Cortinarius steglichii

Cortinarius steglichii is one of the most visually striking webcaps of the Southern Hemisphere - the vivid orange-red to scarlet cap, gills, flesh, and stem colouration is immediately eye-catching and almost unique in the Nothofagus understory.

It belongs to the subgenus Dermocybe (dermocybe-group webcaps), a lineage defined by the production of brightly coloured anthraquinone pigments - the same chemical family responsible for the intense reds and oranges of related species such as Cortinarius sanguineus (blood webcap) of Europe.

The red pigmentation is consistent throughout all tissue: cap surface, gills, flesh, and stem all share the vivid colour, which sets it apart from many other red-capped mushrooms whose gills or flesh are pale or white.

The cap begins convex to bell-shaped in youth, opening to broadly convex or shallowly umbonate, and retains a dry fibrillose-silky surface without any sliminess.

The diagnostic cobwebby cortina of the Cortinarius genus is visible in fresh young specimens and collapses to leave a rust-brown spore-deposit zone on the upper stem - always look for this character when trying to identify a webcap.

Spore print is rust-brown to cinnamon-brown, a reliable genus-level characteristic that immediately separates Cortinarius from orange-red waxcaps (Hygrocybe, white spore print) and from similarly coloured bracket-forming or polypore species.

Cortinarius steglichii should not be consumed. The anthraquinone pigments it contains cause gastrointestinal poisoning, and the species is classified as toxic by mycological authorities.

Beyond its own toxicity, the dangerous lookalike risk is paramount. C. steglichii grows in the same Nothofagus forest where orellanine-bearing Cortinarius species also occur, and those species (including the potentially deadly local webcap complex) cannot always be reliably separated in the field.

Misidentifying a brown or brownish-red Cortinarius as C. steglichii and then extrapolating that it is 'only' a GI irritant would be a potentially fatal error.

Any Cortinarius in South American Nothofagus forest must be treated with full caution.

Cortinarius steglichii produces dermocybin, physcion, and related anthraquinone (hydroxyanthraquinone) pigments - the same chemical family that gives the whole Dermocybe group their characteristic intense red, orange, and yellow colouration.

These compounds are pharmacologically active and cause gastrointestinal irritation when ingested raw or cooked.

In experimental and epidemiological studies, some anthraquinone-bearing Cortinarius species have also been associated with nephrotoxic potential, though the dominant documented clinical effect in humans is gastrointestinal.

Importantly, C. steglichii does NOT belong to the subgenera (Phlegmacium/Telamonia) primarily associated with orellanine nephrotoxins. However, given the scientific incompleteness of South American Cortinarius toxicology and the rule that all members of this genus carry some risk, any ingestion must be treated with caution and medical supervision.

Ingestion of dermocybe-group webcaps typically produces gastrointestinal symptoms within 1-3 hours:

• Nausea
• Vomiting
• Abdominal cramps
• Diarrhoea

These symptoms are usually self-limiting but can be severe and require supportive care (rehydration, anti-emetics) if significant quantities are consumed.

There are no reliable reports of the delayed nephrotoxic syndrome (characteristic of orellanine-bearing Cortinarius) following ingestion of dermocybe-group species in clinically documented cases.

However, some anthraquinones exert nephrotoxic effects in animal models, and the possibility of kidney effects from large doses or repeated exposure cannot be entirely excluded on current evidence.

Do not eat Cortinarius steglichii or any other Cortinarius in South American Nothofagus forest. The species is toxic due to anthraquinone pigments and belongs to a genus that includes some of the world's deadliest mushrooms.

There is no reliable way to confirm which Cortinarius you have found without microscopic spore measurement, pigment chemistry, and ideally DNA analysis - the stakes of error are too high for field identification alone.

If ingestion has occurred, seek medical advice promptly:

• In Chile, contact CITUC (Centro de Información Toxicológica, +56 2 2635 3800).
• In Argentina, contact CIAT or local emergency services.

If symptoms are predominantly gastrointestinal and onset was within 1-3 hours, standard GI poisoning supportive care applies.

If symptoms are delayed by days or weeks and include thirst, urinary changes, or back pain, emergency renal evaluation is required immediately.

This species is an obligate ectomycorrhizal partner of native South American southern beech forests (Nothofagus forest). It grows only where established Nothofagus trees are present, embedded in the dense mat of humus and decomposing leaf litter that characterises the forest floor of Valdivian and Patagonian Nothofagus woodland.

The Valdivian temperate rainforest of south-central Chile (and the adjacent Argentine Andean foothills) is one of the most biodiverse temperate forest systems in the Southern Hemisphere. Its mycorrhizal fungal community is substantially endemic - many species evolved here alongside these beeches and occur nowhere else.

C. steglichii is an element of this endemic flora, so finding it requires being in intact or near-intact Nothofagus habitat. It will not appear in clearings, pastures, eucalyptus plantations, or degraded forest fragments.

Fruiting is tied to the Southern Hemisphere autumn cooling cycle, broadly February through June, with peak activity in March and April.

The underlying trigger is the combination of declining soil temperature after the austral summer and the reliable increase in rainfall as the South American westerlies strengthen heading into autumn.

In the wettest Valdivian coastal rainforest sites (annual rainfall exceeding 2000 mm), the soil is seldom truly dry, and fruiting can begin earlier and extend later than at more continental Andean sites.

A general rule: look for this species when day temperatures consistently drop below about 15°C and the soil is moist but not waterlogged.

Like all Cortinarius species, C. steglichii is a strict ectomycorrhizal obligate. Its mycelium forms a sheath-like hyphal mantle around the fine feeder roots of host Nothofagus trees, creating a symbiotic exchange of soil minerals (especially phosphorus) for tree-derived carbohydrates.

The visible mushroom is the reproductive structure of this much larger underground partnership, which persists for years or decades in the same location.

Fruiting bodies appear singly or in small scattered groups following the root lines of host trees; dense clustering is not typical.

Because the mycelium is perennial, the same microsites may produce fruiting bodies in multiple successive seasons, especially in stable, undisturbed Nothofagus forest.

Southern Hemisphere autumn fruiter. Fruiting is triggered by the combination of soil cooling below ~15°C and adequate soil moisture from autumn rains. In the Valdivian rainforest the soil is rarely dry, so the temperature cue dominates; in drier eastern Andean sites a discrete rain event (20+ mm over 14 days) is the stronger trigger. Flush lag estimated at 7-21 days based on analogy with related Nothofagus-associated Cortinarius. Peak March-April.

The bright red gills and flesh make C. steglichii fairly distinctive within its habitat, but several species demand attention.

The most critical dangerous confusion: several other Cortinarius species with red-orange to brownish-orange tones occur in South American Nothofagus forests, including potentially orellanine-bearing brown webcaps that could be confused with faded or aged specimens of C. steglichii as colours dull. Any red-orange webcap in South American Nothofagus forest should be treated as toxic.

Other species to distinguish:

• Hygrocybe coccinea (scarlet waxcap) and related waxcaps are also vivid scarlet to orange-red with wet, waxy gills - but Hygrocybe species have white spore prints, no cortina whatsoever, and a distinctly waxy (slippery-feeling between fingers) gill texture, and are not ectomycorrhizal.
• Cantharellus species (chanterelles) are orange-yellow but have distinctive blunt, forking false gills (ridges) rather than true blade gills, a white spore print, and no cortina.
• Phlebia and other crust fungi with red-orange colours lack the typical gilled mushroom morphology entirely.
• Cortinarius sanguineus of the Northern Hemisphere is the closest ecological and morphological counterpart - similarly blood-red in all parts, also a dermocybe - but does not occur in South America.