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 Gomphillaceae are a family of lichen-forming fungi in the order Graphidales. Species in this family are found mostly in tropical regions.
The Stictidaceae are a family of fungi in the order Ostropales. It has 30 genera and about 240 species.
Roccella is a genus of 23 species of lichens in the family Roccellaceae. The genus was circumscribed by Swiss botanist Augustin Pyramus de Candolle in 1805, with Roccella fuciformis as the type species.
The Caliciaceae are a family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. Although the family has had its classification changed several times throughout its taxonomic history, the use of modern molecular phylogenetic methods have helped to establish its current placement in the order Caliciales. Caliciaceae contains 39 genera and about 670 species. The largest genus is Buellia, with around 300 species; there are more than a dozen genera that contain only a single species.
Alyxoria is a genus of lichen-forming fungi in the family Lecanographaceae.
Opegraphaceae is a family of lichen-forming and lichenicolous fungi in the order Arthoniales. It was originally proposed by German lichenologist Ernst Stizenberger in 1862. It fell into disuse, but was resurrected in a molecular phylogenetic study of the order Arthoniales published in 2010. It now includes taxa that were previously referred to the family Roccellaceae, its sister group.
Lathagrium is a genus of lichen-forming fungi in the family Collemataceae. It has 10 species of gelatinous lichens. Species in this genus typically grow on calcareous rocks, often amidst mosses, but can also be found on siliceous or serpentine rocks, mortar, or soil.
Roccellographaceae is a family of lichen-forming fungi in the order Arthoniales. It contains three genera: Dimidiographa, Fulvophyton, and Roccellographa.
Leucodermia is a genus of lichen-forming fungi in the family Physciaceae.
Sporastatiaceae is a small family of crustose lichens in the order Rhizocarpales. It contains two genera, Sporastatia and Toensbergia, with a total of five species. Sporastatiaceae was circumscribed in 2013 by Mika Bendiksby and Ernst Timdal.
Gossypiothallon is a fungal genus of uncertain familial placement in the order Arthoniales. It contains the single species Gossypiothallon appendisporum, a corticolous (bark-dwelling), crustose lichen found in South Solomons. Both the genus and species were described as new to science in 2014 by Dutch lichenologist André Aptroot. The type specimen was collected from Kolombangara island at an altitude of 700 m (2,300 ft), where it was found growing on bark.
Candelinella is a genus of lichen-forming fungi in the family Candelariaceae. It contains two species of crustose lichens. It is visually similar to the genus Candelina but has unique features, including a distinct thallus and unique spore structures. It was established by Sergey Kondratyuk in 2020, with Candelinella makarevichiae assigned as the type species. The genus is distinguished by the small, crustose thallus that ranges from a granular to areolate or squamulose texture, and the simple to 1-septate, narrowly ellipsoid to oblong ascospores. Its lack of a lower cortex and medulla further sets it apart from Candelina.
Dimidiographa is a genus of lichen-forming fungi in the family Roccellographaceae. It has three species of crustose lichens, with Dimidiographa loandensis serving as the type species.
Fulvophyton is a genus of lichen-forming fungi in the family Roccellographaceae. It has 11 species. Fulvophyton is characterised by its crust-like thallus, which is often pale yellowish-brown in colour. This genus features a photobiont from the green algal genus Trentepohlia and exhibits a unique arrangement of reproductive structures.
Upretia is a genus of lichen-forming fungi in the family Teloschistaceae. It has three species of saxicolous (rock-dwelling), crustose lichens. Upretia is characterised by its small ascospores and narrow, rod-shaped conidia. The distribution of the genus ranges from mid-altitude rocky terrains in India to both arid and higher altitudinal environments in China.
Macroconstrictolumina is a genus of lichen-forming fungi in the family Trypetheliaceae. It has four species.
The Pyrenotrichaceae are a small family of fungi in the order Chaetothyriales. It contains two genera, and a total of six species. The genus Pyrenothrix has two species of bark- or leaf-dwelling lichens, while Neophaeococcomyces has four species of saprobic fungi.
Nitidochapsa is a genus of lichen-forming fungi in the family Graphidaceae. It has five species of corticolous (bark-dwelling), crustose lichens.
