Tremella caloplacae (Zahlbr.) Diederich is a species complex including at least nine different species. Here, we formally describe the new species Tremella elegantis, T. nimisiana, T. parietinae, T. pusillae and T. sorediatae. Tremella elegantis induces galls in the hymenium of Rusavskia elegans and forms 2-celled basidia, where cells rarely elongate and sometimes give the appearance of two immature, independent basidia. Tremella nimisiana has small basidiomata (less than 1 mm diam.), narrowly ellipsoid to pyriform 2-celled, occasionally clavate to subcylindrical 3-celled basidia, and grows in the hymenium of Xanthocarpia species. Tremella parietinae is characterized by the exclusive growth in the hymenium of Xanthoria parietina, the broadly fusiform to ellipsoid probasidia, and the subspherical, pyriform or ellipsoid 2(–3)-celled basidia. Tremella pusillae has ellipsoidal probasidia, 2(–3)-celled pyriform or ellipsoidal basidia that sometimes are constricted at the septum, and grows only on Calogaya pusilla. Tremella sorediatae is characterized by inducing galls on the thallus of Rusavskia sorediata and by pyriform to ellipsoid basidia that sometimes are constricted at the septum. Three species are not formally described and are left unnamed as Tremella sp. 13 on Calogaya biatorina, Tremella sp. 14 on Calogaya decipiens and Tremella sp. 15 on Polycauliona sp. Tremella caloplacae in the strict sense is re-circumscribed as a species confined to Variospora species.

Gene expression variation can be partitioned into different components (regulatory, genetic and acclimatory effects) but for lichen-forming fungi, the relative importance of each of these effects is unclear. Here, we studied gene expression in the lichen-forming fungus Lobaria pulmonaria in response to thermal stress and parasitism by the lichenicolous fungus Plectocarpon lichenum. Our experimental procedure was to acclimate lichen thalli to 4 °C over three weeks and then expose them to 15 °C and 25 °C for 2 hours each, sampling infected and visually asymptomatic thalli at each temperature. Quantitative Real-Time PCR was utilized to quantify gene expression of six candidate genes, normalizing expression values with two reference genes. We found that two genes encoding heat shock proteins (hsp88 and hsp98), two polyketide synthase genes (rPKS1, nrPKS3) and elongation factor 1-1-α (efa) were upregulated at higher temperatures. Moreover, we observed higher expression of hsp98 at 25 °C in samples infected by P. lichenum than in uninfected samples. Finally, in partial redundancy analyses, most of the explained variation in gene expression was related to temperature treatment; genetic variation and long-term acclimatization to sites contributed far less. Hence, regulatory effects (i.e. direct adjustments of gene expression in response to the temperature change) dominated over genetic and acclimatory effects in the gene expression variability of L. pulmonaria. This study suggests that L. pulmonaria could become a valuable lichen model for studying heat shock protein responses in vivo.

A new Arthothelium species, A. hymeniicola in the apothecia of an unidentified Bacidia sp., is described from Campbell Island, New Zealand. The new species is remarkable, not only by being the first lichenicolous Arthothelium species, but also by being an endohymenial fungus not forming ascomatal structures. Previously, no Arthoniaceae species were reported as parasitic from Bacidia spp. However, both generic and family placements are tentative and the possibility of a placement in the Cookellaceae is also discussed. Differences between Arthoniaceae and Cookellaceae, and the generic delimitations within them, are generally based on the structures of the fruiting bodies, rendering the taxonomic placement of the new species challenging without molecular data; neither fruiting bodies nor molecular data are available for the new species and the Cookellaceae.

A diversity of filamentous microfungi was discovered from thallus surfaces of epiphytic lichens preserved in Bitterfeld and Baltic amber. We report seven distinct morphologies of dematiaceous hyphomycetes, some of which closely resemble species of the extant genera Sporidesmium, Taeniolella s. lat. and Taeniolina. Both the placement of the fungi on their substrates and the exquisite preservation of delicate structures indicate that the fungi were fully developed before they were engulfed by fresh resin. The lichens probably grew on the trunks of resin producing trees and became embedded in resin flows together with their fungal associates. The findings demonstrate that a wide range of presumably specialised fungi have lived on living and decomposing lichen thalli at least since the Paleogene. The findings add an interesting new component to the as yet poorly known mycota of the ancient European amber forests.

The new genus and species Bicoloromyces kyffinensis is described as new to science from a sterile crustose lichen, perhaps Lecanora fuscobrunnea or Lecidella sp. from Ebony Ridge of Mount Kyffin, Antarctica. The fungus recalls superficially the lichenicolous species referred to Taeniolella, but differs in having semi-macronematous conidiophores, tissues encrusted with calcium oxalate, aeruginose to blue-black colouration under the microscope, and conidia which are distoseptate and formed in basipetal chains. Energy dispersive spectroscopy established that the encrustations were of calcium oxalate. Differences from genera of rock-inhabiting fungi described from the Antarctic are discussed. This appears to be the furthest south any lichen-inhabiting fungus has been reported.

Two new genera and four new species of bulbil-forming basidiomycetes are described. Phylogenetic analyses of nuLSU and ITS sequences place them in Cantharellales. A facultative lichenicolous species with yellow to orange-yellow bulbils from South America groups with the type of Burgella and is consequently described as B. lutea. The new species and genus Burgellopsis nivea is introduced for material from Scotland with white bulbils overgrowing saxicolous lichens. An obligate lichenicolous species with particularly large, applanate bulbils developing over Peltigerales in South America could not be placed accurately using ITS sequences and is described as the new species and genus Bulbilla applanata. A European species with brown, facultatively lichenicolous bulbils grouped with Ceratobasidium and Thanatephorus species and is described as the new Ceratobasidium bulbillifaciens.

Heteroacanthella ellipsospora is described as new to science. It is the only known lichenicolous Heteroacanthella, always found parasitizing apothecia and the surrounding thallus of the crustose epiphytic lichen Lecanora carpinea. The new parasite has so far only been found in two Spanish provinces, Jaén and Madrid. The shape and size of its basidiospores, the basidia with acanthoid ornamentation, acanthohyphidia, as well as its parasitic lichenicolous habitat, with a replacement of host tissues by the parasite hymenium, are useful diagnostic characters.

A quantitative cluster analysis of lichen distribution data demonstrates that the main biogeographical subdivision in the world's lichen biota is into a Gondwanan and a Laurasian element. Patterns at smaller scales mainly reflect local climate. Wallace's line is not a significant boundary for lichens. The Gondwana / Laurasia split also applies to lichenicolous fungi. To a considerable extent, it applies to many of the larger families and orders of lichens too, though at these ranks the affinities of the lichen biota of eastern Asia and temperate North America are sometimes ambiguous.

Thamnolia vermicularis is a globally widespread arctic-alpine lichen with two distinct chemotypes. The intermixing of these chemotypes at the local scale and lack of genetic variation between them is puzzling given the apparent absence of specialized reproductive structures. Apothecia and conidiomata were originally reported for Thamnolia in the second half of the 19th century, but putative apothecia proved to be parasitic in origin. This study presents conclusive microscopic evidence for the existence of pycnidial conidiomata containing conidia on thalli of Thamnolia vermicularis from geographically widespread locations. Sequences of the internal transcribed spacer (ITS) region of ribosomal DNA from excised pycnidial conidiomata matched that of thallus tips from individual Thamnolia thalli. Our examination of the historic literature found that the occurrence of pycnidial conidiomata was never disproved, but this information was lost from the post-1920s English-language literature. Our rediscovery of pycnidial conidiomata indicates that Thamnolia vermicularis possesses a reproductive strategy with the potential for long-distance dispersal of multitudes of mitotically produced conidia, providing a plausible explanation for the cosmopolitan distribution of the species and the low levels of genetic variation among populations. Reversible processes, for example alternative splicing, warrant consideration as explanations for chemotype intermixing.

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.

Plectocarpon dirinariae Ertz & van den Boom is described from Cape Verde from the thallus of saxicolous Dirinariaapplanata. The new species is characterized by convex rounded ascomata not inducing basally constricted galls, non-carbonized sterile stromatic tissue, mainly 4–6-spored asci and 3-septate ascospores. Similar Plectocarpon sp. are discussed.

Pronectria collematis, growing on Collema auriforme, C. cristatum, and C. undulatum, is described from Germany and Spain.

Fungi that are unrelated to the mycobiont species frequently colonize lichens. Some of these fungal colonists are described lichenicolous fungi, lichen parasites and pathogens that produce recognizable morphological characters, while others apparently produce no noticeable structures. Here we apply the single strand conformation polymorphism (SSCP) technique to directly assess the abundance of different fungi in lichens. Twenty-eight lichen thalli were chosen, some with and some without externally visible symptoms of parasite infection, and these were subjected to total DNA extraction. PCR was conducted with fungal-specific primers for the ITS region of ribosomal DNA. Single strands of the products were separated on native acrylamide gels. The majority of lichen specimens, both infected and those without symptoms, displayed more than one band in the stained gels. In one case, 14 bands were detected using SSCP. Some of these bands apparently represent other neighbouring lichens in the habitat, but many are apparently non-lichen-forming. Since few lichen-associated fungi have been cultured and sequenced, it is difficult to know if SSCP bands represent obligate lichenicolous fungi, other asymptomatic lichen parasites, or fungi not obligately associated with lichens, but our results indicate that large numbers of non-lichen-forming fungi commonly co-occur with lichens in nature. For specimens of the filamentous lichens Cystocoleus ebeneus and Racodium rupestre we used cloned sequences to compare the number of sequences obtained by the SSCP method to the number obtained by direct sequencing of thallus extracts, and we generally found that more sequences could be detected by SSCP than could be seen by direct sequencing.

Stigmidium humidum is described from Spain and Turkey on Thelenella muscorum (Fr.) Vain. (syn Chromatochlamys muscorum (Fr.) H. Mayrhofer & Poelt). The species is the first Stigmidium s. str. species on a host lichen of the family Thelenellaceae and is compared with other species with ‘Type a’ pseudoparaphyses.

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 genus Labrocarpon is introduced for the species Melaspilea canariensis based on the presence of excipular periphysoids. In addition, Buelliella protoparmeliopsis is described from Chile, the twelfth species of the genus. Notes on the two new taxa and related species are provided.

The new lichenicolous Llimoniella phaeophysciae, known from Italy, Spain and the USA (Arizona) on Phaeophyscia, resembles Geltingia associata in the subcylindrical asci with uniseriate, shortly ellipsoid ascospores, but is distinguished by several important characters. Gelatinopsis acarosporicola, G. heppiae, Geltingia groenlandiae and Psorotichia terricola (syn. nov. Gelatinopsis leptogii) are considered to be congeneric with L. phaeophysciae, although some of them have elongate clavate and not subcylindrical asci and they are consequently combined in Llimoniella. These five species are distinguished from Llimoniella s.str. by a different excipular and epihymenial pigmentation not reacting with KOH and are treated as the informal L. phaeophysciae group. The new L. placopsidis is described from Placopsis in New Zealand. More complex pigmentation patterns are documented for L. pyrenulae and L. ramalinae. A revised key to the species of Llimoniella is presented. Gelatinopsis ericetorum and G. roccellae are combined in Rhymbocarpus. A redescription of Geltingia associata is given.

Fifty-six known lichenicolous, non-lichenized Opegrapha (Roccellaceae, Arthoniales) species (containing some undescribed taxa) are listed here, five of which are known from Caloplaca (Teloschistaceae, Teloschistales). Opegrapha vulpina, a new lichenicolous fungus on endolithic Caloplaca subg. Pyrenodesmia (Caloplaca erodens and rarely C. albopruinosa), is described from Europe. A second new species, Opegrapha hellespontica, lichenicolous on Caloplaca aurantia, is described from the European part of Turkey. Two possible sibling species of Opegrapha rupestris s. l. lichenicolous on Caloplaca cirrochroa and C. variabilis s. l., respectively, are discussed in the paper, but have not been described.

The name Polycoccum opulentum proves to have been wrongly applied to a lichenicolous fungus belonging to the genus Lichenothelia, and which differs from the type material of P. opulentum in having non-ostiolate broadly stipitate ascomata and narrow ascospores with a conspicuous gelatinous sheath. The Lichenothelia represents an hitherto undescribed species, named here as L. renobalesiana, sp. nov. which is associated with verrucarialean lichens on hard limestones in temperate regions. The true P. opulentum is known only from the original collection on Polyblastia hyperborea from Sweden.

The new species Lecanora lasalliae Pérez-Ortega & Etayo is described from Spain. It is included provisionally in Lecanora s. lat as characters such as Lecanora-type ascus, exciple composed of thick radiating hyphae and the usual presence of algal cells in the excipulum or its lichenicolous habitus on Lasallia pustulata, do not fit well within any known genus of lichenicolous or lichenized fungi. Its taxonomic affinities with several taxa are discussed, including the parasitic Lecanora gyrophorina.