Caloboletus frustosus ( D. Arora & J.L. Frank
Index Fungorum 194: 1. 2014.
Common Name: none
Synonyms: Boletus frustosus Snell & Dick; Boletus calopus var. frustosus (Snell & Dick) Miller & Watling; Caloboletus frustosus comb. prov.
For description see Snell & Dick.
Solitary to scattered in soil under firs; not uncommon, fruiting from late summer through fall above 1500 m elevation in the Sierra Nevada and Cascade Ranges.
Inedible, bitter.
Caloboletus frustosus can be recognized by strongly bitter fruitbodies with a dry, tomentose, brown to dark yellowish brown cap that becomes deeply cracked (frustose, hence the epithet) in age, pale yellow pores that bruise blue, and a strongly reticulate stipe with yellow apex and red base. Caloboletus rubripes is similar but has a paler cap and non-reticulate stipe; Caloboletus coniferarum, found rarely in coastal Humboldt and Del Norte counties, differs in forming a less strongly reticulate stipe that lacks red colors. The robust stature and strongly reticulate stipe of Caloboletus frustosus distinguishes it from other species with dry, brown, tomentose caps, such as Xerocomellus atropurpureus, Xerocomellus diffractus, and Xerocomellus mendocinensis.
Arora, D. (1986). Mushrooms Demystified. Ten Speed Press: Berkeley, CA. 959 p.
Bessette, A.E., Roody, W.C. & Bessette, A.R. (2000). North American Boletes: A Color Guide to the Fleshy Pored Mushrooms. Syracuse University Press: Syracuse, NY. 400 p.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Frank, J.L. (2014). Nomenclatural Novelties. IndexFungorum No. 194: 1.
Snell, W.H. & Dick, E.A. (1941). Notes on Boletes. VI. Mycologia 33(1): 23-37. (Protologue)
Thiers, H. D. (1975). California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p. (WWW)
Vizzini, A. (2014). Nomenclatural novelties. Index Fungorum no. 146: 1-2. PDF
