Gastroboletus amyloideus
Brittonia 21: 251. 1969.
Common Name: none
For descriptions see Thiers & Trappe & Siegel et al.
Solitary or in small clusters, hypogeous to subhypogeous under conifers (fir, pine); uncommon, fruiting in fall at high elevations in the Sierra Nevada mountains.
Unknown.
Gastroboletus amyloideus can be distinguished by its globose-stipitate, secotioid fruitbodies that are formed mainly of contorted tubes on a reduced stipe, pores that bruise greenish blue, and amyloid spores. Gastroboletus xerocomoides has a velvety olive-brown cap, yellow pores, white context tissues that bruise blue, and distinctly truncate, inamyloid spores; Gastroboletus brunneus has a dark olive-brown cap, dark brown tubes and pores that do not bruise blue, lacks a stipe, and grows entirely underground. Gastroboletus turbinatus grows in the same habitat but has a brown cap, quickly bruises blue on the pores and context tissues, and has thicker-walled spores that are inamyloid.
Gastroboletus amyloideus may be simply a gastroid form of Boletus smithii. More research/data is need to clarify the situation.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Frank, J., Siegel, N., Schwarz, C., Araki, B. & Vellinga, E. (2020). Xerocomellus (Boletaceae) in western North America. Fungal Systematics and Evolution 6: 265-288. (PDF)
Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. & Ikeda, D. (2019). A Field Guide to the Rare Fungi of California's National Forests. Bookmobile: Minneapolis, MN. 313 p. (PDF)
Thiers, H.D. (1975). California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p.
Thiers, H.D. & Trappe, J.M. (1969). Studies in the genus Gastroboletus. Brittonia 21: 244-254. (Protologue) (PDF)
