''Melanoleuca'' is a poorly known

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ( ...

mushrooms A mushroom or toadstool is the fleshy, spore-bearing Sporocarp (fungi), fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the na ...

traditionally classified in the family

Tricholomataceae The Tricholomataceae are a large family of mushrooms within the Agaricales. Originally a classic "wastebasket taxon", the family included any white-, yellow-, or pink-spored genera in the Agaricales not already classified as belonging to e.g. the ...

. Most are small to medium sized, white, brown, ocher or gray with a cylindrical to subcylindrical stipe and white to pale yellowish

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

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

s are ellipsoid and ornamented with

amyloid Amyloids are aggregates of proteins characterised by a Fibril, fibrillar morphology of 7–13 Nanometer, nm in diameter, a beta sheet (β-sheet) Secondary structure of proteins, secondary structure (known as cross-β) and ability to be Staining, ...

warts. ''Melanoleuca'' is considered a difficult group to study due to their macroscopic similarities among

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

and the need of a thorough microscopic analysis to separate species. DNA studies have determined that this genus is closely related to ''

Amanita The genus ''Amanita'' contains about 600 species of agarics, including some of the most toxic known mushrooms found worldwide, as well as some well-regarded edible species. This genus is responsible for approximately 95% of the fatalities result ...

'' and ''

Pluteus ''Pluteus'' is a large genus of fungi with over 300 species. They are wood rotting saprobes with pink spore prints and gills that are free from the stem. The Latin word ''Pluteus'' means ''shed or penthouse''. Characteristics of the genus ...

'' and that it does not belong to the family Tricholomataceae.

Etymology

The name of the genus is derived from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''melano-'' meaning "black", and ''leukos'' meaning "white".

Description

General

As a genus ''Melanoleuca'' is quite distinctive, and it is not very hard to recognize a mushroom which belongs to it on sight. However the identification of its individual species is difficult due to a lack of clear macroscopic features; the delimiting characters used in descriptions and keys are such properties as the shape of

cheilocystidia A cystidium (plural cystidia) is a relatively large cell found on the sporocarp of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia. Since cystidia have highly varied and distinct shapes that ar ...

(if any are present), the size and ornamentation of the spores, and the structure of the

pileipellis The pileipellis is the uppermost layer of hyphae in the pileus of a fungal fruit body In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowe ...

. Furthermore these characters may be very variable and overlap between taxa or depend on personal experience. Mycologists have up to now had considerable difficulty in establishing a widely accepted classification below the genus level. One recent paper dedicated to these mushrooms describes them as "one of the less appealing fungal genera" and "mostly tedious and drab in appearance and dull in pileus colours".

Macroscopic characters

The

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

of ''Melanoleuca'' are small to medium size ( pileus 10–120 mm in diameter). The pileus is convex, often becoming depressed at the center, and is usually non-viscous and white, brown, ocher, or grey. The gills are

adnexed In mycology, a lamella, or gill, is a papery hymenophore rib under the cap of some mushroom species, most often agarics. The gills are used by the mushrooms as a means of spore dispersal, and are important for species identification. The atta ...

sinuate A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

adnate Adnate may refer to: * Adnation, in botany, the fusion of two or more whorls of a flower * Adnate, in mycology, a classification of lamellae (gills) * Conjoined twins Conjoined twins – sometimes popularly referred to as Siamese twins – are ...

, or subdecurrent, white to yellowish. The stipe is central, cylindrical or slightly swollen at the base, dry and longitudinally striate. There is no

veil A veil is an article of clothing or hanging cloth that is intended to cover some part of the head or face, or an object of some significance. Veiling has a long history in European, Asian, and African societies. The practice has been prominent ...

. Odor and taste are usually indistinctive, mild, fungoid, sweet, or rancid. The

spore print 300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing pinkish-tan spore print. A 3.5-centimeter ...

is white to pale yellowish.

Microscopic characters

The spores of ''Melanoleuca'' are 7.0–11.0 x 4.0–6.0 µm, thin-walled, ellipsoid, amyloid with ornamented warts. They look very similar to the spores of '' Leucopaxillus'', however, ''Melanoleuca'' spores present a

plage Plage may refer to: *Plage (astronomy), a bright region in the chromosphere of the Sun *Plage (mycology), a clear, unornamented area on the basal area of an ornamented fungal spore * "Plage" (song), a 2011 song by English electronic band Crystal F ...

Basidia A basidium () is a microscopic sporangium (a spore-producing structure) found on the hymenophore of fruiting bodies of basidiomycete fungi which are also called tertiary mycelium, developed from secondary mycelium. Tertiary mycelium is highly-c ...

are usually 4-spored, cylindrical to clavate.

Pleurocystidia A cystidium (plural cystidia) is a relatively large cell found on the sporocarp of a basidiomycete (for example, on the surface of a mushroom gill), often between clusters of basidia. Since cystidia have highly varied and distinct shapes that ar ...

and

may be present or absent; if present they are urticoid and thin-walled or fusiform to lageniform and thick-walled. They can have crystals incrusted at the apex. Cystidia are very important to separate species within this genus. The

is a trichoderm, sometimes a cutis. The hymenophoral trama is parallel.

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

s are absent in all parts of the fruit body.

Classification and phylogeny

DNA studies have confirmed ''Melanoleuca'' as

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

(and definitely separate from genus '' Leucopaxillus'', which is morphologically similar and previously thought to be allied). Other phylogenetic studies based on molecular characters have shown that ''Melanoleuca'' does not belong to the Tricholomataceae. Moncalvo et al. presented a

molecular phylogeny Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

of the

Agaricales The fungal order Agaricales, also known as gilled mushrooms (for their distinctive gills) or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13,000 described species, alo ...

based on LSU ribosomal RNA sequence data, including sequences of '' M. alboflavida'' and '' M. cognata''. In this phylogeny ''Melanoleuca'' was clustered with ''Pluteus'' but with low bootstrap support. Matheny et al. performed a phylogenetic analysis of the Agaricales based on six-gene regions, including sequences of '' M. verrucipes''. In this analysis ''Melanoleuca'', ''Pluteus'' and ''

Volvariella ''Volvariella'' is a genus of mushrooms with deep salmon pink gills and spore prints. Description They lack a ring, and have an Amanita-like volva at the stem base. Some species of Amanita look similar, but Amanita has white spores and often ...

'' were recovered as a

monophyletic group A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

and closely related with the aquatic

gasteromycete The gasteroid fungi are a group of fungi in the Basidiomycota. Species were formerly placed in the obsolete class Gasteromycetes Fr. (literally "stomach fungi"), or the equally obsolete order Gasteromycetales Rea, because they produce spores i ...

'' Limnoperdon''. These three genera together with members of the

Amanitaceae The Amanitaceae is a family of mushroom-forming fungi. ''Amanita'' Pers. is one of the most specious and best-known fungal genera. The family, also commonly called the amanita family, is in order Agaricales, the gilled mushrooms. The family co ...

and

Pleurotaceae The Pleurotaceae are a family of small to medium-sized mushrooms which have white spores. The family contains four genera ('' Nematoctonus'' has been synonymized with '' Hohenbuehelia'', but not all of its species have been moved to valid genera) ...

conformed the Pluteoid clade. Garnica et al. and Binder et al. recovered a similar topology with ''Pluteus'', ''Volvariella'' and ''Melanoleuca'' as a monophyletic group. Justo et al. performed a molecular phylogeny of the family

Pluteaceae The Pluteaceae are a family of small to medium-sized mushrooms which have free gill attachment and pink spores. Members of Pluteaceae can be mistaken for members of Entolomataceae, but can be distinguished by the angled spores and attached gill ...

and found ''Melanoleuca'' to be the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to a clade composed of ''Pluteus'' and ''

Volvopluteus ''Volvopluteus'' is a genus of small to medium-sized or big saprotrophic mushrooms growing worldwide. The genus has been segregated from ''Volvariella'' with which it shares some morphological characteristics such as the presence of a volva an ...

''. This clade was poorly supported in their analysis.

Habitat and Distribution

''Melanoleuca'' species are saprotrophic; growing on soil in

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

and

evergreen forest An evergreen forest is a forest made up of evergreen trees. They occur across a wide range of climatic zones, and include trees such as conifers and holly in cold climates, eucalyptus, Live oak, acacias, magnolia, and banksia in more temperate zone ...

s, and

sand dunes A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

. They are

cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...

, but mainly distributed in

temperate regions In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

. Few species are known from the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

Edibility

''Melanoleuca'' species are reported to be edible. The most common species that are consumed are ''M. alboflavida'', ''M. cognata'', ''M. evenosa'', and ''M. melaleuca''. '' Melanoleuca strictipes'' is reported to be slightly toxic.

Species

Murrill published the description of 119 species from

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, those species were revisited by Pfister who concluded that only six belong in ''Melanoleuca'', while the rest belong to other genera as ''

Clitocybe ''Clitocybe'' is a genus of mushrooms characterized by white, off-white, buff, cream, pink, or light-yellow spores, gills running down the stem, and pale white to brown or lilac coloration. They are primarily saprotrophic, decomposing forest grou ...

'' or ''

Tricholoma ''Tricholoma'' is a genus of fungus that contains many fairly fleshy white-spored gilled mushrooms which are found worldwide generally growing in woodlands. These are ectomycorrhizal fungi, existing in a symbiotic relationship with various spec ...

''. Singer considered 48 species worldwide, while Bon recognized 65 species from

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. Kirk et al. consider about 50 species worldwide.

Representative species

*'' Melanoleuca abutyracea'' (Cleland) Grgur. – Found in Australia *'' Melanoleuca alboflavida'' (Peck) Murrill with pileus pallid yellow brown to whitish. It is reported as edible. *'' Melanoleuca brevipes'' (Bull.) Pat. is recognized by a short and relatively thick stipe, which looks out of proportion with the broad pileus. *'' Melanoleuca cinereifolia'' (Bon) Bon is found in sand dunes, among '' Ammophila''. *'' Melanoleuca cognata'' (Fr.) Konrad & Maubl. pileus brown to ochre with gills showing a distinct ochre to pinkish color. It is reported to be edible. *'' Melanoleuca communis'' Sánchez-García & Cifuentes is a species described from

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, found in

coniferous Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extant ...

mixed forest Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions. These fo ...

s, morphologically similar to ''M. polioleuca''. *'' Melanoleuca evenosa'' (Sacc.) Konrad is a species usually found in coniferous forests, and often synonymized with ''M. subalpina'' and ''M. strictipes'', it has a whitish pileus and lageniform cystidia. *'' Melanoleuca excissa'' (Fr.) Singer with urticoid and septate cystidia, often with crystals at the apex. *''

Melanoleuca grammopodia ''Melanoleuca privernensis'' is a species of fungus in the Pluteaceae The Pluteaceae are a family of small to medium-sized mushrooms which have free gill attachment and pink spores. Members of Pluteaceae can be mistaken for members of Entol ...

'' (Bull.) Fayod has a relatively long stipe and urticoid cystidia. *'' Melanoleuca melaleuca'' (Pers.) Murrill has been a very controversial species; some authors recognize this taxon as having cystidia, while some recognized it as not having cystidia. Fontenla et al. put end to this discussion designating a neotype with cystidia. *'' Melanoleuca polioleuca'' (Fr.) Kühner & Maire has been incorrectly named ''M. melaleuca''. It has fusiform to lageniform cystidia. *'' Melanoleuca privernensis'' (consiglio, Contu, Setti & Vizzini) Consiglio, Setti & Vizzini is the only species that has inamyloid spores. *'' Melanoleuca tucumanensis'' Singer is a species described from

Tafí del Valle Tafí del Valle is a city in Tucumán, Argentina. It is located in the department of the same name, of which it is the main settlement, in the west of the Argentine province of Tucumán, 126 km from the provincial capital, San Miguel d ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

*'' Melanoleuca verrucipes'' (Fr.) Singer is easy to recognize by a blackish dotted stipe. *'' Melanoleuca yucatanensis'' Guzman & Bon is a species described from tropical forests in Mexico, it has urticoid cystidia without apical crystals

References

Footnotes Citations

External links

Mushroom Expert - The Genus ''Melanoleuca''
{{taxonbar , from=Q588312 Agaricales enigmatic taxa Agaricales genera Taxa named by Narcisse Théophile Patouillard Taxa described in 1897