Cortinarius torvus Fr. - Stocking Webcap

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Cortinariaceae

Cortinarius torvus, Somerset UK

In the difficult Cortinarius group of fungi Cortinarius torvus is one of the easier species to identify with reasonable confidence from its macroscopic characters - in particular the whitish stocking-like structure left by the universal veil clinging to the lower part of the swollen stem; however, to be quite certain you need to see young and mature specimens and to assess spore size, ornamentation and other microscopic characters.

 

Distribution

Cortinarius torvus is fairly common in Britain and Ireland and is recorded also from many parts of mainland Europe.

Taxonomic history

Cortinarius torvus - cross-section view

Swedish mycologist Elias Magnus Fries described this webcap mushroom in Systema Mycologicum in 1921, giving it the scientific name Agaricus torvus. Later, in his Epicrisis Systematis Mycologici of 1838, Fries transferred the Stocking Webcap to the genus Cortinarius, establishing its currently-accepted scientific name gave it the scientific binomial name Cortinarius torvus.

Synonyms of Cortinarius torvus include Agaricus torvus Fr.

The vast genus Cortinarius is subdivided by many authorities into subgenera, and Cortinarius torvus belongs to the subgenus Telemonia.

Cortinarius torvus

Etymology

The generic name Cortinarius is a reference to the partial veil or cortina (meaning a curtain) that covers the gills when caps are immature. In the genus Cortinarius most species produce partial veils in the form of a fine web of radial fibres connecting the stem to the rim of the cap.

The specific epithet torvus is aLatin word meaning 'staring, keen, piercing, wild, stern, fierce, grim orsavage (esp. in look or expression)', which may not be too far from this webcap's grim colours or its stern look.

Toxicity

This mushroom is recorded by some authorities as 'poisonous'. Because several of the webcaps are known to be deadly poisonous (and some research even suggests that all Cortinarius species may contain at least small amounts of the toxins concerned), in our opinion webcaps should never be gathered for eating.

Identification guide

Mature cap of Cortinarius torvus

Cap

The convex, slightly hygrophanous (paler when dry) caps of Cortinarius torvus are pinkish clay brown, covered with pallid radial fibrils, and expanding to between 4 and 10cm in diameter; not generally umbonate. Cap surface is fairly smooth when young, sometimes breaking up into very fine scales or developing a marbled pattern when mature.

A short-lived whitish cortina joins the stem to the cap rim and conceals the gills of very young specimens.

Gills of Cortinarius torvus

Gills

Adnate or emarginate with a decurrent tooth, moderately spaced to distant; at first violet eventually maturing reddish brown.

Stem

The longitudinally fibrillose stem is 4-9cm long and 1-1.5cm in diameter, clavate or somewhat bulbous (swollen in the lower part) above a tapering base; covered below the ring zone in a stocking-like sheath (the remains of the universal veil); stem flesh is greyish-white with a violaceous tinge above the ring zone.

Spore of Cortinarius torvus

Spores

Broadly ellipsoidal or ovoid; moderately to strongly verrucose (with a roughened surface), 8-11 x 5-7µm; dextrinoid.

Show larger image

Spore print

Dark rusty-brown.

Odour/taste

Odour strongly sweet and unpleasant; some say like camphor. Taste reported to be bitter or acidic and unpleasant, but it is generally considered unwise to taste any Cortinarius species because several of them are deadly poisonous.

Habitat & Ecological role

Mycorrhizal, in broadleaf and mixed woodland, most often with Beeches but also found occasionally under Hazel, oaks, limes and other broadleaf trees.

Season

August to November in Britain and Ireland.

Similar Species

Cortinarius anomalus is similar and occurs in the same kinds of habitats, but it does not have a stocking-like structure on its stem.

Cortinarius mucifluoides, the Purple Stocking Webcap, has a less clavate stem and a purple stocking-like sheath on its lower stem; it is a much more glutinous mushroom.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

British Mycological Society, English Names for Fungi

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

Cortinarius torvus, young fruitbodies

Acknowledgements

This page includespictures kindly contributed by David Kelly.

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