Fungalpedia – Note 3281, Arthoniomycetes
Arthoniomycetes O.E. Erikss. & Winka, Myconet 1(1): 4 (1997).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Pezizomycotina, Ascomycota, Dikarya, Fungi.
Thallus lichenized with chlorococcoid or trentepohlialean algae or non-lichenized, usually well-developed, crustose, leprarioid, byssoid, placodioid or fruticose, or in form of black yeasts (Phaeococcomyces de Hoog) or stromatic; vegetative lichenized diaspores (isidia, soredia or pseudoisidia) present in some species; ascomata usually present, stromatic (e.g., Etayoa Diederich & Ertz, Lichenostigma Hafellner), apothecioid, rounded to stellate, lirelliform or not well-defined and globose asci loosely scattered in the thallus (Crypthothecia Stirt., Myriostigma Kremp.); hamathecium present in form of paraphysoids (between asci or enclosing the asci) or absent; asci bitunicate, globose to clavate, with a strongly thickened tholus, with K, I+ blue ring in the lower part of the apical dome (near the ocular chamber), sometimes also ascus tholus amyloid; ascospores hyaline to brown, simple, transversely septate or muriform. Conidia simple to muriform, produced by budding or in conidiomata (pycnidia or sporodochia). Lichenized species often produce secondary lichen metabolites. In general taxa can be included in Arthoniomycetes based on unique to the class asci with thickened tholus, with KI+ blue ring in the lower part of the apical dome, and/or on the molecular data, especially in case of sterile, peculiar species (Tehler et al. 2010; Diederich et al. 2012; Ertz and Tehler 2011; Ertz et al. 2011, 2014, 2015; Frisch et al. 2014, 2015; Thiyagaraja et al. 2020).
Life modes and distribution: lichenized, saprotrophic or lichenicolous (parasitic or commensals), on bark of trees, wood, rocks, leaf litter, and other lichens (apothecia or thallus), epiphyllous, cosmopolitan, members of several cryptogamous communities, but do not play important role in building main biomes (Lutzoni et al. 2004; Spatafora et al. 2006; Ertz et al. 2009, 2011, 2014, 2015; Tehler et al. 2010; Ertz and Tehler 2011; Diederich et al. 2012; Frisch et al. 2014, 2015; Thiyagaraja et al. 2020); cosmopolitan, but common in temperate to tropical regions, in coastal, desert, mountainous, or forest habitats.
Notes: At first, the species now placed in Arthoniales were accepted in two orders, Arthoniales and Opegraphales M. Choisy ex D. Hawksw. & O.E. Erikss., by Hawksworth & Eriksson (1986). The similarity and close relationships of Arthoniales and Opegraphales were pointed out by Hafellner (1988) and later included in the class Arthoniomycetes by Eriksson and Winka (1997) within the newly established superclass Leotiomyceta O.E. Erikss. & Winka. Lutzoni et al. (2004) suggested a sister relationship with Dothideomycetes O.E. Erikss. & Winka, but with low support, and Spatafora et al. (2006) confirmed this relationship. At present, Arthoniomycetes includes two orders, Arthoniales (syn. Opegraphales) and Lichenostigmatales, the latter with one family (Phaeococcomycetaceae McGinnis & Schell) and three genera. The majority of taxa are placed in Arthoniales, within seven families (Andreiomycetaceae B.P. Hodk. & Lendemer, Arthoniaceae, Chrysotrichaceae Zahlbr., Lecanographaceae Ertz, Tehler, G. Thor & Frisch, Opegraphaceae Körb. ex Stizenb., Roccellaceae Chevall., Roccellographaceae Ertz & Tehler), however, 21 genera are considered incertae sedis and perhaps more families can be established when more species are included in the phylogeny of the class (Wijayawardene et al. 2022a).
Type order: Arthoniales Henssen ex D. Hawksw. & O.E. Erikss., Syst. Ascom. 5(1): 177 (1986).
Type family: Arthoniaceae Reichenb. ex Reichenb., Deut. Bot. Herb.-Buch: 13 (1841).
Type genus: Arthonia Ach., Neues J. Bot. 1(3. Stück): 3 (1806).
Type species: Arthonia radiata (Pers.) Ach., K. Vetensk-Acad. Nya Handl. 29: 131 (1808).
Other accepted species: Species Fungorum – search Arthoniomycetes.
Figure 1 – Morphology of selected members of Arthoniomycetes. a Alyxoria varia (Poland, UGDA L-41544). b Arthonia radiata – type species (Poland, UGDA L-60149). c Coniocarpon cinnabarinum (Poland, UGDA L-20564). d Herpothallon rubrocinctum with pseudoisidia (Bolivia, UGDA L-19608). e Lecanactis abietina with pycnidia (Poland, UGDA L-25338). f Lichenostigma chlaroterae, stromata on Lecanora pulicaris (Poland, UGDA L-21140). g Myriostigma napoense with not well-defined ascomata (Bolivia, UGDA L-19564). h Roccella tinctoria (Canary Islands, UGDA L-20824). Scale bars: a, b, c, e, f = 500 µm; d, g =1000 µm; h = 10 mm.
References
Eriksson OE, Winka W. 1997 – Supraordinal taxa of Ascomycota. Myconet. 1:1–16.
Hawksworth DL, Eriksson OE. 1986 – The names of accepted orders of Ascomycetes. Systema Ascomycetum 5:175–184.
Entry by
Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka
Published online 25 September 2026