Volvopluteus gloiocephalus

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***Volvopluteus gloiocephalus,*** commonly known as the **big sheath mushroom**, **rose-gilled grisette**, or **stubble rosegill**, is a species of mushroom in the family Pluteaceae. For most of the 20th century it has been known under the names *Volvariella gloiocephala* or *Volvariella speciosa*, but recent molecular studies have placed it as the type species of the genus *Volvopluteus*, newly created in 2011. The cap of this mushroom is about Template:Convert in diameter, varies from white to grey or grey-brown, and is markedly sticky when fresh. The gills start out as white but they soon turn pink. The stipe is white and has a sack-like volva at the base. Microscopical features and DNA sequence data are of great importance for separating *V. gloiocephalus* from related species. *V. gloiocephalus* is a saprotrophic fungus that grows on grassy fields and accumulations of organic matter like compost or woodchips piles. It has been reported from all continents except Antarctica.

## Taxonomy

This taxon has a long and convoluted nomenclatural history. It was originally described as *Agaricus gloiocephalus* by Swiss botanist Augustin Pyramus de Candolle in 1815 and later sanctioned under this name by Elias Magnus Fries in 1821. The French mycologist Claude Gillet transferred it in 1878 to the genus *Volvaria* erected by Paul Kummer just a few years earlier in 1871. The name *Volvaria* was already taken, as it had been coined by De Candolle for a genus of lichens in 1805. The generic name *Volvariella*, proposed by the Argentinean mycologist Carlos Luis Spegazzini in 1899, would eventually be adopted for this group in 1953 after a proposal to conserve Kummer’s *Volvaria* against De Candolle’s *Volvaria* was rejected by the Nomenclature Committee for Fungi established under the principles of the International Code of Botanical Nomenclature.
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Despite the generic name *Volvariella* being adopted in 1953 the name *Volvariella gloiocephala* did not exist until 1986, when the placement of the species in that genus was formally proposed by mycologists Teun Boekhout and Manfred Enderle. The reason for this long interval is that most 20th-century mycologists working on *Volvariella* (e.g. Rolf Singer, Robert L. Shaffer, Robert Kühner, Henri Romagnesi) considered the epithet "*gloiocephalus*" to represent a variety with dark basidiocarps of another species of *Volvariella*, viz. *Volvariella speciosa,* that has white basidiocarps, and therefore would use the name *Volvariella speciosa* var. *gloiocephala* to refer to this taxon. Boekhout & Enderle showed that white and dark basidiocarps can arise from the same mycelium, and that the epithets "*gloiocephalus*" proposed by De Candolle in 1815 and "*speciosa*" proposed by Fries in 1818 should be considered to represent the same species with the former having nomenclatural priority. In 1996 Boekhout and Enderle designated a neotype to serve as a representative example of the species.

The phylogenetic study of Justo and colleagues showed that *Volvariella gloiocephala* and related taxa are a separate clade from the majority of the species traditionally classified in *Volvariella* and therefore another name change was necessary, now as the type species of the newly proposed genus *Volvopluteus*.

The epithet *gloiocephalus* comes from the Greek terms *gloia* (γλοία = glue or glutinous substance) and *kephalē* (κεφαλή = head) meaning "with a sticky head" making reference to the viscid cap surface. It is commonly known as the "big sheath mushroom", "rose-gilled grisette" or the "stubble rosegill".

## Description

 File:Volvaria gloiocephala JPG4.jpg
 File:Volvopluteus gloiocephalus (DC.) Vizzini, Contu & Justo 138276.jpg
The cap of *Volvopluteus gloiocephalus* is between Template:Convert in diameter, more or less ovate or conical when young, then expands to convex or flat, sometimes with a slight central depression in old specimens. The surface is markedly viscid in fresh basidiocarps; the color ranges from pure white to grey or greyish brown. The gills are crowded, free from the stipe, ventricose (swollen in the middle), and up to Template:Convert broad; they are white when young but turn pink with age. The stipe is Template:Convert long and Template:Convert wide, cylindrical, broadening towards the base; the surface is white, smooth or slightly pruinose (covered with fine white powdery granules). The volva is Template:Convert high, sacciform (pouch-like), white and has a smooth surface. The flesh is white on stipe and cap and it does not change when bruised or exposed to air. Smell and taste vary from indistinct to raphanoid (radish-like) or similar to raw peeled potatoes. The spore print is pinkish brown.

The basidiospores are ellipsoid and measure 12–16 by 8–9.5 µm. Basidia are 20–35 by 7–15 µm and usually four-spored, but sometimes two-spored basidia can occur. Pleurocystidia are 60–90 by 20–50 µm with variable morphology: club-shaped, fusiform, ovoid, and sometimes with a small apical papilla. Cheilocystidia are 55–100 by 15–40 µm with similar morphology to the pleurocystidia; they completely cover the gill edge. The cap cuticle (pileipellis) is an ixocutis (parallel hyphae wide embedded in a gelatinous matrix). Stipitipellis is a cutis (parallel hyphae not embedded in a gelatinous matrix). Caulocystidia are sometimes present, measuring 70–180 by 10–25 µm; they are mostly cylindrical. Clamp connections are absent from the hyphae.

Microscopy

### Edibility

*Volvopluteus gloiocephalus* is edible, although it is cited as being mediocre or of poor quality. It was once sold in markets in Perth, Australia. Mature fruit bodies, collected in sufficient quantity, can be used to prepare soup, or added to dishes where wild mushrooms are used, such as stews and casseroles. The mushrooms are best used fresh as they do not preserve well. Young specimens of *Volvopluteus gloiocephalus* have white gills so it is possible to mistake them for an *Amanita* and vice versa. In the United States, there have been several cases of Asian immigrants collecting and eating death caps (*Amanita phalloides*), under the mistaken assumption that they were *Volvariella*. A Greek study determined the nutritional composition of fruit bodies: protein 1.49 g/100 g fresh weight (fw), 18.36 g/100 g dry weight (dw); fat 0.54 g/100 g fw, 6.65 g/100g dw; carbohydrates 5.33 g/100g fw, 65.64 g/100 g dw.

### Similar species

Molecular analyses of the internal transcribed spacer region clearly separate the four species currently recognized in *Volvopluteus*, but morphological identification can be more difficult due to the sometimes overlapping morphological variation among the species. Size of the fruit bodies, color of the cap, spore size, presence or absence of cystidia and morphology of the cystidia are the most important characters for morphological species delimitation in the genus. *V. earlei* has smaller fruit bodies (cap less than Template:Convert in diameter), has no pleurocystidia (usually), and the cheilocystidia usually have a very long apical excrescence (outgrowth). In *V. asiaticus* the majority of the pleurocystidia have an apical excrescence up to 10–15 µm long and the cheilocystidia are predominantly lageniform (flask-shaped). *V. michiganensis* has smaller basidiospores, on average less than 12.5 µm long. *Volvariella acystidiata*, known from central Africa (Zaire) and Italy, somewhat resembles *Volvopluteus gloiocephalus*. It can be distinguished from the latter by its smaller fruit bodies, with caps up to Template:Convert in diameter, and, microscopically, by the complete absence of cheilo- and pleurocystidia.

## Ecology, habitat, and distribution

*Volvopluteus gloicephalus* is a saprotrophic mushroom that grows on the ground in gardens, grassy fields, both in and outside forest areas, and on accumulations of vegetable matter like compost or woodchips piles. It has also been reported fruiting in greenhouses. In China, it grows in bamboo thickets. It usually fruits in groups of several basidiocarps but it can also be found growing solitary. It is not unusual for a season of "spectacular" fruiting to be followed by several years with no appearance of the mushroom.

This species has been reported from all continents except Antarctica, usually under names such as *Volvariella gloiocephala* or *Volvariella speciosa*. Molecular data have so far corroborated its occurrence in Europe and North America but records from other continents remain unconfirmed.

## References

1. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `DeCandolle 1815`
2. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Fries 1821`
3. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Gillet 1878`
4. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Kummer 1871`
5. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `DeCandolle 1805`
6. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Spegazzini`
7. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Fungi 1953`
8. ↑ 8.0 8.1 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Boekhout 1986`
9. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Fries 1818`
10. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Boekhout 1996`
11. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Justo 2011`
12. ↑ 12.0 12.1 12.2 Cite error: Invalid `<ref>` tag; no text was provided for refs named `McKnight 1987`
13. ↑ 13.0 13.1 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Burrows 2005`
14. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `urlRecommended English Names for Fungi`
15. ↑ 15.0 15.1 15.2 15.3 15.4 15.5 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Justo 2011b`
16. ↑ 16.0 16.1 16.2 16.3 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Boekhout 1990`
17. ↑ 17.0 17.1 Cite error: Invalid `<ref>` tag; no text was provided for refs named `Vellinga 1988`
18. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Zhishu 1993`
19. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Davis 2012`
20. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Bougher 1998`
21. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Marley 2010`
22. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Ouzini 2007`
23. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Vizzini 2010`
24. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Healy 2008`

## External links

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* Template:IndexFungorum
* *Volvopluteus gloiocephalus* Mushroomobserver.org name
* Online Atlas of Fungi in Northern Ireland

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