Recent revisions of generic relationships in the pyrenocarpous lichen family Trichotheliaceae by J. Hafellner & K. Kalb (based on perithecial pigmentation and ascus structure) and R. C. Harris (based on morphological, chemical and environmental trends) are assessed. However, most of their conclusions are rejected because the authors used shared or variable characters, insufficient specimens and highly disjointed groups of species.

Lepraria eburnea is shown to comprise three morphologically indistinguishable chemotypes, containing either protocetraric acid, psoromic acid, or neither substance, in addition to alectorialic acid. The holotype of L. frigida contains protocetraric acid and alectorialic acid, and is thus united with L. ebumea under the latter name.

Belonia mediterranea Nav.-Ros. & Llimona sp. nov. is described and compared with other, mainly saxicolous, species of the genus. It is known only from the type locality, Medes Islands (Catalonia, NE Spain), where it occurs on shaded limestone cliffs, near the Mediterranean seashore. It differs from related saxicolous species of Belonia mainly in the appearance of the thallus, ascospore septation and ecology. A key to the European species of Belonia is provided.

The anatomy and chemistry of Lecanora vacillans H. Magn. has been studied. This saxicolous species combines key characters of both the L. subfusca and L. subcarnea groups and indicates that the representative groups should not be segregated at generic level. More particularly L. vacillans resembles the L. subfusca group in its apothecial anatomy but contains chemical substances typical of the L. subcamea group, whereas the morphology is reminiscent of both groups. Lecanora vacillans f. infuscate is reduced to synonymy with L. vacillans.

The genus Australiaena (lichenized Ascomycetes, Physciaceae) with the single species A. streimannii sp. nov. is described as new from tropical Australasia. Morphologically it is characterized by crustose thalli with an often radiate-plicate margin, ascospores with a type-B ontogeny, and filiform spermatia. The chemistry of this taxon is diverse (lobaric acid, conlobaric acid, xanthones, gyrophoric acid, lecanoric acid, 5-O- ethylhiascic acid, perlatolic acid), and three chemotypes are distinguished.

The new genus Vagnia is introduced for the single species V. cirriformia discovered on thalli of Peltigera in Poland; it appears to be a pathogen as the cortex is destroyed in a rounded patch within which the conidiomata occur. The fungus is characterized by cupulate to doliiform conidiomata clothed in white hairs and from which a black columnar cirrus of conidia arises. The simple ellipsoid conidia are hyaline when viewed individually and are formed enteroblastically from elongate conidiogenous cells supported by branched conidiophores.

The response of corticolous lichens to artificially induced chemical damage was compared to symptoms found on damaged lichens in the field. Experimental thalli were damaged and observed (1) in situ in a relatively pristine area, and (2) in a growth chamber either hydrated continuously or periodically. Lichenicolous fungi encountered included Cornutispora lichenicola, Lichenoconium erodens, Phoma cytospora, Vouauxiomyces truncatus, Hobsonia christiansenii, Pronectria oligospora, Nectria rubefaciens and its anamorph, Acremonium rhabdosporum, and a variety of hyphomycetes. The results support the idea that both thallus necrosis and moist conditions are necessary to produce the full suite of symptoms observed on ailing lichens in the field.

Net photosynthesis (NP) and dark respiration (DR) of thalli of the lichen species Umbilicaria grisea and U. freyi growing together in the same habitat the Sierra de Guadarrama, central Spain, were measured under controlled conditions in the laboratory and under natural conditions in the field over a range of photosynthetic photon flux densities (PPFD), thallus temperatures and thallus water contents. Laboratory experiments revealed that the photosynthetic response to PPFD at optimum thallus water content is very similar in both species. The light compensation points of NP increased from PPFD of c. 20 µmol m−2 s−1 at 0°C up to c. 100 µmol m−2 s−1 PPFD at 25°C. In both species light saturation was not reached up to 700 µmol m−2 s−1 PPFD except at 0°C. By contrast, the temperature dependence of CO2 gas exchange differed substantially between U. grisea and U. freyi. Both species gave significant rates at 0°C. Optimal temperatures of NP were always higher in U. grisea at various PPFD levels if the samples were kept at optimal thallus water content. NP showed maximal rates at 95% dw in U. grisea and 110% dw in U. freyi respectively. In U. grisea a much stronger depression of NP was observed with only 5% of maximal NP reached at 180% dw. At all PPFD and temperature combinations U. freyi showed higher rates of NP and more negative rates of DR if calculated on a dry weight basis. This was also true under natural conditions at the same site, when U. freyi was always more productive than U. grisea. The differences in the photosynthetic response to temperature between both species correlated well with the different distribution patterns of both species. The possibility of genetic control of the physiological performance of these species and its influence on their distribution patterns and autecology is discussed.

The FT-Raman spectra of encrustations of Dirina massiliensis f. sorediata on a variety of substrata collected from several locations have been recorded and analysed. This is the first time that such a comprehensive spectroscopic study has been made of lichen encrustations of the same species on different substrata. This lichen is able to bring about deterioration in all six different lichen substrata studied. Calcium oxalate dihydrate is produced in significant amounts by the reaction of lichen-generated oxalic acid with various calcareous rock substrata, as well as particles of the particular substratum itself. However, for specimens growing on a non-calcareous substratum in an exposed maritime location only traces of calcium oxalate are produced and more noticeable quartz particles are incorporated into the thalli. The results indicate that this lichen can degrade its substratum highly effectively and there is evidence of different strategies being exhibited by lichens in different habitats and geographical locations.

Peltigera canina thalli have been successfully transplanted onto soil in a garden and in flowerpots. Garden samples showed marked seasonality and achieved growth rates of 6·4 cm per year. Pot-grown samples showed variation in the growth of individual thallus lobes and established that, under different soil hydration regimes, permanently hydrated thalli could sustain considerable linear growth rates for at least 140 days.