Systematics and Biodiversity 13(1): 33. 2014.
Common Name: none
Synonyms: Pachylepyrium carbonicola (A.H. Smith) Singer; Kuehneromyces carbonicola A.H. Smith; Pholiota subangularis A.H. Smith & Hesler; Crassisporium funariophilum (M.M. Moser) Matheny, P.-A. Moreau & Vizzini
Cap 1.5-3.0 cm broad, convex, becoming plano-convex, sometimes with a low umbo or the disc slightly depressed; margin at first incurved, then decurved; surface glabrous, reddish-brown with innate fibrils, lubricous when moist, hygrophanous, fading to dingy tawny reddish-brown; context 1.0-2.5 mm thick at the disc, rapidly thinning towards the margin, soft, cream colored, unchanging; odor not distinctive; taste mild.
Gills notched, close, at first light-brown, becoming dull rusty-brown in age, relatively broad, 5-7 mm wide, edges lighter than the faces; lamellulae in 3-4 series.
Stipe 1.5-3.5 cm long, 2.0-3.5 mm thick, straight, sometimes with a basal bend, equal to to slightly enlarged at the base and apex, the core hollow at maturity; surface covered with white fibrils over a reddish-brown ground color; partial veil superior, evanescent, sparse, fibrillose, colored reddish-brown by spore drop.
Spores 9.0-11.0 x 7.0-8.5 µm, rhomboid to lemon-shaped in face-view; 9.0-11 x 6-6.5 µm, elliptical in profile; spores smooth, thick-walled, reddish-brown mounted in KOH, truncate, with an apical germ pore; hilar apendage not conspicuous; spores reddish-brown in deposit.
Scattered to clustered on burnt soil; fruiting after snow-melt in montane regions; fairly common in its preferred habitat.
This montane species is recognized by its reddish-brown, glabrous cap, sparse rust-brown fibrillose veil and preference for fruiting on burnt ground. Microscopically the thick-walled spores, angular (rhomboid) in face-view are also distinctive. It is often found with Pholiota highlandensis, another "burn species." The latter is similar in size but differs in possessing a tawny-brown, appressed-fibrillose cap and spores that are elliptical in face-view, not thick-walled.
Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.
Matheny, P.B., Moreau, P.-A. , Vizzini, A., Harrower, E., De Haan, A., Contu, M. & Curti, M. (2014). Crassisporium and Romagnesiella: two new genera of dark-spored Agaricales. Systematics and Biodiversity 13(1): 28-41. (PDF)
Singer, R. (1957). New genera of fungi X. Pachylepyrium. Sydowia 11: 320-322.
Smith, A.H. (1956). Additional new or unusual North American Agarics. Sydowia Beih. 1: 46-61. (Protologue for Kuehneromyces carbonicola)
Smith, A.H. & Hesler, L.R. (1968). The North American Species of Pholiota. Hafner Publishing Company: New York, NY. 492 p.