''Phellodon niger'', commonly known as the black tooth, is a species of

tooth fungus The hydnoid fungi are a group of fungi in the Basidiomycota with basidiocarps (fruit bodies) producing spores on pendant, tooth-like or spine-like projections. They are colloquially called tooth fungi. Originally such fungi were referred to the g ...

in the family

Bankeraceae The ''Bankeraceae'' are a family of fungi in the order Thelephorales. Taxa are terrestrial, and ectomycorrhizal with plant species in families such as Pinaceae or Fagaceae. The family was circumscribed by Marinus Anton Donk in 1961. According ...

, and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

of the genus ''

Phellodon ''Phellodon'' is a genus of tooth fungi in the family Bankeraceae. Species have small- to medium-sized fruitbodies with white spines on the underside from which spores are released. All ''Phellodon'' have a short stalk or stipe, and so the g ...

''. It was originally described by Elias Magnus Fries in 1815 as a species of ''

Hydnum ''Hydnum'' is a genus of fungi in the family Hydnaceae. They are notable for their unusual spore-bearing structures of teeth rather than gills. The best known are the edible species ''Hydnum repandum'' and '' H. rufescens''. There are no known t ...

''. Petter Karsten included it as one of the original three species when he

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polyg ...

''Phellodon'' in 1881. The fungus is found in Europe and North America, although molecular studies suggest that the North American populations represent a similar but genetically distinct species.

Taxonomy

''Phellodon niger'' was originally described by Swedish mycologist

Elias Fries Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist. Career Fries was born at Femsjö (Hylte Municipality), Småland, the son of the pastor there. He attended school in Växjö. He acquired an ...

in 1815 as a species of ''

''. The genus ''

'' was

in 1881 by Finnish mycologist Petter Karsten to contain white-toothed fungi. Karsten included three species: '' P. cyathiformis'', '' P. melaleucus'', and the type, ''P. niger'' (originally published with the epithet "nigrum"). The

variety Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

''Phellodon niger'' var. ''alboniger'', published by Kenneth Harrison in 1961, is considered synonymous with ''Phellodon melaleucus''. Lucien Quélet's 1886 ''Calodon niger'' is a synonym of ''Phellodon niger''. Taxonomic synonyms (i.e., based on a different type) include: ''Hydnum olidum'' (Berkeley, 1877); ''Hydnum cuneatum'' (Lloyd 1925); and ''Hydnum confluens'' (Peck 1874). The DNA sequences of the

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. I ...

regions of collections from the United Kingdom were compared with collections made in the Southern United States. They showed a 92–93% similarity, suggesting that the North American populations are a different species with very similar morphological characteristics. ''Phellodon niger'' is commonly known as the "black scented spine fungus", and the "black tooth".

Description

2011-07-09 Phellodon niger 2 71274 cropped

Fruitbodies of ''Phellodon niger'' have a

cap A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. Caps typically have a visor, or no brim at all. They are popular in casual and informal se ...

and a stipe, and so fall into the general class of "stipitate hydnoid fungi". Individual caps are up to in diameter, but caps of neighboring fruitbodies often fuse together to create larger compound growths. Caps are flat to depressed to somewhat funnel-shaped, with a felt-like texture at first before developing concentric pits, wrinkles, and ridges. Initially whitish (sometimes with purplish tints), the cap later darkens in the center to grey, grey-brown, or black. The stipe, measuring up to long, is roughly the same color as the cap. On the underside of the caps are grey spines, up to 4 mm long. The outer covering of the stipe is a thick felty layer of

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates ...

that absorbs water like a sponge. In conditions of high humidity, ''P. niger'' can form striking drops of black liquid on the actively growing caps. The

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscles, fats and other loose connective tissues, but ...

has an odor of fenugreek when it is dry. The mushroom tissue turns bluish-green when

tested ''Tested'' is a live album by punk rock band Bad Religion. It was recorded in the USA, Canada, Germany, Estonia, Denmark, Italy and Austria, in 1996, and released in 1997. It is Bad Religion's second live album. Instead of using crowd microphon ...

with a solution of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...

. The ellipsoid, hyaline (translucent) spores measure 3.5–5 by 3–4 µm. The

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- ...

(spore-bearing cells) are club-shaped, four-spored, and measure 25–40 by 5–7 µm. ''Phellodon niger'' has a monomitic hyphal system, producing generative hyphae with a diameter of 2.5–5 µm. This fungus is considered inedible.

Habitat and distribution

The ectomycorrhizae that ''P. niger'' forms with Norway spruce (''Picea abies'') has been comprehensively described. It is distinguished from the ectomycorrhizae of other Thelephorales species by the unique shape of its

chlamydospore A chlamydospore is the thick-walled large resting spore of several kinds of fungi, including Ascomycota such as '' Candida'', Basidiomycota such as '' Panus'', and various Mortierellales species. It is the life-stage which survives in unfavourable ...

Stable isotope ratio The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abunda ...

analysis of the abundance of the stable isotope

carbon-13 Carbon-13 (13C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. As one of the environmental isotopes, it makes up about 1.1% of all natural carbon on Earth. Detection by mass spectrometry A mas ...

shows that ''P. niger'' has a metabolic signature close to that of

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 ( ...

fungi, indicating that it may be able to obtain carbon from sources other than a tree host. ''Phellodon niger'' is found in continental Europe, where it has a widespread distribution, and in North America. In a preliminary assessment for a

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 the world's most comprehensive inventory of the global conservation status of biologi ...

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

British fungi, ''P. niger'' is considered rare. In Switzerland, it is considered a

vulnerable species A vulnerable species is a species which has been categorized by the International Union for Conservation of Nature as being threatened with extinction unless the circumstances that are threatening its survival and reproduction improve. Vulnera ...

. ''Phellodon niger'' was included in a Scottish study to develop species-specific PCR primers that can be used to detect the mycelia of stipitate hydnoids in soil. Collections labelled as ''P. niger'' from the United Kingdom that were DNA tested, revealed additional

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. Analysis using PCR can determine the presence of a ''Phellodon'' species up to four years after the appearance of fruitbodies, allowing a more accurate determination of their possible decline and threat of extinction.

Chemistry

''Phellodon niger'' has been a source for several bioactive compounds: the cyathane-type

diterpenoid Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being ...

s, nigernin A and B; a

terphenyl Terphenyls are a group of closely related aromatic hydrocarbons. Also known as diphenylbenzenes or triphenyls, they consist of a central benzene ring substituted with two phenyl groups. There are three substitution patterns: ''ortho''-terpheny ...

derivative called phellodonin (2',3'-diacetoxy-3,4,5',6',4''-pentahydroxy-''p''-terphenyl); grifolin; and 4-''O''-methylgrifolic acid. Additional nigernins (C through F) were reported in 2011. Fruitbodies are used to make a gray-blue or green dye.

References

External links

* * {{Taxonbar, from=Q10684413 Fungi described in 1815 Fungi of Europe Fungi of North America Inedible fungi

niger ) , official_languages = , languages_type = National languagesTaxa named by Elias Magnus Fries