Myxarium nucleatum
Encyclopedia
Myxarium nucleatum is a jelly fungus in the family Hyaloriaceae
. The sporocarps (fruit bodies) are watery white and gelatinous with small, white, mineral inclusions. It is a common, wood-rotting
species in Europe and North America, typically growing on dead attached or fallen branches of broadleaf trees.
in 1833, who found it growing on hawthorn
in Germany. He placed it in his new genus Myxarium based on its visible white inclusions which he interpreted as spore
s. Wallroth noted its similarity to Naematelia nucleata, but nonetheless described Myxarium nucleatum as a new species, using the same epithet.
Lewis David von Schweinitz
had previously described Tremella nucleata from the United States, a species that was later transferred to the genus Exidia
by Burt. Many subsequent publications, summarized by Donk (1966) and Reid
(1970), have discussed whether the European Myxarium nucleatum is conspecific with the American Exidia nucleata. The consensus now seems to be that they are the same species, but this is based on morphological
similarity not on comparing DNA sequences.
Donk preferred the name Myxarium hyalinum (based on Tremella hyalina Pers.) for this species, but most later authors have followed Reid
in considering Tremella hyalina a nomen dubium
(name of uncertain application) that might originally have referred to any whitish or transparent jelly fungus. Persoon had made no mention of white inclusions when originally describing the species.
. The spore-bearing surface (hymenium
) is smooth. With age, the fruit bodies may become brownish and eventually dry to a thin, varnish-like film. The spore print
is white. The fungus does not have any distinct taste or smell; it is inedible.
, and measure 11–16 x 9–10.5 µm
, with a stalk cell up to 28 µm long that becomes enucleate on maturity. The spores are allantoid (sausage-shaped), measuring 8.5–14 x 3.5–5 µm. Hyphae
are produced in a gelatinous matrix
and are clamped
, hyaline, and 1.5 to 2.5 µm wide.
are similarly coloured, but are typically more opaque and often appear pleated. They do not (or very rarely) contain white, granular inclusions. Microscopically, E. thuretiana can be distinguished by its sessile (not stalked) basidia. Fruit bodies of several gelatinous Tremella
species may also appear similar, but never contain granular inclusions. All can be distinguished microscopically by their non-allantoid spores.
species, typically found on dead attached or fallen branches. It was originally recorded on hawthorn
, but is also known from many other broadleaf trees and shrubs, including beech
, ash, sycamore, and ivy
. Myxarium nucleatum typically fruits in autumn and winter. It is widely distributed in Europe, North, Central and South America, and New Zealand.
The fruit bodies can serve as host
to the auricularioid
parasite Zygogloea gemellipara. This fungus grows thin thread-like hyphae—too small to be viewed with the naked eye—on the hymenium of its host. The hyphae of the parasite attach to the host hyphae through twisting, tendril-like haustorial cells.
Hyaloriaceae
The Hyaloriaceae are a family of fungi in the order Auriculariales. Species within the family have gelatinous basidiocarps that produce spores on septate basidia and, as such, were formerly referred to the "heterobasidiomycetes" or "jelly fungi". All appear to be saprotrophic, growing on dead wood...
. The sporocarps (fruit bodies) are watery white and gelatinous with small, white, mineral inclusions. It is a common, wood-rotting
Wood-decay fungus
A wood-decay fungus is a variety of fungus that digests moist wood, causing it to rot. Some wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria , are parasitic and colonize living trees. Fungi that not only grow on wood but actually cause it to decay, are called...
species in Europe and North America, typically growing on dead attached or fallen branches of broadleaf trees.
History
The species was originally described by Karl Friedrich Wilhelm WallrothKarl Friedrich Wilhelm Wallroth
Karl Friedrich Wilhelm Wallroth was a German botanist. His name is abbreviated Wallr. as a taxon authority.-References:...
in 1833, who found it growing on hawthorn
Crataegus
Crataegus , commonly called hawthorn or thornapple, is a large genus of shrubs and trees in the rose family, Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe,...
in Germany. He placed it in his new genus Myxarium based on its visible white inclusions which he interpreted as spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s. Wallroth noted its similarity to Naematelia nucleata, but nonetheless described Myxarium nucleatum as a new species, using the same epithet.
Lewis David von Schweinitz
Lewis David von Schweinitz
Lewis David de Schweinitz was a German-American botanist and mycologist. He is considered by some the "Father of North American Mycology", but also made significant contributions to botany.-Education:...
had previously described Tremella nucleata from the United States, a species that was later transferred to the genus Exidia
Exidia
Exidia is a genus of fungi in the family Auriculariaceae. Species are saprotrophic, growing on dead attached or recently fallen wood, and produce gelatinous basidiocarps . The fruit bodies are variously pustular, lobed, button-shaped, or top-shaped...
by Burt. Many subsequent publications, summarized by Donk (1966) and Reid
Derek Reid
Derek Agutter Reid was an English mycologist.-Background and education:Reid was born in Leighton Buzzard, Bedfordshire, the son of a picture-framer. He was educated at Cedars School and the University of Hull, where he studied geology and botany...
(1970), have discussed whether the European Myxarium nucleatum is conspecific with the American Exidia nucleata. The consensus now seems to be that they are the same species, but this is based on morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similarity not on comparing DNA sequences.
Donk preferred the name Myxarium hyalinum (based on Tremella hyalina Pers.) for this species, but most later authors have followed Reid
Derek Reid
Derek Agutter Reid was an English mycologist.-Background and education:Reid was born in Leighton Buzzard, Bedfordshire, the son of a picture-framer. He was educated at Cedars School and the University of Hull, where he studied geology and botany...
in considering Tremella hyalina a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
(name of uncertain application) that might originally have referred to any whitish or transparent jelly fungus. Persoon had made no mention of white inclusions when originally describing the species.
Current status
The species is still frequently referred to the genus Exidia, but molecular research, based on cladistic analysis of DNA sequences, has indicated that it belongs in a Myxarium clade that is quite separate from the Exidia clade.English names
Its recommended English name in the UK is "crystal brain"; in North America it has also been called "granular jelly roll".Description
Myxarium nucleatum forms scattered, pustular, gelatinous fruit bodies 0.2 to 1 cm (0.078740157480315 to 0.393700787401575 in) in diameter. These often coalesce, forming compound fruit bodies that may be irregularly cerebriform (brain-like) and up to 6 cm (2.5 in) across. Fruit bodies are hyaline (colourless) to whitish, occasionally with lilac or pinkish tints. Opaque, white, spherical, mineral inclusions are often evident and are made of calcium oxalateCalcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
. The spore-bearing surface (hymenium
Hymenium
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia or...
) is smooth. With age, the fruit bodies may become brownish and eventually dry to a thin, varnish-like film. The spore print
Spore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
is white. The fungus does not have any distinct taste or smell; it is inedible.
Microscopic characters
The basidia are ellipsoid, longitudinally septateSeptum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
, and measure 11–16 x 9–10.5 µm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
, with a stalk cell up to 28 µm long that becomes enucleate on maturity. The spores are allantoid (sausage-shaped), measuring 8.5–14 x 3.5–5 µm. Hyphae
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
are produced in a gelatinous matrix
Matrix (biology)
In biology, matrix is the material between animal or plant cells, in which more specialized structures are embedded, and a specific part of the mitochondrion that is the site of oxidation of organic molecules. The internal structure of connective tissues is an extracellular matrix...
and are clamped
Clamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...
, hyaline, and 1.5 to 2.5 µm wide.
Similar species
Fruit bodies of Exidia thuretianaExidia thuretiana
Exidia thuretiana is a jelly fungus in the family Auriculariaceae. The fruit bodies are white and gelatinous with brain-like folds...
are similarly coloured, but are typically more opaque and often appear pleated. They do not (or very rarely) contain white, granular inclusions. Microscopically, E. thuretiana can be distinguished by its sessile (not stalked) basidia. Fruit bodies of several gelatinous Tremella
Tremella
Tremella is a genus of fungi in the family Tremellaceae. All Tremella species are parasites of other fungi and most produce anamorphic yeast states. Basidiocarps , when produced, are gelatinous and are colloquially classed among the "jelly fungi". Over 100 species of Tremella are currently...
species may also appear similar, but never contain granular inclusions. All can be distinguished microscopically by their non-allantoid spores.
Habitat, distribution, and ecology
Myxarium nucleatum is often found in association with old pyrenomycetes, but is presumed to be a wood-rottingWood-decay fungus
A wood-decay fungus is a variety of fungus that digests moist wood, causing it to rot. Some wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria , are parasitic and colonize living trees. Fungi that not only grow on wood but actually cause it to decay, are called...
species, typically found on dead attached or fallen branches. It was originally recorded on hawthorn
Crataegus
Crataegus , commonly called hawthorn or thornapple, is a large genus of shrubs and trees in the rose family, Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe,...
, but is also known from many other broadleaf trees and shrubs, including beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...
, ash, sycamore, and ivy
Ivy
Ivy, plural ivies is a genus of 12–15 species of evergreen climbing or ground-creeping woody plants in the family Araliaceae, native to western, central and southern Europe, Macaronesia, northwestern Africa and across central-southern Asia east to Japan and Taiwan.-Description:On level ground they...
. Myxarium nucleatum typically fruits in autumn and winter. It is widely distributed in Europe, North, Central and South America, and New Zealand.
The fruit bodies can serve as host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
to the auricularioid
Auriculariales
The Auriculariales are an order of fungi in the class Agaricomycetes. Species within the order were formerly referred to the "heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps that produce spores on septate basidia...
parasite Zygogloea gemellipara. This fungus grows thin thread-like hyphae—too small to be viewed with the naked eye—on the hymenium of its host. The hyphae of the parasite attach to the host hyphae through twisting, tendril-like haustorial cells.