Lecanora caledonica is described as new to science. Molecular analyses show that it belongs to the L. intumescens group. It is also rather similar in appearance to L. intumescens, but differs mainly chemically in containing only atranorin and an unknown UV+ ice blue substance. There are also anatomical and morphological differences to the other species of the group. The new species has a pronounced oceanic distribution and is so far known only from western Norway and Scotland.

Recent field trips to Amapá and the adjacent states of Amazonas and Pará uncovered unknown lichen species with unexpected relationships. The following new species of Arthoniales are described, mainly from Amapá in North Brazil: Neosergipea hyphosa, a corticolous species with an olive-green thallus, central part verrucose, marginal zone of 5–10 mm wide consisting of procumbent branching rhizohyphae, surrounded by a pinkish brown hyphal prothallus c. 3 mm wide into which the rhizohyphae protrude, globose ascomata, c. 0·1 mm diam., arranged in stromatoid groups of 5–15, with hyaline walls, without ascospores; Neosergipea septoconidiata, a corticolous species with a bluish grey thallus and bright orange, mostly conical pycnidia with fluffy hyphal surface, hyaline conidia, 3–6-septate, filiform, 12–23×1·5–2·0 μm, with rounded ends; Nyungwea pycnidiata, from a termite nest on a tree, with abundant pycnidia that are whitish, papillate, smooth, c. 0·1–0·2 mm diam., c. 0·2–0·4 mm high, at the base covered by thallus, and hyaline conidia that are simple, ellipsoid, 2·5–4·0×1·5–2·0 μm; and Opegrapha ramisorediata, a corticolous species with a thallus with initially rounded soralia that soon cover the complete thallus with a layer of fine yellowish green branched soredia, and containing gyrophoric acid. Apothecia are not known from any of these species but sequencing elucidated their generic affiliation. The genera Neosergipea and Nyungwea were previously monotypic and Nyungwea was known only from Africa. Nyungwea anguinella (Nyl.) Aptroot comb. nov. is a further new species in the latter genus, and through these two extra species we now know about the morphology of the pycnidia and apothecia of Nyungwea, which were unknown in the type species (a sterile crust).

The new corticolous lichen species Bactrospora angularis is described from Brazil. It has apothecia that are usually irregular in outline and transversely (19–)28–35-septate, filiform ascospores (85–)120–150 × 5–7 μm with some constrictions. A revised world key is given to all currently known species of Bactrospora.

Three new corticolous Diorygma species are described from Brazil. Diorygma incantatum has transversely 29–31-septate, filiform ascospores 105–108×6 µm, and produces an unidentified substance with Rf 44 in solvent C. Diorygma pauciseptatum produces norstictic and connorstictic acids and has transversely 7–9-septate, I+ blue-violet, large ascospores 28–32×7 µm, surrounded by a gelatinous sheath c. 2 µm wide that is often somewhat expanded at one end. Diorygma tocantinense contains protocetraric acid and has muriform, broadly fusiform ascospores with rounded ends, 24–40×10–15 µm, surrounded by an gelatinous sheath up to c. 5 µm wide that is somewhat expanded at central parts of the ascospore. A revised world key is given to all currently known species of Diorygma.

The following new corticolous species are described. Thelopsis cruciata Aptroot & M. Cáceres, with an olive-green thallus, immersed red-brown perithecia and c. 50–100 cruciate ascospores per ascus, 7–10×4–7 µm, from Brazil. Topelia argentinensis Aptroot, L. I. Ferraro & M. Cáceres, with a verrucose, partly almost isidiate, greenish grey thallus, immersed pinkish perithecia and 8 uniseriate muriform ascospores per ascus, 12–17×7–11 µm, from Argentina. Topelia tetraspora Aptroot & M. Cáceres, with a c. 0·1–0·6 mm thick layer of coralloid to usually flattened, irregularly palmately branched isidia c. 0·05 mm diam., ascospores 15–19×2–6-septate, muriform, ellipsoid, 39–50×11–16 µm, only up to 4 per ascus maturing, from Brazil. Thelopsis inordinata is reported for the first time from South America, from Guyana. A key is given to all currently known species of Topelia and Thelopsis. The distinction between these genera has become arbitrary with the recent addition of more or less intermediate species.

Three new corticolous Arthoniaceae are described from the Chapada do Araripe, an isolated table mountain in the state of Ceará, in NE Brazil. Arthonia stipitata, lichenicolous on unidentified sorediate crusts, with red, tiny, stipitate apothecia, 3-septate ascospores, 10–12×3·0–3·5 µm. Stirtonia lucida with rather small ascigerous areas, lichexanthone and zeorin in the thallus, globose asci, ascospores 8 per ascus, ellipsoid, 17–19×8–10 µm, with occasionally some longitudinal septa. Stirtonia ochracea with rather small ochraceous ascigerous areas, thallus without secondary metabolites, ascospores 8 per ascus, (7–)9(–11)-septate, 47–55×14–20 µm. These species were found during a study aiming at an inventory of the lichen biodiversity of the Cerrado forests in the area, and were not found during earlier ecological studies in the Caatinga forests in the same area. Stirtonia lucida is the first species assigned to this genus which occasionally has some longitudinal septa in the ascospores. Such specimens might be confused with Cryptothecia species.

Two new species of the small genus Crypthonia are described from the Chapada do Araripe, an isolated table mountain in the state of Ceará, in NE Brazil. Both share the thallus and ascoma organization with the other known species of the genus, and are mainly characterized by differences in ascospores and chemistry. Crypthonia lichexanthonica A. A. Menezes, M. Cáceres & Aptroot has 7-septate ascospores and contains lichexanthone in the thallus, and C. submuriformis A. A. Menezes, M. Cáceres & Aptroot has (sub)muriform ascospores and also contains lichexanthone, but only in the ascigerous areas. A key to all known species of the genus Crypthonia is provided, in which Crypthonia olivacea Frisch & G. Thor is newly reported from Argentina. The new species Syncesia byssolomoides A. A. Menezes, M. Cáceres & Aptroot is described from the same area. It also has a thin byssoid thallus, but differs by the narrowly fusiform ascospores and by containing psoromic acid. It differs from all Syncesia species by the absence of carbonization and the presence of psoromic acid. The epiphytic lichen flora in this Caatinga forest area is dominated by crustose lichens, with Graphis and Polymeridium as the most speciose genera.

The new lichen genus Sergipea M. Cáceres, Ertz & Aptroot is described in the Roccellaceae, based on the new species Sergipea aurata M. Cáceres, Ertz & Aptroot from NE Brazil. The species was found in a remnant of Atlantic transition forest in Sergipe. It is similar in many respects to species of the genus Enterographa, but it is characterized by bright orange stromata, due to the presence of an anthraquinone, and a thallus with a somewhat byssoid hypothallus. Phylogenetically it is close to the genera Dichosporidium and Erythrodecton. The phylogenetic position of the generic type of Dichosporidium confirms the close relationship of the genus to Erythrodecton in the basal branch of the Roccellaceae. A new species of Enterographa is also described from NE Brazil. Enterographa rotundata E. L. Lima, M. Cáceres & Aptroot has solitary, round apothecia, which is unusual in this genus with mainly elongated apothecia or punctiform apothecia arranged in lines. It was found in Caatinga forest in Pernambuco.

Leiorreuma subpatellulum is described as new to science. The new species has a completely carbonized exciple, an inspersed hymenium and brown ascospores with 6–12 locules, tapering at one end.

This study investigates how anatomical characters can be used to differentiate two morphologically close species, Melanohalea olivacea (L.) O. Blanco et al. and M. septentrionalis (Lynge) O. Blanco et al. Although the two species are morphologically differentiated, mainly based on the position and shape of pseudocyphellae on the lobes, poorly-developed specimens can be difficult to identify based on morphology alone. For example, in Switzerland, both species are at the south-west limit of their distribution range and most specimens are small and not fully developed. In such cases, anatomical characters are particularly useful in separating the two species. Five anatomical characters were studied: spore length and width; hymenium, subhymenium and hypothecium height. A nested ANOVA showed that variation of spore length was 155 times greater between species than between individuals of the same species, itself 5 times higher than within individuals. In a Principal Component Analysis, despite a substantial variation of the anatomical characters within both species, a significant species differentiation appeared distinctly on the first axis (P < 0·001), which accounted for 62·35% of the total variance, and the type specimens nested within each species. Finally, a Discriminant Linear Analysis assigned 100% of the individuals to their species class, the best predictors to discriminate between the two species being subhymenium height and spore length. These characters proved to be powerful in identifying specimens with a poorly-developed morphology and confirmed the presence of M. olivacea in Switzerland.

The first sorediate species in the genus Llimonaea, L. sorediata is described from coastal areas of western Europe. This new species is easily mistaken for Dirina massiliensis f. sorediata with which it often co-occurs. It grows on vertical or overhanging acidic cliffs. Fertile specimens were recently collected in Portugal. A description of the species together with notes on distribution, ecology and chemistry are provided and a key to the species of Llimonaea is also provided.

Two new corticolous species, Hafellia alisioae and H. gomerana (lichenized Ascomycetes, Physciaceae), collected from twigs of coastal shrubs on the Canary Islands are described. The new species are discussed in relation to other Hafellia species with similar characters. An overview and a key for 23 corticolous species of Hafellia with 2-celled ascospores is provided.