Lepiota brunneoincarnata known as the deadly dapperling, is a gilled mushroom of the genus Lepiota in the order Agaricales. Distributed in Europe and temperate regions of Asia as far east as China, it grows in grassy areas such as fields and gardens, is mistaken for edible mushrooms; the mushroom has a brown scaled cap up to 4 cm wide with white gills. It is toxic, with several deaths having been recorded as it resembles the edible grey knight and fairy ring champignon; the species was described by Swiss botanists Robert Hippolyte Chodat and Charles-Édouard Martin in 1889, who noted it growing on roadsides in Geneva in Switzerland. Genetic analysis of DNA showed it is related to other amatoxin-containing species such as Lepiota subincarnata and L. elaiophylla. The cap is 2.7–4 cm across, hemispherical at first before becoming more convex without an obvious boss. It is red-brown. There is a large unbroken scale in the centre of the cap; the cap margin is inrolled and the cap is fleshy. The thick uncrowded gills are white, with smaller gills in between.
They are free. The spore print is white; the cylindrical stem is 2–3.5 cm tall by 0.6–0.9 cm wide. The upper part of the stem is pinkish tan, they are separated by a dark brown ring-like zone. The thick flesh reddens on bruising or cutting, smells somewhat like unripe fruit; the taste is mild. The oval spores are 6–7.5 µm long by 3.5–5 µm wide, are dextrinoid – they turn red-brown in Melzer's reagent. The deadly dapperling is found in warmer parts of Europe the south, but has been recorded from Britain and Germany. In Asia, it has been recorded from Turkey, Pakistan and eastern China; the fruit bodies come up on roadsides and hedges. It is known to contain deadly amounts of alpha-amanitin and was responsible for a fatal poisoning in Spain in 2002, a poisoning outbreak in Iran in 2018 and for the deaths of four young members of the same family in Tunisia in 2010. A person survived after eating five specimens picked alongside Agaricus bisporus in Kaynarca, Sakarya, in Turkey in 2013; the symptoms are gastrointestinal, with nausea and vomiting around ten hours after consumption, followed by liver damage a few days later.
100 g of Lepiota brunneoincarnata may result in severe liver damage. It resembles the fairy ring champignon, found in grassy areas, though the pale brown cap of this species lacks scales. Mistakes are made when people pick mushrooms in their garden, as the dapperlings grow in grassy areas. A family in Salon-de-Provence in France was poisoned after mistaking them for the grey knight. Amanitin can be detected in the urine 36 to 48 hours after ingestion; the acute gastric symptoms may mislead medical management if the mushroom is not identified, delay specific liver-protective measures. Intravenous silibinin has a role in reducing amanitin uptake. Other specific measures include penicillin G and n-acetylcysteine as well as general supportive measures such as rehydration. List of deadly fungi List of Lepiota species
Galerina is a genus of small brown-spore saprobic mushrooms, with over 300 species found throughout the world, from the far north to remote Macquarie Island in the Southern Ocean. Species are small and hygrophanous, with a slender and brittle stem, they are found growing on wood, when on the ground have a preference for mossy habitats. This group is most noted for toxic species which are confused with hallucinogenic species of Psilocybe. Galerina means helmet-like; the genus Galerina is defined as small mushrooms of mycenoid stature, similar in form to Mycena species: a small conical to bell-shaped cap, gills attached to a long and slender cartilaginous stem. Species have a pileipellis, a cutis, ornamented spores that are brown in deposit, where the spore ornamentation comes from an extra spore covering. Galerina fruiting bodies are small, undistinguished mushrooms with a typical "little brown mushroom" morphology and a yellow-brown, light brown to cinnamon-brown spore print; the pileus is glabrous and hygrophanous, a cortina-type veil is present in young specimens of half of recognized species, though it sometimes disappears as the mushroom ages in many of these species.
Microscopically, they are variable as well, though most species have spores that are ornamented, lack a germ pore, have a plage. Many species have characteristic tibiiform cystidia. However, there are many exceptions, many species of Galerina lack one or more of these microscopic characteristics. Ecologically, all Galerina are saprobic, growing in moss; the spores of Galerina feature an ornamentation that comes from the outer layer of the spore breaking up on maturity to produce either warts, wrinkles or "ears", flaps of material loosened from where the spore was attached to the basidia. This outer layer of the spore is not complete, but has a clear patch in many species just above the attachment, this clear patch is called a plage; this plage is not evident in all species, the spore covering does not always breakup in all species, making it sometimes difficult to determine a mushroom of this genus. The specific features that define the genus require a microscope to confirm. In the wild it can be difficult to determine a Galerina from a number of similar genera, such as Pholiota, Conocybe, Agrocybe, Gymnopilus and Psilocybe.
For the most part, Galerinas will be found associated with moss, this can separate out the genus in nature well. But this identification is more difficult in the section Naucoriopsis, which does not associate with moss, is a decomposer of wood. Phaeogalera is a genus, segregated from Galerina by Kühner. Galerina has been found to be polyphyletic, consisting of at least three unrelated clades, although not all species were studied and for most recognized species is uncertain still in which they belong; each of these clades corresponds to a subgenus of Galerina. The great diversity of micromorphology found in Galerina is due to the polyphyly of the genus. Many Galerina contain other amatoxins. Galerina steglichii is rare, bruises blue and contains the hallucinogen psilocybin; the extreme toxicity of some Galerina species means that recognition of Galerina is of great importance to mushroom hunters who are seeking hallucinogenic Psilocybe mushrooms. Species like Galerina marginata may bear a superficial resemblance to Psilocybe cyanescens and other Psilocybe species, has been found growing amongst and around Psilocybe cyanescens and other Psilocybe species, making identification all the more confusing to the uninitiated.
Galerina can be distinguished from psilocybin Psilocybe by the following characteristics: Spore print color: blackish-brown to lilac-brown in Psilocybe, light brown to rusty brown in Galerina. Spore color can be seen by taking a spore print or by looking for evidence of spore drop on the stipe or on surrounding mushrooms. Staining reaction: Psilocybin Psilocybe fruiting bodies stain blue to varying degrees when bruised, while Galerina do not; the strength of this reaction varies with the amount of psilocin present in the tissues of the mushroom. Fruiting bodies with little psilocin will stain weakly if at all, while sporocarps with a high psilocin content will stain blue. Only one rare Galerina has blue-staining tissue, though in some cases the flesh will blacken when handled, this may be misinterpreted as a bluing reaction. Although these rules are specific to the separation of Galerina from certain Psilocybe, since mixed patches of Psilocybe and Galerina can occur, it is essential to be sure of the identity of each sporocarp collected.
Galerina present some risk of confusion with several species of small edible mushrooms, notably Kuehneromyces mutabilis and candy caps. Galerina vittiformis is the type species of the genus Galerina; this species is common in beds of damp moss. There are a number of variations of this species that have been named over the years: var. vittiformis f. vittiformis is a 2-spored species. Galerina marginata is a poisonous species found throughout the temperate regions of the world, in habitats as diverse as forests and urban parklands, wherever rotting wood is found. DNA studies found that Galerina autumnalis and five other species of Galerina with similar morphologies were, in fact, synonyms of Ga
Protein Data Bank
The Protein Data Bank is a database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The data obtained by X-ray crystallography, NMR spectroscopy, or cryo-electron microscopy, submitted by biologists and biochemists from around the world, are accessible on the Internet via the websites of its member organisations; the PDB is overseen by an organization called the Worldwide Protein Data Bank, wwPDB. The PDB is a key in areas such as structural genomics. Most major scientific journals, some funding agencies, now require scientists to submit their structure data to the PDB. Many other databases use protein structures deposited in the PDB. For example, SCOP and CATH classify protein structures, while PDBsum provides a graphic overview of PDB entries using information from other sources, such as Gene ontology. Two forces converged to initiate the PDB: 1) a small but growing collection of sets of protein structure data determined by X-ray diffraction.
In 1969, with the sponsorship of Walter Hamilton at the Brookhaven National Laboratory, Edgar Meyer began to write software to store atomic coordinate files in a common format to make them available for geometric and graphical evaluation. By 1971, one of Meyer's programs, SEARCH, enabled researchers to remotely access information from the database to study protein structures offline. SEARCH was instrumental in enabling networking, thus marking the functional beginning of the PDB; the Protein Data Bank was announced in October 1971 in Nature New Biology as a joint venture between Cambridge Crystallographic Data Centre, UK and Brookhaven National Laboratory, USA. Upon Hamilton's death in 1973, Tom Koeztle took over direction of the PDB for the subsequent 20 years. In January 1994, Joel Sussman of Israel's Weizmann Institute of Science was appointed head of the PDB. In October 1998, the PDB was transferred to the Research Collaboratory for Structural Bioinformatics; the new director was Helen M. Berman of Rutgers University.
In 2003, with the formation of the wwPDB, the PDB became an international organization. The founding members are PDBe, RCSB, PDBj; the BMRB joined in 2006. Each of the four members of wwPDB can act as deposition, data processing and distribution centers for PDB data; the data processing refers to the fact that annotate each submitted entry. The data are automatically checked for plausibility; the PDB database is updated weekly. The PDB holdings list is updated weekly; as of 17 October 2018, the breakdown of current holdings is as follows: 120,052 structures in the PDB have a structure factor file. 9,734 structures have an NMR restraint file. 3,486 structures in the PDB have a chemical shifts file. 2,531 structures in the PDB have a 3DEM map file deposited in EM Data BankThese data show that most structures are determined by X-ray diffraction, but about 10% of structures are now determined by protein NMR. When using X-ray diffraction, approximations of the coordinates of the atoms of the protein are obtained, whereas estimations of the distances between pairs of atoms of the protein are found through NMR experiments.
Therefore, the final conformation of the protein is obtained, in the latter case, by solving a distance geometry problem. A few proteins are determined by cryo-electron microscopy; the significance of the structure factor files, mentioned above, is that, for PDB structures determined by X-ray diffraction that have a structure file, the electron density map may be viewed. The data of such structures is stored on the "electron density server". In the past, the number of structures in the PDB has grown at an exponential rate, passing the 100 registered structures milestone in 1982, the 1,000 in 1993, the 10,000 in 1999, the 100,000 in 2014. However, since 2007, the rate of accumulation of new protein structures appears to have plateaued; the file format used by the PDB was called the PDB file format. This original format was restricted by the width of computer punch cards to 80 characters per line. Around 1996, the "macromolecular Crystallographic Information file" format, mmCIF, an extension of the CIF format started to be phased in.
MmCIF is now the master format for the PDB archive. An XML version of this format, called PDBML, was described in 2005; the structure files can be downloaded in any of these three formats. In fact, individual files are downloaded into graphics packages using web addresses: For PDB format files, use, e.g. http://www.pdb.org/pdb/files/4hhb.pdb.gz or http://pdbe.org/download/4hhb For PDBML files, use, e.g. http://www.pdb.org/pdb/files/4hhb.xml.gz or http://pdbe.org/pdbml/4hhbThe "4hhb" is the PDB identifier. Each structure published in PDB receives a four-character alphanumeric identifier, its PDB ID; the structure files may be viewed using one of several free and open source computer programs, including Jmol, Pymol, VMD, Rasmol. Other non-free, shareware programs
RNA polymerase II
RNA polymerase II is a multiprotein complex. It is one of the three RNAP enzymes found in the nucleus of eukaryotic cells, it catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA. A 550 kDa complex of 12 subunits, RNAP II is the most studied type of RNA polymerase. A wide range of transcription factors are required for it to bind to upstream gene promoters and begin transcription. Early studies suggested a minimum of two RNAPs: one which synthesized rRNA in the nucleolus, one which synthesized other RNA in the nucleoplasm, part of the nucleus but outside the nucleolus. In 1969, science experimentalists Robert Roeder and William Rutter definitively discovered an additional RNAP, responsible for transcription of some kind of RNA in the nucleoplasm; the finding was obtained by the use of DEAE-Sephadex ion-exchange chromatography. The technique separated the enzymes by the order of the corresponding elutions, Ι,ΙΙ,ΙΙΙ, by increasing the concentration of ammonium sulfate.
The enzymes were named according to the order of the elutions, RNAP I, RNAP II, RNAP IΙI. This discovery demonstrated that there was an additional enzyme present in the nucleoplasm, which allowed for the differentiation between RNAP II and RNAP III; the eukaryotic core RNA polymerase II was first purified using transcription assays. The purified enzyme has 10-12 subunits and is incapable of specific promoter recognition. Many subunit-subunit interactions are known. DNA-directed RNA polymerase II subunit RPB1 – an enzyme that in humans is encoded by the POLR2A gene and in yeast is encoded by RPO21. RPB1 is the largest subunit of RNA polymerase II, it contains a carboxy terminal domain composed of up to 52 heptapeptide repeats that are essential for polymerase activity. The CTD was first discovered in the laboratory of C. J. Ingles by JL Corden at Johns Hopkins University. In combination with several other polymerase subunits, the RPB1 subunit forms the DNA binding domain of the polymerase, a groove in which the DNA template is transcribed into RNA.
It interacts with RPB8. RPB2 – the second-largest subunit that in combination with at least two other polymerase subunits forms a structure within the polymerase that maintains contact in the active site of the enzyme between the DNA template and the newly synthesized RNA. RPB3 – the third-largest subunit. Exists as a heterodimer with another polymerase subunit, POLR2J forming a core subassembly. RPB3 interacts with RPB1-5, 7, 10-12. RNA polymerase II subunit B4 – encoded by the POLR2D gene is the fourth-largest subunit and may have a stress protective role. RPB5 – In humans is encoded by the POLR2E gene. Two molecules of this subunit are present in each RNA polymerase II. RPB5 interacts with RPB1, RPB3, RPB6. RPB6 – forms a structure with at least two other subunits that stabilizes the transcribing polymerase on the DNA template. RPB7 -- may play a role in regulating polymerase function. RPB7 interacts with RPB1 and RPB5. RPB8 – interacts with subunits RPB1-3, 5, 7. RPB9 – The groove in which the DNA template is transcribed into RNA is composed of RPB9 and RPB1.
RPB10 – the product of gene POLR2L. It interacts with RPB1-3 and 5, with RPB3. RPB11 – the RPB11 subunit is itself composed of three subunits in humans: POLR2J, POLR2J2, POLR2J3. RPB12 – Also interacts with RPB3 is RPB12. RPB3 is involved in RNA polymerase II assembly. A subcomplex of RPB2 and RPB3 appears soon after subunit synthesis; this complex subsequently interacts with RPB1. RPB3, RPB5, RPB7 interact with themselves to form homodimers, RPB3 and RPB5 together are able to contact all of the other RPB subunits, except RPB9. Only RPB1 binds to RPB5; the RPB1 subunit contacts RPB7, RPB10, more weakly but most efficiently with RPB8. Once RPB1 enters the complex, other subunits such as RPB5 and RPB7 can enter, where RPB5 binds to RPB6 and RPB8 and RPB3 brings in RPB10, RPB 11, RPB12. RPB4 and RPB9 may enter. RPB4 forms a complex with RPB7. Enzymes can catalyze up to several million reactions per second. Enzyme rates depend on substrate concentration. Like other enzymes POLR2 has a maximum velocity, it has a kcat.
The specificity constant is given by kcat/Km. The theoretical maximum for the specificity constant is the diffusion limit of about 108 to 109, where every collision of the enzyme with its substrate results in catalysis. In yeast, mutation in the Trigger-Loop domain of the largest subunit can change the kinetics of the enzyme. Bacterial RNA polymerase, a relative of RNA Polymerase II, switches between inactivated and activated states by translocating back and forth along the DNA. Concentrations of eq = 10 μM GTP, 10 μM UTP, 5 μM ATP and 2.5 μM CTP, produce a mean elongation rate, turnover number, of ~1 bp −1 for bacterial RNAP, a relative of RNA polymerase II. RNA polymerase II is inhibited by other amatoxins. Α-Amanitin is a poisonous substance found in many mushrooms. The mushroom poison has different effects on the each of the RNA Polyermases: I, II, III. RNAP I is unresponsive to the substance and will function while RNAP III has a moderate sensitivity. RNAP II, however, is inhibited by the toxin.
Alpha-Amanitin inhibits RNAP II by strong interactions in the enzyme's "funnel", "cleft", the key "bridge α-helix" regions of the RPB-1 subunit. RNA polymerase II
Galerina marginata is a species of poisonous fungus in the family Hymenogastraceae of the order Agaricales. Prior to 2001, the species G. autumnalis, G. oregonensis, G. unicolor, G. venenata were thought to be separate due to differences in habitat and the viscidity of their caps, but phylogenetic analysis showed that they are all the same species. The fruit bodies of this fungus have brown to yellow-brown caps; the gills give a rusty spore print. A well-defined membranous ring is seen on the stems of young specimens but disappears with age. In older fruit bodies, the caps stems browner; the species is a classic "little brown mushroom"—a catchall category that includes all small to medium-sized, hard-to-identify brownish mushrooms, may be confused with several edible species. Galerina marginata is widespread in the Northern Hemisphere, including Europe, North America, Asia, has been found in Australia, it is a wood-rotting fungus. An poisonous species, it contains the same deadly amatoxins found in the death cap.
Ingestion in toxic amounts causes severe liver damage with vomiting, diarrhea and eventual death if not treated rapidly. About ten poisonings have been attributed to the species now grouped as G. marginata over the last century. What is now recognized as a single morphologically variable taxon named Galerina marginata was once split into five distinct species. Norwegian mycologist Gro Gulden and colleagues concluded that all five represented the same species after comparing the DNA sequences of the internal transcribed spacer region of ribosomal DNA for various North American and European specimens in Galerina section Naucoriopsis; the results showed no genetic differences between G. marginata and G. autumnalis, G. oregonensis, G. unicolor, G. venenata, thus reducing all these names to synonymy. The oldest of these names are Agaricus marginatus, described by August Batsch in 1789, Agaricus unicolor, described by Martin Vahl in 1792. Agaricus autumnalis was described by Charles Horton Peck in 1873, moved to Galerina by A. H. Smith and Rolf Singer in their 1962 worldwide monograph on that genus.
In the same publication they introduced the G. autumnalis varieties robusta and angusticystis. Another of the synonymous species, G. oregonensis, was first described in that monograph. Galerina venenata was first identified as a species by Smith in 1953. Since Agaricus marginatus is the oldest validly published name, it has priority according to the rules of botanical nomenclature. Another species analysed in Gulden's 2001 study, Galerina pseudomycenopsis could not be distinguished from G. marginata based on ribosomal DNA sequences and restriction fragment length polymorphism analyses. Because of differences in ecology, fruit body color and spore size combined with inadequate sampling, the authors preferred to maintain G. pseudomycenopsis as a distinct species. A 2005 study again failed to separate the two species using molecular methods, but reported that the incompatibility demonstrated in mating experiments suggests that the species are distinct. In the fourth edition of Singer's comprehensive classification of the Agaricales, G. marginata is the type species of Galerina section Naucoriopsis, a subdivision first defined by French mycologist Robert Kühner in 1935.
It includes small brown-spored mushrooms characterized by cap edges curved inwards, fruit bodies resembling Pholiota or Naucoria and thin-walled, obtuse or acute-ended pleurocystidia that are not rounded at the top. Within this section, G. autumnalis and G. oregonensis are in stirps Autumnalis, while G. unicolor, G. marginata, G. venenata are in stirps Marginata. Autumnalis species are characterized by having a viscid to lubricous cap surface while Marginata species lack a gelatinous cap—the surface is moist, "fatty-shining", or matte when wet. However, as Gulden explains, this characteristic is variable: "Viscidity is a notoriously difficult character to assess because it varies with the age of the fruitbody and the weather conditions during its development. Varying degrees of viscidity tend to be described differently and applied inconsistently by different persons applying terms such as lubricous, fatty-shiny, viscid, glutinous, or slimy."The specific epithet marginata is derived from the Latin word for "margin" or "edge", while autumnalis means "of the autumn".
Common names of the species include the "marginate Pholiota", "funeral bell", "deadly skullcap", "deadly Galerina". G. autumnalis was known as the "fall Galerina" or the "autumnal Galerina", while G. venenata was the "deadly lawn Galerina". The cap reaches 1.7 to 4 cm in diameter. It starts convex, sometimes broadly conical, has edges that are curved in against the gills; as the cap grows and expands, it becomes broadly convex and flattened, sometimes developing a central elevation, or umbo, which may project prominently from the cap surface. Based on the collective descriptions of the five taxa now considered to be G. marginata, the texture of the surface shows significant variation. Smith and Singer give the following descriptions of surface texture: from "viscid", to "shining and viscid to lubricous when moist", to "shining, lubricous to subviscid or moist, with a fatty appearance although not distinctly viscid", to "moist but not viscid"; the cap surface remains smooth and changes colors with humidity, pale to dark ochraceous tawny over the disc and yellow-ochraceous on t
Amanita bisporigera is a deadly poisonous species of fungus in the family Amanitaceae. It is known as the eastern North American destroying angel or just as the destroying angel, although the fungus shares this latter name with three other lethal white Amanita species, A. ocreata, A. verna and A. virosa. The fruit bodies are found on the ground in mixed coniferous and deciduous forests of eastern North America south to Mexico, but are rare in western North America; the mushroom has a smooth white cap that can reach up to 10 cm across, a stipe, up to 14 cm long by 1.8 cm thick, that has a delicate white skirt-like ring near the top. The bulbous stipe base is covered with a membranous sac-like volva; the white gills are free from attachment to the stalk and crowded together. As the species name suggests, A. bisporigera bears two spores on the basidia, although this characteristic is not as immutable as was once thought. Amanita bisporigera was described as a new species in 1906, it is classified in the section Phalloideae of the genus Amanita together with other amatoxin-containing species.
Amatoxins are cyclic peptides which inhibit the enzyme RNA polymerase II and interfere with various cellular functions. The first symptoms of poisoning appear 6 to 24 hours after consumption, followed by a period of apparent improvement by symptoms of liver and kidney failure, death after four days or more. Amanita bisporigera resembles a few other white amanitas, including the deadly A. virosa and A. verna. These species, difficult to distinguish from A. bisporigera based on visible field characteristics, do not have two-spored basidia, do not stain yellow when a dilute solution of potassium hydroxide is applied. The DNA of A. bisporigera has been sequenced, the genes responsible for the production of amatoxins have been determined. Amanita bisporigera was first described scientifically in 1906 by American botanist George Francis Atkinson in a publication by Cornell University colleague Charles E. Lewis; the type locality was New York, where several collections were made. In his 1941 monograph of world Amanita species, Édouard-Jean Gilbert transferred the species to his new genus Amanitina, but this genus is now considered synonymous with Amanita.
In 1944, William Murrill described the species Amanita vernella, collected from Gainesville, Florida. Amanita phalloides var. striatula, a poorly known taxon described from the United States in 1902 by Charles Horton Peck, is considered by Amanita authority Rodham Tulloss to be synonymous with A. bisporigera. Vernacular names for the mushroom include "destroying angel", "deadly amanita", "white death cap", "angel of death" and "eastern North American destroying angel". Amanita bisporigera belongs to section Phalloideae of the genus Amanita, which contains some of the deadliest Amanita species, including A. phalloides and A. virosa. This classification has been upheld with phylogenetic analyses, which demonstrate that the toxin-producing members of section Phalloideae form a clade—that is, they derive from a common ancestor. In 2005, Zhang and colleagues performed a phylogenetic analysis based on the internal transcribed spacer sequences of several white-bodied toxic Amanita species, most of which are found in Asia.
Their results support a clade containing A. bisporigera, A. subjunquillea var. alba, A. exitialis, A. virosa. The Guangzhou destroying angel has two-spored basidia, like A. bisporigera. The cap is 3–10 cm in diameter and, depending on its age, ranges in shape from egg-shaped to convex to somewhat flattened; the cap surface is white, sometimes with a pale tan - or cream-colored tint in the center. The surface is either dry or, when the environment is moist sticky; the flesh is thin and white, does not change color when bruised. The margin of the cap, rolled inwards in young specimens, does not have striations, lacks volval remnants; the gills white, are crowded together. They are either free from attachment to the stipe or just reach it; the lamellulae are numerous, narrow. The white stipe is 6–14 cm by 0.7–1.8 cm thick and tapers upward. The surface, in young specimens is floccose, fibrillose, or squamulose; the bulb at the base of the stipe is nearly so. The delicate ring on the upper part of the stipe is a remnant of the partial veil that extends from the cap margin to the stalk and covers the gills during development.
It is white, thin and hangs like a skirt. When young, the mushrooms are enveloped in a membrane called the universal veil, which stretches from the top of the cap to the bottom of the stipe, imparting an oval, egg-like appearance. In mature fruit bodies, the veil's remnants form a membrane around the base, the volva, like an eggshell-shaped cup. On occasion, the volva remains underground or gets torn up during development, it is white, sometimes lobed, may become pressed to the stipe. The volva is up to 3.8 cm in height, is about 2 mm thick midway between the top and the base attachment. The mushroom's odor has been described as "pleasant to somewhat nauseous", becoming more cloying as the fruit body age
Lepiota clypeolaria known as the shield dapperling or the shaggy-stalked Lepiota, is a common, toxic mushroom in the genus Lepiota. It is distributed in northern temperate zones, where it grows in deciduous and coniferous forest. Fruit bodies have a brownish cap, a shaggy stipe with a collapsed, sheathing ring or ring zone, spindle-shaped spores; the species was first described in 1789 as Agaricus clypeolarius by French mycologist Jean Baptiste Francois Bulliard. Paul Kummer transferred it to Lepiota in 1871, it is known as the "shaggy-stalked Lepiota". The cap is egg-shaped when young, soon broadly bell-shaped and has pale straw- or orange-brown scales on a pale background; the central umbo is covered with a well-delimited uniform disk of the same colour as the scales. It grows to a diameter of 4–7 cm; the gills are white, free from attachment to the stipe. The white stem has an indistinct ring, below which it is coarsely woolly, giving an appearance, sometimes described as "booted"; the stipe, which measures 5–12 cm long by 0.3–1 cm thick, is hollow and slender, expanding at the base into a club shape.
The flesh has an unpleasant smell. The spore print is white. Spores are fuse-shaped, they have dimensions of 12–16 by 5–6 µm. Cystidia on the gill edge are club-shaped to cylindrical, measure 20–40 by 5–15 µm; the species Lepiota ochraceosulfurescens may be distinguished as having a less defined dark area in the cap centre, a smell of rubber or melted butter, yellow flesh in the stipe base, but in Species Fungorum and Funga Nordica this name is regarded as a synonym. Lepiota magnispora is similar in appearance and confused with L. clypeolaria. The former species has brighter colours with a more intensely coloured cap center, longer spores. L. Clypeolaria is the best known of the section Fusisporae within genus Lepiota, whose members are characterized by long spindle-shaped spores and a fluffy stem beneath the ring; the fruit bodies of Lepiota clypeolaria grow singly or in small groups on the ground in deciduous and coniferous forests. A common species, it is widespread in temperate regions of the Northern Hemisphere, has been reported from Asia, North America, South America.
Fruiting occurs in autumn. In China, it is known from the provinces of Heilongjiang, Liaoning, Jiangsu and Yunnan. List of Lepiota species E. Garnweidner. Mushrooms and Toadstools of Britain and Europe. Collins. 1994. H. Knudsen & J. Vesterholt. Funga Nordica. Agaricoid and cyphelloid genera. Nordsvamp, Copenhagen 2008. Lepiota clypeolaria in Index Fungorum Lepiota clypeolaria in MycoBank