Tricholoma terreum var. cystidiotum
Index Fungorum 217: 1. 2015.
Common Name: none
Synonym: Tricholoma myomyces var. cystidiotum Shanks
Cap 15-50 mm broad, convex, expanding to plano-convex, often with a central umbo; margin incurved in youth, wavy, with adhering pallid fibrils, decurved to upturned in age; surface of disc dark grey to blackish, felty-tomentose, becoming appressed fibrillose-squamulose and lighter overall; context thin, grey; odor and taste not distinctive.
Gills close, sinuate, moderately broad, pale-grey, pallid in age.
Stipe 25-50 mm x 5-10 mm in width, equal, solid, developing a thin, hollow core at maturity; surface of apex with scattered scales, smooth to silky below, pallid when young, dingy light-grey in age; partial veil fibrillose, evanescent, leaving remnants high on the stipe or on the young cap margin.
Spores 5.0-7.5 x 3.5-4.5(5) µm, elliptical in face-view, similar in profile, smooth, thin-walled, inamyloid; spores white in deposit; hypodermium of thin-walled inflated cells.
Scattered to gregarious under conifers in coastal forests; common with Pseudotsuga menziesii (Douglas fir) and pines (Pinus spp.); fruiting from fall to mid-winter; fairly common in most years.
Questionable; apparently edible and sometimes abundant, but too little is known about this and related species to recommend it.
This diminutive Tricholoma is recognized by a dark-grey to almost blackish, squamulose cap when young with contrasting pale margin and sparse cortina-like veil. The species epithet refers to this species's distinctive hypodermium of inflated cells. It was first described as Tricholoma myomyces var. cystidiotum, a name previously used here. Recent research, however, has concluded that T. myomyces is conspecific with Tricholoma terreum an older name and thus is a synonym. The result is that var. cystidiotum has been transferred to Tricholoma terreum. Besides Tricholoma terreum var. cystidiotum, several other small Tricholoma species occur in California. A common often oak-dwelling species in the San Francisco Bay area is Tricholoma scalpturatum. It is recognized by a strong farinaceous odor, a character lacking in T. terreum var. cystidiotum and a paler fibrillose-squamulose cap. Tricholoma cingulatum, a willow (Salix spp.) associated species with a pale grey fibrillose cap, is distinguished by a cottony white ring. A third Tricholoma, T. moseri, is found in montane regions and fruits in the spring near melting snowbanks. Its small size, a grey-brown appressed fibrillose-squamulose cap, mild odor, lack of a partial veil, and relatively large spores are fieldmarks.
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