Summary:
Features include 1) resupinate growth on spruce, pine, or willow, 2) a cobwebby to pellicular fruitbody, the surface blackish brown and smooth, the margin paler and the subiculum much paler, rhizomorphs evident under 10x lens, 3) spores that are irregularly round to lobed, dull brown to pale yellowish, with warts that are sometimes bifurcated, 4) 2-4-spored basidia with encrusting material and contents bright green to blackish green in KOH, 5) a dimitic hyphal system, without clamp connections.

Microscopic:
SPORES 5.5-6.5(7) microns, irregularly round to distinctly symmetrically lobed, often appearing roughly triangular when immature, "warted, the warts sometimes bifurcate, parts often greenish in KOH, walls dull brown to pale yellowish"; BASIDIA 2-4-spored, 40-60 x 6-8 microns, spheropedunculate to napiform [turnip-shaped] when immature, clavipedunculate when mature, sterigmata up to 7 microns long, encrusting material and contents of basidia bright green to blackish green in KOH, "simple-septate at the base, median simple septa present"; HYPHAE dimitic; SUBHYMENIAL HYPHAE 2-3 microns wide, simple-septate, thin-walled, walls colorless, parts greenish in KOH; SUBICULAR HYPHAE of 2 types: 1) generative, 2-2.5 microns wide, "simple-septate, contents often dull yellowish brown", walls dull brown to colorless, adhering encrusting material sometimes purplish in KOH, 2) skeletal, 1.5-2 microns wide, aseptate, thick-walled, walls pale yellowish; CORDONS up to 30 microns wide, dull brown, individual hyphae 2-2.5 microns wide, simple-septate, (Larsen, M.J.(8))

Notes:
Pseudotomentella atrofusca has been found in BC, ID, AB, AZ, and Sweden, (Larsen, M.J.(8)).

Synonyms and Alternate Names:
Polyporus tardus Berk.
Poria tarda (Berk.) Cooke