Lichenicolous fungi represent a highly specialized and successful group of organisms that live exclusively on lichens, most commonly as host-specific parasites, but also as broad-spectrum pathogens, saprotrophs or commensals. We present here the most recent update to the classification of lichenicolous fungi in the Ascomycota and Basidiomycota to genus level, arranged phylogenetically according to published classifications. For each genus, all known lichenicolous taxa (obligately lichenicolous taxa, lichenicolous lichens, and facultatively lichenicolous taxa) are listed, along with information about types, synonyms, pertinent literature and whether or not molecular data are available for any of the listed species. The number of accepted lichenicolous fungi is now 2319, with 2000 obligately lichenicolous species, subspecies or varieties, 257 lichenicolous lichens and 62 facultatively lichenicolous taxa. These species are found in 10 different classes of Fungi (Ascomycota and Basidiomycota), 55 orders, 115 families and 397 genera. The 2319 total taxa is an increase from the 1559 total species reported in the last published catalogue in 2003, and a larger number than the approximately 1800 reported in the most recent online checklist (www.lichenicolous.net) posted in January 2018. Of the total number of taxa, 2219 (96%) are ascomycetes and 100 (4%) are basidiomycetes. Of the 397 genera containing lichenicolous species, c. 50% (198) are entirely lichenicolous. In addition, six families (Abrothallaceae, Adelococcaceae, Cyphobasidiaceae, Obryzaceae, Polycoccaceae, Sarcopyreniaceae) and two orders (Abrothallales, Cyphobasidiales) are entirely lichenicolous. Sequence information is available for lichenicolous species in 128 (32%) of the 397 genera containing lichenicolous species, and in 56 (28%) of the 198 entirely lichenicolous genera. Many species are known from only one host lichen, but it is likely that broader host ecologies will be discovered as new sequence information is obtained from ongoing microbiome studies. Phaeopyxis Rambold & Triebel is considered as a new synonym of Bachmanniomyces D.Hawksw., resulting in five new combinations B. australis (Rambold & Triebel) Diederich & Pino-Bodas (≡ P. australis), B. carniolicus (Arnold) Diederich & Pino-Bodas (≡ Biatora carniolica), B. muscigenae (Alstrup & E.S.Hansen) Diederich & Pino-Bodas (≡ P. muscigenae), B. punctum (A.Massal.) Diederich & Pino-Bodas (≡ Nesolechia punctum) and B. varius (Coppins, Rambold & Triebel) Diederich & Pino-Bodas (≡ P. varia). As a consequence of a phylogenetic analysis including new sequences, Dactylospora Körb. is regarded as a new synonym of Sclerococcum Fr.: Fr., resulting in one new name (S. acarosporicola Ertz & Diederich) and 46 new combinations. Sclerococcaceae Réblová, Unter. & W.Gams is considered as a new synonym of Dactylosporaceae Bellem. & Hafellner. The new Sclerococcum ophthalmizae Coppins is described. Sclerophyton occidentale Herre is lectotypified on the lichenicolous fungus present in the type specimen and becomes a younger synonym of Sclerococcum parasiticum. A replacement name is Arthonia polydactylonis Diederich & Ertz (≡ A. ceracea). Further new combinations are Abrothallus lobariae (Diederich & Etayo) Diederich & Ertz (≡ Phoma lobariae), A. psoromatis (Zhurb. & U. Braun) Diederich & Zhurb. (≡ P. psoromatis), Asteroglobulus pyramidalis (Etayo) Diederich (≡ Cornutispora pyramidalis), Didymocyrtis grumantiana (Zhurb. & Diederich) Zhurb. & Diederich (≡ Phoma grumantiana), Epithamnolia atrolazulina (Etayo) Diederich (≡ Hainesia atrolazulina), Gyalolechia epiplacynthium (Etayo) Diederich (≡ Fulgensia epiplacynthium), Nesolechia doerfeltii (Alstrup & P.Scholz) Diederich (≡ Phacopsis doerfeltii), N. falcispora (Triebel & Rambold) Diederich (≡ P. falcispora), N. oxyspora var. fusca (Triebel & Rambold) Diederich (≡ P. oxyspora var. fusca), Preussia peltigerae (Brackel) Diederich (≡ Sporormiella peltigerae), Scutula curvispora (D.Hawksw. & Miadl.) Diederich (≡ Libertiella curvispora), S. didymospora (D.Hawksw. & Miadl.) Diederich (≡ L. didymospora), Stigmidium haesitans (Nyl.) Diederich (≡ Verrucaria haesitans), and S. parvum (Henssen) Diederich (≡ Pharcidia parvum). © 2018 by The American Bryological and Lichenological Society, Inc.