• Proposed
  • 2Under Assessment
  • 3Preliminary Assessed
  • 4Assessed
  • 5Published

Cortinarius verrucisporus Thiers & A.H. Sm.

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Scientific name
Cortinarius verrucisporus
Thiers & A.H. Sm.
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Described from a collection made at Silver Lake in Eldorado National Forest (Thiers & Smith, 1969).

The name Cortinarius verrucisporus has been misapplied to two other yellow ‘velate’ species; C. saxamontanus (Fogel1994), and a still undescribed species (Ammirati and S. Adams in. ed.). Additional work is in progress on this group, which should help clarify names.

Why suggested for a Global Red List Assessment?

Cortinarius verrucisporus is a medium-sized Cortinarius with a short, stout stature, and hypogeous fruiting habit (typically fruiting under the duff). It belongs to the group of ‘velate’ Cortinarius; a subset of species in western North America with often hypogeous growth, and thick partial veils. C. verrucisporust is recognized by the buff to bright greenish-yellow cap, a thick, yellow partial veil of radial fibrils that remains mostly unbroken, and lots of rusty brown spores. Currently known from ~25 locations in the California and southern Oregon mountains.

Geographic range

Occurring 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.

Population and Trends

Apparently stable, but data is lacking, and collections need to be reexamined to insure proper identification. Population is fairly widespread in California and southern Oregon. Although the habitat is in threat overall from stand-replacing fires, and changing climate; these changes have not been tied directly to affecting this species.

Population Trend: Uncertain

Habitat and Ecology

Solitary, scattered, or in small clusters under duff or in soil. Rarely becoming exposed, or occasionally breaking the surface in areas with hard-packed ground and/or a thin duff layer. Occurring in mid to high elevation mature forests. Ectomycorrhizal with conifers, likely primarily with Abies. Fruiting in late spring and summer; rarely occurring in fall.

Being typically hypogeous in fruiting, this species appears to be at least partially dependent on mycophagy (primarily eaten by small mammals) for spore dispersal, and to a lesser degree wind-dispersal.


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.

Increase in fire frequency/intensityDroughts

Conservation Actions

Research needed

With the added knowledge of cryptic species, existing collections of Cortinarius verrucisporus need to be reexamined to insure proper identification; especially those reported from the Rocky Mountains.
More habitat information; is this species dependent on mature or old growth forests?

Use and Trade

None known.


Desjardin, D.E., M.G. Wood & F.A. Stevens. 2015. California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR.
ortal. Mycology Collections Portal. Available at: http://www.mycoportal.org

Fogel, R. 1994. Materials for a Hypogeous Mycoflora of the Great Basin and Adjacent Cordilleras of the Western United States II. Two Subemergent Species Cortinarius saxamontanus, sp. nov., and C. magnivelatus, Plus Comments on Their Evolution. Mycologia, 86(6), 795-801.

Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. and Ikeda, D. 2019. A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.

Thiers, H.D. & A.H. Smith. 1969. Hypogeous Cortinarii. Mycologia 61: 526–536.

Wood, M. & F. Stevens. 2020. Mykoweb: California Fungi.  http://mykoweb.com/CAF/species/Cortinarius_verrucisporus.html

Country occurrence

Regional Population and Trends

Country Trend Redlisted