Summary:
Features include 1) resupinate growth on dead branches and twigs of conifers especially Douglas-fir and Western Hemlock, 2) corticioid patches up to 0.3cm across which become confluent, the color light buff to cream-buff, the margin distinct and tightly attached, 3) round to suboval spores that are amyloid with a spiny surface in Melzer''s reagent, with germ pores at opposite ends of the spore, 4) a catahymenium composed of a) basidial elements, b) simple paraphysoids, c) ampulliform pseudocystidia (often with a conspicuous globe-like mass inside, and bearing one or more asexual propagules at the tip), and d) numerous, thin-walled acanthophyses with delicate acicular projections toward the apex, and 5) context monomitic with clamp connections.

Microscopic:
SPORES 15.5-20(25) x (13)14-19(21) microns, round to suboval, flattened adaxially, walls appearing smooth to roughened in KOH, echinate [spiny] in Melzer''s reagent, walls amyloid, "thickened at maturity up to 2 microns thick, and then bearing opposite germ-pores at the poles of the spore"; spores of fruitbodies from Picea sitchensis with a larger average spore range, 22-25 x 15-21 microns; catahymenium composed of basidial elements, simple paraphysoids, ampulliform pseudocystidia, and numerous, thin-walled acanthophyses; BASIDIA (2)4-spored, 55-90(110) x 16-24 microns, clavate, thin-walled, often with lateral acicular prongs, sterigmata 14-19 microns long, 4-5 microns wide at base, subulate, slightly incurved; PARAPHYSOIDS (1.5)2-2.5 microns wide, simple to branched, hyphal-like; PSEUDOCYSTIDIA embedded at first, (35)50-60(75) x (9)10-12 microns, flexuous-cylindric to emergent-ampulliform, bearing one to several apical gemmae [asexual propagules], contents of pseudocystidia often "with a conspicuous globoid, hyaline in KOH, not darkening in sulphobenzaldehyde"; ACANTHOPHYSES 20-100 x 5-20 microns, cylindric to broadly clavate, uniformly thin-walled, bearing scattered, delicate, acicular prongs mostly toward apex, the individual prongs seen to advantage in Melzer''s reagent, 3-7 microns long and about 0.7 microns wide; CONTEXT monomitic, composed of hyphae that are 2-2.5(3) microns wide, subregular, branched, thin-walled, and clamped, (Lemke)

Notes:
Aleurodiscus penicillatus has been recorded from BC, WA, OR, ID, ON, PQ, CA, NH, NY, NC, and VT, (Ginns). Collections were examined from BC, OR, ID, ON, PQ, CA, NY, and VT, (Lemke).

Synonyms and Alternate Names:
Peniophora atkinsonii Ellis & Everh.
Thelephora chailletii (Pers.) Fr.