''Onygena equina'', commonly known as the horn stalkball, is a species of
fungus
A fungus ( : fungi or funguses) is any member of the 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, separately from t ...
in the family
Onygenaceae
The Onygenaceae are a family of fungi in the Ascomycota, class Eurotiomycetes.
Genera
These are the genera that are in the Onygenaceae, according to a 2021 review of fungal classification. Following the genus name is the taxonomic authority (t ...
. The fungus grows on
putrefying hooves and horns, and can digest the
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
in those
substrates.
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 ...
are small and white, with thick
stipes supporting a "head" shaped like a flattened sphere. The skin, or
peridium
The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of gasteroid fungi.
Description
Depending on the species, the peridium may vary from being paper-thin to thick and rubbe ...
, of the head appears powdery or like a white crust, and breaks open in maturity, falling off in irregular pieces to expose the pale reddish-brown powdery
spores
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
within. The fungus is known from Europe and North America.
Taxonomy
The species was first
described by
Carl Ludwig von Willdenow as ''
Lycoperdon
''Lycoperdon'' is a genus of puffball mushrooms. The genus has a widespread distribution and contains about 50 species. In general, it contains the smaller species such as the pear-shaped puffball and the gem-studded puffball. It was formerly cla ...
equinum'' in 1787.
Christian Hendrik Persoon
Christiaan Hendrik Persoon (1 February 1761 – 16 November 1836) was a German mycologist who made additions to Linnaeus' mushroom taxonomy.
Early life
Persoon was born in South Africa at the Cape of Good Hope, the third child of an i ...
transferred it to the genus ''
Onygena
''Onygena'' is the type genus of the fungal family Onygenaceae
The Onygenaceae are a family of fungi in the Ascomycota, class Eurotiomycetes.
Genera
These are the genera that are in the Onygenaceae, according to a 2021 review of fungal clas ...
'' in 1800, giving it the name by which it is known today.
The
specific epithet ''equina'' is the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word for "horse". The
common name for the fungus is "horn stalkball".
Description
The fruit bodies have a spherical, flattened head that is whitish to cream before becoming brownish. Its white to brownish cylindrical stipe measures by thick. The perineum (outer skin) of the head breaks when the fruit body is mature, which exposes the brown and powdery
spores
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
inside. Spores are broadly elliptical, smooth, light brown, and measure 8–9 by 4.5–5.5
µm. They contain one or two oil droplets. The
asci (spore-bearing cells) are 14–20 by 12–14 µm, nearly spherical and
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 stain ...
.
Fruit bodies of ''O. equina'' are not
edible
An edible item is any item that is safe for humans to eat. "Edible" is differentiated from "eatable" because it does not indicate how an item tastes, only whether it is fit to be eaten. Nonpoisonous items found in nature – such as some mushroo ...
.
''
Onygena corvina'' is a similar species that grows on the remains of small mammals in owl
pellets, on old feathers, or on tufts of animal hair. Another lookalike, ''
Phleogena faginea'', grows on wood and smells of curry.
Development
British botanist
Harry Marshall Ward was able to cultivate the fungus and described its
life cycle
Life cycle, life-cycle, or lifecycle may refer to:
Science and academia
*Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring
* Life-cycle hypothesis ...
in an 1899 publication. He determined that the white powder on the fruit bodies were
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 ...
s, which were formed at the ends up erect hyphae. As the fruit bodies mature, the hyphae that held the chlamydospores fuse and form the peridium of the fruit body. This is followed by additional changes in the internal hyphae, which form claw-like filaments that push their way into the internal spaces and cavities of the fruit bodies. These claw-shaped hyphae form asci, which disappear as the spores mature, leaving the spores lying loose in the
gleba
Gleba (, from Latin ''glaeba, glēba'', "lump") is the fleshy spore-bearing inner mass of certain fungi such as the puffball or stinkhorn.
The gleba is a solid mass of spores, generated within an enclosed area within the sporocarp. The contin ...
.
William Broadhurst Brierley studied spore
germination in the 1910s. He determined that fully grown ("ripe") ascospores can be germinated after a lengthy resting period, but a pretreatment with
gastric acids reduced the time required. The time that mature spores need to germinate is correlated to the thickness and color of the spore wall. Treating "unripe" ascospores and chlamydospores with gastric juice did not decrease their germination time, and decreased their viability the longer they were treated. These observations confirmed and extended those already published by Ward; taken together, the results indicate that the spores need to pass through the digestive tract of a cow to be viable.
Habitat and distribution
The fruit bodies of ''Onygena equina'' grow singly or in tufts or clusters, on rotting horns of cattle and sheep, as well as remains of hooves. Fruiting occurs from spring to autumn.
Fruit bodies are often overlooked by
mushroom hunters, as animal remains are not a typical substrate for macrofungi. The species has been recorded from Europe and North America.
References
External links
*
Sociedad Micológica ExtremeñaHigh-resolution images
{{Taxonbar, from=Q13360827
Onygenales
Fungi described in 1787
Fungi of Europe
Fungi of North America
Inedible fungi
Taxa named by Carl Ludwig Willdenow