Red-Veil Webcap

Cortinarius rubrivelatus is an ochraceous to rust-orange webcap whose defining and name-giving feature is the distinctly reddish to rufous (reddish-brown) cobwebby cortina - the gossamer partial veil that bridges cap margin to upper stem in young specimens.

Most webcaps (Cortinarius) have a whitish or pale lilac cortina; in rubrivelatus this veil is noticeably reddish, and its collapsed remnant leaves a reddish to rust-stained zone on the upper stem that persists into maturity.

Cap

The cap progresses from convex to nearly flat, tawny-orange to rusty ochre, moist and finely fibrillose, with the intensest colour at the centre.

Gills

Gills start pale cream and reliably brown to cinnamon-rust as spore development proceeds - the generic hallmark of all Cortinarius, shared with no other major mushroom group.

Stem

The stem is fibrillose, pale ochre to whitish.

Flesh

Flesh is whitish to pale ochre and does not change colour when cut.

The spore print is rust-brown to cinnamon-ochre, another non-negotiable Cortinarius character. Microscopically, the spores are ellipsoid to almond-shaped and finely warted, approximately 9-12 × 5-7 µm.

The red cortina is the key field character that separates this species from the many other brown or ochre webcaps in southern South American Nothofagus forest, though it should always be sought in young, unexpanded specimens before the veil breaks.

POTENTIALLY FATAL. Cortinarius rubrivelatus must be treated as deadly based on the precautionary approach universally applied to Cortinarius in southern South American Nothofagus forests.

The orellanin class of nephrotoxins - confirmed in ecologically equivalent Cortinarius species on other continents - causes progressive, potentially irreversible kidney failure. It has resulted in deaths and kidney transplants in documented poisoning cases worldwide.

The key dangers specific to this species are:

1. 1the reddish cortina, though distinctive, is ephemeral and may be degraded by age, moisture, or wear, making confident field identification of this Cortinarius unreliable without microscopy;
2. 2the same Nothofagus forest habitat holds multiple visually similar Cortinarius species of unknown toxicology;
3. 3orellanin is heat-stable and is not neutralised by any cooking method;
4. 4the extreme latency of orellanine poisoning - 2 to 3 weeks before symptoms appear - means that subclinical kidney damage has accumulated extensively before any alert is raised.

If any Cortinarius from this habitat has been consumed, seek emergency medical evaluation immediately and do not wait for symptoms. Bring a specimen or photograph.

No peer-reviewed analytical study has confirmed the specific toxins in Cortinarius rubrivelatus.

But it belongs to the genus Cortinarius, within which orellanin - a thermostable polypyridine N-oxide nephrotoxin - has been documented in species across multiple continents, including:

• the closely related Australasian Nothofagus-associated webcaps (such as Cortinarius archeri and C. australiensis);
• European species (C. orellanus, C. speciosissimus);
• various North American webcaps.

The Nothofagus forest system of southern South America has not been comprehensively screened for orellanin. But the ecological and phylogenetic parallels with confirmed orellanin-bearing webcaps from equivalent Nothofagus ecosystems in Australia and New Zealand are strong.

On this basis, mycological authorities applying the precautionary principle treat Cortinarius species from southern South American Nothofagus forests as carrying potential orellanin-class nephrotoxin risk.

Orellanin, if present, is heat-stable and is not destroyed by any cooking method, drying, freezing, or fermentation.

If orellanin-class compounds are present, the characteristic and defining feature of poisoning is an extremely delayed onset - typically 2 to 3 weeks (range: several days to over a month) between ingestion and the first signs of illness.

This makes orellanine poisoning uniquely treacherous: victims can eat the mushroom, feel entirely well for weeks, and fail to make any causal connection when symptoms eventually appear.

Early symptoms include:

• intense persistent thirst;
• excessive urination followed by decreased or absent urination;
• general fatigue;
• nausea, vomiting, anorexia;
• aching in the lower back or flanks.

These reflect progressive damage to the renal proximal tubules.

As kidney function deteriorates, signs of acute kidney injury or kidney failure appear. Severe cases progress to end-stage renal failure.

The delayed onset also complicates emergency medical diagnosis, because months may have passed between the meal and the clinical presentation.

DO NOT EAT. Cortinarius rubrivelatus is classified as deadly based on the precautionary application of orellanin-class lethal nephrotoxin risk to Cortinarius species from southern South American Nothofagus forests.

No cooking, drying, freezing, pickling, or other preparation method is known to neutralise orellanin.

If there is any possibility that a Cortinarius from this habitat has been consumed - even weeks ago - seek emergency medical evaluation immediately. The extreme latency of orellanine poisoning (typically 2-3 weeks before symptoms appear, up to a month or more) is what makes reporting the potential exposure before symptoms a life-critical step: delayed presentation significantly worsens prognosis.

• In Chile, contact CITUC (Centro de Información Toxicológica UC) at 800 360 777.
• In Argentina, contact the nearest hospital emergency department or CNTOX (Centro Nacional de Toxicología).

Never collect, taste, or experiment with any cobweb-veiled, rust-spored mushroom in southern South American native forest.

This is a strict Nothofagus forest specialist, forming an obligate mycorrhizal partnership with the southern beeches that dominate cool-temperate rainforests and montane forests of Chilean and Argentinian Patagonia.

The Valdivian temperate rainforest and the Nothofagus-dominated forests of the Lake District (from roughly Temuco south to Tierra del Fuego) are the core habitat. Soils are typically moist, acidic, and rich in organic matter from the deep leaf-litter accumulation characteristic of these closed-canopy forests.

Unlike many generalist saprotrophic mushrooms, C. rubrivelatus cannot exist without its living Nothofagus partner. It will not be found in clearings, secondary shrubland, pine plantations, or disturbed ground where the native forest structure has been lost.

This ecological specificity is itself a useful broad-brush safety cue: a rust-orange, cobweb-veiled mushroom with reddish veil remnants on the stem, found in intact native southern beech forest, matches this species' profile and should be treated with full caution.

Fruiting falls in the Southern Hemisphere autumn, broadly March through June, with the peak typically in March-May.

The trigger is the combination of cooling soil temperatures as summer ends and the arrival of reliable autumn rainfall in the Chilean Lake District and Patagonian forest zones. In practice, fruiting flushes tend to follow periods of 20-40 mm rainfall over 7-14 days when soil temperatures are falling through the 8-15 °C range.

High-altitude Nothofagus pumilio and N. antarctica forests (lenga beech zone) fruit slightly later and at lower overall temperatures, typically April-June.

C. rubrivelatus is absent in summer and becomes rare or absent by mid-winter when soil temperatures drop very low.

As an obligate ectomycorrhizal species, Cortinarius rubrivelatus depends entirely on a living Nothofagus host, and cannot be cultivated or found outside native host-tree forest.

The underground mycelial network is perennial and long-lived, with fruiting bodies emerging from this established mycelium each autumn under appropriate weather conditions.

Fruiting bodies appear singly or in small scattered groups of two to five; dense clusters or fairy rings are not characteristic. The same forest site may produce fruit bodies repeatedly over multiple years.

The visible mushroom is only the reproductive structure. The bulk of the organism is an invisible network of fungal filaments woven among the feeder roots of the host tree, exchanging mineral nutrients for photosynthate in the mycorrhizal partnership that is fundamental to the health and nutrient cycling of southern beech forest ecosystems.

Southern Hemisphere autumn ectomycorrhizal fruiter in Nothofagus forest. Fruiting triggered by post-summer cooling (soil temperatures falling below ~15 °C) combined with substantial autumn rainfall (20+ mm over 14 days). Typical flush lag 7-21 days after the triggering rain event. Peak March-May; extends to June at higher altitude or wetter sites.

Several brown to ochre webcaps (Cortinarius) share the same Nothofagus habitat in southern South America, including species in subgenera Phlegmacium and Telamonia. None can be reliably distinguished from C. rubrivelatus or from each other in the field without microscopy and chemical analysis.

The reddish cortina is a useful distinguishing character for C. rubrivelatus specifically, but this character is ephemeral - it is most visible in unexpanded young specimens and may be missed if specimens are old, wet, or worn.

The introduced European death cap (Amanita phalloides) occasionally occurs in southern Chilean cities near planted European trees, but has a very different appearance (pale olive cap, ring, volva, white gills) and presents no confusion.

More practically relevant is potential confusion with species of Rozites (Cortinarius caperatus, the gypsy mushroom, which is edible and occurs in similar forests). It is distinguishable by its distinctly wrinkled cap surface, pallid dry-membranous ring, and lack of a cobwebby cortina in the strict sense.

Any mushroom in Nothofagus forest with a cobwebby veil remnant and a rust-brown spore print is a Cortinarius and must be treated with full caution.