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.
Phlyctis psoromica is a species of corticolous (bark-dwelling) crustose lichen in the family Phlyctidaceae. Native to New South Wales, Australia, it was described as new to science in 2011. This lichen is characterised by its whitish to pale blue-grey crustose thallus and distinctive secondary chemistry.
Lichen morphology describes the external appearance and structures of a lichen. These can vary considerably from species to species. Lichen growth forms are used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves ; others cover the substrate like a crust, others such as the genus Ramalina adopt shrubby forms, and there are gelatinous lichens such as the genus Collema.
Varicellaria is a genus of crustose lichens. It is the only genus in the family Varicellariaceae.
Ochrolechia africana, commonly known as the frosty saucer lichen, is a species of crustose and corticolous (bark-dwelling) lichen in the family Ochrolechiaceae. It is a widely distributed species, found in tropical and subtropical areas of southern Africa, Asia, Australia, North America, and South America. The lichen is characterized by the presence of a white "frosty" or powdery apothecia.
Fuscidea multispora is a species of foliicolous (leaf-dwelling), crustose lichen in the family Fuscideaceae. Found in Bolivia, it is known to occur only in a single high-altitude locality in a national park, where it grows on the leaves of coniferous trees from the genus Podocarpus.
Bacidina pycnidiata is a species of crustose lichen in the family Ramalinaceae. It is widely distributed in Europe and North Asia. It is characterised by its whitish or cream-coloured pycnidia with long and ostiolar necks.
Piccolia is a small genus of crustose lichens in the class Lecanoromycetes. First circumscribed by Italian lichenologist Abramo Bartolommeo Massalongo in 1864, it contains ten species. Due to a lack of molecular data, it has not been assigned to an order or family.
Lecidea tessellata is a species of saxicolous (rock-dwelling), crustose lichen in the family Lecideaceae. It was formally described as a species in 1819 by German botanist Heinrich Flörke. In northern North America, it is common and widely distributed, growing on non-calcareous rocks. It also occurs in Afghanistan, China, Nepal, Europe, and Russian Asia. In India, it has been recorded only from the alpine Western Himalayas at an altitude of 3,450 m (11,320 ft). Its southern distribution extends to James Ross Island, where it is locally common.
Coenogonium australiense is a species of corticolous (bark-dwelling), crustose lichen in the family Coenogoniaceae. Found in Australia, it was formally described as a new species in 2018 by lichenologists Gintaras Kantvilas and Robert Lücking. The type specimen was collected by the first author near Little Fisher River (Tasmania) at an altitude of 880 m (2,890 ft), where it was found in a rainforest growing on Nothofagus cunninghamii. The species epithet australiense refers to its geographical distribution. In addition to Tasmania, the lichen has also been documented from New South Wales and Kangaroo Island. In the latter location it was found in remnant stands of coniferous woodland, where it was growing on the bark of old, fissured Callitris trunks.
Leptogium compactum is a species of corticolous (bark-dwelling), foliose lichen in the family Collemataceae. Found in northwestern North America, it was formally described as a new species in 2016 by Daphne Stone, Frances Anderson, and James Hinds. It is distinguished from related Leptogium species by the tightly packed hyphae in the medulla; this characteristic internal anatomy is alluded to in the species epithet compactum.
Pertusaria galapagoensis is a species of corticolous (bark-dwelling), crustose lichen in the family Pertusariaceae. Found on the Galápagos Islands, it was formally described as a new species in 2015 by Elix, Yánez-Ayabaca, A.W.Archer & Bungartz. The type specimen was collected on Floreana Island at an altitude of 371 m (1,217 ft), where it was found growing on the bark of a south-exposed trunk of Cedrella odorata. The species epithet refers to its distribution.
Candelariella clarkiae is a rare species of crustose lichen in the family Candelariaceae. It was discovered in Colorado, USA, and formally described as a new species in 2015 by lichenologists Erin Tripp and James Lendemer. It was originally published with the species epithet clarki, but this was subsequently corrected to clarkiae. The name honors Dina Clark, Collections Manager at the University of Colorado herbarium, for her significant contributions to the knowledge of the Colorado flora, particularly the high plains ecosystems flanking the Southern Rocky Mountains. The authors note of the lichen that "it is bright and sunny, just like Dina’s disposition".
Lecidea hoganii is a rare species of saxicolous (rock-dwelling), crustose lichen in the family Lecideaceae. It is known to occur only in Boulder, Colorado, where it grows in association with other lichens in mixed saxicolous communities on sandstone in the Fox Hills Formation. The lichen is characterized by its thick white, chalky thallus, sessile to raised apothecia, presence of a dark pink pigment in the hymenium, and absence of secondary compounds.
Candelariella biatorina is a species of corticolous (bark-dwelling), crustose lichen in the family Candelariaceae. It is characterised by its distinct yellow hue and apothecia that are biatorine in form. The lichen grows on the trunks of various conifer species across the western United States, and in the Russian Far East.
Chrysothrix chamaecyparicola is a species of corticolous (bark-dwelling), crustose lichen in the family Chrysotrichaceae. Found in the eastern United States, it was formally described as a new species in 2010 by lichenologist James Lendemer. Initially thought to be a North American population of the lookalike Chrysothrix flavovirens, it is now recognized as a separate species due to its distinguishing characteristics. It is particularly noted for its strong affinity for the bark of Atlantic white cedar trees and its dominance in conifer swamps across eastern North America.
Gyalideopsis aptrootii is a species of corticolous lichen in the family Gomphillaceae. Found in southern Brazil, it was described as a new species in 2018. Defining features of this lichen include the unique crescent-shaped structure of its hyphophores, the single-spored asci, and the relatively small size of the ascospores.
Phlyctis subhimalayensis is a species of corticolous (bark-dwelling), crustose lichen in the family Phlyctidaceae. It is found in certain high-elevations regions of the Himalayas and Southwestern China.
Piccolia nannaria is a species of crustose lichen in the class Lecanoromycetes. It is widespread but uncommon in the coastal plain of southeastern North America. Initially thought to be corticolous (bark-dwelling), later collection of the lichen suggest that it may be lichenicolous (lichen-dwelling).
Ramboldia blochiana is a species of corticolous (bark-dwelling), crustose lichen in the family Ramboldiaceae. The species is characterized by a sorediate thallus and shares chemical and morphological characteristics with the widespread Ramboldia russula, but it also possesses distinct chemical components and a unique geographical distribution. Though it is found across tropical and subtropical regions of the New World on various substrates, its distribution might be wider than currently known due to collection biases against sterile, asexually reproducing crustose lichens.
