All species of Antarctic Acarosporaceae (s. lat., including Biatorellaceae) with yellow thalli are revised. Four genera, Acarospora, Biatorella, Biatorellopsis, Eklundia, and ten species, all of them endemic, were previously reported from Antarctica. Our results indicate that in Antarctica Acarospora subgen. Xanthothallia s. str. includes only two species, A. gwynnii Dodge and A. flavocordia sp. nov.; Biatorella does not occur in Antarctica, the species described by Dodge belonging instead in Candelariella; the genus Eklundia is a synonym of Candelariella; Biatorellopsis does not occur in Continental Antarctica, and the genus is a synonym of Pleopsidium; Pleopsidium is represented in Antarctica by one species, P. chlorophanum, which was treated under very different generic and specific names by earlier authors. Altogether, the number of species of yellow Acarosporaceae known from Antarctica is reduced from ten to three, distributed in two genera: Acarospora and Pleopsidium. The two Acarospora species, A. gwynnii and A. flavocordiaare apparently endemic to Antarctica, whereas P. chlorophanum is a widespread bipolar lichen. A comprehensive list of synonyms and a key are provided.

A new species, Cladonia singhii Ahti & Dixit (type from the state of Arunachal Pradesh), is described. A further seven Cladonia species, C. corniculata, C. kanewskii, C. laii, C. luteoalba, C. mauritiana, C. mongolica and C. rei, are reported as new to the recent checklist of lichens of the Indian subcontinent. The presence of C. cartilaginea in India is confirmed.

Twenty lichens and a cyanobacterium grow as epiphytes on both shoreline and inland coconut palms (Cocos nucifera) on Caye Caulker, Belize, with a difference in distribution of these epiphytes between shoreline and inland trees. Nine epiphytes were also collected from mangrove (Rhizophora mangle): seven lichens, one moss, and one cyanobacterium.

Four new species of Caloplaca are described from Antarctica: C. buelliae is parasitic on Buellia, C. iomma has a characteristic deep reddish orange colour on the apothecia, C. psoromatis is parasitic on Psoroma and Pannaria, and C. siphonospora is a parasitic species of mosses, very similar to C. nivalis, but with much shorter spores.

Descriptions are provided for two new species, Mycomicrothelia lateralis Sipman from Norfolk Island and M. triangularis Aptroot from Puerto Rico, both characterized by lateral ostioles and uniseriate ascospores. Based on the examination of additional fresh material, the genus Ornatopyrenis is included in Mycomicrothelia and the new combination Mycomicrothelia queenslandica (Müll. Arg.) Sipman & Aptroot is made. Ornatopyrenis muriformis Aptroot is proposed as a synonym of M. decipiens (Müll. Arg.) R. C. Harris.

A new Mediterranean species, Waynea cretica, is described. The species is so far known only from Crete (Greece). Waynea cretica has flat to scarcely ascending squamules, an upper cortex being a paraplectenchymatous eucortex, and long, narrow, acicular ascospores with (5–)7 septa. The new taxon is compared with the hitherto known species of Waynea.

Lecidea hercynica Hauck & Schmull is described as a new species from Germany. It is characterized by a poorly developed or bullate to verrucose, areolate thallus on whitened spots of the substratum, numerous plane to yellowish brown to black, convex apothecia with a persistent margin, Micarea type-like asci, and by the presence of atranorin and protocetraric acid. It does not belong to Lecidea s. str., but is provisionally placed in Lecidea s. lat. until a taxonomic treatment of the whole group has been carried out. Lecidea hercynica is widespread in high-elevation forests of Picea abies in the Harz Mountains, where it grows preferably on decorticated wood in open situations.

Recently, nine species of lichenicolous fungi were found growing on Cetraria aculeata (Parmeliaceae) in a sand dune system in the Ukraine. One of them, Didymocyrtis trassii, is described here as new to science. This species is similar to D. pseudeverniae but differs in having smaller pycnidia, smaller obpyriform to clavate conidia as well as its DNA sequence. The new monotypic lichenicolous genus Katherinomyces is described here. Acremonium lichenicola s. l., Eonema pyriforme, Didymocyrtis cladoniicola and Lichenoconium erodens are reported for the first time on Cetraria aculeata. Furthermore, E. pyriforme is reported for the first time from lichen thalli. Acremonium lichenicola, E. pyriforme and Taeniolella rolfii are new for the mycobiota of the Ukraine. A key to the eleven known lichenicolous species on Cetraria aculeata is provided.

New collections are reported of the monospecific genus Polypyrenula, an apparently extinct and doubtfully lichenized fungus, typically classified in the Pyrenulaceae. Anatomical studies reveal that it is facultatively lichenized. The structure of its hamathecium suggests affinities with Dothideomycetes rather than Eurotiomycetes. Molecular analysis using nuLSU and mtSSU markers demonstrates for the first time its inclusion in Trypetheliaceae, outside the core genera as part of the early diverging lineages in this family. The known distribution of Polypyrenula is extended to Mexico and South America, new information on its phorophyte associations is provided, and the name Polypyrenula sexlocularis is reinstated as the correct name for this species.

The new species Megalaria allantoidea Fryday is described from the subantarctic Îles Kerguelen in the southern Indian Ocean, where it grows over terricolous bryophytes or Azorella selago cushions. It differs from all other described species of Megalaria in having large, sausage-shaped ascospores. The systematics of the genus Megalaria is reviewed, ascus structure of some previously described species revised, and the position of the new species in the genus discussed.

The genus Xanthoparmelia (Vain.) Hale (including Neofuscelia Essl.) currently includes more than 800 species (Blanco et al. 2004, 2005), 21 of which have been recorded in the Iberian Peninsula (Llimona & Hladun 2001). During recent studies of the lichen flora of Castilla y León by the first author, a rare, loosely adnate or vagrant, terricolous Xanthoparmelia has been found at two localities in Burgos province. Although a collection (VAL-Lich 20080) from one of the localities (Fresnillo de las Dueñas) was previously reported as the American species X. vagans (Nyl.) Hale (Pérez-Ortega et al. 2002), this collection has now been redetermined as X. pseudohungarica (Gyeln.) Hale.

Lecidea kelica Stirt., formerly accepted as a corticolous species of Catillaria is shown to belong to a new, monospecific genus here described as Stirtoniella in the family Ramalinaceae. Details of Stirtoniellia kelica, its synonymy, chemistry, ecology and distribution are presented. It is known from New Zealand and Tasmania.

Hemithecium isidiatum from the Eastern Himalayas is described as new to science. It is the first isidiate species in the genus Hemithecium and is otherwise characterized by hyaline muriform ascospores and the presence of salazinic acid.

The delimitation of the genus Parmelia s.lat. has been a subject of controversy for the past 30 years. Originally this large group of lichens was split into smaller genera for convenience, based mainly on the colour of the thallus and the presence of marginal cilia (Hale 1974); later conidial and other vegetative characters were used (Hale 1984: 18–20). With time several quite small genera of parmelioid lichens were recognized by a number of authors (e.g. Elix 1994), whilst others, because of the sparsity of characters, continued to regard most of them as still belonging to Parmelia (Purvis et al. 1992). Recent molecular studies have ended this polarization, and an agreed classification is now being adopted (Blanco et al. 2004a, 2004b, 2005).

Based on morphometric and molecular methods, the taxonomy of the infraspecific taxa of Fuscidea cyathoides (Ach.) V. Wirth & Vězda, var. corticola (Fr.) Kalb and var. sorediata (H. Magn.) Poelt, has been assessed. No formal taxonomic recognition should be attributed to the morphological and ecological variation. Accordingly, var. corticola and var. sorediata are synonymized with F. cyathoides var. cyathoides. New synonyms at the specific level are Fuscidea fagicola (Zschacke) Hafellner & Türk and F. stiriaca (A. Massal.) Hafellner.

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.

Menegazzia neotropica sp. nov. is described from upper montane forest remnants and paramos in Ecuador, Colombia and Venezuela. It is characterized by short-pedicellate apothecia with ridged margins that partly obscure the discs, and by narrow, glossy lobes with brown-black margins. Menegazzia dissecta is recorded from South America for the first time and M. terebrata is recorded from Colombia and Ecuador for the first time.