Bacidia neosquamulosa Aptroot & van Herk, a new corticolous lichen species, is described from the Netherlands, where it seems to be rapidly spreading and where it is considered to be a neophytic species. It is also reported from Belgium and Great Britain. It resembles corticolous morphs of the rather variable B. arnoldiana, but differs from this and other species by the longer, conspicuously septate, filiform, curved, macroconidia, the longer ascospores and the squamuloseisidiate thallus.

The new crustose lichen genus Tasmidella, containing the species, T. variabilis sp. nov with two varieties, var. variabilis and var. inactiva var. nov., is described. Tasmidella is most closely related to Megalaria, from which it differs chiefly by having simple ascospores with a layered wall. Relationships with superficially similar genera are discussed. A revised circumscription of the family Megalariaceae is provided to take into account the inclusion of a second genus.

Lecanora compallens and L. sinnosa, two corticolous lichens, are described nas species new to science on the basis of numerous collections. Lecanora compallens is a sorediate species, known only as sterile. It is probably common in Western Europe, but overlooked because it is very similar to L. expallens. Chemically, the new species is identical with L. strobilina, of which it may represent a sorediate counterpart. Lecanora sinuosa is a new species similar to L. chlarotera and so far only known from a limited area in the Netherlands and Germany, although it may be overlooked elsewhere. Lecanora sinuosa is very close to L. hybocarpa with which it shares the puhcaris-type epihymenium inspersed with fine crystals but differs markedly by its thick thallus and thick and sinuous apothecium margin.

Lecanora paramerae is described from Central-East Spain. At the only two known localities it grows on Juniperus thurifera trees in the ‘Serranía de Cuenca’ mountains. It is chemically characterized by the presence of 2′-O-methylperlatolic acid in addition to atranorin and psoromic acid. Anatomically, it can be recognized by the presence of large and irregular crystals in the amphithecium, a pulicaris-type epihymenium and broadly ellipsoid ascospores.

Lecanora barkmaneana, a sorediate corticolous lichen belonging to the Lecanora subfusca group, is described as a species new to science on the basis of numerous sterile collections and two richly fertile collections. It is known so far only from the Netherlands, where it often grows on roadside trees. It seems to be spreading rapidly at nutrient-rich sites.

Steinia australis Kantvilas & P. M. McCarthy is described, based on a specimen from Tasmania. The new species, the second in the genus and only the third in the family Aphanopsidaceae, differs from S. geophana by its larger ascospores, well-developed exciple and scurfy, leprose thallus.

Pyrenocollema montamnn P. M. McCarthy & Kantvilas sp. nov. (Xanihopyreniaceae) is described from moist and aquatic alpine rocks in south-western Tasmania.

Aspicilia crespiana Rico is described as a new species from central Spain and Sardinia (Italy). In central Spain it is common and has a well-defined ecology. It is found at middle to high altitudes (from 400 to 1900 m), overgrowing mosses on exposed and horizontal to more or less vertical siliceous rocks. Closely related to the A. contorta (Hoffm.) Kremp. complex, A. crespiana differs in its muscicolous habit and thallus development, consisting of a network of lichenized squamules interlinked by fungal rhizomorphs.

The lichen symbiosis has evolved several times within the fungal kingdom, although the total number of lichenization events leading to extant taxa is still unclear. Two lichenized families, the Icmadophilaceae and Baeomycetaceae have been classified in the Helotiales. Because the Helotiales are predominantly nonlichenized, this suggests that these families represent independent evolutionary episodes of lichenization from the Lecanorales. As a first step towards understanding the evolution of the lichen symbiosis within this order, we tested recent hypotheses concerning the segregation of lichen genera between the two lichen families. Specifically, we used phylogenetic analyses of nucleotide sequence data from nuclear small-subunit and large-subunit ribosomal DNA to test the morphology-based hypotheses that Dibaeis is a distinct genus from Baeomyces and that Dibaeis is a member of the Icmadophilaceae rather than the Baeomycetaceae. Phylogenetic analyses of nuclear SSU rDNA and combined SSU and LSU rDNA data support the hypothesis that Dibaeis is more closely related to IcmadophUa than it is to Baeomyces. Therefore, these data support the resurrection of Dibaeis from its previous synonymy with Baeomyces based on the characters of ascocarp colour and ascus morphology. The recognition of two distinct genera is also consistent with character state distribution of unique lichen acids.

The genus Biatora is still undercollected in many parts of its distributional range. On the basis of recent collections made by the authors and additional herbarium material not studied previously, more detailed statements on the ecology, distribution and conservational status of Biatora species in Central Europe are possible. Distribution maps are provided for B. fallax, B. mendax, B. ocelliformis, B. rufidula, B. sphaeroidiza, and B. vernalis. Biatora species are almost exclusively non-saxicolous and, in general, prefer humid habitats. Many species are chionophilous and extremely shade-tolerant. Three main distributional patterns can be observed: (sub-)arctic-alpine species, sub-oceanic-montane species, and species of montane coniferous or mixed coniferous forests. Biatora efflorescens, B. flavopunctata and B. subduplex are relatively frequent species and are not threatened. Biatora rufidula and B. vacciniicola must be regarded as extinct in Central Europe. The following species are reported for the first time from the respective countries: B. chrysantha from Romania, B. efflorescens from Romania and Ukraine, B. fallax from Austria and Ukraine, B. mendax from the Czech Republic, B. ocelliformis from Romania, and B. sphaeroidiza from Germany, Austria, the Czech Republic and Romania.

Pocsia mucronata P. M. McCarthy sp. nov. (incert. sed.) is described from Lord Howe Island, New South Wales, Australia. This foliicolous lichen inhabits leaves of the endemic palm, Howea forsteriana.

In the Netherlands a monitoring programme is in operation to map the effects of ammonia pollution with epiphytic lichens. The method is presented here and the results are statistically correlated with abiotic data. The abundance of nitrophytes on Quercus robur appears to be a useful parameter. Detailed spatial patterns of ammonia pollution can be obtained with lichens. To avoid interference, it is important to consider other influences, for example dust, climate, exposure, age of the trees and other pollutants.

The new species, Schaereria bullata Kantvilas from alpine Tasmania, is described and illustrated, with notes on its characterization, distribution and habitat. A key to the seven known species of the genus is provided.

Porina otagensis P. M. McCarthy (Trichotheliaceae) is described from semi-aquatic rocks near Dunedin in the South Island of New Zealand. It has perithecia with a thin, applanate to convex, spreading involucrellum, rather short but broad, 7-septate ascospores that lack a gelatinous sheath, and comparatively broad conidia.

Lecanora demissa (Körb.) Zahlbr. is a crustose, lobate lichen that produces soredia and conidiomata but no apothecia. Its placement in Lecanora has long been questioned but nothing better has been proposed. We have studied the nuclear rDNA of the ITS regions and the SSU of L. demissa. In an alignment of the ITS regions of several representatives of Lecanora s. lat. it could clearly be shown by a PAUP analysis, using Aspicilia caesiocinerea as outgroup, that L. demissa does not belong to Lecanora. In a PAUP analysis of sequences of the SSU from representatives of the order Lecanorales, using members of Saccharomycetales as outgroup, L. demissa clustered on a well-supported branch with Caloplaca chlorina. In a further analysis of the ITS sequences of L. demissa together with representatives of Caloplaca and Xanthoria using Protoparmelia as outgroup two most parsimonious trees were found. In these trees the L. demissa branch was well within a strongly supported clade with C. cerina, the type species of the genus Caloplaca. The sister taxon to L. demissa in this analysis was C. variabilis. Chemical data and characters of the conidiomata support the affinity with Caloplaca and the new combination C. demissa (Körb.) Arup & Grube is therefore proposed. A lectotype for Imbricaria demissa has been designated. The phylogenetic analysis of several representatives of the genera Caloplaca and Xanthoria suggests that these genera are not monophyletic as presently circumscribed. Two large, monophyletic groups of species could be recognized, one with Xanthoria species mixed with lobate and crustose members of Caloplaca, and one with mainly crustose Caloplaca, including both species with orange or black apothecia.

Two new species of Micarea are described from South Africa: M. almbornii Coppins, on loose sandstone from Stellenbosch (Western Cape) and M. endoviolascens Coppins, on damp soil from Transvaal. A note is given on Lecidea geïna Stizenb.

A fourth foliicolous species of Anisomeridium is described. Anisomeridium musaesporoides has so far only been found in Guyana and Panama. It is characterized by applanate perithecia with a white marginal zone, large spores with a submedian septum and apical ostiole. A key to all known foliicolous Anisomeridium species is provided.

The epiphytic lichen floras of different orchards (intensive, semi-intensive apple cultivation and traditional old private garden) in North-West Romania were compared with and without pesticide treatment. Species richness was negatively influenced by the frequency of pesticide treatment.