🍄 Introduction

Cortinarius rubellus (also known as Cortinarius speciosissimus) is one of the most dangerous mushrooms in northern Europe, responsible for a significant number of kidney failures and deaths in Scandinavia, Finland, and Scotland. Like its close relative C. orellanus, it contains orellanine and related nephrotoxic compounds, and its latency period of 2–3 weeks before symptoms appear makes it particularly treacherous. It grows predominantly under conifers, extending its range into habitats where C. orellanus is less common.

The cap is 3–8 cm broad, dry, and covered with distinct, erect, silky fibrils arranged radially, giving it a shaggy appearance. The colour is orange-brown to brick-red or cinnamon-red, sometimes more intensely coloured than C. orellanus. The cap is convex to bell-shaped when young, flattening with a broad umbo in age. The gills are broadly adnate, widely spaced, and the same cinnamon-orange as the cap. The stipe is 6–12 cm tall, 0.7–1.5 cm wide, fibrous, concolorous with the cap, and shows rust-brown cortina remnants as a zone near the apex. The spore print is rust-brown.

Quick Facts

🔍 Identification Guide

Key identification points: orange-brick-red fibrous cap with erect fibrils, widely spaced cinnamon gills, rust-brown spore print, cortina remnants on stipe, conifer association (primarily spruce and pine), and autumn fruiting. The erect-fibril texture of the cap surface is an important separation from C. orellanus. Both species require expert-level confirmation and should be treated as equally deadly.

Morphological Features

Detailed Morphology

The more erect, shaggy fibril texture of the cap distinguishes C. rubellus from C. orellanus, which has a smoother, more radially streaked silky cap surface. Both share the wide gills and rusty overall colour. The stipe of C. rubellus is often more slender and straight. Cut flesh is yellowish-orange and does not change colour. The smell is faintly earthy or radish-like.

🧬 Taxonomy & Classification

Cortinarius rubellus Cooke (1887) is the older valid name; Cortinarius speciosissimus Kühner & Romagn. (1953) is a widely used synonym in Scandinavian literature. Molecular data confirm they are the same species. It belongs to section Leprocybe within Cortinarius, characterised by dry scaly or fibrous caps and nephrotoxic compounds. The broader Cortinarius genus is under active molecular revision and may eventually be split into multiple genera.

⚕️ Edibility & Safety

DEADLY — contains orellanine causing progressive irreversible renal failure with delayed onset of 2–21 days after consumption. The clinical course mirrors C. orellanus: initial silent period during which kidney damage accumulates, followed by burning thirst, polyuria, nausea, headache, and progressive renal insufficiency. Deaths and kidney transplants have been documented in Scandinavia, Finland, Scotland, and France. There is no antidote. Management is supportive; early dialysis can sustain patients pending transplant evaluation. The extreme latency means patients rarely connect their illness to mushroom consumption. Any healthcare provider evaluating unexplained renal failure should inquire about wild mushroom consumption in the preceding 2–6 weeks. Call Poison Control immediately after confirmed or suspected ingestion, even before any symptoms appear.

⚠️ Look-Alikes & Confusions

The most dangerous confusion is with golden chanterelles (Cantharellus cibarius) and their close relatives, particularly in Scandinavia and Scotland where C. rubellus is most common. Chanterelles have false, forking, ridge-like blunt pseudo-gills rather than true bladed gills, white spore print, and apricot or fruity odour. Craterellus tubaeformis (yellowfoot chanterelle) is another edible confusion species in the same conifer/sphagnum habitat, distinguished by its hollow stipe, darker brown cap, and characteristic trumpet shape. The edible Lactarius deterrimus and L. semisanguifluus, which fruit under spruce and share orange-brown colour, are distinguished by their exuding latex when cut.

Known Look-Alikes

🌲 Habitat & Ecology

Cortinarius rubellus is ectomycorrhizal under conifers, particularly Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), often in boggy, mossy, or acidic soil conditions. It is abundant in Scandinavia and Finland, where it grows in sphagnum-rich spruce forests and on the edges of raised bogs. It is also found in Scotland, Ireland, and central Europe. This conifer association differentiates it ecologically from C. orellanus.

Ecological Role

Ectomycorrhizal partner of boreal conifers, contributing to nutrient cycling and tree health in subarctic and boreal forest systems. Its tolerance of acidic, waterlogged conditions extends its ecological contribution to forest types not easily colonised by less stress-tolerant fungal species.

🗺 Distribution Map

Known distribution of Deadly Webcap: Europe, North America. This species is mycorrhizal (ectomycorrhizal).

🧺 Foraging Guide

Must not be foraged. Its habitat in prime Scandinavian forest foraging areas for chanterelles and yellowfoot chanterelles places it in direct contact with inexperienced foragers. No safe use for food exists.

🌱 Cultivation

Cannot be cultivated. Obligate ectomycorrhizal lifestyle precludes ex situ cultivation.

🍳 Culinary Uses

Not edible. Orellanine is heat-stable and not neutralised by any cooking method.

📦 Preservation & Storage

Dried specimens for scientific study retain toxicity. Orellanine fluorescence under UV light can be used in forensic identification of dried or powdered material.

🩹 Medicinal Properties

No medicinal use. Orellanine's selective renal toxicity has been studied as a model in experimental nephrology.

🍂 Seasonal Fruiting

Fruits from July through October in Scandinavia and northern Europe, with peak fruiting August–September, coinciding directly with the height of chanterelle and porcini season.

🔬 Spore Print & Microscopy

Spores are broadly ellipsoid, coarsely verrucose (warted), rust-brown, 8–11 × 5–7 µm. Basidia are clavate, four-spored. The warty spore ornamentation is characteristic of Cortinarius subgenus Leprocybe.

🌀 Varieties & Forms

No formally described varieties. Variation in cap shaggyness and colour intensity is within normal intraspecific range.

📜 History & Ethnomycology

Several landmark poisoning cases in 1970s–1980s Scandinavia and a notable cluster of cases in Scotland involving Polish immigrants established C. rubellus as a major public health concern. The Finnish mycologist Kari Lampe published detailed epidemiological studies of orellanine poisonings in the 1980s. A Scottish outbreak in the 1990s prompted updated NHS poisoning guidelines.

🎓 Beginner's Guide

The most important lesson from C. rubellus is that delayed toxicity is real and extremely dangerous. If you have eaten wild mushrooms and develop kidney-related symptoms — increased thirst, frequent urination, fatigue, back or flank pain — weeks after foraging, tell your doctor immediately and mention the mushroom consumption history even if it seems unrelated.

Photography Tips

Photograph in situ under spruce trees with forest duff or sphagnum in the background to document the habitat. The warm orange-brick tones are best captured in overcast light. A close-up of the cap surface showing the erect fibril texture is diagnostically important. Document the stipe with its cortina remnant zone clearly visible.

Common Mistakes

Troubleshooting

Diagnosis of orellanine poisoning is often missed due to the long delay between consumption and symptoms. Forensic mycological investigation of suspected cases should include UV fluorescence testing of gastric contents, urine, or kidney biopsy material for orellanine. Mushroom identification experts should be consulted alongside nephrologists managing suspected cases.

❓ Frequently Asked Questions