Five species of lichenicolous fungi are described as new to science: Buelliella ohmurae Zhurb. & Diederich (on Icmadophila), with a non-granulose epihymenium, not or only slightly enlarged, pale brown apical cells of paraphysoids and 1-septate, smooth ascospores; Catillaria japonica Zhurb. & Hafellner (on Dibaeis and Pseudobaeomyces), with a medium to dark reddish brown epihymenium, exciple and hypothecium, rather frequently branched and anastomosed paraphyses with only slightly enlarged apical cells without a dark cap, and Catillaria-type asci; Cryptodiscus ihlenii Zhurb. (on Dibaeis), with persistently immersed ascomata, non-amyloid asci and hymenium, not or only slightly enlarged apical cells of paraphyses and narrowly obovate, 1-septate ascospores; Llimoniella chilensis Zhurb. (on Dibaeis and a sterile microsquamulose lichen), with a K+ green exciple and epihymenium and aseptate, broadly ellipsoid ascospores; and Stigmidium phyllobaeidis Zhurb., Etayo & Flakus (on apothecial discs of Phyllobaeis), with a hemiamyloid interascal gel, not previously reported in that genus, well-developed, 1‒2(‒4)-celled periphysoids, elongate asci and hyaline, 1-septate ascospores. An undescribed species of Arthonia (on Pseudobaeomyces) is briefly characterized. Sphaerellothecium coniodes is newly reported for Asia. A key to the 32 species of lichenicolous fungi and lichens known to occur on baeomycetoid lichens and Icmadophila is provided.

The circumscription of the lichenized ascomycete genus Icmadophila Trevis. in the family Icmadophilaceae Triebel was investigated. Sequences of the internal transcribed spacer (ITS) region and large subunit of nuclear ribosomal DNA (nuLSU) were generated for the five Icmadophila species and additional members of Icmadophilaceae from the genera Dibaeis, Endocena, Knightiella, Siphula, Siphulella and Thamnolia. Phylogenetic analyses indicate that three Icmadophila species are closely related: the type, I. ericetorum (L.) Zahlbr., which is widespread in Eurasia and North America, I. aversa (Nyl.) Rambold & Hertel from Central and South America, and I. japonica (Zahlbr.) Rambold & Hertel, which is restricted to Far East Russia and Japan. The genus Knightiella Müll. Arg. is reinstated to accommodate I. splachnirima (Hook.f. & Taylor) D. J. Galloway emend. L. Ludw., which occurs in New Zealand and Australia. Two further species of Knightiella, K. eucalypti (Kantvilas) Kantvilas and K. queenslandica Kantvilas, are found to be unrelated to K. splachnirima, and are accommodated in two newly described genera, Knightiellastrum and Siphulopsis respectively. Knightiellastrum L. Ludw. & Kantvilas is characterized by a squamulose, erhizinate, whitish to pale grey thallus with a green, coccoid photobiont and by containing thamnolic acid. Siphulopsis Kantvilas & A. R. Nilsen is similarly characterized by an erhizinate, whitish to pale grey thallus, with a green, coccoid photobiont and containing thamnolic acid, but is instead fruticose. This study reveals considerable diversity within Australasian Icmadophilaceae; ongoing work in the Southern Hemisphere and tropical regions may reveal additional species in this family and clarify the relationships of these newly described genera.

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.

Candelariella blastidiata Yakovchenko sp. nov. is described. This corticolous species is characterized by biatorine yellow apothecia, a grey squamulose thallus with marginal and lower side blastidia, 8-spored asci, and a northern circumpolar distribution. Candelariella subdeflexa has previously been confused with C. blastidiata, but our analyses of phenotypic and DNA sequence data revealed C. blastidiata should be distinguished from C. subdeflexa. A worldwide key for Candelariella species with grey thalli is provided.

The genus Inoderma (Ach.) Gray is lectotypified with Inoderma byssaceum and resurrected for a small group of species in Arthoniaceae with elevated, white pruinose pycnidia, immersed to adnate white pruinose apothecia and a weakly gelatinized hymenium. Inoderma nipponicum is described from Japan, I. afromontanum from Uganda and the European Lecanactis subabietina is transferred to the genus. Sporodophoron is described for a small group of species in Arthoniaceae related to Inoderma but with a unique type of sporodochia instead of pycnidia. Sterile specimens of this new genus resemble species of Tylophoron but differ in the rounded angular to elliptical to short cylindrical, 0–2-septate sporodochial conidia with unevenly thickened walls which are formed apically in zigzag-shaped and occasionally branched chains. Sporodophoron further differs in thallus chemistry and is genetically distinct. Tylophoron americanum and Schismatomma cretaceum are transferred to Sporodophoron, and the new species S. gossypinum from Japan and S. primorskiense from eastern Russia are described. The genus Glomerulophoron is described for a single species from Mauritius, G. mauritiae, differing from Sporodophoron in the tightly coiled chains of sporodochial conidia and being genetically distinct. A phylogenetic tree showing the position of Inoderma, Sporodophoron and Glomerulophoron in Arthoniaceae is presented. A key to all species of Arthoniaceae with sporodochia or elevated white pruinose pycnidia is presented. Arthothelium spectabile, the type of the large heterogeneous genus Arthothelium, is confirmed for the cryptothecioid subclade in Arthoniaceae.

The activity concentration of 131I, 134Cs and 137Cs radionuclides in lichens was traced one and a half months after the Fukushima nuclear accident. The samples were collected in Tsukuba City, which is located c. 170 km south of the Fukushima Daiichi nuclear power plant (NPP). The activity concentrations differed depending on species and habitat. For example, the maximum activity concentration of 137Cs was 22596 Bq kg–1 dry weight in Physcia orientalis (collected from the trunk of Zelkova serrata on 30 June 2011), and 1928 Bq kg–1 in Hyperphyscia crocata (from the trunk of Quercus myrsinaefolia collected on 8 March 2012). The activity concentration of 137Cs in Dirinaria applanata and Phaeophyscia spinellosa growing on vertical habitats decreased by c. 50% within a year, indicating radionuclides might have been washed off by rain. The radionuclides were apparently derived from the Fukushima NPP accident because: 1) one specimen collected at the same place one year before the accident did not contain radionuclides, 2) high activity concentrations of radionuclides were detected after the accident, 3) 131I, which has a short half-life of 8 days, was detected one and a half months after the accident, and 4) the ratio of 134Cs/137Cs in lichens was 0·90–0·98 on 26 April 2011, which is consistent with the values reported for radiocesium from the Fukushima NPP accident.

The taxonomic position of the Neuropogon group, as inferred from the morphology of representative species of the group and ITS sequences from Usnea antarctica and U. sphacelata, is discussed. Morphological observations revealed that the Neuropogon group does not have annular-pseudocyphellae, which are characteristic of the subgenus Dolichousnea, or a fistulose axis, which is characteristic of the subgenus Eumitria. In addition, the hypothecium of Neuropogon is thin, and the iodine reaction in the axis is negative. These features are consistent with those of the subgenus Usnea. Within the subgenus Usnea, Neuropogon is morphologically distinct from sections Usnea and Ceratinae (i.e. having a sphacelata-type cortex, black pigmentation of the upper thallus and a dark brown apothecial disc). The molecular data suggest that U. antarctica and U. sphacelata are members of the subgenus Usnea and are less closely related to subgenera Dolichousnea and Eumitria. The morphological and molecular phylogenetic analysis suggest that the Neuropogon group is a member of the subgenus Usnea at the level of a section, and the appropriate name for this group is subgenus Usnea section Neuropogon (Nees & Flot.) Mont.