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

Tylopilus humilis Thiers

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Scientific name
Tylopilus humilis
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 collections made near Mendocino, California, USA (Thiers 1966).

Why suggested for a Global Red List Assessment?

Tylopilus humilis is a rare bolete known from coastal forests in northern California.

Until much needed modern taxonomic work has been done on California Tylopilus, I recommend listing this species as Data Deficient (DD).

Geographic range

Known from scattered sites from Santa Cruz County, California, north to Mendocino, California, USA.

Population and Trends

Population is very restricted; currently known from disjunct populations from Mendocino County, California in the north and Santa Cruz County in the south. Data to assess trends is lacking for this species.

Population Trend: Uncertain

Habitat and Ecology

Ectomycorrhizal, based on collection data, either with (Pinus spp.), or possibly with manzanita (Arctostaphylos spp.) or Madrone (Arbutus menziesii). Typically fruiting under duff, and rarely breaking to surface. Fruiting in fall and early winter.


No threats have been directly linked to this species. Overall, the habitat has threats from urban development leading to loss of habitat, and sand mining near the Santa Cruz populations.

Conservation Actions

Protect any populations found on unprotected lands. Invasive plant removal; ie. Scotch broom (Cytisus scoparius) from areas this species in know to occur.

Research needed

Modern taxonomic work on Tylopilus species in California. Assess population trends.

Use and Trade

None known.


Siegel, N. and Schwarz, C. 2016. Mushrooms of the Redwood Coast. Ten Speed Press: Berkeley, CA. 601 p.

Thiers, H.D. 1966. California boletes II. Mycologia 58(6): 815-826.

Thiers, H.D. 1975. California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p

Country occurrence

Regional Population and Trends

Country Trend Redlisted