The presence of these anthraquinone pigments, which confer protection from ultraviolet light, enabled this group to expand from shaded forest habitats to harsher environmental conditions of sunny and arid ecosystems during the Late Cretaceous.

Regarding human interactions and applications, although lacking any major economic impact, several rock-dwelling Teloschistaceae species are known to damage marble surfaces, and others are used in some traditional medicines.

In his initial version, he grouped together foliose and fruticose taxa having polarilocular (i.e. two-locule) or four-locule ascospores, including the genera Xanthoria, Teloschistes, and Lethariopsis.

[15] Studies on several Teloschistaceae species have noted the consistent presence of a cap-like zone at the tip of the ascus that shows a strong reaction to iodine, characteristic of amyloid substances.

This ascus is distinguished by a special outer layer that reacts to certain stains and lacks the typical structures seen at the tip, opening in an unusual pattern during spore release.

[22] In one of the last classifications of the family before the widespread use and implementation of molecular techniques, the Outline of the Ascomycota accepted 12 genera in Teloschistaceae in 2006: Caloplaca, Cephalophysis, Fulgensia, Huea, Ioplaca, Josefpoeltia, Seirophora, Teloschistes, Xanthodactylon, Xanthomendoza, Xanthopeltis, and Xanthoria.

[28] Hosseusiella Tassiloa Villophora Teloschistes Josefpoeltia Stellarangia Kaernefia 'Caloplaca' sp.5 Wilketalia Sirenophila Elixjohnia Haloplaca Teloschistopsis Brownliella Neobrownliella Filsoniana Nevilleiella Aridoplaca Follmannia Harusavskia Wetmoreana Scutaria Cinnabaria Catenarina Shackletonia Pachypeltis Parvoplaca Xanthomendoza Squamulea Huriella Amundsenia Xanthocarpia Cerothallia Gondwania Austroplaca Xanthopeltis Teuvoahtiana Charcotiana Flavoplaca Calogaya Orientophila Xanthoria Dufourea Athallia Solitaria Polycauliona 'Caloplaca' brebissoni Teuvoahtiana Franwilsia Eilifdahlia 'Caloplaca' spp.

[36] The well-supported subfamilies (Xanthorioideae, Caloplacoideae, and Teloschistoideae) encompass a range of growth forms – crustose, foliose, and fruticose – demonstrating the diverse evolutionary paths within the family.

[48] Historically, classification of taxa within the family relied on physical characteristics such as growth form, the nature of the outer layer of the lichen (the cortex), and spore type.

[50] Although Teloschistaceae is now well represented in GenBank, with thousands of DNA sequences, the early molecular studies were limited by having too few examples of each species to draw definitive conclusions.

This insight has prompted numerous proposals to redefine the genus into smaller, monophyletic groups;[53] but such taxonomic changes have sometimes met with resistance due to the vast number of species reclassifications they would entail.

[54] According to the lichenologist Robert Lücking, families like Teloschistaceae, which have undergone several changes in genus classification through various studies, require phylogenetic consolidation through extensive multi-locus analysis, incorporating all available data and employing rigorous analytical methods.

This strategy, akin to approaches taken with families such as Collemataceae, Graphidaceae, Pannariaceae, and Parmeliaceae, is essential for accurately revising the taxonomic classification of this diverse and widespread group of lichens.

[1][57] Although it is an atypical growth form for the Teloschistaceae, members of genus Ioplaca are somewhat umbilicate, meaning they have a somewhat circular, leafy thallus attached to the substrate at a single point.

[57][1] Although the presence of a two-chambered (polarilocular) structure in these ascospores is generally indicative of the Teloschistaceae, the spores lack other distinctive features that could be useful as defining taxonomic characteristics.

Due to their resilience to desiccation, Trebouxia species serve as the main photobionts for lichen-forming fungi found in extreme environments such as the Antarctic, Arctic, alpine regions, and deserts, where lichens face continual exposure to intense dryness and temperature shifts.

[47] Studies of photobionts in the Teloschistaceae, including foliose genera (Xanthoria, Xanthomendoza) and a fruticose genus (Teloschistes), demonstrate a consistent association with specific Trebouxia clades.

Phylogenetic analyses of fungal polyketide synthases (PKSs) reveal a consistent grouping of genes, hinting at a shared ancestral trait for anthraquinone biosynthesis within the subphylum Pezizomycotina.

[63] Between 1897 and 1906, the mycologist Friedrich Wilhelm Zopf and the chemist Oswald Hesse conducted a series of early chemical studies on members of the Teloschistaceae, leading to the extraction of the reddish pigment parietin from selected species.

[65] In 1997, Ulrik Søchting analysed secondary metabolites from species of Caloplaca, Teloschistes, and Xanthoria to look for chemical patterns of consistent combinations and proportions of lichen products.

In the Negev desert, the parietin-containing Teloschistaceae species Elenkiniana ehrenbergii and Seirophora lacunosa are avoided by grazing snails, but they frequently consume lichens like Diploicia canescens and Buellia subalbula (both in family Caliciaceae), which lack parietin.

[68] In their large-scale phylogenetic analysis of the Teloschistaceae, the lichenologists Ulf Arup, Ulrik Søchting, and Patrik Frödén analysed about 4000 specimens of members of the family using high-performance liquid chromatography, and identified more than 100 secondary metabolites, mostly anthraquinones.

[187] Several crustose Teloschistaceae species, typically saxicolous in nature, have been recorded growing on human bone remains recovered at a looted Late Holocene aboriginal cairn burial site in Argentina.

[15] Adapted to environments with high sunlight exposure, Teloschistaceae lichens show an enhanced ability to fix carbon from the atmosphere, a crucial process for their sustenance and growth.

Localised exceptions occur primarily in sunlit locations with either calcareous or nutrient-rich siliceous rock formations; these habitats are predominant in the alpine regions of the Alps and the Carpathian Mountains, as well as in the arid, warm rocky steppes.

[194] Some Teloschistaceae genera have a strong geographic centre of species richness; examples include Elixjohnia (Australasia),[122] Orientophila (east Asia), Shackletonia (Antarctic and subantarctic), Stellarangia (south-western Africa), and Xanthoria (Mediterranean area).

Integrative studies combining molecular data and ecological approaches revealed at least six distinct lineages of T. caloplacae, each specialised to a particular host, indicating a complex of closely related species.

During the early modern era in Europe, Xanthoria parietina was commonly boiled in milk as a treatment for jaundice, a practice also applied to Polycauliona candelaria.

[206] Rusavskia elegans has been studied in experiments where specimens were exposed to outer space conditions, including extreme temperatures, ultraviolet radiation, and ultra-high vacuum.

Further, the changing climate may allow the advancement of southern vegetation communities and the introduction of invasive species, potentially exacerbating the impact on this lichen by altering its native habitat.