The foliicolous genus Phylloblastia is recorded for the first time in the Iberian Peninsula where it is represented by three species: P. fortuita sp. nov. from several localities in the north-east of Spain, P. dispersa, a new record for Europe and reported for the first time outside the tropics, and P. inexpectata. A key to the European species is provided.

A new taxonomy of the Caloplaca citrina group in the Black Sea region is presented. It is based on the nrDNA ITS molecular data, chemistry (anthraquinone contents) and 20 morphological characters. Six species previously known in the region are accepted: Caloplaca arcis, C. calcitrapa, C. dichroa, C. flavocitrina, C. geleverjae, C. limonia. Five new species are described: Caloplaca arcisproxima, C. austrocitrina, C. communis, C. confusa and C. nigromarina. Seven further species, Caloplaca britannica, C. citrina, C. marina, C. maritima, C. microthallina, C. ora and C. phlogina are also treated briefly. Some maritime species known from the Atlantic coast of Europe are absent from the region, and, surprisingly, Caloplaca citrina s. str. could not be confirmed from the study area. A key to the species present in the region is provided, although morphological characters are of very limited value in this group. The variability and taxonomic importance of particular features are discussed. No significant differences in secondary chemistry were observed among the species.

Many examples of convergence and some semi-cryptic species were revealed by molecular data. The term ‘semi-cryptic species’ is introduced here into lichenology for those species which cannot be clearly diagnosed by their morphology, but which are determined by other characters, mainly by their ecology and distribution. We propose to describe formally such species, in spite of difficulties with subsequent morphological identification.

Five new species of Cryptothecia: C. alboglauca, C. bengalensis, C. farinosa, C. multipunctata and C. verruculifera, and two new species of Herpothallon: H. granulosum and H. isidiatum are described from India. Herpothallon australasicum (Elix) Elix & G. Thor and H. granulare (Sipman) Aptroot & Lücking are also reported as new records.

The lichen genus Stirtonia has been revised. Thirteen species are accepted in the genus, including three new to science, viz. S. curvata from Irian Jaya and Java, S. schummii from the Seychelles and S. neotropica from Costa Rica and the Dutch Antilles. The known range of the genus is extended from Asian to pantropical. The genus is most diverse in the palaeotropics.

A new species, Placocarpus americanus, is described from the Santa Monica Mountains in Southern California. It is a juvenile parasite on Protoparmeliopsis muralis and differs from Placocarpus schaereri in having smaller non-halonate ascospores, a negative iodine reaction of the medulla, lack of inspersion of the medulla with small crystals, and having a thallus of dispersed areoles.

Umbilicaria iberica and U. maculata are described as new to science on the basis of morphological and molecular data. Umbilicaria iberica is similar to U. polyphylla but differs in having a monophyllous thallus with a distinctive white reticular pattern over the umbilicus and actinodisc apothecia. Umbilicaria maculata is similar to U. cylindrica but this new species is distinguished by its grey-brown thallus with sparse marginal cilia and white stains on the upper surface especially in the marginal zone, as well as by sessile apothecia with one or a few sterile fissures. Nuclear ITS and LSU rDNA have been used as molecular markers. In the phylogenetic analysis U. polyphylla falls into two well supported clades (A and B), one of which corresponds to the morphotype that is described here as a new taxon. Specimens previously recognized as U.cylindrica fall into three well supported clades: clade C corresponds to the typical morphotype, clade D corresponds to morphotype II described here as a new taxon, and clade E is morphotype III which is recognized as U. cf. umbilicarioides. Typical group I introns have been found in position 1506 of the nuclear SSU rDNA of Umbilicaria; a consensus secondary structure of these introns is presented and we conclude that they represent an important and valuable molecular marker which gives additional support to the ITS and LSU sequence phylogeny obtained.

This study investigates how anatomical characters can be used to differentiate two morphologically close species, Melanohalea olivacea (L.) O. Blanco et al. and M. septentrionalis (Lynge) O. Blanco et al. Although the two species are morphologically differentiated, mainly based on the position and shape of pseudocyphellae on the lobes, poorly-developed specimens can be difficult to identify based on morphology alone. For example, in Switzerland, both species are at the south-west limit of their distribution range and most specimens are small and not fully developed. In such cases, anatomical characters are particularly useful in separating the two species. Five anatomical characters were studied: spore length and width; hymenium, subhymenium and hypothecium height. A nested ANOVA showed that variation of spore length was 155 times greater between species than between individuals of the same species, itself 5 times higher than within individuals. In a Principal Component Analysis, despite a substantial variation of the anatomical characters within both species, a significant species differentiation appeared distinctly on the first axis (P < 0·001), which accounted for 62·35% of the total variance, and the type specimens nested within each species. Finally, a Discriminant Linear Analysis assigned 100% of the individuals to their species class, the best predictors to discriminate between the two species being subhymenium height and spore length. These characters proved to be powerful in identifying specimens with a poorly-developed morphology and confirmed the presence of M. olivacea in Switzerland.

The lichen Usnea longissima was used to examine how distance from forest edge and edge contrast influence growth of pendulous lichens. Thalli of two sizes (12 and 27 cm) were transplanted to the lower canopy of old Picea abies forest at 5, 25 and 100 m distance from cutovers. Sites represented three levels of edge contrast: high (clear-cut), intermediate (3 m tall saplings) and low (6–7 m tall young forest). Lichen growth was assessed as annual length and weight gain. Growth rates of intact thalli were size-dependent, with both growth variables being higher in long than in short thalli. Distance and edge contrast had significant effects on weight gain in long thalli but not in short ones. Weight gain in long thalli was twice as high near the edge (23%) compared to the forest interior (12%). The highest weight gain (31%) occurred at intermediate contrast edges with lower growth at both low (18%) and high contrast edges (20%). Chlorophyll a concentration was highest near the edge and positively correlated with weight gain, suggesting that growth was stimulated by both increased photosynthetic capacity and higher light availability near the edge. The lower part of the canopy in forest edges apparently have favourable growth conditions for U. longissima with growth being influenced by vegetation on adjoining cutovers. Therefore growth responses cannot explain the previously observed decline of pendulous lichens following edge creation. Our results suggest that vegetation buffers can improve conditions for pendulous lichens near forest edges.

The crustose lichen Lecanora conizaeoides has declined markedly around London with progressively diminishing sulphur dioxide pollution of the air since the 1960s. To identify the immediate causes of its decline, we applied S in the form of bisulphite (0·2 & 2 mM) and sulphate (2 mM), and N as nitrate (2 mM) to relict colonies of the lichen on beech trunks in a plantation in Windsor Forest. Growth of the lichen was monitored by estimating changes in percentage cover. By the end of a 25-month period of two-weekly treatments, all the chemical treatments had resulted in significant decreases in cover of L. conizaeoides compared to distilled water controls, with the 2 mM bisulphite causing the greatest loss. Bark surface pH was also lowered by the chemical treatments, but most by the 2 mM bisulphite applications. Similar results were obtained in two laboratory experiments where the nutrient applications were repeated under a controlled environment and thallus area monitored photographically. No evidence was obtained to support the hypothesis that growth of L. conizaeoides is stimulated by an elevated sulphur supply. We conclude that the disappearance of the lichen is linked to gradual increase in bark pH caused by the combined effects of a marked reduction in SO2 emissions and rising emissions of NH3.