Assessment Notes

Justification

Cortinarius verrucisporus is a medium-sized Cortinarius with a short, stout stature, and hypogeous fruiting habit (typically fruiting under the duff). It is currently known from about 25 localities in the California and southern Oregon mountains, but cryptic species have been identified within this complex and additional taxonomic work is needed. Reports of this species from the Rocky Mountains likely correspond to a different species. As the identified range in California, Oregon, and Washington state appears stable, the species is assessed as Least Concern.

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Taxonomic notes

Described from a collection made at Silver Lake in Eldorado National Forest, California, USA (Thiers and Smith, 1969), the name Cortinarius verrucisporus has been misapplied to two other yellow 'velate' species: C. saxamontanus (Fogel 1994), and a still undescribed species (Ammirati and S. Adams in. ed.). Additional work is in progress on this group, which should help clarify names.

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Geographic range

This species occurs in mid to high elevation forests in the Sierra Nevada of California, and southern Cascade Range in California and southern Oregon. Reports from Utah and Colorado should be scrutinized, as they are likely C. saxamontanus.

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Population and Trends

The population is apparently stable but more data are needed, and collections need to be re-examined to ensure proper identification. The known population is fairly widespread in California and southern Oregon. Although the habitat is under pressure overall from stand-replacing fires and changing climate, these changes have not been so far been recorded to affect this species.

Population Trend: unknown

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Habitat and Ecology

Sporocarps occur solitary, scattered, or in small clusters under duff or in soil, occurring in mid- to high-elevation mature forests. It only rarely becomes exposed, or occasionally breaks the surface in areas with hard-packed ground and/or a thin duff layer. It is ectomycorrhizal with conifers, likely primarily with Abies. Fruiting occurs in late spring and summer, rarely in fall. It belongs to the group of 'velate' Cortinarius; a subset of species in western North America with often hypogeous growth, and thick partial veils, and appears to be at least partially dependent on mycophagy (primarily eaten by small mammals) for spore dispersal, and to a lesser degree wind-dispersal.

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Threats

Prolonged droughts and decades of fire suppression have drastically altered western montane forests, leading to thicker, denser, Abies-dominated forests. As a result hotter, stand-replacing fires (rather than patchwork and understory burns) are commonplace altering appropriate habitat drastically, and making it ill-suited for this species.

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Conservation Actions

No specific conservation actions have been identified with regards to this species at this time. Following recognition of cryptic species, existing collections of Cortinarius verrucisporus need to be re-examined to insure proper identification, especially those reported from the Rocky Mountains. More habitat information is required to clarify whether this species is dependent on mature or old-growth forests, since identified threats to this habitat have not been associated with any recorded decline in this species.

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Use and Trade

No use/trade is known.

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Source and Citation

Siegel, N. 2022. Cortinarius verrucisporus. The IUCN Red List of Threatened Species 2022: e.T195924287A195925953. https://dx.doi.org/10.2305/IUCN.UK.2022-1.RLTS.T195924287A195925953.en .Accessed on 3 August 2024

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