Cortinarius praestans
Description
Cortinarius praestans is a basidiomycete mushroom of the genus Cortinarius. The mushroom has orangish-yellow caps that reach up to 20 cm (7.9 in) in diameter, and thick club-shaped stipes up to 15 cm (5.9 in) long.
This edible mushroom is found in Europe and it usually appears in small groups or singly, in broadleaf and conifer woodland on alkaline soil.
The difficulty of identifying Cortinarius fungi with complete certainty makes this a very risky menu item, and its rarity in most countries is further justification for leaving fruitbodies to drop spores rather than gathering them to eat.
Cortinarius praestans extract has demonstrated antibacterial efficacy against Pseudomonas aeruginosa and Staphylococcus aureus
Common names: Goliath Webcap.
Mushroom Identification
Cap
With a sticky or slimy surface, caps of the Goliath Webcap are violet color sometimes with whitish patches and violaceous tints. The hemispherical or convex cap has a narrowly inrolled margin even when fully mature, and the cap surface is often radially wrinkled and the rim slightly or sometimes markedly wavy. Cap diameter ranges from 8 to 20 cm when fully expanded.
Gills
The adnate gills, which are covered by a cortina in young specimens, are white or pale grey at first, becoming clay brown as the spores mature.
Stem
The fibrillose stem, which is white with violaceous tints, is typically 2 to 5cm in diameter and 8 to 18 cm tall; the base is swollen and may be either clavate or bulbous.
Spores
Ellipsoidal to lemon-shaped, 13-17 x 8-10μm; covered densely with tiny warts.
Spore Print
Rusty reddish-brown.
Habitat & Ecological Role
Ectomycorrhizal, found under deciduous broadleaf trees and, less frequently, coniferous trees in chalk or limestone areas.
Look-Alikes
This mushroom is mainly confused with other often very poisonous webcaps (Cortinarius spp.) e.g. as the gassy webcap (Cortinarius violaceus). Since there are many poisonous species in the genus Cortinarius this mushroom should only be collected by experienced foragers.
History
The Goliath Webcap was first described scientifically in 1870 by the French botanist/mycologist François Simon Cordier (1797 -1874), who named it Agaricus praestans. Another French mycologist, Claude-Casimir Gillet (1806 - 1896), transferred it to the genus Cortinarius in 1876.
Synonyms of Cortinarius praestans include Agaricus praestans Cordier, Cortinarius torvus var. berkelyi (Cooke) Boud., and Cortinarius berkeleyi Cooke.
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 praestans comes from Latin and means excellent, outstanding, or superior - accolades that are certainly fully justified in this instance!
Photo sources:
Photo 1 - Author: Marko Vainu (CC BY-SA 3.0)
Photo 2 - Author: Balint Dima/Norsk institutt for naturforskning (CC BY-SA 4.0)
Photo 3 - Author: Traumrune (CC BY-SA 2.5)
