Robust species delimitations provide a foundation for investigating speciation, phylogeography, and conservation. Here we attempted to elucidate species boundaries in the cosmopolitan lichen-forming fungal taxon Lecanora polytropa. This nominal taxon is morphologically variable, with distinct populations occurring on all seven continents. To delimit candidate species, we compiled ITS sequence data from populations worldwide. For a subset of the samples, we also generated alignments for 1209 single-copy nuclear genes and an alignment spanning most of the mitochondrial genome to assess concordance among the ITS, nuclear, and mitochondrial inferences. Species partitions were empirically delimited from the ITS alignment using ASAP and bPTP. We also inferred a phylogeny for the L. polytropa clade using a four-marker dataset. ASAP species delimitations revealed up to 103 species in the L. polytropa clade, with 75 corresponding to the nominal taxon L. polytropa. Inferences from phylogenomic alignments generally supported that these represent evolutionarily independent lineages or species. Less than 10% of the candidate species were comprised of specimens from multiple continents. High levels of candidate species were recovered at local scales but generally with limited overlap across regions. Lecanora polytropa likely ranks as one of the largest species complexes of lichen-forming fungi known to date.

New collections of six Squamarina species from type localities in China were studied. The comparison of morphological characteristics and secondary metabolites with those of the type specimens and phylogenetic analyses suggest that S. callichroa and S. pachyphylla belong to Rhizoplaca, S. semisterilis belongs to Lobothallia and S. chondroderma should be retained in Lecanora temporarily. Only two species, S. kansuensis and S. oleosa, remain in Squamarina. The new combinations Lobothallia semisterilis (H. Magn.) Y. Y. Zhang, Rhizoplaca callichroa (Zahlbr.) Y. Y. Zhang and R. pachyphylla (H. Magn.) Y. Y. Zhang are proposed. Detailed descriptions to aid the identification of these species, distributions and phylogenetic trees, based on multiple collections, are presented. The generic concept of Squamarina is recircumscribed in this study.

Two new species; Lobothallia crenulata Lun Wang & Y. Y. Zhang, L. lobulata Lun Wang & Y. Y. Zhang and one new variety; L. subdiffracta var. rimosa Lun Wang & Y. Y. Zhang, are reported from China and described, based on morphological, chemical and molecular characters. Phylogenetic analyses showed that these new taxa form monophyletic groups. Lobothallia crenulata and L. lobulata, together with L. hydrocharis, L. radiosa and L. recedens, form a well-supported clade, whereas L. subdiffracta var. rimosa is nested within the samples of L. subdiffracta. Lobothallia crenulata is characterised by its placodioid thallus, thickly pruinose upper surface with a rimose appearance, aspicilioid to lecanorine apothecia with a crenate thalline margin and concave, black and pruinose discs. Lobothallia lobulata is characterised by its placodioid thallus, pruinose upper surface with lobules, aspicilioid when immature, lecanorine to zeorine apothecia at maturity and concave to plane, dark brown, shiny and epruinose discs. Lobothallia subdiffracta var. rimosa is characterised by its areolate thallus, rimose and pruinose upper surface, lecanorine apothecia and slightly concave to plane, black and pruinose discs. Secondary metabolites were not detected in the two new species nor the new variety. A key is provided for the species of Lobothallia in China.

Two new multispored species from China, Lecanora anhuiensis Li J. Li & Printzen, sp. nov. and Lecanora pseudojaponica Li J. Li & Printzen, sp. nov. are described and illustrated here, based on morphological, chemical and molecular evidence. Lecanora anhuiensis is characterised by an epruinose, yellowish-brown to deep brown apothecial disc, an epihymenium with fine crystals, an amphithecium with small crystals, 16-spored asci and the presence of zeorin, in addition to atranorin. Lecanora pseudojaponica is characterised by an epruinose, red-brown apothecial disc, an epihymenium without crystals, an amphithecium with small crystals, 8 or 16- spored asci and the presence of zeorin and the stictic acid complex, in addition to atranorin. Phylogenetic reconstructions, based on mtSSU, nrITS and nrLSU suggest that these two species are members of the Lecanora subfusca group. They are compared with morphologically similar and phylogenetically related species, based on a nrITS dataset. Phylogenetic results show that the multispored taxa of Lecanora are polyphyletic. The number of ascospores per ascus appears to be a taxonomic character of minor importance. Detailed descriptions, discussions and figures for the two new species from China and a key for the multispored species of Lecanora worldwide are provided.

In this study, two new species, Rhizoplaca adpressa Y. Y. Zhang & Li S. Wang and R. auriculata Y. Y. Zhang, Li S. Wang & Printzen, are described from Southwest China, based on their morphology, phylogeny and chemistry. In phylogeny, the two new species are monophyletic, and sister to each other within Rhizoplaca chrysoleuca-complex. Rhizoplaca adpressa is characterized by its placodioid and closely adnate thallus, pale green and heavily pruinose upper surface, narrow (ca. 1 mm) and white free margin on the lower surface of marginal squamules, the absence of a lower cortex, and its basally non-constricted apothecia with orange discs that turn reddish-brown at maturity. Rhizoplaca auriculata is characterized by its squamulose to placodioid thallus, yellowish green and marginally pruinose squamules, wide (1−3 mm) and bluish-black free margin on the lower surface of marginal squamules, the absence of a lower cortex, and its basally constricted apothecia with persistently orange discs. Rhizoplaca adpressa and R. auriculata share the same secondary metabolites of usnic and placodiolic acids.

Upretia squamulosa is described as new to science from the arid valley of Jinsha-jiang River, China. It is characterized by a squamulose thallus, greyish green to brown upper surface, lecanorine apothecia, and by containing gyrophoric and lecanoric acids. The other species in the genus, U. amarkantakana, differs from the new species by the crustose to subsquamulose thallus with lobate margin and the absence of gyrophoric and lecanoric acids. A phylogenetic tree based on nrITS for Upretia and related genera in the subfamily Caloplacoideae is established to assess the affinities of the new species.