Summary:
Features include 1) resupinate growth on rotten wood, 2) thin, tomentose, cottony patches that are rust-brown to dark brown, the surface tomentose to slightly verrucose, 3) when fresh, cystidia that may be detected with a hand lens: microscopically they are cylindric, thick-walled, multiply septate, and brown, and arise in clusters, 4) spores that are brown, nearly round, and coarsely verrucose, some of their warts with double tubercles, and 5) a dimitic hyphal system, the hyphae without clamp connections, Ginns(5) gives Tomentellina fibrosa (Berk. & M.A. Curtis) M.J. Larsen as the current name, but Ginns(23) says that Tomentellina is a synonym, giving as the authority the publication where the name Tomentella fibrosa (Berk. & M.A. Curtis) Koeljalg was published in 1996.

Microscopic:
SPORES 7-9(11) microns in diameter, excluding warts, nearly round, coarsely verrucose, some warts with double tubercles, spore brown; BASIDIA 4-spored, 35-45 x 7-8 microns, narrowly clavate, without basal clamp connection; CYSTIDIA arising in clusters from the subiculum, up to 200 x 4-7 microns, cylindric, blunt, thick-walled, multiply septate, brown; HYPHAE dimitic: 1) generative hyphae 2-4 microns wide, colorless to yellowish, thin-walled, septa without clamp connections, 2) skeletal hyphae 3-5 microns wide, brownish, thick-walled, septa without clamp connections; hyphal strands present, (Breitenbach)

Notes:
Tomentella fibrosa has been found in BC, WA, ID, AB, MB, NF, ON, PQ, YT, AK, AL, AZ, CO, ME, MI, MN, MT, NH, NM, NY, SC, UT, VT, and WY, (Ginns(5)). It occurs also in Europe (including Switzerland) and Asia (Breitenbach(2)).