''Calycidium'' 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 ...

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

in the family

Sphaerophoraceae The Sphaerophoraceae are a family of lichenized fungi in the order Lecanorales. Species of this family have a widespread distribution, especially in southern temperate regions. Sphaerophoraceae was circumscribed by mycologist Elias Magnus Fries i ...

. It has two species. It is one of the few lichen genera containing foliose (leafy) species that produce a

mazaedium The following is a glossary of terms used in the description of lichens, composite organisms that arise from algae or cyanobacteria living among filaments of multiple fungus species in a mutualistic relationship. Until the end of the 18th ...

– a powdery mass of

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s. Both species occur in Australasia and South America, where they grow on tree bark or on

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

es.

Taxonomy

The genus was

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

James Stirton James Stirton (1833, Coupar Angus, Perthshire – 14 January 1917, Glasgow) was a Scottish physician and one of Scotland's leading experts on cryptogamic botany. His investigations in bryology and lichenology earned him a world-wide reputation. B ...

in 1877, with ''Calycidium cuneatum'' as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

. '' Calycidium polycarpum'' was transferred to the genus (from ''

Sphaerophorus ''Sphaerophorus'' a genus of lichenized fungi in the order Lecanorales The Lecanorales are an order of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. The order contains 26 families, 269 genera, ...

'') in 2002. In 1929, Alexander Elenkin created the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

family Calycidiaceae to contain this genus. Phylogenetic analysis published in 2013 demonstrated that the Calycidiaceae were closely related to the Sphaerophoraceae. This family was subsumed into the Sphaerophoraceae by

Robert Lücking Robert Lücking (born 1964) is a German lichenologist. He is a leading expert on foliicolous lichens–lichens that live on leaves. Life and career Born in Ulm in 1964, Lücking earned both his master's (1990) and PhD degree (1994) at the Univer ...

and colleagues in their 2016 classification of lichenized fungi; they reasoned: "there is neither a topological nor a morphological reason to maintain the two families, even if both entities are reciprocally monophyletic and Calycidiaceae has been used for many decades".

Description

''Calycidium'' lichens have a more or less smooth, green to brownish-green foliose thallus. The thallus undersurface is white and wrinkled, and the medulla is white. The apothecia are located on the margin of the thallus. They bear the spore mass, the mazaedia, which are brown, comprising more or less spherical

ascospore 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 s ...

s. Secondary chemicals produced by the genus include

xanthone Xanthone is an organic compound with the molecular formula O 6H4CO. It is a white solid. In 1939, xanthone was introduced as an insecticide and it currently finds uses as Insecticide, ovicide for codling moth eggs and as a larvicide. Xanthone ...

s and the orcinol

depside A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, L ...

compound sphaerophorin.

Species

*'' Calycidium cuneatum'' – Australia (Tasmania); New Zealand *'' Calycidium polycarpum'' – South America (Argentina and Chile); Australia (Tasmania); New Zealand Both species occur in cool

temperate rainforest Temperate rainforests are coniferous or broadleaf forests that occur in the temperate zone and receive heavy rain. Temperate rain forests occur in oceanic moist regions around the world: the Pacific temperate rain forests of North American Paci ...

s of the Southern Hemisphere, where they grow on tree bark and sometimes over

es.

References

{{Taxonbar, from=Q10440809 Lecanorales Lichen genera Lecanorales genera Taxa described in 1877 Taxa named by James Stirton