The lichen genus Lecanora is one of the largest genera of lichenized fungi. The core part of the genus is the L. subfusca group and within this group, Lecanora hybocarpa (Tuck.) Brodo, initially described from North America and thought to be endemic, has been reported from several European countries. However, the identity of these European specimens has been increasingly questioned. This study aimed to clarify the relationship between North American L. hybocarpa and European collections, including the morphologically similar L. sinuosa Herk & Aptroot. We performed morphological, chemical (TLC) and molecular analyses (nrITS and mtSSU) on a broad collection of specimens from Europe, Macaronesia and North America. Our phylogenetic analyses revealed that true L. hybocarpa has not yet been confirmed in Europe. Instead, several genetically distinct European taxa share the L. hybocarpa morphotype. Our findings resulted in the description of three new species: Lecanora cryptosinuosa (differing only genetically from L. sinuosa), L. macaronesica (characterized by quite large apothecia with constricted bases and a finely crenulate margin, and the presence of gangaleoidin) and L. subsinuosa (difficult to separate from L. sinuosa, but may sometimes be recognized by darker apothecial discs with inconsistent pigmentation, the occasional presence of a tiny pruina on young discs, and the usually thicker apothecial margin, dentate in the inner edge). Furthermore, we report L. pseudargentata as a new species for Europe. Due to the high morphological variability and cryptic speciation within this group, reliable identification often requires DNA analysis. Therefore, we propose using the name Lecanora hybocarpa agg. for all species sharing this particular morphotype. A key to the epiphytic esorediate species of the L. subfusca group in Europe and northern Africa is provided.

Lecanora s. lat. is a genus of crustose, rarely placodioid lichens comprising c. 1000 recognized species and subdivided into several morphology-based groups. Some of these groups have been supported in phylogenetic analyses and segregated as new genera. One of the remaining groups that has not been previously studied by molecular methods in much detail, the L. saligna-group, includes corticolous and lignicolous crustose lichens, usually containing isousnic or usnic acid (or both) as major secondary metabolites. As part of our ongoing project ‘Lecanomics’, a phylogenetic analysis based on two loci was conducted and found the L. saligna-group to be divided into two main clades and several well-supported minor clades. The L. varia clade, chosen as one of the outgroups, emerged within the L. saligna-group. The majority of the clades are characterized by phenotypic differences. However, several well-supported clades share similarities with their sister groups, suggesting that species circumscriptions based solely on phenotypic characters may be too conservative to characterize the true species diversity present within the group. Also, there is evidence for some geographical separation of lineages; for example, most North American individuals, previously known as Lecanora saligna and L. albellula, form two clades separate from their European namesakes and are here preliminarily called ‘Lecanora sp. B’, ‘Lecanora sp. C’ and ‘Lecanora sp. D’. However, L. saligna and L. albellula also appear to occur in North America, and some specimens from the Caucasus and Iran cluster within the North American clades. Lecanora anopta and L. subravida are reported for the first time from Iran.

Phylogenetic reconstructions based on ITS/5.8S and mtSSU DNA sequence data suggest a close relationship between two Lecanora species containing calycin and usnic acid and the Lecanora polytropa group. Lecanora solaris Yakovchenko & Davydov sp. nov. is described from the Altai Mountains in Russia. Its gross morphology resembles that of L. somervellii as both species have an effigurate, citrine-yellow thallus (due to the production of calycin). However, L. solaris is distinguished from L. somervellii by having a small, squamulose to marginally lobate umbilicate thallus and apothecia with a persistent margin, whereas L. somervellii has a large, distinctly placodioid thallus and an apothecial margin that is soon excluded.

Lecanora inaurata, a corticolous member of the L. subfusca group, is described as new to science. This species is characterized by typically epruinose, reddish brown apothecial discs, a chlarotera-type epihymenium, pulicaris-type amphithecium, and chloroatranorin and zeorin as major constituents, often with accessory calycin in the thalline margins of the apothecia, imparting a distinctive yellow halo appearance when present in sufficient concentrations. Lecanora inaurata occurs in open hardwood-dominated woodlands of the Edwards Plateau and grasslands of the southern Great Plains in Oklahoma and Texas.

Lecanora subjaponica L. Lü & H. Y. Wang from western China is described as new to science. It is the only known Lecanora species having (16–)32-spored asci and it is otherwise characterized by an epruinose, shiny brown apothecial disc, epihymenium lacking granules and the presence of zeorin in addition to atranorin. A worldwide key to the multispored species of Lecanora is also given.

The phylogenetic placement of the genus Maronina was studied, based chiefly on phenotypic characters such as thallus colour and anatomy, secondary chemistry, the anatomy of the excipulum and the ascus-type. DNA sequence data of mitochondrial and nuclear ribosomal loci from some of the species support the hypothesis that Maronina is nested within Protoparmelia. Hence, Maronina is reduced to synonymy with Protoparmelia. Comparison of genetic distances suggests that the two varieties within M. orientalis should be regarded as distinct species. Consequently, the new combinations Protoparmelia australiensis (Hafellner & R. W. Rogers) Kantvilas et al., P. corallifera (Kantvilas & Papong) Kantvilas et al., P. hesperia (Kantvilas & Elix) Kantvilas et al., P. multifera (Nyl.) Kantvilas et al., and P. orientalis (Kantvilas & Papong) Kantvilas et al. are proposed.

Lecanora sorediomarginata Rodrigues, Terrón & Elix sp. nov., described as new to science from Portugal, is characterized morphologically by a crustose whitish-grey to greenish thallus developing soralia from small, marginal warts and chemically by the presence of 3,5-dichloro-2′-O-methylnorstenosporic acid [major], 3,5-dichloro-2′-O-methylanziaic acid [minor], 3,5-dichloro-2′-O-methylnordivaricatic acid [minor], 5-chloro-2′-O-methylanziaic acid [trace], atranorin [minor], chloroatranorin [minor], and usnic acid [trace]. It is chemically similar to L. lividocinerea, to which it shows phylogenetic affinities based on ITS rDNA sequence analysis, and to L. sulphurella. Lecanora sorediomarginata is epiphytic on Pinus pinaster and P. pinea, in pine forests on sand dunes along the Portuguese coast.

The new species, Maronina orientalis Kantvilas & Papong, with two varieties, var. orientalis and var. corallifera Kantvilas & Papong, is described, based on material from Thailand. The genus Maronina, now containing four species, is reassessed. It is characterized by having a crustose thallus, lecanorine apothecia and polysporous asci of a modified Lecanora-type.

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.

Ameliella Fryday & Coppins gen. nov. is proposed to accommodate two inconspicuous, undescribed species, A. andreaeicola and A. grisea, collected from high altitude in the Scottish Highlands. Outside the Scottish Highlands, Ameliella andreaeicola is known from single collections from Norway and Canada, and A. grisea from a single collection from Norway. The new genus appears to have some affinity with Miriquidica.

Lecidea rubrocastanea T. Sprib. & Printzen is described as new from conifer bark and wood in montane valleys of inland British Columbia, Idaho, Montana, Oregon and Washington State. It is characterized by its combination of a crustose olivaceous thallus lacking secondary lichen substances, small, dark burgundy-red or maroon apothecia, dark-capped paraphyses, Lecidella-type ascus, small, thin-walled ascospores, and bacilliform conidia. The generic affinities of the species based on analysis of ITS DNA are unclear, but it has numerous morphological traits in common with Japewia.