The Arthoniales is the second largest order of mainly crustose lichens, but fruticose lichens are present as well. The order contains around 1500 species, while the largest order with lichenized fungi, the Lecanorales, contains more than 14000 species.
The Arthoniaceae are a family of lichenized, lichenicolous and saprobic fungi in the order Arthoniales. The Arthoniaceae is the largest family of Arthoniales, with around 800 species. Most species in Arthoniaceae belong in Arthonia which is the largest genus with 500 species. The second and third largest genus is Arthothelium with 80 species, and Cryptothecia with 60 species.
Porina is a genus of lichens in the family Trichotheliaceae. A 2020 estimate places about 145 species in the widespread genus.
Cryptothecia is a genus of white to greenish crustose lichens that grow on bark, wood, or leaves, in tropical or subtropical areas worldwide. It has a conspicuous prothallus that develops around its periphery which can be bright red in some species, hence the common name wreath lichen. The main vegetative body (thallus) lacks a cortex (ecorticate and is often immersed in the substrate or byssoid. The medulla is white, well defined, and often peppered with calcium oxalate crystals. Ascomata are not well defined, being cushions of soft white mycelium immersed in the medullary tissue, hence the name from the Greek krypto = "to conceal" and theke = "a container or sheath". It contains Trentepohlia, a green alga, as its photobiont partner.
Chiodecton is a genus of lichens in the family Roccellaceae. The genus was circumscribed by lichenologist Erik Acharius in 1814, with Chiodecton sphaerale assigned as the type species.
Enterographa is a genus of lichens in the family Roccellaceae.
Synarthonia is a genus of lichen-forming fungi in the order Arthoniales. The genus has not been placed into a family. Synarthonia was circumscribed by Swiss lichenologist Johannes Müller Argoviensis in 1891.
Chrysothrix is a genus of lichen-forming fungi in the family Chrysothricaceae. They are commonly called gold dust lichens or sulfur dust lichens, because they are bright yellow to greenish-yellow, sometimes flecked with orange, and composed entirely of powdery soredia. Apothecia are never present in North American specimens.
Malmidea is a genus of crustose lichens and the type genus of the family Malmideaceae. It was established in 2011 to contain a phylogenetically distinct group of species formerly placed in the genus Malcolmiella. The crust-like thallus of Malmidea lichens has a surface that varies from smooth to rough, featuring textures such as verrucose (wart-like), granulose (grainy), or pustulate (pimpled). These textures are often formed by goniocysts, which are spherical clusters of green algal cells from the family Chlorococcaceae, encased in fungal hyphae. Malmidea comprises nearly 70 mostly tropical species that grow on bark, although a few grow on leaves.
Alyxoria is a genus of lichen-forming fungi in the family Lecanographaceae.
Coenogonium is a genus of filamentous lichens in the monotypic family Coenogoniaceae. It has about 90 species. Most species are leaf-dwelling or grow on bark, although a few are known to grow on rocks under certain conditions, and some are restricted to growth on termite nests. The genus was circumscribed in 1820 by German naturalist Christian Gottfried Ehrenberg.
Herpothallon is a genus of crustose lichens in the family Arthoniaceae. It has about 50 species.
Wirthiotrema is a genus of lichen-forming fungi in the family Graphidaceae. The genus was circumscribed in 2010 by Eimy Rivas Plata, Klaus Kalb, Andreas Frisch, and H. Thorsten Lumbsch, with Wirthiotrema glaucopallens assigned as the type species. Wirthiotrema contains species that were formerly considered part of the Thelotrema glaucopallens species group. The genus name honours lichenologist Volkmar Wirth, "for his numerous outstanding contributions to lichenology".
Crypthonia is a genus of lichen-forming fungi in the family Arthoniaceae. It has 16 species. The genus was circumscribed in 2010 by Andreas Frisch and Göran Thor, with Crypthonia polillensis assigned as the type species.
Reichlingia is a genus of lichen-forming fungi in the family Arthoniaceae. It has seven species. The genus was originally circumscribed by Paul Diederich and Christoph Scheidegger in 1996, with Reichlingia leopoldii as the type, and at that time, only species. The fungus was at first thought to be a lichenicolous (lichen-dwelling) fungus, but is now considered a lichenised hyphomycete.
Gintarasia is a genus of lichen-forming fungi in the family Graphidaceae. It has seven species, all of which are found in Australia. Gintarasia species are corticolous (bark-dwelling), crustose lichens with a thelotremoid form.
Fouragea is a genus of lichen-forming fungi in the family Opegraphaceae. It has nine species.
Coniocarpon is a genus of lichen-forming fungi in the family Arthoniaceae. It has eight species of corticolous (bark-dwelling) lichens. This genus is distinct for its crystalline orange, red, and purple quinoid pigments in the ascomata that turn purple in potassium hydroxide solution, its colourless, transversely septate ascospores with large apical cells, and its rounded to lirellate ascomata.
