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.
The Roccellaceae are a family of fungi in the order Arthoniales, circumscribed by French botanist François Fulgis Chevallier in 1826. This family is distinguished by a wide variety of growth forms, including crustose and fruticose thalli, and a diverse range of reproductive structures. Roccellaceae species typically have apotheciate or lirellate ascomata, often with distinct carbonised (blackened) margins. The family has been extensively studied through molecular phylogenetics, revealing significant genetic diversity and complex evolutionary histories.
Ochrolechia is a genus of crustose lichens in the family Ochrolechiaceae. These lichens typically form uneven, often thick, crust-like growths on various surfaces and are characterised by their white to pale grey thalli, which may have a greenish tint. The genus has a long evolutionary history, with fossils dating back to the Paleogene period, about 34 million years ago. Ochrolechia species have disc-like apothecia, which are usually yellowish or brownish-pink and often covered with a fine white powdery coating. The genus is widely distributed and includes both common and rare species, with some found in extreme environments such as arctic and alpine regions. Ochrolechia lichens produce diverse secondary metabolites, including orcinol depsides, depsidones, and xanthones.
Brian John Coppins is a botanist and lichenologist, considered a world authority on crustose lichens and a leading expert on the genus Micarea.
Synarthonia leproidica is a species of saxicolous (rock-dwelling) and crustose lichen in the order Arthoniales. Found in Luxembourg, it was formally described as a new species in 2020 by lichenologists Damien Ertz, André Aptroot, and Paul Diederich. The type specimen was collected in the Vallée du Lellgerbaach (Lellingen) at an elevation of 323 m (1,060 ft). Here the lichen was found on a siliceous wall at the edge of a forest path in an oak-hornbeam forest. It has a pale greyish crust-like thallus with dark brown/violet tinges. It has a leproid growth form, meaning that it looks like it is made of granules; the specific epithet refers to this characteristic. The thallus forms patches that are about 0.5–5 mm in diameter, although neighbouring patches can coalesce to form larger patches up to 10 cm (4 in) in diameter. Synarthonia leproidica contains psoromic acid, a secondary chemical that can be detected with thin-layer chromatography.
Loxospora cristinae is a fungal species classified in 2018, found in a few European countries. It belongs to the division Ascomycota and the family Sarrameanaceae. It was first identified and described in the 19th century, but the species would not be correctly classified until almost two centuries later. Loxospora cristinae is a sterile crustose lichen, meaning it reproduces by a type of vegetative spore that has evolved specifically to produce morphological structures.
Inoderma is a genus of lichen-forming fungi in the family Arthoniaceae. It was resurrected for use in 2015 for a small group of species with the following features: elevated, white pruinose pycnidia, immersed to adnate white pruinose apothecia, and a weakly gelatinized hymenium. Inoderma byssaceum was assigned as the type species for the genus.
Inoderma sorediatum is a species of crustose lichen in the family Arthoniaceae. It is only known to occur on the bark of trees in Poland's Białowieża National Park. It is differentiated from other species in genus Inoderma by the form of its thallus, which is entirely made of powdery, granular soredia, as well as by the presence of a unique combination of lichen products.
Psoronactis is a monotypic fungal genus in the family Roccellaceae. It contains the single species Psoronactis dilleniana, a saxicolous (rock-dwelling), crustose lichen. This species was first described in 1799 by Swedish lichenologist Erik Acharius as Lichen dillenianus. The taxon was shuffled to several genera in the 1800s as different authors had different opinions on how to classify the species; in more modern times, it was transferred to genus Lecanographa in 2013. Psoronactis was circumscribed in 2014 by Damien Ernst and Anders Tehler, following molecular phylogenetic analysis and revision of the Roccellaceae that showed the species occupied a distinct lineage in the family. The genus name alludes to the lichen products present in its thallus: psoromic acid and 2'-O-demethylpsoromic acid. It is these compounds that differentiate it chemically from the similar genus Lecanactis.
Diromma is a monotypic fungal genus in the family Roccellaceae. It contains the single species Diromma dirinellum, a rare crustose lichen that grows as a parasite on the lichen Dirina ceratoniae. It has a distribution restricted to the Mediterranean Basin.
Isalonactis is a monotypic fungal genus in the family Roccellaceae. It contains the single species Isalonactis madagascariensis, a saxicolous (rock-dwelling), crustose lichen found in Madagascar. Both the genus and species were described as new in 2014 by Damien Ertz, Anders Tehler, Eberhard Fischer, Dorothee Killmann, Tahina Razafindrahaja, and Emmanuël Sérusiaux. The type was collected on the Isalo Massif at an altitude of 851 m (2,792 ft); there, it was found growing on sheltered mesozoic sandstone cliffs. The genus name alludes to both Isalo Massif, the type locality, and the phylogenetic relatedness to genus Lecanactis.
Vigneronia spieri is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. It is found in the Galápagos Islands, mainland Ecuador and the Antilles (Curaçao).
Sporodophoron is a genus of lichen-forming fungi in the family Arthoniaceae. It includes four corticolous (bark-dwelling) crustose lichen species. Sporodophoron is uniquely characterised by the formation of fruiting structures called sporodochia, which are open conidiomata in the form of tufts of conidiophores on the thallus. Although these lichens bear a strong resemblance to Inoderma, another genus within the same family, Sporodophoron's distinct chemical makeup sets it apart from its lichen relatives. Collectively, the genus has a widespread geographical distribution in the Northern Hemisphere, with species found in distinct habitats in North America, Europe, Japan, and the Russian Far East.
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.
Loekoesia is a genus of lichen-forming fungi in the family Teloschistaceae. It contains three species of saxicolous (rock-dwelling), crustose lichens. Collectively, the genus occurs in South Korea, Mauritius, and the United States. The genus is distinguished by its grey, crust-like thallus, which can be either whole or divided into patch-like segments. Loekoesia lichens have bright white, rounded soralia, which produce bluish to whitish powdery propagules (soredia) and are arranged in irregular groups on the thallus.
Glomerulophoron is a small genus of lichen-forming fungi in the family Arthoniaceae. The genus contains two species of corticolous (bark-dwelling) crustose lichens. It was circumscribed in 2015 by the lichenologists Andreas Frisch, Damien Ertz, and Göran Thor. It was created to contain a single species from Mauritius, G. mauritiae, which was distinct from the similar genus Sporodophoron both genetically and morphologically, in the tightly coiled chains of sporodochial conidia. The genus gained another member in 2024 when the Brazilian species G. confluentisorediatum was added to it. It is distinguished from the type species by the absence of sporodochia.
Cryptophaea is a genus of lichen-forming fungi in the family Arthoniaceae. Initially described as a monotypic genus in 2016 with the type species, C. phaeospora, from the Congo Basin, it was expanded in 2024 to include four species of crustose lichens found in Brazil. Cryptophaea species are characterised by their firmly attached thalli, which are typically whitish grey-green and hydrophobic. The genus has diverse morphological features, including pseudoisidia and soredia in some species. Cryptophaea lichens are corticolous, growing on tree bark in various tropical forest ecosystems, from near sea level to elevations over 1000 metres. Recent molecular phylogenetic studies have revealed complex relationships between Cryptophaea and other genera within Arthoniaceae, suggesting potential taxonomic revisions may be necessary as more data becomes available.
Arthonia thoriana is a species of bark-dwelling fungus in the family Arthoniaceae. It is found in the grazed pasture woodlands of Somerset, Great Britain.
Sparria is a small genus of lichen-forming fungi in the family Opegraphaceae.
