 sites in the urban area of Bratislava (Slovakia) under current conditions. The content of chlorophylls, cortical and medullar secondary metabolites and soluble proteins were explored. We then examined the relationship of these parameters with the environmental quality status, reflected by the diversity of epiphytic lichens. The results showed that the physiological status of E. prunastri did not change significantly after exposure. Positive correlations were found between lichen diversity in the sampling sites and physiological parameters (photosynthetic pigments and phaeophytinization quotient) in the transplants. Transplants from sampling sites with a greater proportion of nitrophilous lichens displayed a decrease in photosynthetic pigments. Sites where E. prunastri naturally occurred had a lower proportion of nitrophilous species in comparison to sites where E. prunastri was not present. This suggests that the indicator species E. prunastri may also recolonize sites with low eutrophication in urban environments under decreased air pollution, and the information on its presence can help to assess the pressure caused by nitrogen excess.

Cladina subtenuis is the most commonly found ‘ reindeer lichen ’ in the southeastern United States. In the present study C. subtenuis was examined for polymorphism in the small subunit (SSU) ribosomal DNA (rDNA) within and among small clumps of podetia, here referred to as mats, from five geographical locations. Polymorphism in the SSU rDNA was not detected among podetia within mats, but polymorphism was detected among mats from a single location. Therefore, mats of C. subtenuis may represent a single genetic individual, although genetically distinct mats may occur in close proximity. Their proximity couldencourage sexual reproduction between genetically distinct individuals, which would maintain variation in these populations. The SSU rDNA types represented three different lengths and restriction-site patterns, reflecting the presence of sequence insertions of at least 200 nucleotides in the SSU rDNA coding region. Thei nsertions, differing in position, number and sequence, are group I introns similar to those previously reported in the Cladonia chlorophaea complex. The intron variation among the SSU rDNA types indicates that molecular evolution has occurred within this species, perhaps since its divergence from related taxa and dispersal across the southeastern United States.