''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, button-shaped or cup-shaped. Several species, including the type species '' Exidia glandulosa'', 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'' along with many other gelatinous fungi. The genus ''Exidia'' was separated from ''Tremella'' by Fries 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 ''Heterochaete'' is a genus of fungi in the order Auriculariales. Species produce effused, gelatinous, waxy, or leathery basidiocarps (fruit bodies) on wood, partly or wholly covered in small sterile spines or pegs. The presence of these steril ...

''. 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

hyphae 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 or ...

with clamp connections in a gelatinous matrix. The spore-bearing surface is initially covered in a layer of branched hyphidia below which the basidia are formed. The basidia are tremelloid (ellipsoid and vertically septate), giving rise to long, sinuous sterigmata or epibasidia on which the

basidiospores 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 nucleus that is the product of meiosis, and they are pro ...

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

Representative species

*'' Exidia aeruginosa'' *'' Exidia alveolata'' *'' Exidia cartilaginea'' *'' Exidia glandulosa'' (synonym ''E. truncata'') *'' Exidia japonica'' *'' Exidia nigricans'' (synonym ''E. plana'') *'' Exidia novozealandica'' *'' Exidia pithya'' *'' Exidia pusilla'' *'' Exidia recisa'' *'' Exidia repanda'' *'' Exidia saccharina'' *''

Exidia thuretiana ''Exidia thuretiana'' (common name white brain ) is a jelly fungus in the family Auriculariaceae. The fruit bodies are white and gelatinous with brain-like folds. It is a common, wood-rotting species in Europe, typically growing on dead attached ...

References

{{Taxonbar, from=Q387146 Auriculariales Agaricomycetes genera