A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. 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 Cladoniaceae are a family of lichenized fungi in the order Lecanorales. It is one of the largest families of lichen-forming fungi, with about 560 species distributed amongst 17 genera. The reindeer moss and cup lichens (Cladonia) belong to this family. The latter genus, which comprises about 500 species, forms a major part of the diet of large mammals in taiga and tundra ecosystems. Many Cladoniaceae lichens grow on soil, but other can use decaying wood, tree trunks, and, in a few instances, rocks as their substrate. They grow in places with high humidity, and cannot tolerate aridity.
The Agaricomycetes are a class of fungi in the division Basidiomycota. The taxon is roughly identical to that defined for the Homobasidiomycetes by Hibbett & Thorn, with the inclusion of Auriculariales and Sebacinales. It includes not only mushroom-forming fungi, but also most species placed in the deprecated taxa Gasteromycetes and Homobasidiomycetes. Within the subdivision Agaricomycotina, which already excludes the smut and rust fungi, the Agaricomycetes can be further defined by the exclusion of the classes Tremellomycetes and Dacrymycetes, which are generally considered to be jelly fungi. However, a few former "jelly fungi", such as Auricularia, are classified in the Agaricomycetes. According to a 2008 estimate, Agaricomycetes include 17 orders, 100 families, 1147 genera, and about 21000 species. Modern molecular phylogenetic analyses have been since used to help define several new orders in the Agaricomycetes: Amylocorticiales, Jaapiales, Stereopsidales, and Lepidostromatales.
The Baeomycetales are an order of mostly lichen-forming fungi in the subclass Ostropomycetidae, in the class Lecanoromycetes. It contains 8 families, 33 genera and about 170 species. As a result of molecular phylogenetics research published in the late 2010s, several orders were folded into the Baeomycetales, resulting in a substantial increase in the number of taxa.
The Verrucariaceae are a family of mostly lichenised fungi in the order Verrucariales. The lichen-forming species, which comprise the vast majority of the family, have a wide variety of thallus forms, and include crustose (crust-like), foliose (bushy), and squamulose (scaly) representatives. Several characteristics of the spore-bearing structures, the ascomata, define the family, including their perithecioid form–more or less spherical or flask-shaped, with a single opening and otherwise completely enclosed by a wall. Squamulose members of the Verrucariaceae with simple ascospores, and without algae in the spore-bearing region are known as catapyrenioid lichens; there are more than 80 of these species. The family has several dozen lichenicolous (lichen-dwelling) examples, including a few genera that contain solely lichenicolous members. An unusually diverse variety of photobiont partners have been recorded, mostly green algae, but also brown algae and yellow-green algae.
Psilolechia is a genus of four species of crustose lichens. It is the only member of Psilolechiaceae, a family that was created in 2014 to contain this genus.
Nyungwea is a genus of lichen-forming fungi in the family Opegraphaceae. It was circumscribed in 2006 by Emmanuël Sérusiaux, Eberhard Fischer, and Dorothee Killmann, with Nyungwea pallida assigned as the type species.
Dictyonema is a genus of mainly tropical basidiolichens in the family Hygrophoraceae.
The clavarioid fungi are a group of fungi in the Basidiomycota typically having erect, simple or branched basidiocarps that are formed on the ground, on decaying vegetation, or on dead wood. They are colloquially called club fungi and coral fungi.
Multiclavula is a genus of basidiolichens in the family Hydnaceae. The widespread genus contains 14 species.
Ertzia is a monospecific genus in the family Lepidostromataceae. The sole species is Ertzia akagerae. The genus was circumscribed in 2014 by Brendan Hodkinson and Robert Lücking. Ertzia is distinguished from all other lichenized clavarioid fungi by having a microsquamulose thallus that forms contiguous glomerules with a cortex of jigsaw puzzle-shaped cells. Ertzia akagerae grows on soil in the African tropics.
Sulzbacheromyces is a genus of basidiolichens in the family Lepidostromataceae. The genus is distinguished from the other genera of Lepidostromataceae by having an entirely crustose thallus and from Multiclavula (Cantharellales) by having a chlorococcoid photobiont. The type species grows on soil in the neotropics.
Lepidostroma is a genus in the family Lepidostromataceae. The genus is distinguished from all other lichenized clavarioid fungi by having a distinctly squamulose thallus with scattered to dense rounded to reniform squamules. Four species are known from the tropics of Africa and the Americas.
Malmideaceae is a family of crustose and corticolous lichens in the order Lecanorales. It contains eight genera and about 70 species.
Emmanuël Sérusiaux is a Belgian lichenologist. His career, spanning more than four decades, has combined both lichenology research and political aspects of nature conservation. He spent several periods working as a researcher at the National Fund for Scientific Research and the University of Liège, the latter in which he accepted a faculty position as professor and head of the Plant Taxonomy and Conservation Biology unit. Sérusiaux also served for three non-consecutive appointments as Deputy Chief of Staff in the Government of Wallonia. He retired from both his academic and political positions in 2019.
Savoronala is a fungal genus in the family Malmideaceae. It is monotypic, containing the single species Savoronala madagascariensis. This lichen produces unique conidia that each include a single algal cell.
Multiclavula ichthyiformis is a species of terricolous (ground-dwelling) basidiolichen in the family Hygrophoraceae. Found in Costa Rica, it was formally described as a new species in 2007 by Matthew Nelsen, Robert Lücking, Loengrin Umaña, Marie Trest, and Susan Will-Wolf. The type collection was collected in the Macizo de la Muerte section of Tapantí National Park at an elevation of 2,700 m (8,900 ft). Here, in a disturbed high-altitude peat bog in a rainforest, it was found growing on the ground along a brook and a road bank.
The following outline provides an overview of and topical guide to lichens.
James D. Lawrey is a biologist, specialising in lichens. He is known for leading long-term monitoring projects, taxonomy and studies of the evolution of the fungi in lichens.
Isalonactis is a monotypic fungal genus in the family Roccellaceae. It contains the single species Isalonactis madagascariensis, a saxicolous (rock-dwelling), crustose lichen found in Madagascar. Both the genus and species were described as new in 2014 by Damien Ertz, Anders Tehler, Eberhard Fischer, Dorothee Killmann, Tahina Razafindrahaja, and Emmanuël Sérusiaux. The type was collected on the Isalo Massif at an altitude of 851 m (2,792 ft); there, it was found growing on sheltered mesozoic sandstone cliffs. The genus name alludes to both Isalo Massif, the type locality, and the phylogenetic relatedness to genus Lecanactis.
