''Aspicilia'' (sunken disk lichen) is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of mostly

crustose Crustose is a habit of some types of algae and lichens in which the organism grows tightly appressed to a substrate, forming a biological layer. ''Crustose'' adheres very closely to the substrates at all points. ''Crustose'' is found on rocks and ...

areolate Lichens are composite organisms made up of multiple species: a fungal partner, one or more photosynthetic partners, and sometimes a basidiomycete yeast. They are regularly grouped by their external appearance – a characteristic known as their ...

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.apothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...

discs that are slightly immersed in the areolas, hence the

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Most of the species of this genus grow on

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...

and acidic rocks and most of the taxa prefer

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

and arctic habitats. Some members of the genus ''Aspicilia'' are

pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so m ...

on granite and other hard rock, after which members of other lichen species may grow on them, such as members of '' Acarospora''.ACAROPSPORA, Lichen Flora of the Greater Sonoran Desert Region. Vol 3., Nash, T.H., Ryan, B.D., Gries, C., Bugartz, F., (eds.) 2001

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Description

Members of this genus are weakly cracked to distinctly areolate, with a scattered to whole thallus, thalli. Some of the species of this genus are disc-shaped with plicate lobes at the circumference; these lobes may appear chalky white, grayish, greenish or brownish. Some possess vegetative means of propagation such as

isidia An isidium is a vegetative reproductive structure present in some lichens. Isidia are outgrowths of the thallus surface, and are corticated (i.e., containing the outermost layer of the thallus), usually with a columnar structure, and consisting o ...

(column-like structures of fungal and algal cells normally found on the top-side or outer cortex of the lichen) and

soredia Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria or ...

(structures that produce soralia, granule-like masses of intertwined fungal and algal cells occurring on top of the cortex and on the margins). They have characteristic

ascomata An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mos ...

which are mostly immersed but occasionally emergent. They have 4 to 8 spored asci that are cylindrical to club-shaped. Their

ascospores An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or ...

are typically

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

globose A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the ce ...

in shape, colorless and thin-walled. They often contain β-orcinol depsidones (

secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...

s of lichens) such as

norstictic acid Norstictic acid is a depsidone produced as a secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fun ...

and stictic acids; others have

fatty acids In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

triterpenes Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squale ...

. In genus ''Aspicilia'' dramatic changes in growth forms are very common, and some taxa may display extreme transitions within the same population or even changes within the same thallus.

Classification

Previously placed in the family Hymeneliaceae,

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analyses indicate that the genus is better placed in the family Megasporaceae.

Species

Species Fungorum ''Index Fungorum'' is an international project to index all formal names (scientific names) in the fungus kingdom. the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and the Institute of Mi ...

accepts 70 species of ''Aspicilia''. *'' Aspicilia abbasiana'' *'' Aspicilia albosparsa'' *'' Aspicilia angelica'' *'' Aspicilia aquatica'' *'' Aspicilia arizonica'' *'' Aspicilia armeniaca'' *'' Aspicilia aurantiaca'' *'' Aspicilia auricularis'' *'' Aspicilia berntii'' *'' Aspicilia bicensis'' *'' Aspicilia blastidiata'' *'' Aspicilia boykinii'' *'' Aspicilia brucei'' *'' Aspicilia calcitrapa'' *'' Aspicilia californica'' *'' Aspicilia candida'' *'' Aspicilia cinerea'' *'' Aspicilia confusa'' *'' Aspicilia corallophora'' *'' Aspicilia cuprea'' *'' Aspicilia cyanescens'' *'' Aspicilia desertorum'' *'' Aspicilia dubertretii'' *'' Aspicilia endochlora'' *'' Aspicilia epiglypta'' *'' Aspicilia euphratica'' *'' Aspicilia expansa'' *'' Aspicilia fluviatilis'' *'' Aspicilia fruticulosofoliacea'' *'' Aspicilia fumosa'' *'' Aspicilia granulosa'' *'' Aspicilia grisea'' *'' Aspicilia guadalupensis'' *'' Aspicilia humida'' – South Korea *'' Aspicilia knudsenii'' *'' Aspicilia laevata'' *'' Aspicilia major'' –

Falkland Islands The Falkland Islands (; es, Islas Malvinas, link=no ) is an archipelago in the South Atlantic Ocean on the Patagonian Shelf. The principal islands are about east of South America's southern Patagonian coast and about from Cape Dubouzet ...

Gallery

Image:Aspicilia_caesiocinerea-2.jpg, '' Aspicilia caesiocinerea'' Image:Aspicilia_cinerea-1.jpg, '' Aspicilia cinerea'' Image:Aspicilia_caesiocinerea-7.jpg, Photograph of a cross section of an apothecium of ''A. caesiocinerea'' taken through a compound microscope, x 100. Note the dark olive epihymenium. Image:Aspicilia cinerea-2.jpg, Photograph of a section of an apothecium of ''A. cinerea'' taken through a compound microscope (x400) showing algae in the amphithecium of the thalline margin. (Lecanorine-type apothecium) Image:Aspicilia caesiocinerea-9.jpg, Photograph of an ascus from ''A. caesiocinerea'' taken through a compound microscope (x1000) showing 8 spores per ascus. (Spores measure approximately 15 x 11 micrometres.)

References

* {{Taxonbar, from=Q4807987 Pertusariales Lichen genera Pertusariales genera Taxa named by Abramo Bartolommeo Massalongo Taxa described in 1852