A new lichen species is described from specimens growing on Fraxinus trees north of Eindhoven (the Netherlands). Morphological and genetic studies suggest that the new species belongs in the genus Catillaria, and the name Catillaria flexuosa is proposed because of its flexuose apothecia. The new species is characterized by the relatively large apothecia (up to 0.9 mm diam.) and relatively thick, knobby to ±subsquamulose, greenish, thallus. Due to their similar morphological features, C. flexuosa can be easily confused with Catillaria chalybeia, C. fungoides or C. nigroclavata, so it is therefore compared with these species. In addition, Arthonia epiphyscia is reported being a very rare species in the Netherlands.

The new lichen species Lecidea phaeophysata is described from rocks close to the coast in Italy, Portugal, France and Ireland. Distinguishing features include Porpidia-type asci and simple paraphyses that are fuscous brown pigmented in their upper section. Its systematic position is discussed but is unclear as molecular data are lacking (all collections are c. 20 years old). Therefore, we chose to describe the species in a broadly-circumscribed Lecidea rather than erecting a new monotypic genus. A key to saxicolous lecideoid lichens present on Atlantic coasts in Europe is also provided.

Detailed morphological and anatomical studies informed by molecular inferences with mtSSU as a marker revealed two new species of Micarea in Western Europe, both belonging to the core group of the genus, namely the M. prasina group: M. herbarum from the Netherlands and Poland and M. meridionalis from Portugal and Italy. Micarea herbarum looks like a small or depauperate M. denigrata but clearly differs by the lack of gyrophoric acid, while M. meridionalis is distinguished by its granular thallus and the production of micareic acid.

Amandinea lobarica, a new corticolous lichen species, is described from high elevations in Guatemala. It is characterized by a thin, granulose, brownish thallus containing lobaric acid, small, convex lecideine apothecia, filiform conidia and large, narrowly ellipsoid ascospores with roughly ornamented walls. The new species is compared with other Buellia s. lat. taxa that possess rather large and strongly ornamented ascospores, such as Buellia hypothallina, here placed in synonymy with Gassicurtia vaccinii, Amandinea leucomela, A. mediospora, A. megaspora, A. subduplicata and five very closely related taxa treated here as belonging to the Amandinea incrustans group. Two tables summarizing the main differences between these species and a key are provided. New data on the chemistry of A. leucomela and a new record of A. montana for Guatemala are also included.

Detailed anatomical and chemical studies conducted on recent collections made in almost all suitable habitats on Réunion, a small remote tropical island in the Indian Ocean, yielded a surprising diversity in the widespread lichen genus Micarea (Pilocarpaceae, Lecanorales). Twenty-one species are recognized, including 13 described here as new to science. They are: Micarea alectorialica, M. bebourensis, M. borbonica, M. boryana, M. cilaoensis, M. hyalinoxanthonica, M. isidiosa, M. melanoprasina, M. pseudocoppinsii, M. pseudolignaria, M. sublithinella, M. takamakae and M. tenuispora. Notes on local ecology and important biogeographical features are also given and a key to the species is provided. Isidiiform areolae are reported for the first time in the genus (M. isidiosa and M. tenuispora), as well as the production of protolichesterinic and confluentic acids (M. sublithinella and M. takamakae, respectively). Two groups within the genus are species-rich on the island: the M. peliocarpa group with possibly 5 species, including 3 new to science, and the M. prasina group with 4 species, including 2 new to science. Micarea levicula is reported here for the first time since its description, and the status of the material that can be referred to M. micrococca s. lat. needs further study.

The new species Micarea usneae is described from Madeira. It has been found at two localities where it grew on epiphytic Usnea thalli. Micarea usneae is distinguished by a very thin pale brownish thallus, pallid to greyish black or bluish subglobose apothecia of 0·1–0·3 mm diameter, very narrow (1·5–2·5 µm) ascospores, black pycnidia and strongly curved to sigmoid macroconidia. Phylogenetic analyses using mtSSU sequences place the new species in the Micarea peliocarpa group. Catillaria usneicola and Cladonia parasitica are recorded for the first time from Madeira. A key to the lichenicolous species on Usnea in Macaronesia is provided.

Buellia subericola, a new corticolous species characterized by a brown, blastidiate thallus without secondary chemistry and triseptate to occasionally submuriform ascospores, is described from the southern Iberian Peninsula. The species occurs on Quercus suber in grass-woodlands of cork-oak in the mesomediterranean belt with a warm mediterranean climate and oceanic influence. It is compared with other known Buellia s. lat. taxa which also reproduce asexually and have similar ascospores.

Lecania chlorotiza and L. falcata, described here as new from Spain/Navarra, the Canary Islands and the Azores, do not belong to Lecania s. str. They belong to a strongly supported clade comprising Bacidia, Bacidina, Scutula and Toninia when examined with maximum parsimony, maximum likelihood and Bayesian inferences using mtSSU, nuLSU and nuITS sequences. This clade represents the Bacidiaceae and is included in the Ramalinaceae s. lat. Most genera included in that family need further work before a new genus can possibly be described for Lecania chlorotiza and L. falcata.

Well-developed ascospores of Rinodina flavosoralifera have been observed for the first time. The ascospores are described and illustrated and new data on the chemistry and distribution of this species are provided. New chorological data on Rinodina disjuncta are also included.

Lecanographa uniseptata is described as new to science. It is characterized by having small rounded to lirellate ascomata, and 1-septate ascospores. The species is known from tropical Africa (Gabon) and tropical America (Guatemala).

Melanotopelia africana is described as new to science from Rwanda (continental Africa) and La Réunion (Mascarenes archipelago). Topeliopsis muscigena is here reported for the first time from La Réunion.

The silicicolous lichen species, Rinodina etayoi Giralt & van den Boom, is described as new from inland localities of Fuerteventura and Lanzarote (Canary Islands). It is characterized by a crustose, whitish thallus containing atranorin, zeorin, chloroatranorin and stictic acid, hemispheric pseudolecanorine apothecia containing, a proper exciple inspersed with numerous and large oil drops, and by ascospores of the Mischoblastia-type. The joint occurrence of pannarin, stictic acid and Mischoblastia-type ascospores makes R. etayoi unique within the genus.

Examination of Rinodina specimens from the Cape Verde Islands revealed three new species, which are described here: Rinodina capeverdeana Giralt & van den Boom, R. inspersoparietata Giralt & van den Boom and R. polymorphaespora Giralt & van den Boom. Additional information is given for six further species, of which five are new records for the archipelago. Rinodina punctosorediata Aptroot & Sparrius was found to be conspecific with R. stictica Sheard & Tønsberg.

A revision of the Lecanora saligna-group is provided, based on specimens mainly from western and central Europe. Four new Lecanora species related to L. saligna are described: L. calabrica, L. coppinsii, L. pseudosarcopidoides and L. subsaligna, as well as a new variety, L. albellula var. macroconidiata. The species treated have in common relatively short and ± curved or bacilliform conidia and/or isousnic acid as a secondary metabolite. Species without isousnic acid, containing exclusively filiform conidia are excluded. Notes on various types of conidia (macroconidia, microconidia, mesoconidia and leptoconidia), morphology, ecology, chemistry and distribution are given and a key to the treated species is provided. Detailed descriptions are presented for eight related species in order to highlight the distinguishing characters.

A new species, Lecania belgica, is described and illustrated. It is a saxicolous lichen known only from the type locality in Belgium. It is characterized by apothecia with pruinose, irregularly undulating discs, relatively short ascospores, and by having 12–16 spores in the asci. It was found on mortar together with Diplotomma alboatrum.

Caloplaca squamuloisidiata van den Boom & V. J. Rico is described as new to science. It is a saxicolous species, pale green to grey, with olivaceous patches, with a rimose-areolate, squamulose, lobulate and isidiate thallus, growing on inland exposed acid rock faces in the western half of the Iberian Peninsula in the Mediterranean region. Its ecology and distribution, and the lichen communities in which it was found are presented. A key to the isidiate and granular-isidiate Caloplaca species in Western Europe is also included.

Lecania fructigena has been found in western Europe. This species, previously known only from western North America and north-western Mexico, is described and compared with related species. It is easily overlooked for L. aipospila. Lecania sampaiana is a synonym of L. aipospila.

Lichen material from the Iberian Peninsula of Melanelia commixta, M. hepatizon and M. sorediella has been studied and compared on the basis of morphology, chemistry, habitat and distribution. The new combination Melanelia sorediella is proposed and Cetraria commixta f. sorediella is lectotypified. Chemotypes I and III have been detected in M. commixta. Melanelia sorediella is characterized mainly by the formation of pycnoisidia and soralia-like structures in the lamina and margins of the thallus and by the absence of pseudocyphellae and apothecia. The pycnoisidium is here described as a combination of isidia-like proliferations of the thallus surface containing pycnidia, carrying algae and acting as vegetative symbiotic propagules. Non detached pycnoisidia grow into lobuli in central parts of the thallus, regenerating it. Pycnoisidia, soralia-like areas and lobuli are formed as a consequence of pycnidia development. Melanelia sorediella is morphologically and chemically close to M. commixta and is currently known from mountains of central and south-west Europe where it grows on acid rocks. In south-western Europe, the meridional limit of the distribution of the three species studied seems to be located in the mountains of the central part of the Iberian Peninsula (Sistema Central Ibérico). Relevant data on the three species are provided and a key is also included.

Two species of Halecania from Asia, H. lobulata van den Boom & Elix and H. pakistanica van den Boom & Elix are described as new to science. In addition, the new combination Halecania pepegospora (H. Magn.) van den Boom is made. The ecology, distribution and chemistry of some selected species are discussed and a key to the fifteen species known worldwide is given.