Rhodotus
Encyclopedia
Rhodotus is a genus
in the Physalacriaceae
family of fungi
. It is a monotypic genus and consists of the single mushroom
species Rhodotus palmatus, known in the vernacular
as the netted Rhodotus, the rosy veincap, or the wrinkled peach. This uncommon species has a circumboreal
distribution, and has been collected in eastern North America, northern Africa, Europe, and Asia; declining populations in Europe have led to its appearance in over half of the European fungal Red Lists of threatened species. Typically found growing on the stumps and logs of rotting hardwood
s, mature specimens may usually be identified by the pinkish color and the distinctive ridged and veined surface of their rubbery caps
; variations in the color and quantity of light received during development lead to variations in the size, shape, and cap color of fruit bodies
.
The unique characteristics of R. palmatus have made it difficult for taxonomists
to agree on how it should be classified, resulting in an elaborate taxonomical history and an extensive synonymy
. First named Agaricus palmatus by Bulliard
in 1785, it was reclassified into several different genera before becoming Rhodotus in 1926. The familial
placement of the genus Rhodotus within the order Agaricales
has also been subject to dispute, and the taxon
has been transferred variously to the families Amanitaceae
, Entolomataceae
, and Tricholomataceae
. More recently, molecular phylogenetics analysis has helped determine that Rhodotus is most closely related to genera in the Physalacriaceae
.
of genus Rhodotus was originally described as Agaricus palmatus in 1785 by French botanist Jean Bulliard
; mycologist Elias Magnus Fries
later included it under the same name in his Systema Mycologicum. It was transferred to the then newly described genus Rhodotus in a 1926 publication by French mycologist René Maire
. The specific epithet is derived from the Latin
palmatus, meaning "shaped like a hand"—possibly a reference to the resemblance of the cap surface to the lines in the palm of a hand. Common name
s for R. palmatus include the netted Rhodotus, the rosy veincap, and the wrinkled peach.
called the species Pleurotus subpalmatus in 1876. A 1986 paper reported that the species Pleurotus pubescens, first described by American mycologist Charles Horton Peck
in 1891, was the same as Rhodotus palmatus, making their names synonymous
. According to the same publication, another synonym is Lentinula reticeps, described by William Alphonso Murrill in 1915, who thought it to be synonymous with Agaricus reticeps (described by Montagne in 1856), Agaricus reticulatus (Johnson, 1880), Agaricus alveolatus (Cragin, 1885), Pluteus alveolatus (Saccardo
, 1887), and Panus meruliiceps (Peck
, 1905).
order is uncertain, and various authors have offered solutions to the taxonomic
conundrum. In 1951, Agaricales specialist Rolf Singer
placed Rhodotus in the Amanitaceae
because of similarities between the tribes
Amaniteae and Rhodoteae, such as spore
color and ornamentation (modifications of the spore wall that result in surface irregularities), structure of the hypha
e and trama
, and chlamydospore
production during culture
growth.In 1953, French mycologists Robert Kühner
and Henri Romagnesi
placed Rhodotus in the Tricholomataceae
family—a traditional "wastebasket taxon"—on the basis of spore color. In 1969, Besson argued for the placement of Rhodotus with the Entolomataceae
after studying the ultrastructure
of the spores. By 1986, Singer had revised the placement of Rhodotus in his latest edition of The Agaricales in Modern Taxonomy, noting that "It has formerly been inserted in the family Amanitaceae but is obviously closer to tribus Pseudohiatuleae of the Tricholomataceae." Tribe Pseudohiatuleae included such genera as Flammulina
, Pseudohiatula
, Cyptotrama
, and Callistodermatium
. In 1988, a proposal was made to split the Tricholomataceae family into several new families, including a Rhodotaceae family to contain the problematic genus.
The use of molecular phylogenetics has helped to clarify the proper taxonomic placement of Rhodotus. Studies of the ribosomal DNA
sequences from a wide variety of Agaric
fungi have corroborated Kühner and Romagnesi's placement of Rhodotus in the Tricholomataceae as then understood. A large scale phylogenetic analysis published in 2005 showed Rhodotus to be in the "core Euagarics clade
", a name given to a grouping of gilled mushrooms corresponding largely to the suborder
Agaricineae as defined by Singer (1986), but also including taxa
that were traditionally classified in the Aphyllophorales
(e.g., Clavaria
, Typhula
, Fistulina
, Schizophyllum
, etc.) and several orders of Gasteromycetes (e.g., Hymenogastrales, Lycoperdales
, Nidulariales). These results corroborated a previous study which showed Rhodotus to be part of a clade containing species such as Cyptotrama asprata
, Marasmius trullisatus, Flammulina velutipes
, Xerula furfuracea, Gloiocephala menieri, and Armillaria tabescens
. The genera containing these latter species have been reassigned to the Physalacriaceae
family; as of 2009, both Index Fungorum
and MycoBank
also list Rhodotus as belonging to the Physalacriaceae.
of Rhodotus has a cap
, and stem
without a ring
or volva
. The cap initially assumes a convex shape before flattening somewhat with age, and typically reaches widths of 2 –. The edges of the cap are rolled inwards, and the cap surface typically has a conspicuous network of lightly colored ridges or veins that outline deep and narrow grooves or pits—a condition technically termed sulcate or reticulate. Between the ridges, the surface color is somewhat variable; depending on the lighting conditions experienced by the mushroom during its development, it may range from salmon-orange to pink to red. The texture of the cap surface is gelatinous, and the internal flesh
is firm but rubbery, and pinkish in color.
The gills have an adnate attachment to the stem, that is, broadly attached to the stem along all or most of the gill width. The gills are thick, packed close to each other, with veins and color similar to, but paler than, the cap. Some of the gills do not extend the full distance from the edge of the cap to the stem. These short gills, called lamellulae, form two to four groups of roughly equal length. The stem is 1.5 – tall and 0.4 – thick (usually slightly larger near the base), and may be attached to the underside of the cap in a central or lateral manner. Like the cap color, stem size is also affected by the type of light received during fruit body maturation.
In nature, Rhodotus palmatus is sometimes seen "bleeding" a red- or orange-colored liquid. A similar phenomenon has also been observed when it is grown in laboratory culture
on a petri dish
: the orange-colored drops that appear on the mat formed by fungal mycelia precede the initial appearance of fruit bodies. The mature fruit body will turn green when exposed to a 10% aqueous solution of Iron(II) sulfate
(FeSO4), a common mushroom identification test
known as iron salts.
, the spore
color of Rhodotus palmatus has been described most commonly as pink, but also as cream
colored. Viewed microscopically, the spores of Rhodotus have a roughly spherical shape, with dimensions of 6–7.2 by 5.6–6.5 µm
; the spore surface is marked with numerous wart-like projections (defined as verricose), typically 0.5–0.7 µm long. The spores are non-amyloid
—unable to take up iodine
stain in the chemical test with Melzer's reagent
.
The spore-bearing cells, the basidia
, are club-shaped and 4-spored, with dimensions of 33.6–43.2 by 5.6–8 µm. Although this species lacks cells called pleurocystidia (large sterile cells found on the gill face in some mushrooms), it contains abundant cheilocystidia (large sterile cells found on the gill edge) that are 27.2–48 by 4.8–8 µm in size. Clamp connection
s are present in the hypha
e. The outer cellular layer of the cap cuticle
is made of bladder-shaped, thick-walled hyphae, each individually supported by a small stalk that extends down into a "gelatinized zone".
Chlamydospore
s are asexual reproductive units made by some fungi that allow them to exist solely as mycelium, a process which helps them survive over periods unsuitable for growth; Rhodotus was shown experimentally to be capable of producing these structures in 1906. The chlamydospores of Rhodotus are thick-walled cells that develop from single hyphal compartments, and have dimensions of 12–8 by 8–6 µm.
activity of mushrooms, Rhodotus palmatus was one of 204 species screened against a panel of human clinical pathogen
s and laboratory control strains. Using a standard laboratory method
to determine antimicrobial susceptibility, the mushroom was shown to have moderate antibacterial
activity against Bacillus subtilis
, and weak antifungal activity against both Saccharomyces cerevisiae
and Aspergillus fumigatus
.
, meaning it obtains nutrients from decomposing organic matter. It grows scattered or clustered in small groups on rotting hardwood
s, such as basswood
, maple, and especially elm
; in Europe it is known to grow on horse chestnut. The mushroom prefers low-lying logs in areas that are periodically flooded and that receive little sunlight, such as areas shaded by forest canopy. A pioneer species
in the fungal colonization of dead wood, it prefers to grow on relatively undecayed substrates
. It is often found growing on dark-stained wood, especially the dried-out upper parts of trunks that have lost their bark
. R. palmatus tends to fruit in cooler and moister weather, from spring to autumn in the United States, or autumn to winter in Britain and Europe.
Described as having a circumboreal
distribution, R. palmatus has been reported from Canada, Iran, Hungary, Italy, Poland, Slovakia, Denmark, Sweden, Norway, Germany, the area formerly known as the USSR, Korea, Japan, and New Zealand. In the United States it has been found in Indiana
, and elsewhere in eastern North America. Although often described as "rare", a 1997 study suggests that it may be relatively common in Illinois
. It has been suggested that an increase in the number of dead elms, a byproduct of Dutch elm disease
, has contributed to its resurgence.
has been observed to be required for the development of R. palmatus fruit bodies, contrary to the typical requirement for blue light seen with many other mushroom species. Fruiting occurs in the presence of green, yellow or red light with wavelength
s above 500 nm
, but only when blue light (under 500 nm) is absent. Consequently, phenotypic
variations observed in the field—such as size, shape, and cap color—may be influenced by differing conditions of light color and intensity. For example, specimens grown in the laboratory under green light had fruit bodies with short, straight stems and pale orange, large caps with well-developed ridges and pits, an appearance similar to specimens found in the field that were growing under a canopy of green leaves. Laboratory-grown specimens under amber
light had bright orange, small caps with less pronounced reticulations; similarly, field specimens found in autumn, after the leaves had fallen, were more orange to orange-pink in color.
, as well as changing land use
practices coincided with reports of declines in the populations of certain mushrooms. Consequently, a number of fungal conservation
initiatives were started to better understand fungal biodiversity
; as of October 2007, 31 European countries have produced fungal Red Lists
of threatened species. Rhodotus palmatus is a candidate species in over half of the European fungal Red Lists, and is listed as critically endangered
, endangered, or near threatened
(or the equivalent) in 12 countries. In the Baltic countries Estonia
, Latvia
, and Lithuania
, it is considered by the Environmental Protection Ministries (a branch of government charged with implementing the Convention on Biological Diversity
) to be regionally extinct, reported as "extinct or probably extinct". It was one of 35 fungal species to gain legal protection in Hungary
in 2005, making it a fineable offense to pick them.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
in the Physalacriaceae
Physalacriaceae
Physalacriaceae are a family of fungi in the order Agaricales. Species in the genus have a widespread distribution, but most are found in the tropics, particularly in South-East Asia and Australasia. Molecular studies suggested that Physalacria, formerly the sole genus in this family, is related to...
family of fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
. It is a monotypic genus and consists of the single mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...
species Rhodotus palmatus, known in the vernacular
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
as the netted Rhodotus, the rosy veincap, or the wrinkled peach. This uncommon species has a circumboreal
Circumboreal Region
The Circumboreal Region is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan....
distribution, and has been collected in eastern North America, northern Africa, Europe, and Asia; declining populations in Europe have led to its appearance in over half of the European fungal Red Lists of threatened species. Typically found growing on the stumps and logs of rotting hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
s, mature specimens may usually be identified by the pinkish color and the distinctive ridged and veined surface of their rubbery caps
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
; variations in the color and quantity of light received during development lead to variations in the size, shape, and cap color of fruit bodies
Sporocarp (fungi)
In fungi, the sporocarp is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne...
.
The unique characteristics of R. palmatus have made it difficult for taxonomists
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
to agree on how it should be classified, resulting in an elaborate taxonomical history and an extensive synonymy
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
. First named Agaricus palmatus by Bulliard
Jean Baptiste François Pierre Bulliard
Jean Baptiste François Pierre Bulliard was a French physician and botanist....
in 1785, it was reclassified into several different genera before becoming Rhodotus in 1926. The familial
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
placement of the genus Rhodotus within the order Agaricales
Agaricales
The fungal order Agaricales, also known as gilled mushrooms , or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13000 described species, along with five extinct genera known only from the fossil record...
has also been subject to dispute, and the taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
has been transferred variously to the families Amanitaceae
Amanitaceae
Amanitaceae are a family of fungi or mushrooms. The family, also commonly called the Amanita family, is in order Agaricales, gilled mushrooms...
, Entolomataceae
Entolomataceae
The Entolomataceae, also known as Rhodophyllaceae are a large family of pink spored terrestrial gilled mushrooms which includes the genera Entoloma, Rhodocybe, and Clitopilus. The family collectively contains over 1500 species, the large majority of which are in Entoloma...
, and Tricholomataceae
Tricholomataceae
The Tricholomataceae are a large family of mushrooms within the Agaricales. A classic "wastebasket taxon", the Tricholomataceae is inclusive of any white-, yellow-, or pink-spored genera in the Agaricales not already classified as belonging to the Amanitaceae, Lepiotaceae, Hygrophoraceae,...
. More recently, molecular phylogenetics analysis has helped determine that Rhodotus is most closely related to genera in the Physalacriaceae
Physalacriaceae
Physalacriaceae are a family of fungi in the order Agaricales. Species in the genus have a widespread distribution, but most are found in the tropics, particularly in South-East Asia and Australasia. Molecular studies suggested that Physalacria, formerly the sole genus in this family, is related to...
.
History and etymology
The type speciesType species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of genus Rhodotus was originally described as Agaricus palmatus in 1785 by French botanist Jean Bulliard
Jean Baptiste François Pierre Bulliard
Jean Baptiste François Pierre Bulliard was a French physician and botanist....
; mycologist Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
later included it under the same name in his Systema Mycologicum. It was transferred to the then newly described genus Rhodotus in a 1926 publication by French mycologist René Maire
René Maire
René Charles Joseph Ernest Maire was a French botanist and mycologist. His major work was the Flore de l'Afrique du Nord in 16 volumes published posthumously in 1953. He collected plants from Algeria, Morocco, France, and Mali for the herbarium of the National Botanic Garden of Belgium.- Biography...
. The specific epithet is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
palmatus, meaning "shaped like a hand"—possibly a reference to the resemblance of the cap surface to the lines in the palm of a hand. Common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s for R. palmatus include the netted Rhodotus, the rosy veincap, and the wrinkled peach.
Synonymy
French botanist Claude GilletClaude Casimir Gillet
Claude Casimir Gillet, born 19 May 1806, died 1896, was a French botanist and mycologist. He initially trained as a medical doctor and veterinarian.-Publications:* Claude-Casimir Gillet, * Claude-Casimir Gillet, , 230 pp...
called the species Pleurotus subpalmatus in 1876. A 1986 paper reported that the species Pleurotus pubescens, first described by American mycologist Charles Horton Peck
Charles Horton Peck
Charles Horton Peck, born March 30, 1833 in Sand Lake, New York, died 1917 in Albany, New York, was an American mycologist of the 19th and early 20th centuries...
in 1891, was the same as Rhodotus palmatus, making their names synonymous
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
. According to the same publication, another synonym is Lentinula reticeps, described by William Alphonso Murrill in 1915, who thought it to be synonymous with Agaricus reticeps (described by Montagne in 1856), Agaricus reticulatus (Johnson, 1880), Agaricus alveolatus (Cragin, 1885), Pluteus alveolatus (Saccardo
Pier Andrea Saccardo
Pier Andrea Saccardo was an Italian botanist and mycologist.- Life :...
, 1887), and Panus meruliiceps (Peck
Charles Horton Peck
Charles Horton Peck, born March 30, 1833 in Sand Lake, New York, died 1917 in Albany, New York, was an American mycologist of the 19th and early 20th centuries...
, 1905).
Taxonomy
The placement of the genus Rhodotus in the AgaricalesAgaricales
The fungal order Agaricales, also known as gilled mushrooms , or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13000 described species, along with five extinct genera known only from the fossil record...
order is uncertain, and various authors have offered solutions to the taxonomic
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
conundrum. In 1951, Agaricales specialist Rolf Singer
Rolf Singer
Rolf Singer was a German-born mycologist and one of the most important taxonomists of gilled mushrooms in the 20th century....
placed Rhodotus in the Amanitaceae
Amanitaceae
Amanitaceae are a family of fungi or mushrooms. The family, also commonly called the Amanita family, is in order Agaricales, gilled mushrooms...
because of similarities between the tribes
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
Amaniteae and Rhodoteae, such 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...
color and ornamentation (modifications of the spore wall that result in surface irregularities), structure of the hypha
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...
e and trama
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
, and chlamydospore
Chlamydospore
A Chlamydospore is the thick-walled big resting spore of several kinds of fungi. It is the life-stage which survives in unfavourable conditions, such as dry or hot seasons....
production during culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
growth.In 1953, French mycologists Robert Kühner
Robert Kühner
Robert Kühner, born Paris 15 March 1903, died Lyon 27 February 1996, was a French mycologist most notable for reviewing many agaric genera.-References:...
and Henri Romagnesi
Henri Romagnesi
Henri Charles Louis Romagnesi was a French mycologist who was notable for a thorough review and monograph of the agaric genus Entoloma , as well as extensive work on the large genus Russula, of which he described several new species.-References:...
placed Rhodotus in the Tricholomataceae
Tricholomataceae
The Tricholomataceae are a large family of mushrooms within the Agaricales. A classic "wastebasket taxon", the Tricholomataceae is inclusive of any white-, yellow-, or pink-spored genera in the Agaricales not already classified as belonging to the Amanitaceae, Lepiotaceae, Hygrophoraceae,...
family—a traditional "wastebasket taxon"—on the basis of spore color. In 1969, Besson argued for the placement of Rhodotus with the Entolomataceae
Entolomataceae
The Entolomataceae, also known as Rhodophyllaceae are a large family of pink spored terrestrial gilled mushrooms which includes the genera Entoloma, Rhodocybe, and Clitopilus. The family collectively contains over 1500 species, the large majority of which are in Entoloma...
after studying the ultrastructure
Ultrastructure
Ultrastructure is the detailed structure of a biological specimen, such as a cell, tissue, or organ, that can be observed by electron microscopy...
of the spores. By 1986, Singer had revised the placement of Rhodotus in his latest edition of The Agaricales in Modern Taxonomy, noting that "It has formerly been inserted in the family Amanitaceae but is obviously closer to tribus Pseudohiatuleae of the Tricholomataceae." Tribe Pseudohiatuleae included such genera as Flammulina
Enokitake
Enokitake , also Enokidake or Enoki are long, thin white mushrooms used in East Asian cuisine . These mushrooms are cultivars of Flammulina velutipes also called golden needle mushroom...
, Pseudohiatula
Pseudohiatula
Pseudohiatula is a genus of fungi in the Tricholomataceae family. The genus contains five species that are widely distributed in tropical areas....
, Cyptotrama
Cyptotrama
Cyptotrama is a genus of mushrooms in the Physalacriaceae family.-Species:*Cyptotrama asprata Redhead & Ginns *Cyptotrama chrysopeplum Cyptotrama is a genus of mushrooms in the Physalacriaceae family.-Species:*Cyptotrama asprata (Berk.) Redhead & Ginns (1980)*Cyptotrama chrysopeplum Cyptotrama is...
, and Callistodermatium
Callistodermatium
Callistodermatium is a genus of fungi in the Tricholomataceae family. It is a monotypic genus, and contains the single species Callistodermatium violascens. The holotype was found in Brazil, and described by mycologist Rolf Singer in 1981....
. In 1988, a proposal was made to split the Tricholomataceae family into several new families, including a Rhodotaceae family to contain the problematic genus.
The use of molecular phylogenetics has helped to clarify the proper taxonomic placement of Rhodotus. Studies of the ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
sequences from a wide variety of Agaric
Agaric
An agaric is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe , with lamellae on the underside of the pileus. "Agaric" can also refer to a basidiomycete species characterized by an agaric-type fruiting body...
fungi have corroborated Kühner and Romagnesi's placement of Rhodotus in the Tricholomataceae as then understood. A large scale phylogenetic analysis published in 2005 showed Rhodotus to be in the "core Euagarics clade
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
", a name given to a grouping of gilled mushrooms corresponding largely to the suborder
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Agaricineae as defined by Singer (1986), but also including taxa
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
that were traditionally classified in the Aphyllophorales
Aphyllophorales
The Aphyllophorales is an obsolete order of fungi in the Basidiomycota. The order is entirely artificial, bringing together a miscellany of species now grouped among the clavarioid fungi, corticioid fungi, cyphelloid fungi, hydnoid fungi, and poroid fungi....
(e.g., Clavaria
Clavaria
Clavaria is a genus of fungi in the family Clavariaceae. Species of Clavaria produce basidiocarps that are either cylindrical to club-shaped or branched and coral-like. They are often grouped with similar-looking species from other genera, when they are collectively known as the clavarioid fungi...
, Typhula
Typhula
Typhula is a genus of clavarioid fungi in the order Agaricales. Species of Typhula are saprotrophic, mostly decomposing leaves, twigs, and herbaceous material. Basidiocarps are club-shaped or narrowly cylindrical and are simple , often arising from sclerotia. The anamorphic genus Sclerotium is a...
, Fistulina
Fistulina
Fistulina is a genus of fungi in the Fistulinaceae family. Species in the genus cause a brown rot of both dead and living hardwood trees....
, Schizophyllum
Schizophyllum
Schizophyllum is a genus of fungi in the family Schizophyllaceae. The widespread genus contains six wood-rotting species.-External links:*...
, etc.) and several orders of Gasteromycetes (e.g., Hymenogastrales, Lycoperdales
Lycoperdales
The Lycoperdales are a now outdated order of fungi. The order included some well-known types such as the giant puffball, the earthstars, and other tuberous fungi...
, Nidulariales). These results corroborated a previous study which showed Rhodotus to be part of a clade containing species such as Cyptotrama asprata
Cyptotrama asprata
Cyptotrama asprata , commonly known as the Golden-scruffy Collybia, is a saprobic species of mushroom in the Physalacriaceae family. Widely distributed in tropical regions of the world, it is characterized by the bright orange to yellow cap that in young specimens is covered with tufts of fibrils...
, Marasmius trullisatus, Flammulina velutipes
Enokitake
Enokitake , also Enokidake or Enoki are long, thin white mushrooms used in East Asian cuisine . These mushrooms are cultivars of Flammulina velutipes also called golden needle mushroom...
, Xerula furfuracea, Gloiocephala menieri, and Armillaria tabescens
Armillaria tabescens
Armillaria tabescens is a species of fungus in the Physalacriaceae family of mushroom. It is a plant pathogen.- External links :* *...
. The genera containing these latter species have been reassigned to the Physalacriaceae
Physalacriaceae
Physalacriaceae are a family of fungi in the order Agaricales. Species in the genus have a widespread distribution, but most are found in the tropics, particularly in South-East Asia and Australasia. Molecular studies suggested that Physalacria, formerly the sole genus in this family, is related to...
family; as of 2009, both Index Fungorum
Index Fungorum
Index Fungorum, an international project to index all formal names in the Fungi Kingdom. Somewhat comparable to the IPNI, but with more contributing institutions....
and MycoBank
MycoBank
MycoBank is an online database, documenting new mycological names and combinations, eventually combined with descriptions and illustrations. It is run by the Centraalbureau voor Schimmelcultures fungal biodiversity center in Utrecht....
also list Rhodotus as belonging to the Physalacriaceae.
Characteristics
The fruit bodySporocarp (fungi)
In fungi, the sporocarp is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne...
of Rhodotus has a cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
, and stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
without a ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...
or volva
Volva (mycology)
The volva is a mycological term to describe a cup-like structure at the base of a mushroom that is a remnant of the universal veil. This macrofeature is important in wild mushroom identification due to it being an easily observed, taxonomically significant feature which frequently signifies a...
. The cap initially assumes a convex shape before flattening somewhat with age, and typically reaches widths of 2 –. The edges of the cap are rolled inwards, and the cap surface typically has a conspicuous network of lightly colored ridges or veins that outline deep and narrow grooves or pits—a condition technically termed sulcate or reticulate. Between the ridges, the surface color is somewhat variable; depending on the lighting conditions experienced by the mushroom during its development, it may range from salmon-orange to pink to red. The texture of the cap surface is gelatinous, and the internal flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
is firm but rubbery, and pinkish in color.
The gills have an adnate attachment to the stem, that is, broadly attached to the stem along all or most of the gill width. The gills are thick, packed close to each other, with veins and color similar to, but paler than, the cap. Some of the gills do not extend the full distance from the edge of the cap to the stem. These short gills, called lamellulae, form two to four groups of roughly equal length. The stem is 1.5 – tall and 0.4 – thick (usually slightly larger near the base), and may be attached to the underside of the cap in a central or lateral manner. Like the cap color, stem size is also affected by the type of light received during fruit body maturation.
In nature, Rhodotus palmatus is sometimes seen "bleeding" a red- or orange-colored liquid. A similar phenomenon has also been observed when it is grown in laboratory culture
Tissue culture
Tissue culture is the growth of tissues or cells separate from the organism. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, such as broth or agar...
on a petri dish
Petri dish
A Petri dish is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch...
: the orange-colored drops that appear on the mat formed by fungal mycelia precede the initial appearance of fruit bodies. The mature fruit body will turn green when exposed to a 10% aqueous solution of Iron(II) sulfate
Iron(II) sulfate
Iron sulfate or ferrous sulfate is the chemical compound with the formula FeSO4. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material...
(FeSO4), a common mushroom identification test
Chemical tests in mushroom identification
Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi. The most useful tests are Melzer's reagent and potassium hydroxide.- Ammonia :Household ammonia can be used. A couple of drops are placed on the flesh...
known as iron salts.
Microscopic features
In depositSpore 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...
, the spore
Basidiospore
A basidiospore is a reproductive spore produced by Basidiomycete fungi. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are produced by specialized fungal cells called basidia. In grills under a cap of one common species in the phylum of...
color of Rhodotus palmatus has been described most commonly as pink, but also as cream
Cream (colour)
Cream is the colour of the cream produced by cattle grazing on natural pasture with plants rich in yellow carotenoid pigments, some of which are incorporated into the cream, to give a yellow tone to white. Cream is the pastel colour of yellow, much like as pink is to red. Cream is used as a skin...
colored. Viewed microscopically, the spores of Rhodotus have a roughly spherical shape, with dimensions of 6–7.2 by 5.6–6.5 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...
; the spore surface is marked with numerous wart-like projections (defined as verricose), typically 0.5–0.7 µm long. The spores are non-amyloid
Amyloid
Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various neurodegenerative diseases.-Definition:...
—unable to take up iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
stain in the chemical test with Melzer's reagent
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
.
The spore-bearing cells, the basidia
Basidium
thumb|right|500px|Schematic showing a basidiomycete mushroom, gill structure, and spore-bearing basidia on the gill margins.A basidium is a microscopic, spore-producing structure found on the hymenophore of fruiting bodies of basidiomycete fungi. The presence of basidia is one of the main...
, are club-shaped and 4-spored, with dimensions of 33.6–43.2 by 5.6–8 µm. Although this species lacks cells called pleurocystidia (large sterile cells found on the gill face in some mushrooms), it contains abundant cheilocystidia (large sterile cells found on the gill edge) that are 27.2–48 by 4.8–8 µm in size. Clamp connection
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...
s are present in the hypha
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...
e. The outer cellular layer of the cap cuticle
Pileipellis
thumb|300px||right|The cuticle of some mushrooms, such as [[Russula mustelina]] shown here, can be peeled from the cap, and may be useful as an identification feature....
is made of bladder-shaped, thick-walled hyphae, each individually supported by a small stalk that extends down into a "gelatinized zone".
Chlamydospore
Chlamydospore
A Chlamydospore is the thick-walled big resting spore of several kinds of fungi. It is the life-stage which survives in unfavourable conditions, such as dry or hot seasons....
s are asexual reproductive units made by some fungi that allow them to exist solely as mycelium, a process which helps them survive over periods unsuitable for growth; Rhodotus was shown experimentally to be capable of producing these structures in 1906. The chlamydospores of Rhodotus are thick-walled cells that develop from single hyphal compartments, and have dimensions of 12–8 by 8–6 µm.
Edibility
Depending on the source consulted, the edibility of Rhodotus palmatus is typically listed as unknown or inedible. The species has no distinguishable odor, and a "bitter" taste, although one early description referred to the taste as "sweet".Antimicrobial activity
As part of a Spanish research study to evaluate the antimicrobialAntimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
activity of mushrooms, Rhodotus palmatus was one of 204 species screened against a panel of human clinical pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
s and laboratory control strains. Using a standard laboratory method
Kirby-Bauer antibiotic testing
Kirby-Bauer antibiotic testing is a test which uses antibiotic-impregnated wafers to test whether particular bacteria are susceptible to specific antibiotics. A known quantity of bacteria are grown on agar plates in the presence of thin wafers containing relevant antibiotics...
to determine antimicrobial susceptibility, the mushroom was shown to have moderate antibacterial
Antiseptic
Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
activity against Bacillus subtilis
Bacillus subtilis
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium commonly found in soil. A member of the genus Bacillus, B. subtilis is rod-shaped, and has the ability to form a tough, protective endospore, allowing the organism to tolerate...
, and weak antifungal activity against both Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
and Aspergillus fumigatus
Aspergillus fumigatus
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
.
Habitat and distribution
Rhodotus palmatus is saprobicDetritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
, meaning it obtains nutrients from decomposing organic matter. It grows scattered or clustered in small groups on rotting hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
s, such as basswood
Tilia
Tilia is a genus of about 30 species of trees native throughout most of the temperate Northern Hemisphere. The greatest species diversity is found in Asia, and the genus also occurs in Europe and eastern North America, but not western North America...
, maple, and especially elm
Elm
Elms are deciduous and semi-deciduous trees comprising the genus Ulmus in the plant family Ulmaceae. The dozens of species are found in temperate and tropical-montane regions of North America and Eurasia, ranging southward into Indonesia. Elms are components of many kinds of natural forests...
; in Europe it is known to grow on horse chestnut. The mushroom prefers low-lying logs in areas that are periodically flooded and that receive little sunlight, such as areas shaded by forest canopy. A pioneer species
Pioneer species
Pioneer species are species which colonize previously uncolonized land, usually leading to ecological succession. They are the first organisms to start the chain of events leading to a livable biosphere or ecosystem...
in the fungal colonization of dead wood, it prefers to grow on relatively undecayed substrates
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
. It is often found growing on dark-stained wood, especially the dried-out upper parts of trunks that have lost their bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
. R. palmatus tends to fruit in cooler and moister weather, from spring to autumn in the United States, or autumn to winter in Britain and Europe.
Described as having a circumboreal
Circumboreal Region
The Circumboreal Region is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan....
distribution, R. palmatus has been reported from Canada, Iran, Hungary, Italy, Poland, Slovakia, Denmark, Sweden, Norway, Germany, the area formerly known as the USSR, Korea, Japan, and New Zealand. In the United States it has been found in Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
, and elsewhere in eastern North America. Although often described as "rare", a 1997 study suggests that it may be relatively common in Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
. It has been suggested that an increase in the number of dead elms, a byproduct of Dutch elm disease
Dutch elm disease
Dutch elm disease is a disease caused by a member of the sac fungi category, affecting elm trees which is spread by the elm bark beetle. Although believed to be originally native to Asia, the disease has been accidentally introduced into America and Europe, where it has devastated native...
, has contributed to its resurgence.
Light requirements
Light at the red end of the visible spectrumVisible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
has been observed to be required for the development of R. palmatus fruit bodies, contrary to the typical requirement for blue light seen with many other mushroom species. Fruiting occurs in the presence of green, yellow or red light with wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s above 500 nm
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
, but only when blue light (under 500 nm) is absent. Consequently, phenotypic
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
variations observed in the field—such as size, shape, and cap color—may be influenced by differing conditions of light color and intensity. For example, specimens grown in the laboratory under green light had fruit bodies with short, straight stems and pale orange, large caps with well-developed ridges and pits, an appearance similar to specimens found in the field that were growing under a canopy of green leaves. Laboratory-grown specimens under amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
light had bright orange, small caps with less pronounced reticulations; similarly, field specimens found in autumn, after the leaves had fallen, were more orange to orange-pink in color.
Conservation status
In the 1980s in Europe, increases in the levels of air pollutionAir pollution
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or cause damage to the natural environment or built environment, into the atmosphere....
, as well as changing land use
Land Use, Land-Use Change and Forestry
Land use, land-use change and forestry is defined by the United Nations Climate Change Secretariat as "A greenhouse gas inventory sector that covers emissions and removals of greenhouse gases resulting from direct human-induced land use, land-use change and forestry activities."LULUCF has impacts...
practices coincided with reports of declines in the populations of certain mushrooms. Consequently, a number of fungal conservation
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
initiatives were started to better understand fungal biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
; as of October 2007, 31 European countries have produced fungal Red Lists
Regional Red List
A Regional Red List is a report of the threatened status of species within a certain country or region. It is based on the IUCN Red List of Threatened Species, an inventory of the conservation status of species on a global scale...
of threatened species. Rhodotus palmatus is a candidate species in over half of the European fungal Red Lists, and is listed as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
, endangered, or near threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
(or the equivalent) in 12 countries. In the Baltic countries Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...
, Latvia
Latvia
Latvia , officially the Republic of Latvia , is a country in the Baltic region of Northern Europe. It is bordered to the north by Estonia , to the south by Lithuania , to the east by the Russian Federation , to the southeast by Belarus and shares maritime borders to the west with Sweden...
, and Lithuania
Lithuania
Lithuania , officially the Republic of Lithuania is a country in Northern Europe, the biggest of the three Baltic states. It is situated along the southeastern shore of the Baltic Sea, whereby to the west lie Sweden and Denmark...
, it is considered by the Environmental Protection Ministries (a branch of government charged with implementing the Convention on Biological Diversity
Convention on Biological Diversity
The Convention on Biological Diversity , known informally as the Biodiversity Convention, is an international legally binding treaty...
) to be regionally extinct, reported as "extinct or probably extinct". It was one of 35 fungal species to gain legal protection in Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
in 2005, making it a fineable offense to pick them.
External links
- Rhodotus at Index FungorumIndex FungorumIndex Fungorum, an international project to index all formal names in the Fungi Kingdom. Somewhat comparable to the IPNI, but with more contributing institutions....
- Picture of spores