• Proposed
  • Under Assessment
  • Preliminary Assessed
  • Assessed
  • DDPublished

Tylopilus humilis Thiers

Search for another species...

Scientific name
Tylopilus humilis
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Assessment date
IUCN Red List Category
Siegel, N.
Dahlberg, A.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/198479762/198489261


Tylopilus humilis is a rare bolete known from fewer than 10 locations in coastal forests of northern California. Until much-needed modern taxonomic work has been conducted on Californian Tylopilus, it is not possible to accurately assess the status of this species. Therefore, it is assessed as Data Deficient (DD).

Taxonomic notes

It was described from collections made near Mendocino, California, USA (Thiers 1966).

Geographic range

It is known from scattered sites from Santa Cruz County, California, north into Mendocino County, California, USA.

Population and Trends

Based on current knowledge, the population is very restricted, with the species being currently known from fewer than 10 disjunct subpopulations from Mendocino County, California in the north and Santa Cruz County in the south. Data to assess trends are lacking for this species.

Population Trend: unknown

Habitat and Ecology

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


No threats have been directly linked to this species. Overall, though the habitat is subject to pressure from urban development, and sand mining near the Santa Cruz subpopulations. The invasive Scotch Broom (Cytisus scoparius) is also potentially impacting the species' habitat, but the overall impact is uncertain because of the paucity of information currently available.

Conservation Actions

There is a need to protect any subpopulations found on unprotected lands. Work should be conducted in order to assess population trends. Invasive plant removal, specifically Scotch Broom (Cytisus scoparius), from areas this species is known to occur could be beneficial. Modern taxonomic work is needed on Tylopilus species in California.

Use and Trade

No use/trade is known.

Source and Citation

Siegel, N. 2021. Tylopilus humilis. The IUCN Red List of Threatened Species 2021: e.T198479762A198489261. https://dx.doi.org/10.2305/IUCN.UK.2021-2.RLTS.T198479762A198489261.en .Accessed on 1 October 2023

Country occurrence