Cortinarius delibutus

Description

Cortinarius delibutus is a basidiomycete fungus of the genus Cortinarius. The fruit bodies are medium-sized, with shiny yellow caps on a sticky, yellow-banded club-shaped stem. The mushroom is found in Europe and North America, usually near birch or beech trees.

Common names: Bluegill Webcap, The Yellow Webcap.

Mushroom Identification

1. Cap

   The greasy (slimy when wet) hemispherical to convex yellow caps of Cortinarius delibutus are 3-6cm in diameter and eventually become flattened or even slightly depressed in the center, but the margin remains inrolled or at least downturned. Flesh yellowish, with a faint bluish tinge in young specimens.

   A short-lived yellowish cortina joins stem to the cap rim of young fruitbodies, concealing the immature gills.

2. Gills

   Adnate, moderately spaced to distant; at first violet or bluish, becoming buff tinged with violet as the spores mature.

3. Stem

   Finely fibrillose, 5-9cm long and 3-6mm in diameter, clavate or sometimes slightly bulbous at base; surface sticky (slimy in wet weather), covered with yellowish veil remnants that stain rust-brown once spores begin to fall.

4. Basidia

   Four-spored.

5. Spores

   Ellipsoidal to subspherical; coarsely verrucose (with a roughened surface), 7-9.5 x 6-7µm.

6. Spore Print

   Rusty-brown.

7. Odor and Taste

   Odor not distinctive. Taste is reported to be mild, but it is generally considered unwise to taste any Cortinarius species because several of them are deadly poisonous.

8. Habitat & Ecological Role

   Mycorrhizal, particularly with Beech and Birch but also occasionally in mixed woodland with Spruce.

Look-Alikes

1. Cortinarius triumphans

   Is a larger yellow webcap with much longer spores.

2. Cortinarius lewisii

   Has a dry yellow cap, a dry cream-colored stem with a white basal mycelium, and a dense white yellow partial veil, and flesh that has a musky to radish musky odor.

History

In 1838 the famous Swedish mycologist Elias Magnus Fries described the Yellow Webcap and gave it the scientific name Cortinarius delibutus. This remains its generally accepted scientific name.

Synonyms of Cortinarius delibutus include Cortinarius fulvoluteus Britzelm., Cortinarius naevosus Fr., Cortinarius suratus Fr., Gomphos delibutus (Fr.) Kuntze, Gomphos naevosus (Fr.) Kuntze, and Gomphos suratus (Fr.) Kuntze.

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

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 fibers connecting the stem to the rim of the cap.

The specific epithet delibutus means greasy.

Photo sources:

Photo 1 - Author: James Lindsey (CC BY-SA 2.5)

Photo 2 - Author: Holger Krisp (CC BY 3.0)

Photo 3 - Author: Dimitar Bojantchev (dimitar) (CC BY-SA 3.0)