Summary:
Features include 1) resupinate growth on conifers, hardwoods, and polypores, 2) a hypochnoid to tomentose or submembranous fruitbody that is dark brown to purplish brown, the surface smooth to minutely punctate, the subiculum and the cottony margin colored as or darker than spore-bearing surface, 3) spores that are round to nearly round, strongly echinulate, and brownish, 4) 2-4-spored basidia with transverse septa, 5) hyphae that are brown, often wavy, the subicular walls (and often subhymenial hyphae) swelling in KOH, and 6) clamp connections.

Microscopic:
SPORES (7)8-9.5(11.5) microns in diameter, round to nearly round, strongly echinulate, brownish; BASIDIA 35-60 x 8-11(13) microns; SUBHYMENIAL HYPHAE 4-6(8) microns wide; SUBICULAR HYPHAE (2.5)3-6(8) microns wide, brown, often wavy, becoming thick-walled, subicular hyphal walls swelling in 10% KOH, (Stalpers), SPORES (7)8-9.5(11.5) microns in diameter, round to nearly round, aculeate or more rarely echinulate, pale brown to deep hazel; BASIDIA 2-4-spored, 45-55(60) x 8-11(12) microns, clavate, clamp connection at base, transverse septa present, sterigmata up to 9 microns long; SUBHYMENIAL HYPHAE 4-6(8) microns wide, with clamp connections, "thin-walled, localized wall thickening apparent in some instances", cell walls often reacting to KOH by swelling (upon continuous exposure to 2% KOH and immediately so upon exposure to 10% KOH), dull brown to yellowish brown; SUBICULAR HYPHAE (2.5)3-5.5(6.5) microns wide, hyphal cells up to 70 microns long and irregular in outline or wavy (not straight or uniform), septate, with frequent clamp connections, "becoming thick-walled, with the lumen sometimes not evident (wall thickening frequently localized and cell wall strata often discernible)", cell walls swelling in KOH as for subhymenial hyphae, dark brown to yellowish brown, (Larsen)

Notes:
Tomentella stuposa has been found at least in BC (J. Ginns, pers. comm.), also AB, NF, ON, AR, AZ, MD, MI, MN, NJ, NM, NY, OH, TN, and VT, (Ginns(5)). The distribution also includes Czechoslovakia, Denmark, Finland, Germany, Sweden, Turkey, and India, (Larsen).

Synonyms and Alternate Names:
Tomentella ruttneri Litsch.