''Exidia'' 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 ...

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

Auriculariaceae The Auriculariaceae are a family (biology), family of fungi in the order (biology), order Auriculariales. Species within the family were formerly referred to the "heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps (fr ...

. The species are

saprotrophic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ...

, occurring in attached or recently fallen dead wood, and produce gelatinous

basidiocarps In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do no ...

(fruit bodies). The fruit bodies are diverse, pustular, lobed, button-shaped or cup-shaped. Several species, including the type species ''

Exidia glandulosa ''Exidia glandulosa'' is a species of fungus in the family Auriculariaceae. In the UK, it has the recommended English name of witch's butter. In North America it has variously been called black witches' butter, black jelly roll, or warty jelly fu ...

'', have sterile pegs or pimples on their spore-bearing surface. The genus has a cosmopolitan distribution and around 20 species are currently recognized worldwide. Initial molecular research indicates the genus is artificial.

Taxonomy

''Exidia'' species were originally placed in the genus ''

Tremella ''Tremella'' is a genus of fungi in the family (biology), family Tremellaceae. All ''Tremella'' species are parasitism, parasites of other fungi and most produce anamorphic yeast states. Basidiocarps (fruit bodies), when produced, are gelatinous ...

'' along with many other gelatinous fungi. The genus ''Exidia'' was separated from ''Tremella'' by

Fries French fries, or simply fries, also known as chips, and finger chips (Indian English), are ''List of culinary knife cuts#Batonnet, batonnet'' or ''Julienning, julienne''-cut deep frying, deep-fried potatoes of disputed origin. They are prepa ...

in 1822, based mainly on fruit body shape. Fries initially included species now assigned to '' Auricularia'' within the genus. Recent molecular research has indicated that ''Exidia'' as currently circumscribed is an artificial grouping, the species not being clearly differentiated from similar, but effused species assigned to the genera '' Exidiopsis'' and '' Heterochaete''. Only a few species have yet been sequenced, however.

Description

''Exidia'' fruit bodies are gelatinous, most having a distinct spore-bearing upper surface and a sterile undersurface. These surfaces are either smooth or (in some species) covered in dense or scattered sterile pegs or pimples. Fruit bodies grow either separately or in clusters, in which case they may coalesce.

Microscopic characters

''Exidia'' fruit bodies are composed of

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e with

clamp connection A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of basidiomycete fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rece ...

s in a gelatinous matrix. The spore-bearing surface is initially covered in a layer of branched hyphidia below which the

basidia A basidium (: basidia) is a microscopic spore-producing structure found on the hymenophore of reproductive bodies of basidiomycete fungi. The presence of basidia is one of the main characteristic features of the group. These bodies are also ...

are formed. The basidia are tremelloid (ellipsoid and vertically

septate In biology, a septum (Latin for ''something that encloses''; septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Human anatomy * Interatrial se ...

), giving rise to long, sinuous

sterigma In biology, a sterigma (: sterigmata) is a small supporting structure. It commonly refers to an extension of the basidium (the spore-bearing cells) consisting of a basal filamentous part and a slender projection which carries a spore at the tip ...

ta or epibasidia on which the

basidiospore A basidiospore is a reproductive spore produced by basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid Ploidy () is the number of complete sets of chromos ...

s are produced. These spores are allantoid (sausage-shaped) or less commonly oblong to cylindrical.

Species

The list below includes species of ''Exidia'' that have recently been described or redescribed. Some additional older species may also be valid, but lack a modern description. The type locality (but not the wider distribution) is given for each species.

References

{{Authority control Auriculariales Agaricomycetes genera