Described as Boletus dryophilus (Thiers 1975), later transferred to Xerocomus (Singer 1986). Based on genetic and morphological studies (Frank 2014, Frank et al. 2020) it was transferred to the genus Xerocomellus.
Xerocomellus dryophilus has been misapplied to a species in Europe, which was recently described as X. redeuilhii (Simonini et al. 2016).
Xerocomellus dryophilus is a common bolete in southern and central California, USA. It occurs mostly with Coast Live Oak (Quercus agrifolia), and can be found in urban areas.
Anecdotal observations have remarked that the parasitic attacks from a bolete mold (Hypomyces microspermus s.l.) have become more prevalent in recent years, and may have a detrimental effect on this species.
That being said, this species is very common, and occurs over a widespread area; therefore I recommend listing as Least Concern (LC).
From Baja California, Mexico north in the coastal zone of California, USA to Sonoma County, inland around the Central Valley in California, and scattered records from the WIllamette Valley in Oregon.
Population is fairly widespread, and it is abundant in suitable habitat in southern and central California. Some populations appear to be highly susceptible to parasitism by Hypomyces microspermus s.l., which sometimes affecting a high percentage of basidiomata and preventing sporulation (Douhan & Rizzo 2003, Frank et al. 2020). It remains unknown if this has increased in recent years.
Population Trend: Uncertain
Ectomycorrhizal, commonly associated with Coast Live Oak (Quercus agrifolia) forests throughout the range, occasionally, and more scattered in distribution with other oaks (Quercus spp) on the east side of the Central Valley in California, also rarely found in Oregon with Oregon White Oak (Quercus garryana).
Some populations appear to be highly susceptible to parasitism by Hypomyces microspermus s.l., which sometimes affecting a high percentage of basidiomata and prevents sporulation (Douhan & Rizzo 2003, Frank et al. 2020). Anecdotal observations have remarked that the parasitic attacks have become more prevalent in recent years, especially in the Santa Barbara area (B. Cummings, pers. comm.).
Research on if parasitic attacks by Hypomyces becoming more prevalent, and if it has a detrimental effect on this species.
This species is edible, and occasionally collected for food.
Douhan, G.W. and Rizzo, D.M. 2003. Host-parasite relationships among bolete infecting Hypomyces species. Mycological Research 107: 1342–1349.
Frank, J.L. 2014. Nomenclatural Novelties. IndexFungorum No. 179: 1.
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.
Simonini, G., Gelardi, M. and Vizzini, A. 2016. Xerocomellus redeuilhii sp. nov. Rivista di Micologia 59: 123–127.
Singer, R. 1986. The Agaricales in Modern Taxonomy. Koeltz Scientific Books. Koenigstein, Germany. 981p.
Wood, M. and Stevens, F. 2020. Mykoweb; The Fungi of California. https://www.mykoweb.com/CAF/species/Xerocomellus_dryophilus.html