Subruddy Webcap

Cortinarius subrufus is a modestly-coloured webcap whose key identifying features follow the universal Cortinarius template: a rusty-brown spore print, a cobwebby cortina visible on young specimens, and the progressive rust-staining of the stem left by that cortina as spores deposit on it.

Within this framework, the species stands out - or perhaps stands slightly back - for its subdued, softly tawny colouring. The name subrufus (Latin: somewhat rusty or somewhat reddish) captures this character well: it is rufous, but only partially, as if the pigment has been washed back by mild light.

Cap

Where its close relative Cortinarius rufus has a distinctly vibrant, almost brick-red cap, C. subrufus is a quieter rufous-brown, more ochre-tawny than truly red, paler at the margin. The surface is dry to slightly hygrophanous - it picks up moisture in wet weather and looks darker, then dries back to a pale tan-buff.

Gills

The gills begin as pale clay and warm gradually to cinnamon-rust as spores mature.

Stem

The stem is concolorous or slightly paler than the cap, never dramatically differently coloured. In young fruitbodies the cortina is the feature to search for first - a spider-web of pale ochre silky threads stretched from the cap edge to the upper stem. Once it collapses, the rust-brown spore deposit it leaves on the stem provides proof of genus membership even in mature or collected specimens.

Flesh

Flesh is pallid throughout and does not change colour when cut.

The danger of an uncharacterised Cortinarius from a high-risk genus in remote Andean-Patagonian forest involves three compounding factors:

1. 1The toxicological gap: C. subrufus has not been analytically screened, so neither its safety nor its toxicity can be confirmed from the literature - and absence of published data is not a safety guarantee.
2. 2The latency trap: if orellanine-class nephrotoxins are present, a forager can eat this mushroom, feel entirely well for weeks, and only recognise the causal link when kidneys are failing - a window in which the fungal-root partnership has long since resumed its quiet work underground, entirely indifferent to human outcomes.
3. 3The look-alike hazard: in Chilean and Patagonian Nothofagus forest, C. subrufus grows alongside confirmed or strongly suspected orellanine-bearing species (C. rufus, C. magellanicus, others) that cannot be reliably distinguished from it in the field without laboratory equipment.

The precautionary principle is the only rational stance: never collect or consume any tawny to rufous-brown webcap from South American Nothofagus forest.

The specific toxin content of Cortinarius subrufus has not been confirmed by published analytical chemistry. It is classified as potentially poisonous on the basis of genus-level and clade-level risk.

Cortinarius globally produces orellanine-class bipyridine N-oxide nephrotoxins - confirmed in C. orellanus, C. rubellus, and multiple Australasian species. The South American endemic clade (sect. Austroamericani) includes species suspected of analogous nephrotoxic compounds.

Orellanine is a thermostable compound that selectively destroys proximal tubule cells in the kidney by generating reactive oxygen species that overwhelm mitochondrial function, producing irreversible tubular necrosis.

Even if orellanine itself is absent, uncharacterised GI-irritant compounds may be present independently. The toxin profile of an unstudied species in a high-risk genus cannot be assumed benign.

If orellanine-class toxins are present - as the precautionary classification assumes is plausible - symptoms would follow the distinctive orellanine latency pattern: an insidious delay of two days to three weeks between ingestion and the first noticeable signs.

During this window the victim feels normal or only mildly unwell, and the connection to a mushroom meal weeks earlier may be completely overlooked.

When symptoms finally emerge they include:

• intense thirst
• altered urination (excessive at first, then reduced as renal function fails)
• nausea
• vomiting
• headache
• fatigue
• burning sensations in the mouth
• dull flank or back pain

These progress to acute tubular necrosis, acute kidney injury, and in severe or untreated cases to permanent chronic renal failure requiring long-term dialysis or kidney transplantation.

No specific antidote exists; treatment is supportive with management of renal failure.

Treat Cortinarius subrufus as potentially toxic and do not eat it under any circumstances.

Membership in Cortinarius sect. Austroamericani, an endemic South American clade phylogenetically nested within the globally nephrotoxic Cortinarius genus, is sufficient grounds for a precautionary poisonous classification. No specific toxicological data clear this species of suspicion, and the genus as a whole contains some of the world's most dangerous mushroom toxins.

If any webcap has been consumed - even days or weeks previously - seek emergency medical advice from a poisons centre without waiting for symptoms: orellanine poisoning produces no useful early warning for two to three weeks, by which time potentially irreversible kidney damage may already be established.

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

Bring a photograph of the mushroom or preserve a fragment in a sealed bag to assist clinicians.

Cortinarius subrufus lives in the Nothofagus forests of southern South America - one of the world's great mycological frontiers.

The genus Nothofagus (southern beech) dominates the temperate rainforests of the Chilean and Argentine Andes from roughly 35°S southward to Tierra del Fuego, forming forests that are among the oldest in the Southern Hemisphere, shaped by the breakup of Gondwana and the development of the Andes.

The ectomycorrhizal fungi co-evolved with these trees in long isolation from the Northern Hemisphere, producing a largely endemic mycobiota. Cortinarius sect. Austroamericani - the clade to which C. subrufus belongs - is one expression of this southern isolation, comprising webcap species found nowhere outside South American Nothofagus forest.

C. subrufus grows on the forest floor among leaf litter, mosses, and decomposing organic matter where the mycelium is already threaded through the soil in partnership with tree roots.

It cannot exist without a living Nothofagus host and will never appear in plantations of exotic conifers or eucalypts, farmland, or urban parks - only in intact or near-intact native beech forest.

Fruiting follows the Southern Hemisphere seasonal cycle: the species emerges in late summer and peaks through autumn, broadly February to May, with the main flush in March and April.

The trigger is the transition from the warm, relatively dry austral summer to the wetter, cooler autumn - a combination of soil temperatures falling below approximately 14 °C and significant rainfall penetrating the soil profile.

In the Valdivian lake district (around 39-42°S), this transition is typically abrupt; fruiting bodies can appear quite suddenly after the first sustained autumn rain event.

At higher elevations along the Andean cordillera, the season may shift earlier and finish more quickly as winters set in rapidly.

Along the Chilean coast south of the lake district, the mild oceanic climate extends the potential fruiting window slightly, but peak activity remains firmly in March and April.

The mushrooms are short-lived, typically persisting for five to ten days before collapsing.

Like all Cortinarius species, C. subrufus is an obligate ectomycorrhizal organism and cannot grow independently of a living Nothofagus host.

The visible mushroom represents only a brief reproductive phase of a much larger, longer-lived organism: a perennial network of mycelium threaded through the mineral soil and root zone around the host trees.

This underground partnership quietly exchanges phosphorus, water, and other soil minerals for the tree's photosynthetically derived sugars, sustaining both partners through years of growth.

When conditions are right - appropriate soil temperature, moisture, and light - the mycelium sends up reproductive fruiting bodies singly or in loose scattered groups along root corridors. Dense gregarious clusters are unusual; more typically one sees one to three fruitbodies scattered across a small area.

The same spots often produce mushrooms in multiple successive years because the underground mycelium is perennial; observant foragers and mycologists notice these recurring micro-sites.

Southern Hemisphere autumn species. Fruiting is primarily governed by cooling soil temperatures falling below approximately 14 °C after the austral summer, combined with sustained autumn rainfall delivering 20+ mm over 14 days. Flush lag 7-21 days from the triggering combination of rain and temperature drop; shorter at lower elevations with warmer soils, longer at higher Andean sites. Based on the known ecology of Cortinarius sect. Austroamericani in Chilean-Patagonian Nothofagus forests.

The most significant dangerous confusions are with other Cortinarius species sharing the same forest and season.

• Cortinarius rufus is closely related and co-occurs in Nothofagus forest; its cap is more intensely rufous-red than the subdued tawny-ochre of C. subrufus, but colour alone is not a reliable separator given natural variation - both are members of sect. Austroamericani and carry equivalent precautionary risk.
• Cortinarius magellanicus and other Patagonian webcaps share the same rust-brown spore print, cortina remnants, and Nothofagus habitat; species-level separation requires microscopy and molecular tools.
• Chanterelles (Cantharellus species, including endemic South American species) grow in the same Nothofagus forests and share a golden to ochre colouring at a distance, but are separated absolutely by three features: their forked, blunt, ridge-like false gills (not true blade gills), the absence of any cortina or cortina remnant, and a white to pale cream spore print rather than cinnamon-rust - these three characters together exclude Cortinarius completely.
• Russula species in the same forest may share a brownish to reddish cap but are easily distinguished by their extremely brittle, chalk-like flesh (a Russula gill snaps rather than bends), white to cream spore print, and complete absence of any cortina.
• Galerina species, which carry deadly amatoxins, co-occur in the same forest and share a rust-brown spore print; they are generally smaller, often grow on or near decaying wood, and bear a persistent membranous ring (annulus) on the stem rather than a mere cortina-stain zone.