A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: Xanthoparmelia, Usnea, Parmotrema, and Hypotrachyna.
The Leotiomycetes are a class of ascomycete fungi. Many of them cause serious plant diseases.
The Lecanoraceae are a family of lichenized fungi in the order Lecanorales. Species of this family have a widespread distribution.
Tibellia is a genus of lichenized fungi in the family Ramalinaceae. This is a monotypic genus, containing the single species Tibellia dimerelloides. The genus is named after Swedish lichenologist Leif Tibell.
Fellhaneropsis is a genus of lichenized fungi in the family Pilocarpaceae. The genus is named in honour of Austrian lichenologist Josef Hafellner.
Roccellographa is a genus of lichen-forming fungi in the family Roccellographaceae. The genus was circumscribed by Austrian lichenologist Julius Steiner in 1902, with Roccellographa cretacea assigned as the type, and at that time, the only species. Three additional species have since been transferred to the genus from other genera.
Xanthopyreniaceae is a family of lichen-forming fungi in the order Collemopsidiales. The family was circumscribed by lichenologist Alexander Zahlbruckner in 1926.
Frigidopyrenia is a fungal genus in the family Xanthopyreniaceae. It is a monotypic genus, containing the single species Frigidopyrenia bryospila, a subarctic crustose lichen. This lichen was originally described by Finnish lichenologist William Nylander in 1864 as Verrucaria bryospila. It was shuffled to several genera in its taxonomic history before Martin Grube circumscribed Frigidopyrenia in 2005 to contain it. As of 2017, no molecular sequence data was available for Frigidopyrenia.
Stephanocyclos is a genus of lichen-forming fungi in the family Lecideaceae. It is a monotypic genus, containing the single species Stephanocyclos henssenianus. This crustose lichen was formally described as a new species in 1983 by German lichenologist Hannes Hertel as part of a set of exsiccata. The type specimen was collected from volcanic rock found on Marion Island, one of the two Prince Edward Islands in the southern Indian Ocean. The specific epithet henssenianus honours lichenologist Aino Henssen.
Leifidium is a genus of lichenized fungi in the family Sphaerophoraceae. The genus is monotypic, containing the single species Leifidium tenerum, found in Australia and South America. The genus is named in honour of Swedish lichenologist Leif Tibell.
Alexander Zahlbruckner was an Austrian-Hungarian botanist who specialized in the study of lichens. Johann Babtist Zahlbruckner, an earlier Austrian botanist, was his grandfather.
André Aptroot is a Dutch mycologist and lichenologist.
Vilmos Kőfaragó-Gyelnik was a Hungarian botanist and lichenologist.
Josef Hafellner is an Austrian mycologist and lichenologist. He was awarded the Acharius Medal in 2016 for his lifetime contributions to lichenology. Before his retirement, he was a professor at the Karl-Franzens-Universität in Graz. Hafellner started developing an interest in lichens while he was a student at this institution, studying under Josef Poelt. He earned a master's degree in 1975 and a PhD in 1978, defending a doctoral thesis about the genus Karschia. In 2003, Hafellner received his habilitation. By this time, he had studied with French lichenologist André Bellemère (1927–2014) at Saint-Cloud, where he learned techniques of transmission electron microscopy and how their application in studying asci could be used in lichen systematics. His 1984 work Studien in Richtung einer natürlicheren Gliederung der Sammelfamilien Lecanoraceae und Lecideaceae has been described as "probably the single most influential publication in lichen systematics in the latter half of the 20th century".
Helge Thorsten Lumbsch is a German-born lichenologist living in the United States. His research interests include the phylogeny, taxonomy, and phylogeography of lichen-forming fungi; lichen diversity; lichen chemistry and chemotaxonomy. He is the Associate Curator and Head of Cryptogams and Chair of the Department of Botany at the Field Museum of Natural History.
Timdalia is a fungal genus in the family Acarosporaceae. It is a monotypic genus, containing the single species Timdalia intricata, a saxicolous (rock-dwelling), crustose lichen. This species was first formally described by Swedish lichenologist Adolf Hugo Magnusson in 1935, based on a collection made by Eduard Frey in Austria. It was initially classified in the genus Acarospora. Josef Hafellner circumscribed Timdalia to contain the species in 2001. It was initially placed in the family Lecanoraceae, but molecular phylogenetic studies showed Timdalia to belong in the Acarosporaceae. The genus name honours Norwegian lichenologist Einar Timdal.
