Inocybe praetervisa
Encyclopedia
Inocybe praetervisa is a small, yellow and brown mushroom in the Inocybaceae
Inocybaceae
The Inocybaceae are a family of fungi in the Agaricales order. According to a 2008 estimate, the family contains 13 genera and 821 species. Members of this family have a widespread distribution in tropical and temperate areas.-Taxonomy:...

 family, distinguished from other members of the genus by its unusual 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...

s and bulb. The unusual spores led to the species being named the type species
Type 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 the now-abandoned genus Astrosporina; recent studies have shown that such a genus could not exist, as the species with the defining traits do not form a monophyletic group. However, it is a part of several clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

s within the genus Inocybe
Inocybe
Inocybe is a large, complex genus of mushrooms. Members of Inocybe are mycorrhizal, and some evidence shows that the high degree of speciation in the genus is due to adaptation to different trees and perhaps even local environments.-Description:...

. I. praetervisa grows on the ground in woodland, favouring beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...

 trees, and can be found in Europe, North America and Asia. It is inedible and probably poisonous
Mushroom poisoning
Mushroom poisoning refers to harmful effects from ingestion of toxic substances present in a mushroom. These symptoms can vary from slight gastrointestinal discomfort to death. The toxins present are secondary metabolites produced in specific biochemical pathways in the fungal cells...

 due to the presence of muscarine
Muscarine
Muscarine, L--muscarine, or muscarin is a natural product found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly C. dealbata. Mushrooms in the genera Entoloma and Mycena have also been found to contain levels of muscarine which can be dangerous if ingested...

. The ingestion of muscarine can lead to SLUDGE syndrome, and could potentially lead to death due to respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...

.

Taxonomy and naming

Inocybe praetervisa was first described
Species description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...

 by Lucien Quélet
Lucien Quélet
thumb|Lucien QuéletLucien Quélet was a French mycologist and naturalist who discovered several species and was the founder of the Société mycologique de France, a society devoted to mycological studies....

 in the first volume of Giacomo Bresadola
Giacomo Bresadola
Giacomo Bresadola 14 February 1847 – Trento 9 June 1929) was an eminent Italian mycologist. Fungi he named include the deadly Lepiota helveola and Inocybe patouillardii, though the latter is now known as Inocybe erubescens as this latter description predated Bresadola's by a year...

's 1883 publication Fungi tridentini. The species was moved to the genus Astrosporina by Joseph Schröter
Joseph Schröter
Joseph Schröter was a noted German mycologist, doctor and scientist. During his lifetime, he wrote several books and texts, and discovered and described many species of flora and fungi...

 in 1889, but this was rejected, and the name Astrosporina praetervisa is now considered an obligate synonym
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...

. Astrosporina praetervisa was the type species of the no longer recognised genus. The specific epithet praetervisa comes 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...

 word meaning "overlooked".

Within the genus Inocybe, I. praetervisa has been placed in the subgenus
Subgenus
In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

 Inocybe. Mycologist 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....

 places the species in the section
Section (botany)
In botany, a section is a taxonomic rank below the genus, but above the species. The subgenus, if present, is higher than the section, and the rank of series, if present, is below the section. Sections are typically used to help organise very large genera, which may have hundreds of species...

 Marginatae; mycologist Thom Kuyper considers Marginatae a supersection, and includes I. praetervisa along with I. abietis, I. calospora and I. godeyi
Inocybe godeyi
Inocybe godeyi is a species of Inocybaceae fungus found in Europe. The species produces mushrooms with cone-shaped caps up to in diameter. The caps are cream, becoming browner, but they bruise red. The stem is up to long, and has a "bulb" at the base. The white flesh has a strong smell and an...

. Phylogenetics
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...

 has shown that, in addition to the large clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 of subgenus Inocybe, I. praetervisa forms a clade with I. calospora, I. lanuginosa and I. leptophylla. The species are similar in that all four have basidiospore
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...

s with small nodules; it was this feature that defined the genus Astrosporina, with then A. praetervisa as its type species. However, when phylogenetic analysis later concluded that nodulose-spored Inocybe species do not form a monophyletic group, the name Astrosporina was deemed inappropriate at a generic level. But it may be considered useful at a lower level to refer to the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 of the four Inocybe species. Of those four, I. praetervisa is most closely related to I. calospora, with which it forms a smaller and closer clade. A different study also found the close relationship between I. praetervisa and I. calospora; it also named I. teraturgus as a part of the clade containing I. praetervisa, I. calospora, I. lanuginosa and I. leptophylla.

Description

Inocybe praetervisa has a bell-shaped (later expanding) 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...

 of 3 to 5 cm (1.2 to 2 in) in diametre, which is a yellowish-brown colour. It is fibrous, and splits from the margin (which curves inwards) to the centre. The 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...

 is from 5 to 6 cm (2 to 2.4 in) in height, and from 3 to 8 mm (0.118110236220472 to 0.31496062992126 in) thick. It is white, maturing to a pale straw-yellow, and the whole stem is farinaceous, meaning it is covered in particles resembling meal
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...

. The stem has a distinct bulb at the base, which is moderately marginate, and lacks 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...

. The 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 white, and discolours to yellowish in the stem. The gills are initially whitish, but later become a clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

-brown with toothed, white edges. They are adnexed, meaning they connect to the stem by only part of their depth, and are crowded closely together.

Microscopic features

Inocybe praetervisa leaves a clay-brown spore print
Spore 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...

, while the 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...

s themselves are rectangular with a large number of "distinct, angular knobs". In size, the spores measure between 10 um in length by between 7 um in width. Inocybe praetervisa has both pleuro- and cheilocystidia
Cystidium
A cystidium is a relatively large cell found on the hymenium of a basidiomycete , often between clusters of basidia. Since cystidia have highly varied and distinct shapes that are often unique to a particular species or genus, they are a useful micromorphological characteristic in the...

 which are relatively spindle
Spindle (textiles)
A spindle is a wooden spike used for spinning wool, flax, hemp, cotton, and other fibres into thread. It is commonly weighted at either the bottom middle or top, most commonly by a circular or spherical object called a whorl, and may also have a hook, groove or notch, though spindles without...

-shaped with apical encrustation. The cystidia have hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...

 or pale yellow walls
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...

.

Similar species

The species can be differentiated from the similar I. cookei
Inocybe cookei
Inocybe cookei, commonly known as the straw fibrecap, is a species of mushroom in the Inocybaceae family. It was first described in 1892 by Giacomo Bresadola, and is named in honour of Mordecai Cubitt Cooke. The species can be found in Europe, Asia and North America...

by its "irregular, lumpy spores". It is also similar to I. rimosa, but differs in the presence of a bulb. Another species that can be differentiated by the lack of a bulb is I. numerosigibba.

Habitat and distribution

Inocybe praetervisa is an ectomycorrhizal species, and can be found on the ground in mixed, deciduous or even coniferous woodland. It typically favours beech
Beech
Beech is a genus of ten species of deciduous trees in the family Fagaceae, native to temperate Europe, Asia and North America.-Habit:...

. Mushrooms grow solitarily or in "trooping groups" in late summer and throughout autumn, though it is not commonly encountered species. It can be found in Europe, Asia and North America.

Edibility and toxicity

The species has a mild, indistinct taste, and a faint smell of flour. Mycologist Roger Phillips describes its edibility as "suspect", recommending that it be avoided, and notes that it is possible that the species is poisonous; most species of Inocybe have been shown to contain poisonous chemicals. Mycologist Ian Robert Hall lists the mushroom as containing the poisonous compound muscarine
Muscarine
Muscarine, L--muscarine, or muscarin is a natural product found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly C. dealbata. Mushrooms in the genera Entoloma and Mycena have also been found to contain levels of muscarine which can be dangerous if ingested...

. Consumption of muscarine could lead to a number of physiological effects, including: excess salivation, lacrimation, uncontrollable urination
Urination
Urination, also known as micturition, voiding, peeing, weeing, pissing, and more rarely, emiction, is the ejection of urine from the urinary bladder through the urethra to the outside of the body. In healthy humans the process of urination is under voluntary control...

 and defecation
Defecation
Defecation is the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material from the digestive tract via the anus. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum...

, gastrointestinal problems and emesis (vomiting); this array of symptoms is also known by the acronym SLUDGE. Other potential effects include a drop in blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

, sweating
Sweating
Perspiration is the production of a fluid consisting primarily of water as well as various dissolved solids , that is excreted by the sweat glands in the skin of mammals...

 and death due to respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...

.
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