''Neohygrocybe nitrata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

agaric An agaric () is a type of fungal fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. It is a type of mushroom (or toadstool) ...

(gilled mushroom) 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 ...

Hygrophoraceae The Hygrophoraceae are a family (biology), family of fungi in the order (biology), order Agaricales. Originally conceived as containing white-spored, thick-gilled agarics (gilled mushrooms), including ''Hygrophorus'' and ''Hygrocybe'' species (th ...

. It has been given the recommended English name of nitrous waxcap, based on its smell. The species has a European distribution, occurring mainly in agriculturally unimproved grassland. Threats to its habitat have resulted in the species being assessed as globally " vulnerable" on the

IUCN Red List of Threatened Species The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological spe ...

Taxonomy

The species was first described in 1801 by

mycologist Mycology is the branch of biology concerned with the study of fungi, including their taxonomy, genetics, biochemical properties, and use by humans. Fungi can be a source of tinder, food, traditional medicine, as well as entheogens, poison, and ...

Christiaan Hendrik Persoon Christiaan Hendrik Persoon (31 December 1761 – 16 November 1836) was a Cape Colony mycologist who is recognized as one of the founders of mycology, mycological Taxonomy (biology), taxonomy. Early life Persoon was born in Cape Colony at ...

as ''Agaricus nitratus''. Czech mycologist

Josef Herink Josef Herink (26 December 1915 – 20 August 1999) was a Czech physician and mycologist. Life and career Josef Herink was born in Prague on 26 December 1915. He completed his medical studies at Charles University in Prague before practicing as ...

transferred it to the genus ''Neohygrocybe'' in 1958, but this combination was not validly published. It was later validly combined by Alexander Kovalenko in 1989. Recent

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 confirmed that ''Neohygrocybe nitrata'' is a distinct species but does not belong in ''

Hygrocybe ''Hygrocybe'' is a genus of agarics (gilled fungi) in the family Hygrophoraceae. Called waxcaps in English (sometimes waxy caps in North America), basidiocarps (fruit bodies) are often brightly coloured and have dry to waxy pileus (mycology), cap ...

sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

Description

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 ...

are

agaricoid An agaric () is a type of fungal fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. It is a type of mushroom (or toadstool), ...

, up to 60 mm (5 in) tall, the cap convex to flat, up to 70 mm (3 in) across. The cap surface is smooth, dry, sometimes breaking up into scales when old, grey-brown. The

lamellae Lamella (: lamellae) means a small plate or flake in Latin, and in English may refer to: Biology * Lamella (mycology), a papery rib beneath a mushroom cap * Lamella (botany) * Lamella (surface anatomy), a plate-like structure in an animal * Lame ...

(gills) are waxy, pale grey to buff with whiter margins. The stipe (stem) is smooth, pale grey to buff, lacking a

ring (The) Ring(s) may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell Arts, entertainment, and media Film and TV * ''The Ring'' (franchise), a ...

. 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 warm orange ("tussock") color spore print. ...

is white, the spores (under a microscope) smooth,

inamyloid In mycology a tissue or feature is said to be amyloid if it has a positive amyloid reaction when subjected to a crude chemical test using iodine as an ingredient of either Melzer's reagent or Lugol's solution, producing a blue to blue-black staini ...

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

, measuring about 8 to 9 by 4.5 to 5.5

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

. Basidiocarps have a distinctly nitrous smell.

Similar species

''Neohygrocybe pseudoingrata'', recently described from the Czech Republic and Slovakia, has a similar nitrous smell, but basidiocarps are typically larger and paler with white stipes. The more widespread European '' Neohygrocybe ingrata'' has a context that stains reddish.

Distribution and habitat

The Nitrous Waxcap is widespread but generally rare throughout Europe. Like other waxcaps, it occurs in old, agriculturally unimproved, short-sward grassland (pastures and lawns). Recent research suggests waxcaps are neither

mycorrhizal A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

nor

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 ...

but may be associated with mosses.

Conservation

''Neohygrocybe nitrata'' is typical of

waxcap grassland Waxcap grassland is short-wikt:sward, sward, nutrient-poor grassland that supports a rich assemblage of larger fungi, particularly waxcaps (species of ''Hygrocybe'' and related genera), characteristic of such habitats. Waxcap grasslands occur pr ...

s, a declining habitat due to changing agricultural practices. As a result, the species is of global conservation concern and is listed as "vulnerable" on the IUCN Red List of Threatened Species. ''Neohygrocybe nitrata'' also appears on the official or provisional national

red list The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological sp ...

s of threatened fungi in several European countries, including Croatia, Czech Republic, Denmark, Germany, and Norway.

References