The mushroom Cortinarius speciosissimus, known as the Deadly Webcap or Spotted Cort, contains a lethal kidney-damaging toxin. This species, along with Cortinarius rubellus, requires accurate identification to prevent tragic outcomes.
Identifying the Spotted Cort
Its cap typically measures between 2 and 8 centimeters in diameter, displaying a conical shape that expands to broadly bell-shaped with a pointed central bump. The cap color ranges from reddish-brown to rusty-brown, and its surface is dry and covered in fine fibers or scales.
Beneath the cap, the gills are thick and spaced apart, starting with an ochre-orange hue before maturing to a rusty-brown color as the spores develop. These gills are attached to the stem. The stem itself is generally 5 to 11 centimeters tall and 0.6 to 1 centimeter thick, often a paler reddish-brown or yellowish-brown than the cap, and can be cylindrical or slightly thicker at the base.
Yellowish, fibrous veil remnants often adorn the stem. Young specimens display a cobweb-like partial veil, or cortina, which covers the gills and eventually leaves a rusty-stained ring zone on the upper part of the stem. The spore print is rusty-brown or orange-brown. This species is typically found in coniferous forests, particularly under spruce and pine trees, growing in mossy ground from late summer through autumn.
The Deadly Threat of Spotted Cort
Ingesting Cortinarius speciosissimus is dangerous due to orellanine, a potent nephrotoxin that causes severe, often irreversible kidney damage, including interstitial nephritis. This toxin is not destroyed by cooking, freezing, or drying, so prepared mushrooms remain just as dangerous as fresh ones.
Orellanine poisoning has a delayed onset of symptoms, making diagnosis challenging. Initial signs typically appear two to four days after ingestion, though this period can extend up to fourteen days. Early symptoms often mimic flu-like illnesses, including nausea, vomiting, abdominal pain, headache, myalgia, and chills.
As the toxin progresses, specific renal symptoms emerge, such as intense thirst, frequent urination, and flank pain. Kidney function deteriorates, leading to decreased or absent urine output and complete kidney failure. The kidney damage can be permanent, often necessitating lifelong dialysis or a kidney transplant.
Distinguishing from Look-Alikes
Distinguishing Cortinarius speciosissimus from other fungi is crucial, as many species, even within the Cortinarius genus, can be mistakenly identified. Some Cortinarius are toxic, so identifying a mushroom as merely “a Cortinarius” is insufficient for determining edibility.
Chanterelle mushrooms (Cantharellus cibarius or Craterellus tubaeformis) are sometimes confused with the Deadly Webcap. However, chanterelles possess false gills or ridges rather than true gills, and their cap shapes are different. Other edible species like blewits (Lepista nuda) and honey mushrooms (Armillaria) have pale pink or white spore prints, unlike the rusty-brown spore print of Cortinarius speciosissimus.
Species from the Agaricus genus are differentiated by their chocolate brown spore prints and a stem structure that cleanly separates from the cap. Some Galerina species, which produce rusty-brown spores, can also be mistaken for the Deadly Webcap. Careful examination of multiple features, including the cortina, gill structure, and habitat, is necessary to differentiate these look-alikes.
Foraging Safety and Emergency Protocols
When foraging for wild mushrooms, never consume one unless its identification is absolutely certain. A fundamental rule is: “when in doubt, throw it out.” Avoid gathering mushrooms from polluted areas, such as roadsides or sites treated with pesticides, as fungi can absorb harmful substances.
In cases of suspected mushroom ingestion, immediate medical attention is required. Do not wait for symptoms to manifest, as the delayed onset of orellanine poisoning can be misleading. Contact a poison control center right away.
If feasible, bring a sample of the suspected mushroom to the medical facility for identification. There are no home remedies for orellanine poisoning, and cooking does not eliminate its toxins. Medical treatment focuses on supportive care, including hydration, and may involve dialysis to support kidney function.