''Calycidium'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

-forming

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

in the family

Sphaerophoraceae The Sphaerophoraceae are a family (biology), family of lichen-forming fungi in the order (biology), order Lecanorales. Species of this family have a widespread distribution, especially in southern temperate regions, with particular diversity in c ...

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

foliose A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common lichen growth forms, growth forms of lichens. It typically has distinct upper and lo ...

(leafy) species that produce a mazaedium – a powdery mass of

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

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

moss Mosses are small, non-vascular plant, non-vascular flowerless plants in the taxonomic phylum, division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Wilhelm Philippe Schimper, Schimp. 1879) may also refer to the parent group bryo ...

es.

Taxonomy

The genus was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

by James Stirton in 1877, with ''Calycidium cuneatum'' as the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

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

Sphaerophorus ''Sphaerophorus'' a genus of lichenized fungi in the order (biology), order Lecanorales. Members of ''Sphaerophorus'' are List of common names of lichen genera, commonly called ball lichens, coral lichens,Field Guide to California Lichens, Steph ...

'') 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 "unisp ...

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, known for his extensive research on foliicolous lichens (lichens that live on leaves) and his significant contributions to the taxonomy, ecology, and biodiversity of fungi and lichens. He e ...

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 (: ascomata), 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. As ...

are located on the margin of the thallus. They bear the spore mass, the mazaedia, which are brown, comprising more or less spherical

ascospore In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...

s. Secondary chemicals produced by the genus include

xanthone Xanthone is an organic compound with the molecular formula C13H8O2. 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 use ...

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 is ...

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

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 rainforests with coniferous or Broad-leaved tree, broadleaf forests that occur in the temperate zone and receive heavy rain. Temperate rainforests occur in oceanic moist regions around the world: the Pacific temperate ...

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