Volume one of a new worldwide flora of lichenicolous fungi – Basidiomycota

This is the first volume of a worldwide ‘‘Flora of Lichenicolous Fungi,’’ with focus on Basidiomycota, a group that is exceptionally familiar to Paul Diederich, the first author of this work. A total of 197 strictly lichenicolous or frequently licheninhabiting species are accepted, and 13 additional taxa are introduced, but without formal names. Species that are opportunistically found on lichens and those that are only known from their yeast stage are excluded. Who would have imagined 30 years ago that 210 species of fungi with basidia were able to colonize lichens? Furthermore, the authors estimate that the global diversity of lichenicolous basidiomycetes must be around five times more than what is known today. The first lichenicolous basidiomycete described by Diederich (1986) was Tremella lichenicola (on Violella fucata) and two years later T. coppinsii on Platismatia (Diederich & Marson 1988). Diederich & Christiansen (1994) demonstrated that the pinkish galls called Biatoropsis usnearum Räsänen were basidiomata of a heterobasidiomycete. Shortly after, Paul published his first major work, ‘‘The Lichenicolous Heterobasidiomycetes’’ (Diederich 1996), in which he (himself or with colleagues) described 41 new taxa and six other, unnamed species. Out of these six, only Tremella sp. 2 on Lecanora rimicola remains unnamed in the Flora now published. Since then, several new species (22) were described by Paul and collaborators in different papers, and the present book is the most complete treatment of lichenicolous Basidiomycota up to date. His co-authors, Ana Millanes, Mats Wedin and James Lawrey, are well known by their various studies on lichens and lichenicolous fungi, including phylogenetic analyses and chemical interaction between lichens and lichenicolous fungi (Lawrey & Diederich 2003; Lawrey et al. 2016; Millanes et at. 2016, 2021). As such, the four authors constitute an ideal team to tackle this group of fungi from diverse angles. In this exhaustive book, three new genera are described: Parmeliicida (Agaricomycetes, Cantharellales), Zyzygomyces (Tremellomycetes, Filobasidiales), previously referred to as Syzygospora in Diederich (1996), and Kriegeriopsis (Microbotryomycetes). Furthermore, no less than 74 new species are introduced in the genera Biatoropsis (6), Cyphobasidium (7), Kriegeriopsis (1), Parmeliicida (1), Syzygospora (1), Tremella (52), and Zyzygomyces (6), accompanied by one new subspecies and three new combinations. Difficult species complexes are resolved into several species, such as Biatoropsis usnearum s.l. (six new species), Syzygospora physciacearum s.l. (four new species in Zyzygomyces), Tremella parmeliarum s.l. (six new species), and T. pertusariae s.l. (four new species). Diederich and colleagues describe several species of Biatoropsis and Tremella that produce conidia in the basidia, with epibasidia acting as diaspores or with a layer of conidiogenous cells producing clamped conidia. To complete their taxonomic work, six lichenicolous galls probably induced by bacteria are also described but unnamed.