Assessment Notes

Justification

Cortinarius olympianus is uncommon to rare, documented from ~50 known sites. This species appears to be restricted to mature and old-growth conifer forests. While there are likely scattered threats to this species, its population is not thought to be under rapid decline. It is assessed as Least Concern.

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Taxonomic notes

This species was described by Smith (1939) from a collection made at Olympic Hot Springs, in Olympic National Park, Washington in 1935.

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Geographic range

This species is known from southern British Columbia, Canada, south through the Cascade and Olympic Mountains in the Pacific Northwest, less common in the Coast Ranges, and coastal regions, east to the northern Rocky Mountains in Idaho, south to scattered sites in the Klamath Ranges and a single historic site in the Sierra Nevada in California, USA (although these is some question regarding the identity of this collection).

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Population and Trends

It is widespread in the Pacific Northwest and northern California; currently known from 50+ sites but likely occurs in many more. Most collections come from mature and old growth forests, which is in decline but its population is not thought to be under rapid decline.

Population Trend: Unknown

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Habitat and Ecology

It is ectomycorrhizal with conifers; either restricted to, or with a preference for mature and old growth forests. It is solitary or scattered, growing from soil or duff, often in small patches. It is more commonly observed in Cascade forests, and is occasional in coastal or coast range forest in the Pacific Northwest.

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Threats

Little is known about this species’ life history and ecology so potential threats are based on informed conjecture. Some parts of its range are impacted by logging, while fire is an additional threat since stand replacing fires could severely diminish the extent of suitable habitat.

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Conservation Actions

Surveys should be undertaken to identify and protect habitat known to host this species. Logging and machine clearing of understory vegetation should be limited in mature (or old growth forest) in areas where this species is likely to occur. Habitat limitations for this species should be identified as it may be restricted to mature and old growth forests in the Pacific Northwest.

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Use and Trade

No use/trade is known.

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Source and Citation

Mueller, G.M. & Siegel, N. 2025. Cortinarius olympianus. The IUCN Red List of Threatened Species 2025: e.T272556158A272556246. Accessed on 22 November 2025.

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• Country occurrence