Eurotiomycetes

Eurotiomycetes is a large class of ascomycetes with cleistothecial ascocarps within the subphylum Pezizomycotina, currently containing around 3810 species according to the Catalogue of Life. It is the third largest lichenized class, with more than 1200 lichen species that are mostly bitunicate in the formation of asci. It contains most of the fungi previously known morphologically as "Plectomycetes".

Internal relationships
The class Eurotiomycetes was circumscribed in 1997 by Swedish mycologists Ove Erik Eriksson and Katarina Winka. At that time it only contained the order Eurotiales, which together with the next order added, Onygenales, form a monophyletic group comprising most of the fungi in "Plectomycetes", a group no longer in use that unified fungi under exclusively morphological characteristics.

As more orders were added to Eurotiomycetes, the first two along with Arachnomycetales became constrained to the first subclass, Eurotiomycetidae. In 2001, the second subclass, Chaetothyriomycetidae, was erected to accommodate Chaetothyriales and its sister group Verrucariales, as well as Pyrenulales since 2004. These two remain as the major subclasses of Eurotiomycetes.

The remaining subclasses were created through more phylogenetic analyses to accommodate outlying taxa or newly discovered groups: Mycocaliciomycetidae in 2007, Coryneliomycetidae and Sclerococcomycetidae in 2016, and lastly Cryptocaliciomycetidae in 2021. The following cladogram shows the relationships between all Eurotiomycetes orders and monotypic subclasses as of 2021:

External relationships
The class Eurotiomycetes forms a clade with Lecanoromycetes, the largest lichenized class of fungi.

Taxonomy
As of 2022, the taxonomy of Eurotiomycetes recognizes 5 subclasses, 10 orders, 34 families and 289 valid genera. The families are listed here followed by the number of genera.
 * Subclass Chaetothyriomycetidae Doweld 2001
 * Order Chaetothyriales M.E. Barr 1987
 * Family Chaetothyriaceae Hansf. ex M.E. Barr 1979 – 19 genera
 * Family Coccodiniaceae Höhn. ex O.E. Erikss. – 4 genera
 * Family Cyphellophoraceae Réblová & Unter. – 2 genera
 * Family Epibryaceae S. Stenroos & Gueidan – 1 genus
 * Family Herpotrichiellaceae Munk – 17 genera
 * Family Lyrommataceae Lücking – 1 genus
 * Family Microtheliopsidaceae O.E. Erikss. – 1 genus
 * Family Paracladophialophoraceae Crous – 1 genus
 * Family Pyrenotrichaceae Zahlbr – 2 genera
 * Family Trichomeriaceae Chomnunti & K.D. Hyde (=Strelitzianaceae Crous & M.J. Wingf.) – 9 genera
 * Chaetothyriales incertae sedis – 11 genera
 * Order Phaeomoniellales K.H. Chen, A.E. Arnold, Gueidan & Lutzoni
 * Family Celotheliaceae Lücking, Aptroot & Sipman (=Phaeomoniellaceae P.M. Kirk) – 11 genera
 * Order Pyrenulales Fink ex D. Hawksw. & O.E. Erikss.
 * Family Pyrenulaceae Rabenh. – 12 genera
 * Pyrenulales incertae sedis – 2 genera
 * Order Verrucariales Mattick ex D. Hawksw. & O.E. Erikss.
 * Family Adelococcaceae Triebel – 3 genera
 * Family Sarcopyreniaceae Nav.-Ros. & Cl. Roux – 1 genera
 * Family Verrucariaceae Zenker – 52 genera
 * Verrucariales incertae sedis – 4 genera
 * Chaetothyriomycetidae incertae sedis
 * Family Rhynchostomataceae Winka & O.E. Erikss. – 2 genera
 * Subclass Cryptocaliciomycetidae M. Prieto, Etayo and Olariaga 2021
 * Order Cryptocaliciales M. Prieto, Etayo and Olariaga 2021
 * Family Cryptocaliciaceae Etayo, Olariaga and M. Prieto – 1 genus
 * Subclass Coryneliomycetidae A.R. Wood, Damm, J.Z. Groenew., Cheew. & Crous
 * Order Coryneliales Seaver & Chardon
 * Family Coryneliaceae Sacc. ex Berl. & Voglino – 8 genera
 * Family Eremascaceae Engl. & E. Gilg – 2 genera
 * Subclass Eurotiomycetidae Geiser & Lutzoni
 * Order Arachnomycetales Gibas, Sigler & Currah
 * Family Arachnomycetaceae Gibas, Sigler & Currah – 2 genera
 * Order Eurotiales G.W. Martin ex Benny & Kimbr.
 * Family Aspergillaceae Link (=Monascaceae J. Schröt.) – 14 genera
 * Family Elaphomycetaceae Tul. ex Paol. – 2 genera
 * Family Penicillaginaceae Houbraken, Frisvad & Samson – 1 genus
 * Family Thermoascaceae Apinis – 2 genera
 * Family Trichocomaceae E. Fisch. – 9 genera
 * Order Onygenales Cif. ex Benny & Kimbr.
 * Family Ajellomycetaceae Unter., J.A. Scott & Sigler – 7 genera
 * Family Arthrodermataceae Currah – 11 genera
 * Family Ascosphaeraceae L.S. Olive & Spiltoir – 3 genera
 * Family Gymnoascaceae Baran. – 11 genera
 * Family Nannizziopsidaceae Guarro, Stchigel, Deanna A. Sutton & Cano – 1 genus
 * Family Onygenaceae Berk. – 34 genera
 * Family Spiromastigaceae Guarro, Cano & Stchigel – 4 genera
 * Onygenales incertae sedis – 3 genera
 * Eurotiomycetidae incertae sedis – 5 genera
 * Subclass Mycocaliciomycetidae Tibell
 * Order Mycocaliciales Tibell & Wedin
 * Family Mycocaliciaceae A.F.W. Schmidt (=Sphinctrinaceae M. Choisy) – 7 genera
 * Subclass Sclerococcomycetidae Réblová, Unter. & W. Gams
 * Order Sclerococcales Réblová, Unter. & W. Gams
 * Family Dactylosporaceae Bellem. & Hafellner (=Sclerococcaceae Réblová, Unter. & W. Gams) – 7 genera

Only one genus, Neocladophialophora, remains incertae sedis within the class.

Nomenclature
The scientific classification for this particular class is particularly tricky, with one particular species having both the anamorph (asexual form), and teleomorph (sexual form) names used in reference to them.
 * e.g. anamorph form = Penicillium; teleomorph form = Talaromyces or Eupenicillium.

Morphology
Many members (Eurotiales, Onygenales) produce an enclosed structure cleistothecium within which they produce their spores.