California Fungi—Xerocomellus truncatus
Xerocomellus truncatus (Singer, Snell & E.A. Dick) Klofac
Öst. Z. Pilzk. 20: 39. 2011.
Common Name: none
Synonyms: Boletus truncatus (Singer, Snell, & Dick) Pouzar; Xerocomus truncatus Singer, Snell, & Dick
Cap 5-10 cm broad, convex, broadly convex to nearly plane in age; surface dry, tomentose, brown to olive-brown, usually cracking early in development revealing underlying yellowish to pinkish tissue, the latter more prevalent toward the margin; flesh thick, light yellow, blueing irregularly when injured; odor mild, taste acidic.
Pores +/- 1 per mm, dull yellow to yellowish-green, bruising rapidly blue; tubes up to 1.5 cm long, narrowly depressed near stipe, yellowish-green, quickly and strongly bruising blue.
Stipe 5-10 cm long, 1.5-2.5 cm thick, solid, equal, or the base slightly narrowed; surface dry, smooth to slightly striate, yellowish at the apex, otherwise reddish; yellowish-green mycelium at base.
Spores 12-15 x 4.5-6 µm, smooth, elliptical to fusiform, truncate at one end; spore print olive-brown.
Solitary to in small groups in hardwood/conifer woods from fall to mid-winter.
Edible and good.
This nondescript bolete is closely related to and often confused with Xerocomellus chrysenteron. Both have an olive-brown to brown tomentose cap typically areolate at maturity, similarly colored stipe, and yellowish mycelium at the base. Xerocomellus truncatus, however, is less likely than X. chrysenteron to develop pinkish tones in cracks near the cap margin, and in our experience the pores bruise blue almost instantly, while in X. chrysenteron, this reaction takes several seconds with the blueing never as intense. Nonetheless, a microscope is required to make a positive identification. Xerocomellus truncatus spores are, as the species name suggests, blunt or clipped at one end, those of X. chrysenteron, rounded.
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.
Klofac, W. (2011). Rotfußröhrlinge (Gattung Xerocomellus) in aktueller Sicht. Österreichische Zeitschrift für Pilzkunde 20: 35-43.
Ladurner, H. & Simonini, G. (2003). Xerocomus s.l. Edizioni Candusso: Alassio. 527 p.
Smith, A.H. & Thiers, H.D. (1971). The Boletes of Michigan. University of Michigan Press: Ann Arbor, MI. 426 p.
Snell, W.H., Singer, R. & Dick, E.A. (1959). Notes on Boletes. XI. Mycologia 51(4): 564-577. (Protologue)
Thiers, H.D. (1975). California Mushrooms—A Field Guide to the Boletes. Hafner Press: New York, NY. 261 p. (WWW)