Described from collections made near Mendocino, California, USA (Thiers 1966).
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).
Known from scattered sites from Santa Cruz County, California, north to Mendocino, California, USA.
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
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.
Protect any populations found on unprotected lands. Invasive plant removal; ie. Scotch broom (Cytisus scoparius) from areas this species in know to occur.
Modern taxonomic work on Tylopilus species in California. Assess population trends.
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