The new lichenicolous genus Ameroconium (dematiaceous hyphomycetes), with its type species A. cladoniae and the new lichenicolous species Phoma psoromatis (pycnidial coelomycetes), are described, discussed and illustrated. Phoma lobariae is recorded for the first time from the Arctic, Russia and Asia on Lobaria linita.

Morphological and chemical data from 64 genera of Parmeliaceae, including the most common genera in Europe, were analysed by means of neighbour–joining and parsimony analysis. Two presence/absence matrices were constructed, one for the 64 genera and a smaller one for the most common European genera. Probabilities were too low to allow grouping of the genera and only a few pairs of genera had a probability of >50% for both matrices. A molecular matrix (nuclear rDNA-ITS) of the most common genera in Europe was constructed and analysed by the method of maximum likelihood. These results were much more informative than the non-molecular matrix for establishing phylogenetic relationships among the genera.

The formation of vegetative cells from zoospores and the morphogenesis of the multilayered cell walls during this process was observed in some Trebouxia and Pseudotrebouxia species. In Trebouxia species, e.g. Trebouxia erici, the wall of the vegetative cell is formed around the zoospore while in Pseudotrebouxia species, e.g. Pseudotrebouxia corticola, firstly an autosporangium with its wall is formed then the autosporangium further divides.

The limestone plateau of Derbyshire is intensively farmed but supports terricolous lichens associated with unimproved grazing, derelict lead mining ground and modern fluorspar working. The assemblages identified include a number of relict species now very rare in central England. Reworking mine waste for fluorspar can result in the development of communities containing particularly interesting lichens. Land-use is now the chief determinant of terricolous lichen communities in the area studied.

Western North America is the global centre of diversity for Letharia, a distinctive and cryptically diverse genus of lichenized fungi belonging to the Parmeliaceae. The genus is characterized by a shrubby, fruticose habit and presence of vulpinic acid. Previous studies using multiple fungal nuclear loci revealed the existence of two distinct species-level lineages within the traditional concept of L. vulpina and four such lineages within L. columbiana. Here we use molecular sequence data in an attempt to settle long-standing taxonomic issues in the genus. Our results confirm the widespread existence within L. vulpina s. lat. of two distinct species-level groups, each forming a mutually exclusive partnership with a separate algal clade within Trebouxia jamesii s. lat. Accordingly, we formally describe the segregate species L. lupina sp. nov. Our results also support the evolutionary independence of four candidate species previously circumscribed from L. columbiana s. lat. One of these lineages, L. ‘gracilis’, has already received species recognition as L. gracilis, while a second, L. ‘lucida’, is epitypified here against L. columbiana s. str. Based on results from species delimitation analyses under the multispecies coalescent model, the two remaining lineages, L. ‘barbata’ and L. ‘rugosa’, also warrant formal taxonomic recognition; however, we refrain from describing these species pending additional studies of diagnostic characters, ecological preference, and distributions.

Photosynthetic performance in lichens can vary throughout the year. We investigate the variation in the PSII quantum efficiency as a proxy for the physiological state of the photosynthetic apparatus in two umbilicate species from the genus Lasallia. Temporal variation in F v/F m in both species was monitored at a field site in Central Spain where both species coexist. Subsequent measurements were carried out in the laboratory after 48 h preconditioning. Both species showed clear variation during the year in PSII performance, with a marked depression in F v/F m during the summer. Lasallia pustulata consistently had higher F v/F m values than L. hispanica. Both species reached higher F v/F m values after 48 h of preconditioning in the laboratory and this recovery was particularly notable in the summer months. F v/F m was highly related to antecedent weather conditions during the two days prior to measurement.

Growth rates and the ability to date an organism can greatly contribute to understanding its population biology and community dynamics. 1n 1954, V. N. Andreev proposed a method to date regularly branched members of Cladonia, a fruticose lichen, using total thallus length and number of internodes. No research, however, has demonstrated the reliability of this technique or compared its estimates to those derived by other means. In this study, we demonstrate the utility of 14C/C ratios to determine lichen age and growth rate in Cladonia stygia (Fr.) Ruoss collected from north-western Alaska, USA. The average growth rate using 14C/C ratios was 6·5 mm yr−1, which was not significantly different from growth rates derived by Andreev's internode method (average = 6·2 mm yr−1); thus, suggesting the reliability of Andreev's simple field method for dating lichens.

Two species of Placopyrenium, P. cinereoatratum and P. formosum, occur on siliceous rocks at the margins of rivers and lakes. Placopyrenium cinereoatratum is sometimes parasitic on Staurothele fissa; P. formosum is described as a new species, and is initially parasitic on Aspicilia aquatica.

Twenty-six species recently described from Thailand are revised. Eleven taxa are reduced to synonymy with previously described species, including Leptotrema phaeosporum var. vainiona Räsänen. The following new combinations are proposed: Chapsa calathiformis (Vain.) Lumbsch & Papong, C. laemensis (Homchantara & Coppins) Lumbsch & Papong, Melanotrema melanophthalmum (Homchantara & Coppins) Lumbsch & Papong, Ocellularia albocincta (Hale) Divakar & Mangold, O. guianensis (Sipman) Divakar & Mangold, O. khunantensis (Homchantara & Coppins) Lumbsch & Papong, O. percolumellata (Sipman) Divakar & Mangold, O. subcalvescens (Nyl.) Divakar & Mangold and Ocellularia subgranulosa (Homchantara & Coppins) Lumbsch & Papong.

The Thelotremataceae are represented on Aldabra by three species: Leucodecton compunctum, Thelotrema euphorbiae, and Thelotrema hniatukii. The latter is described here as new. It is closely related to T. euphorbiae and know so far only from Aldabra.

Six new species of foliicolous lichenized fungi are described as new to science from lowland rainforest in the Congo Basin: Bapalmuia serusiauxiana Van den Broeck, Lücking & Ertz (Pilocarpaceae) characterized by (7–)15(–19)-septate ascospores of (40–)50–65(–72)×1·5–2·5 μm, Microtheliopsis ramazaniana Van den Broeck, Lücking & Ertz (Microtheliopsidaceae) characterized by 1-septate ascospores of 13–16×3–5 μm, Phylloblastiaverheyeniana Van den Broeck, Lücking & Ertz (Verrucariaceae) characterized by 3-septate ascospores of 13–15(–17)×3·0–4·5 μm, Porina duduana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by 3-septate ascospores of 11·0–14·5×2·5–3·0 μm, perithecia 130–150(–170) μm diam. and a photobiont with angular-rounded and irregularly arranged cells, Porina gryseelsiana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by orange-brown perithecia and 7–9(–12)-septate ascospores of 29–46×5·0–7·5 μm, Porina weghiana Van den Broeck, Lücking & Ertz (Porinaceae) characterized by the presence of disc-shaped isidia, yellow perithecia without apical appendages and (7–)9-septate ascospores of 33–50×5·0–6·5 μm. In addition, 53 species new for the Democratic Republic of the Congo are listed, including five species new for tropical Africa and six new for the Palaeotropics, thus raising the number of species known from the Democratic Republic of the Congo from 150 to 209. Keys are presented to all known species of Microtheliopsis and to species of Porina with disc-shaped isidia.

The lichenicolous fungus Lichenostigma rupicolae Fdez.-Brime & Nav.-Ros., collected in France, Spain and Turkey, is described as new to science. It is found growing on the surface of the thalli and apothecia of Pertusaria rupicola, where it forms black patches of radiating plurihyphal strands connecting the fertile stromata. An updated key of the species of subgenus Lichenogramma is included.

The new species Diploschistes elixii is described from Western Australia. It is characterized by perithecioid ascomata and large ascospores. It resembles D. hensseniae but is readily distinguished by larger ascospores (up to 45 μm), having lecanoric acid as major constituent, and an epruinose thallus surface. It is currently known from several localities in south-western Australia, where it grows on soil.

The new species, Sphinctrina paramerae, is proposed. Characteristics of ascospores (size, morphology and ornamentation), apothecia (morphology, size and chemical reactions) and ecological features revealed significant differences between S. paramerae and the currently known species of Sphinctrina with non-septate ascospores. The new species grows on Pertusaria paramerae, epiphytic on the bark of Juniperus thurifera, which occurs on well-exposed areas of parameras in the Iberian high plateau and other montane Mediterranean areas.

The thallus of Peltigera rufescens has a cladomian structure. It is developed from axial filaments which are lodged in the veins and from which are developed several, short, ventral pleuridia and numerous well-developed, which are developed, dorsal ramifications.

The latter form the remainder of the thallus.

The ascocarps develop directly from a small number of marginal, dorsal pleuridia which form a well-delimited primordium from which is built up a primary corpus, similar to the type formed in graphidian and lecanorian species. To this is added a parathecial apparatus. Although this development is to be qualified lecanorian, certain peculiarities may be noted; these are a very long angiocarpic stadium in the course of which are built up a parathecioid envelope and a marginal crown, the characters of which are intermediate between those of primary and secondary elements.

The asci are bitunicate and ‘archaeascé’.

We investigated the phylogenetic relationships in the cyanolichen family Placynthiaceae to test the current generic delimitations, where the monotypic Collolechia is currently accepted as distinct, based on differences in ascospores, ascus apex characteristics and the leprose thallus. Bayesian and maximum likelihood phylogenetic analyses of two sequence marker datasets confirmed that Collolechia caesia is nested within Placynthium, and should be called Placynthium caesium (Fr.) Jatta. We reassessed the spore and ascus characteristics and showed that Placynthium caesium falls well within the variation in Placynthium and is thus yet another example of a species that differs from close relatives by its crustose-leprose thallus structure.

Histochemical aspects of the amorphous layers in two species of Parmelia apseudocyphellate and a pored epicorticate, were compared. In P. saxatilis this layer, called the ‘ syncortex ’ (a new term), is composed of strongly acidic (sulphated) polysaccharides containing hyaluronic acid. It is easily distinguishable histochemically from the cortical interhyphal matrix. In P. caperata the mild acidic polysaccharidic composition of the epicortex and the interhyphal matrix is shown. The function of these amorphous layers is discussed on the basis of these results.

The new species Oropogon evernicus Essl. & S. Leavitt and O. protocetraricus S. Leavitt & Essl. are described from montane regions of Central America, further increasing the diversity of this genus in the New World. Oropogon evernicus is separated from O. americanus by the presence of medullary tissue directly beneath the pseudocyphellae, while O. protocetraricus is separated from O. caespitosus by the presence of protocetraric acid. The segregation of both species is confirmed by molecular sequence data (nuclear ITS, nuLSU, and β-tubulin). Both species appear to have split from their most recent common ancestor during the Miocene, supporting Miocene-dominated diversification of neotropical Oropogon species found in Central America.