Cortinarius rubellus

Cortinarius rubellus, the Deadly Webcap, is a rusty orange to reddish-brown mushroom of coniferous and mixed forests, recognized by its cobweb-like partial veil and rusty-brown spore print. It typically fruits in late summer and autumn as a mycorrhizal partner of conifers and, sometimes, deciduous trees. Despite its unremarkable appearance, it is one of the most dangerous mushrooms in the world: it contains orellanine, a potent nephrotoxin that causes severe, often irreversible kidney failure. There is no specific antidote.

History

The deadly potential of webcaps went unrecognized for centuries because Cortinarius was long believed to be a harmless genus. The nephrotoxicity of orellanine was first identified in the 1950s after a mass poisoning in Poland, where dozens of people developed kidney failure traced to webcaps gathered from a single location. C. rubellus (formerly known as C. speciosissimus, and also reported as C. ranierensis or C. orellanoides) was later confirmed to belong to the lethal Cortinarius orellanus complex. A high-profile case involving the family of author Nicholas Evans renewed public awareness of these mushrooms in the modern era.

Overview

Ecologically, Cortinarius rubellus forms mycorrhizal relationships with forest trees and plays a role in nutrient cycling. It has no culinary or medicinal value and is never cultivated. Its danger lies in delayed toxicity: after ingestion, symptoms such as flu-like illness, headache, and vomiting are typically delayed by 3 to 20 days, by which point severe interstitial nephritis and irreversible renal damage may already be advanced. Many victims require long-term dialysis or a kidney transplant, and deaths have occurred. Foragers risk confusing it with chanterelles and with other webcaps in the same toxic complex, so any rusty-brown, cobweb-veiled mushroom should be left alone.