''Tremella'' 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 Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Tremellaceae. All ''Tremella'' species are

parasites Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The en ...

of other fungi and most produce

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

states.

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), when produced, are gelatinous and are colloquially classed among the " jelly fungi". Over 100 species of ''Tremella'' (in its wide sense) are currently recognized worldwide. One species, '' Tremella fuciformis'', is commercially cultivated for food.

Taxonomy

History

''Tremella'' was one of the original genera created by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in his ''

Species Plantarum ' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genus, genera. It is the first work to consistently apply binomial nomenclature ...

'' of 1753. The name comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''tremere'' meaning "to tremble". Linnaeus placed ''Tremella'' in the

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

, including within it a variety of gelatinous growths, including

seaweeds Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

, and myxomycetes, as well as fungi. Subsequent authors added additional species to this mix, until Persoon revised ''Tremella'' in 1794 and 1801, repositioning the genus within the fungi. Persoon's reinterpretation of ''Tremella'' was sufficiently radical to be considered a separate genus (''Tremella'' Pers.) from that originally created by Linnaeus (''Tremella'' L.). ''Tremella'' Pers. has now been conserved under the

International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN or ICNafp) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all tho ...

, with ''

Tremella mesenterica ''Tremella mesenterica'' (common names include yellow brain, golden jelly fungus, yellow trembler, and witches' butter) is a common jelly fungus in the family Tremellaceae of the Agaricomycotina. The gelatinous, orange-yellow fruit body of th ...

'' 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 ...

Current status

Molecular A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

research, based on

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis of

DNA sequences A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the ...

, has shown that ''Tremella'' (as previously understood) is

polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...

(and hence artificial), with most species not closely related to the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

. Accordingly, some species have been transferred to new genera and new families: ''Tremella foliacea'' and related species are now placed in the genus '' Phaeotremella'' within the family Phaeotremellaceae; ''Tremella encephala'' and related species are now placed in the genus '' Naematelia'' within the Naemateliaceae; ''Tremella moriformis'' and related species are now placed in the genus '' Pseudotremella'' within the Bulleraceae; and ''Tremella polyporina'' is now placed in the genus '' Carcinomyces'' within the Carcinomycetaceae. Several other species groups have not yet been renamed, pending further research. More than 500 species have been described in ''Tremella'', but most of these are old names either of doubtful application or for species later transferred to other genera. In its strict sense the genus ''Tremella'' now contains some 30-40 species, including the type ''

'' and the cultivated species '' T. fuciformis''.

Description

Fruit bodies, when present, are gelatinous. In some species they are small (under 5 mm across) and pustular to pulvinate (cushion-shaped). In others they are much larger (up to 150 mm across) and may be variously lobed, cephaliform (like a brain, with folds and ridges), or foliose (with leaf-like or seaweed-like fronds). Many ''Tremella'' species, however, are hymenial parasites, producing spores within the fruit bodies of their hosts, and are only visible microscopically.

Microscopic characters

''Tremella'' species produce

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 o ...

that are typically (but not always) clamped and have haustorial cells from which hyphal filaments seek out and penetrate the hyphae of the host. 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 "tremelloid" (globose to ellipsoid, sometimes stalked, and vertically or diagonally septate), giving rise to long, sinuous

sterigmata 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 ...

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 pr ...

are produced. These spores are smooth, globose to ellipsoid, and germinate by hyphal tube or by

cells.

Conidiophores A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

are often present, producing conidiospores that are similar to yeast cells.

Habitat and distribution

Species are mainly parasitic on wood-rotting fungi in the

phyla Phyla, the plural of ''phylum'', may refer to: * Phylum, a biological taxon between Kingdom and Class * by analogy, in linguistics, a large division of possibly related languages, or a major language family which is not subordinate to another Phy ...

Ascomycota Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...

and

Basidiomycota Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...

, particularly on species that occur on dead attached branches. Hosts include members of the corticioid fungi and

Dacrymycetales The Dacrymycetes are a class of fungi in the Basidiomycota. The class currently contains the single order Dacrymycetales, with a second proposed order Unilacrymales now treated at the family level. The order contains four families and has a cosmo ...

in the Basidiomycota and species of ''

Diaporthe ''Diaporthe'' is a genus of endophytic filamentous fungal plant pathogens. ''Diaporthe'' species have been shown to transform the infection-inhibiting factors (+)-catechin and (−)-epicatechin into the 3,4-cis-dihydroxyflavan derivatives. Som ...

'', other

Sordariomycetes Sordariomycetes is a class of fungi in the subdivision Pezizomycotina (Ascomycota). It is the second-largest class of Ascomycota, with a worldwide distribution that mostly accommodates terrestrial based taxa, although several can also be found in ...

, and

lichens 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 ...

in the Ascomycota. Some ''Tremella'' species parasitize the fruit bodies of their hosts, others parasitize the mycelium within the wood. As a group, ''Tremella'' species occur worldwide, though individual species may have a more restricted distribution.

Species and hosts

The list below includes species of ''Tremella'' (in the wide sense) that have recently been described or redescribed based on fruit bodies. Species based on yeasts are not included. 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 together with the host fungus, where known. Species belonging to ''Tremella'' in the strict sense are marked as such, as are those that have been transferred to new genera.

References

{{Authority control * Taxa described in 1801 Yeasts