The identification of mycocalicioid species continues to be based on morphological and chemical characters, even though molecular data and substratum preferences can provide many important insights into specific problems associated with species delimitation and other taxonomic challenges. Our results reinforce the usefulness of many morphological and chemical characteristics and reveal several new features that can be used for both species delimitation and identification. Given the fact that mycocalicioid species can rarely be distinguished by just a single character, combinations of different chemical and morphological characteristics must be used. Additional characteristics must also be sought, including those that have previously been overlooked or still need to be discovered. As a result of this search, we introduce a new term, pseudohemiamyloid, for a reversible, KOH resistant/enhanced reaction in Lugol's solution.

The new species Alyxoria sierramadrensis is described from Mexico where it inhabits limestone rocks. The lichen developing from this fungus is characterized by a placodioid to subfoliose thallus with a white pruinose surface; rounded to shortly elongated ascomata with a black epruinose margin and a widely exposed, white pruinose hymenial disc; hyaline, 3-septate ascospores, 17–25 × 7–9 μm; the presence of anthraquinones rendering the medulla orange. Phylogenetic analyses of nuLSU, mtSSU and RPB2 sequences place this species in the genus Alyxoria (Lecanographaceae). This generic affiliation is surprising because all known Alyxoria species have a crustose thallus. Lecanographaceae mainly includes species without a thallus (lichenicolous taxa) or with a thin crustose thallus, the only exception being Simonyella variegata with a fruticose thallus. The new species belongs to the Alyxoria ochrocheila subgroup, which includes lichens also frequently known to have anthraquinones, white pruinose hymenial discs and 3-septate ascospores. Phylogenetic analyses further determined the systematic position of the monotypic genus Phoebus. This genus, considered as an Arthoniales of uncertain family affiliation, is shown to belong to the Lecanographaceae. With its placodioid thallus, it is another example of a lichenized fungus with a deviating morphology in thallus structure for the family, increasing the number of remarkable cases of parallel evolution of lichen growth forms within the Arthoniales. Phoebus hydrophobius is newly recorded for Mexico.

The identity of Lecanora ecorticata has been uncertain due to conflicting reports of the presence of zeorin and the loss of the holotype. Phylogenetic analysis suggests that the species probably belongs in Ramalinaceae, where it is the first leprose species reported. Zeorin was found to be absent in recently collected material of L. ecorticata, including specimens from the type locality, and the report of zeorin in the lost holotype is considered to be due to contamination. A new genus, Lithocalla, is erected to accommodate L. ecorticata and a second closely related species, that occurs in the Falkland Islands, is newly combined as Lithocalla malouina. A lectotype is selected for L. ecorticata. Lithocalla is characterized by a leprose thallus containing usnic acid with fatty acids and terpenoids, but no zeorin; ascomata and conidiomata are unknown.

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.