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

Xerocomellus diffractus N. Siegel, C.F. Schwarz & J.L. Frank

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Scientific name
Xerocomellus diffractus
N. Siegel, C.F. Schwarz & J.L. Frank
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

This western North America ‘Cracked-capped Bolete’ has long been known by the misapplied European name Xerocomellus (or Boletus) chrysenteron. It was recently described as a distinct species (Frank et al. 2020).

Why suggested for a Global Red List Assessment?

Xerocomellus diffractus is a common and widespread bolete in western North America. It occurs in a wide variety of habitat types, from young to mature forests, associating with both conifers and hardwoods. No decline has been observed. We recommend it should be listed as Least Concern (LC).

Geographic range

From southern California, USA, through the Pacific Northwest into British Columbia, Canada, east to the Rocky Mountains of Wyoming, and south into Arizona (Frank et al. 2020).

Population and Trends

Population is widespread and stable across western North America.  Occurring in many different habitat types; from young to mature forest, and especially common in urban areas.

Population Trend: Stable

Habitat and Ecology

Ectomycorrhizal with both conifers (Especially Pinus and Pseudotsuga) and hardwoods (esp. Quercus), in a wide variety of habitat types; from live oak woodlands in southern and central California, into northern Californian mixed evergreen forests and throughout the Pacific Northwest coast to montane conifer forests. Also quite common in urban and parkland settings. Fruiting in fall and early winter, or occasionally in spring on the California and Oregon coast, and summer in the Southwest, and at higher elevations.


This species is common and widespread in a wide variety of habitats, and no threats have been observed.

Conservation Actions

None needed.

Research needed

More collections from the Rocky Mountains. It is currently known from Arizona and Wyoming, but no collections were noted in between (Frank et al. 2020).

Use and Trade

This species is edible, and occasionally collected for food.

Food - human


Frank J.L., Siegel, N., Schwarz, C.F., Araki, B. and Vellinga, E.C. 2020. Xerocomellus (Boletaceae) in western North America. Fungal Systematics and
Evolution 6: 265–288

Siegel, N. and Schwarz, C. 2016. Mushrooms of the Redwood Coast: A Comprehensive Guide to the Fungi of Coastal Northern California. Ten Speed Press, Emeryville, CA. 602 pp.

iNaturalist. 2020. https://www.inaturalist.org/

Country occurrence

Regional Population and Trends

Country Trend Redlisted