Summary:
Resupinatus urceolatus features 1) gregarious, grayish, spherical to vase-shaped fruiting bodies 0.03-0.15cm in diam, externally farinaceous with short, incrusted hairs, 2) underlying subiculum sparse and wispy or lacking, and 3) round to nearly round spores 4.5-6 microns in diam.

Microscopic:
spores 4.5-5.5 microns, round, smooth, inamyloid, colorless, with droplets [one in the illustration]; basidia 2-4-spored, 25-30 x 6-8.5 microns, clavate, with basal clamp connection; cystidia not seen; hyphal system monomitic, hyphae in the wall of the cups 1-5-2.5 microns across, brownish, thin-walled, in part slightly gelatinized, with clamp connections, hyphae in margin "branched like dendrophyses to drawn out into a beak and ventricose", (Breitenbach), spores 5.5-7 microns in diameter, round to nearly round, "smooth, granular inside, appearing minutely punctate, yellowish"; basidia 4-spored, 15-20 x 6-8 microns, in tight palisade, clamped at base; cystidia absent; hyphae 1.5-3 microns wide, colorless to yellowish, with simple septa, simple clamp connections, and medallion clamp connections, subgelatinous 1.4-1.8 microns wide in subhymenial area, (Cooke)

Notes:
Resupinatus urceolatus has been recorded from BC, (combining Thorn(4) with Redhead(21)), likely occurs elsewhere in North America, and is also found in Europe including Switzerland (Breitenbach) and South Africa (Cooke).

Synonyms and Alternate Names:
Peniophora crassa Burt
Stereum karstenii Bres.