The morphological circumscription of selected Central European freshwater species in the lichen genus Thelidium was re-examined against the background of a molecular phylogeny based on ITS sequences. Molecular data reveal a close relationship between Thelidium methorium, T. pertusatii and Verrucaria latebrosa contradicting the traditional separation of Verrucaria and Thelidium by ascospore septation. Thelidium methorium and T. pertusatii are closely related species. The distinction of Thelidium methorium and T. submethorium was supported both by differences in ITS sequences and morphology. Thelidium minutulum, T. pluvium and T. zwackhii form a distinct clade with small perithecia and a thin or absent involucrellum. Thelidium rehmii and T. minutulum differ morphologically only in larger variability of ascospore length and the arrangement of photobiont cells, but are clearly separated by their ITS sequences as well their ecological requirements. An identification key for epilithic freshwater species of Thelidium in Central Europe is given, a lectotype for T. pertusatii is chosen, and detailed remarks for each species are provided.

The species of Lecanora sensu stricto occurring in Thailand are revised. Twenty-eight species are accepted with one new species, L. kansriae described for a taxon with small crystals in the amphithecium and containing the stictic acid chemosyndrome. Eight species are recorded from Thailand for the first time: L. coronulans, L. farinacea, L. interjecta, L. leproplaca, L. melaleuca, L. plumosa, L. pseudargentata, and L. toroyensis. Previous records of L. casuarinophila, L. insignis, L. pulicaris, and L. subgranulata are shown to be based on misidentifications. The new combination Vainionora flavidorufa is proposed for Lecanora flavidorufa Hue (syn. L. lividocarnea Vain. and L. lividoglauca Vain.). A key for the identification of the treated species is provided.

Some lichenized ascomycetes synthesize melanic pigments in their upper cortices when exposed to ultraviolet light and high solar radiation. Our previous work showed that melanized chloro- and cyanolichens from both high light and more shaded habitats were less photoinhibited than pale ones during controlled exposure to high light. However, protection from high light might not necessarily be the consequence of just sun-screening by melanins in upper cortices. An inherent problem with earlier experiments was that the photobionts of melanized thalli might have received more light than those beneath pale cortices. The photobionts may therefore have possessed other light-induced tolerance mechanisms that gave protection from photoinhibition. Here, we aimed to test directly the inherent tolerance of lichen photobionts to photoinhibition. The method involved removing the lower cortices and medullas of three lichen species, Cetraria islandica, Crocodia aurata and Lobaria pulmonaria, and exposing the photobionts to light from below. Results confirmed that most of the improvement in tolerance to photoinhibition in melanized lichens derives from fungal melanization in the upper cortex. However, in C. islandica, the most heavily melanized species, algae from melanized thalli possessed a significantly higher tolerance to photoinhibition than those from pale thalli, suggesting that photobionts can also adapt themselves to high light.

The lichen flora was sampled at each of the five sites on a near-vertical gneiss rock face. The sites were ranked according to the degree ofweathering of the rock surface and were taken to represent different stages in a succession. The succession shows an increase in species richness and diversity over time, although the proportion of the rock face unoccupied by lichens increases at the oldest site. The succession will be driven by allogenic processes, physical weathering of the rock, facilitation, especially the effects of lichens on surface erosion, and by inhibition, through competition for space. At the oldest site mortality of lichen thalli becomes important, continually opening up new areas for recolonization and maintaining community diversity. The succession may be described by four phases: (1) colonization, (2) growth,(3) competition and (4) senescence.

The phylogenetic placement of the genus Maronina was studied, based chiefly on phenotypic characters such as thallus colour and anatomy, secondary chemistry, the anatomy of the excipulum and the ascus-type. DNA sequence data of mitochondrial and nuclear ribosomal loci from some of the species support the hypothesis that Maronina is nested within Protoparmelia. Hence, Maronina is reduced to synonymy with Protoparmelia. Comparison of genetic distances suggests that the two varieties within M. orientalis should be regarded as distinct species. Consequently, the new combinations Protoparmelia australiensis (Hafellner & R. W. Rogers) Kantvilas et al., P. corallifera (Kantvilas & Papong) Kantvilas et al., P. hesperia (Kantvilas & Elix) Kantvilas et al., P. multifera (Nyl.) Kantvilas et al., and P. orientalis (Kantvilas & Papong) Kantvilas et al. are proposed.

Eumitrioid Usnea species are characterized by a tubular central axis throughout the entire thallus. Four species were identified in South America: Usnea baileyi is a (sub-) tropical species occurring both in continental South America and the Galapagos; U. perplectata has a scattered distribution worldwide and occurs in continental South America, mainly on the eastern range; U. flaveola and the newly described species U. subflaveola are both so far endemic to the Neotropical Andes. Distinct chemotypes, as well as anatomical characters, such as the thickness ratio of the medulla or the presence of medullar pigmentation, are diagnostic in delimiting these species. A detailed description of the species is provided together with an identification key.

Interaction effects of UV-B and CO2 on three lichens species, Cladonia arbuscula, Cetraria islandica and Stereocaulon paschale, from two latitudinal sites, 68°N and 56°N, were studied in a laboratory experiment. The response of the plants was recorded by measuring their chlorophyll fluorescence. All species had a similar response to enhanced UV-B depending on the latitude from which the population came and the time of the season when they were sampled. Overall, there was a significant increase in photosystem II yield (as measured by a fluorescence technique) due to UV-B and no separate effect due to enhanced CO2, although there was a significant interaction between CO⊂2 and UV-B. The increase due to UV-B was at the low CO2 level. There were also significant differences in response due to latitude. The results contradict our hypotheses that negative effects of UV-B would be larger in the North than in the South and that a negative response hould be especially large during the early season.

The morphological, anatomical and chemical characteristics of five taxa of Usnea (e.g.U. scabrida, U. elegans, U. molliuscula, U. queenslandica and U.ramulosissima), which belong to the U. scabrida- U. molliuscula complex are described.Usnea scabrida subsp. tayloriana is described as new. Usnea elegans and U.queenslandica are reduced to subspecies: U. scabrida subsp.elegans and U. molliuscula subsp. queenslandica. The species U. consimilis Stirton is considered synonymous with U. scabrida. A canonical discriminant analysis of geographic and climatic data was undertaken, which demonstrated that the species under investigation generally occupied discrete non-overlapping zones, indicating that the differences in thallus morphology correlated with particular climatic regions.

This comparative investigation on ascus fine structure and function substantiates the findings of Chadefaud (1960) and his coworkers indicating a close taxonomic relationship between the Baeomycetaceae and Leotia, a non-lichenized member of the Helotiales, rather than between the Baeomycetaceae and the Cladoniaceae and other members of the Lecanorales. Besides the distinct differences in ascus structure and function, cytological divergences were noted between the Baeomycetaceae and Leotia on one hand, and Cladoniaceae on the other. The occurrence of glycogen in the Baeomycetaceae and Leotia, but not in the Cladoniaceae and other members of the Lecanorineae, and the differences in phycobiont preference and thus in the mycobiont–phycobiont contact in the Baeomycetaceae and Cladoniaceae were discussed.

For a long time it has been discussed as to whether Melanelixia fuliginosa comprises one or two species: one darker, mainly saxicolous, and one lighter, mainly corticolous. To settle the question, a morphometric and a molecular analysis were carried out and analyzed using a principal component analysis (PCA). The morphometric analysis indicates a differentiation in several characters between material previously recognized as subspecies fuliginosa and glabratula, but also a considerable overlap in some of them. The molecular analysis of the nrITS DNA gene reveals a clear division of the taxa. Specimens belonging to Melanelia fuliginosa fall out in two different clades, which have good bootstrap support, corresponding to the subspecies fuliginosa and glabratula. Accordingly, we propose that the subspecies should be acknowledged as separate species, Melanelixia fuliginosa (Fr. ex Duby) O. Blanco et al. and Melanelixia glabratula (Lamy) Sandler & Arup.

The FV/FM ratio of Lobaria pulmonaria with decreasing pH in samples from a boreal forest influenced by acid rain in SE Norway, suggesting that low pH has an effect on the optimal quantum yield of PSII. The pH was measured of distilled deionized water in which lobes from different habitats were rinsed, probably indicating the ionic environment of the lichen. The best prediction of FV/FM was found in a multiple regression model including the explanatory variables: pH, a/b-ratio and chlorophyll degradation measured as the 666/666a ratio, all correlated positively with FV/FM but not with each other. The commonly used chlorophyll degradation 435/415 ratio cannot be used for L. pulmonaria because of an unidentified, habitat-influenced brownish pigment with high absorbance in the 415–435 nm wavelength range.

Usnea hirta, an important member of the lichen family Parmeliaceae, has long been used as a bio-monitor of air pollution, particularly of sulphur dioxide in North America. Although U. hirta has a wide geographical distribution, it is important to be able to identify accurately the optimal habitat conditions for air pollution-sensitive species, thus making it possible to more effectively and efficiently establish air quality bio-monitoring stations. We modelled the distribution of U. hirta as a function of nine variables, five macroclimatic variables: average monthly precipitation, average monthly minimum temperature, average monthly maximum temperature, solar radiation, and integrated moisture index, and four topographic variables: elevation, slope, aspect, and land forms and uses for the White River National Forest, Colorado. The response variable was developed based on the presence or absence of U. hirta at each of 72 bio-monitoring baseline sites established in selected portions of four intermountain area states. Our model was developed using Non-Parametric Multiplicative Regression (NPMR) analysis, a modelling approach that analyzes environmental gradients, or predictor variables, against known locations for individuals of the model species. Finally, we evaluated our model on the basis of log β values and overall improvement over a naïve model and the Monte Carlo Permutation Test with 1000 randomized runs. The best model for U. hirta included four variables – solar radiation, average monthly precipitation, and average monthly minimum and maximum temperatures (log β=3·68). Among these four variables, average monthly maximum temperature was the most influential predictor (sensitivity=0·71) for the distribution of U. hirta. The occurrence rate for U. hirta, based on field validation, was 45·5%, 65·4%, and 70·4% for low, medium, and high probability areas, respectively. This study showed that our model was successful in predicting the distribution of U. hirta in the White River National Forest. Based on these results, the north-eastern and western portions of the forest appear to offer the most favourable conditions for the installation of future air quality bio-monitoring baseline sites.

Arthonia anglica Coppins, A. anombrophila Coppins & P. James (syn. A. cinereopruinosa auct. brit.) and A. ligniariella Coppins are newly described, and Arthothelium ilicinum var. dictyosporum is given specific rank. British material of ‘Arthonia exilis’ is shown to be Bryostigma leucodontis Poelt & Döbb., which is transferred to Arthonia. Arthonia granitophila Th. Fr. (syn. Melaspilea subarenacea J. Nowak & Kiszka) is transferred to Melaspilea. Arthonia ligniaria Hellb. is added to the British list. Arthonia astroidestra Nyl. is lectotypified and shown not to be conspecific with A. stellaris Krempelh., while A. excipienda Nyl. (syn. A. hibernica Nyl.) is found not to be a synonym of A. dispersa (Schrader) Nyl. Catillaria ooliticola W. Watson is made a synonym of A. lapidicola (Taylor) Branth & Rostrup; Arthonia punctilliformis Leighton is excluded from that genus; and A. dispersa and A. patellulata Nyl. are excluded from the British list. In addition, four new lichenicolous species on corticolous hosts are introduced: Arthonia cohabitans Coppins, A. graphidicola Coppins, A. invadens Coppins and A. thelotrematis Coppins.

A method using TLC to recognize compound patterns consisting almost entirely of chloroxanthones in European saxicolous species of Lecidella is described. These are necessary for diagnosis of the taxa studied and of their chemotypes. Two solvents with complementary separatingqualities were required: C, toluene-glacial acetic acid (100:15); J, dichloromethane-acetone (4:1). Although the Rf values in solvent J strongly depend on the concentration of the substances, it is very suitable for identification because the xanthones in this system reveal distinct and characteristic fluorescence colours in UV light, simplifying interpretation enormously. No spray reagents are used. Identifications are made by co-chromatography with authentic lichencompounds

Field emission scanning electron microscopy was used to characterize mycobiont wall surfaces in Umbilicaria hyperborean from Greenland. To determine the precise intrathalline distribution of phenolics, comparisons were made of hyphal surface features and dimensions before and after acetone extraction. Stratification was evident within the medulla, as extracellular phenolics were observed only on hyphae near or within the algal zone. The outside diameter of hyphae in this region was thus significantly greater than in the remainder of the medulla. Surface deposits were also examined in 1350-year-old subfossil thalli and hyphal diameters were compared statistically to those in extant thalli. The mean hyphal diameter in the upper medulla was not significantly less in subfossil specimens than in recent thalli, suggesting that phenolic cover was maintained in spite of glaciation. However, after ice burial phenolic masses tended to be flatter than in recent specimens and finely tubcrculate. The appearance of mycobiont hyphae in the cortex of subfossil thalli seemed to be the same as in extant thalli, except that there tended to be more compressible, smaller and less conglutinated filaments near the algal layer.

The Leptogium azureum group in Europe is revised. Leptogium britannicum sp. nov., a species growing among grass on coastal rocks, is described. Leptogium azureum (Sw.) Mont. is shown to be absent from Europe, most of the material so named is Leptogium cochleatum (Dickson) comb. nov. Leptogium rivulare (Ach.) Mont. and Leptogium corticola (Tayl.) Tuck. are shown to have very limited distributional areas in central Sweden and the north-west U.S.S.R., and northern Italy and northern Yugoslavia respectively; both are in danger of extinction. The nomenclature of all species, including also Leptogium cyanescens (Rabenh.) Körber, is discussed.

Leptogium juressianum C. Tav., a species of the Leptogium lichenoides-group with hairs on the upper surface, is reported from south-west Ireland; the first record since it was described from Portugal.