Lepraria is a genus of leprose crustose lichens that grows on its substrate like patches of granular, caked up, mealy dust grains. Members of the genus are commonly called dust lichens. The main vegetative body (thallus) is made of patches of soredia. There are no known mechanisms for sexual reproduction, yet members of the genus continue to speciate. Some species can form marginal lobes and appear squamulose. Because of the morphological simplicity of the thallus and the absence of sexual structures, the composition of lichen products are important characters to distinguish between similar species in Lepraria.
Crustose lichens are lichens that form a crust which strongly adheres to the substrate, making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Lecanora muralis(Protoparmeliopsis muralis) is a waxy looking, pale yellowish green crustose lichen that usually grows in rosettes radiating from a center (placodioid) filled with disc-like yellowish-tan fruiting bodies (apothecia). It grows all over the world. It is extremely variable in its characteristics as a single taxon, and may represent a complex of species. The fruiting body parts have rims of tissue similar to that of the main nonfruiting body (thallus), which is called being lecanorine. It is paler and greener than L. mellea, and more yellow than L. sierrae. In California, it may be the most common member of the Lecanora genus found growing on rocks (saxicolous).
Lepraria santosii is a species of crustose lichen in the family Stereocaulaceae. It occurs in Tenerife, in the Canary Islands.
Acarospora pseudofuscata is a species of saxicolous (rock-dwelling) crustose lichen in the family Acarosporaceae. It occurs on a few islands in the Aegean Sea and in Turkey.
Lepraria granulata is a species of crustose and leprose lichen in the family Stereocaulaceae. It is found in mountainous locations of Eastern and Central Europe, where it usually grows over moss.
Opegrapha ramisorediata is a rare species of corticolous (bark-dwelling), crustose lichen in the family Opegraphaceae. Known to occur only in northeastern Brazil, it was described as a new species in 2017. It is characterised by a thin, pale greenish-mauve thallus.
Chrysothrix chlorina, the sulphur dust lichen, is a species of leprose (powdery) crustose lichen in the family Chrysotrichaceae. Originally described scientifically by the Swedish lichenologist Erik Acharius over 200 years ago, it has been shuffled to many different genera in its taxonomic history before finally being transferred to Chrysothrix in 1981. The lichen has a circumboreal distribution, meaning it occurs in northern boreal regions across the planet. It is typically saxicolous (rock-dwelling), particularly on the underside of rock overhangs, but has in rare instances been recorded growing on bark and various other surfaces.
Rinodina maronisidiata is a species of corticolous (bark-dwelling), crustose lichen in the family Physciaceae, first described in 2018. Found at high altitudes in the Venezuelan Andes, it is characterised by its unique isidia-covered thallus and specific ascospore morphology.
Astrothelium trematum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae, first described in 2018. Found only in Brazil, it is characterised by its lack of lichexanthone and pigments, and distinctive ascospores.
Allographa hypostictica is a species of saxicolous (rock-dwelling), crustose lichen in the family Graphidaceae, Found in Brazil, it was described as a new species in 2018. Its thallus contains hypostictic acid and its distinctive apothecia and ascospores.
Astrothelium simplex is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae, first described in 2016. It is found in the Atlantic Forest of Brazil.
Astrothelium longisporum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. It occurs in the Atlantic Forest of Brazil.
Enterographa aldabrensis is a species of corticolous (bark-dwelling), crustose lichen in the family Roccellaceae. It is only known to occur in Aldabra in the Seychelles.
Caloplaca lecanorocarpa is a species of saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae. Found in Brazil, it was formally described as a new species in 2016 by the lichenologists André Aptroot and Marcela Cáceres. It is named for its overall appearance to lichens in the Lecanora subfusca species complex.
Fissurina isohypocrellina is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae]. Newly described to science in 2022, it is found in the rainforests of Acre, Brazil. This species is notable within the genus Fissurina genus for the presence of isohypocrellin, a rare secondary metabolite that contributes to its unique wine-red apothecia.
Corticorygma is a monotypic fungal genus in the subfamily Graphidoideae of the family Graphidaceae. It contains a single species, the corticolous (bark-dwelling) crustose lichen Corticorygma stellatum. This script lichen is found in the shaded understory of rainforests in the Brazilian states of Rondônia and Paraná.
Lepraria torii is a species of corticolous and lignicolous, leprose lichen in the family Stereocaulaceae. It is found in northwestern North America.
Lepraria xerophila is a species of leprose lichen in the family Stereocaulaceae. Found in Europe and northwestern North America, it was formally described as a new species in 2004 by the Norwegian lichenologist Tor Tønsberg.
Lepraria bergensis is an uncommon crustose lichen in the family Stereocaulaceae. It occurs in Northern and Central Europe, where it grows on siliceous (silicon-rich) rock walls, particularly under small overhangs, and on mosses on vertical to slightly sloping rock surfaces. The lichen thallus forms as a pale bluish-grey crust-like growth on rocks and mosses. The lichen begins as small, rounded patches a few millimetres wide, which may eventually coalesce into larger areas exceeding 1 centimetre in diameter. The thallus has a powdery texture, consisting of minute granules known as soredia and consoredia, which facilitate the lichen's asexual reproduction. The chemical composition of Lepraria bergensis is distinguished by the presence of several secondary metabolites: atranorin, rangiformic acid or jackinic acid, trace amounts of their respective derivatives, and a variety of anthraquinones. These chemical components cause the lichen to fluoresce a dull yellow under long-wave ultraviolet light.
