''Calycidium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of lichen-forming

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

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 Frie ...

. It has two species. It is one of the few lichen genera containing

foliose Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in divers ...

(leafy) species that produce a mazaedium – 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, ...

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 ...

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 po ...

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 ''Calycidium'' is a genus of lichen-forming fungi in the family Sphaerophoraceae. It has two species. It is one of the few lichen genera containing foliose (leafy) species that produce a mazaedium – a powdery mass of spores. Both species occu ...

'' was transferred to the genus (from ''

Sphaerophorus ''Sphaerophorus'' a genus of lichenized fungi in the order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wher ...

'') in 2002. In 1929,

Alexander Elenkin Alexander Alexandrovich Elenkin (1873–1942, russian: Еленкин, Александр Александрович) was a Russian lichenologist. He was born in Warsaw and took his degree in botany at the University of Warsaw, graduating in 1893 ...

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 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

thallus. The thallus undersurface is white and wrinkled, and the medulla is white. The

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 ...

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 o ...

s. Secondary chemicals produced by the genus include

xanthone Xanthone is an organic compound with the molecular formula O 6H4sub>2CO. It is a white solid. In 1939, xanthone was introduced as an insecticide and it currently finds uses as ovicide for codling moth eggs and as a larvicide. Xanthone is also ...

s and the

orcinol Orcinol is an organic compound with the formula CH3C6H3(OH)2. It occurs in many species of lichens including ''Roccella tinctoria'' and ''Lecanora''. Orcinol has been detected in the "toxic glue" of the ant species '' Camponotus saundersi''. It i ...

depside compound sphaerophorin.

Species

*''

Calycidium cuneatum ''Calycidium'' is a genus of lichen-forming fungi in the family Sphaerophoraceae. It has two species. It is one of the few lichen genera containing foliose (leafy) species that produce a mazaedium – a powdery mass of spores. Both species occu ...

'' – Australia (Tasmania); New Zealand *''

'' – 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 P ...

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