Summary:
Features include 1) tiny, circular or wavy or distorted, yellowish brown then blackish fruitbodies, the spore-bearing surface concave then convex, colored dark olivaceous brown to black, the margin at first thick, raised, and yellowish brown, 2) consistency leathery to horny (fleshy-leathery when moist), 3) erumpent growth on birch, and 4) microscopic characters.

Microscopic:
spores (13)15-20(22) x 4-7 microns, narrowly elliptic to subfusiform, straight or slightly curved, colorless becoming yellowish, 1-4-celled, irregularly biseriate to uniseriate in ascus; asci 8-spored, (85)100-120(150) x 12-15 microns, "cylindric-clavate, tapering toward the base"; paraphyses 1.5-2.0 microns wide, filiform, colorless, "septate, simple or branched", "the tips slightly swollen, embedded in a yellowish matrix and forming a dark epithecium"; conidia 50-75 x 2.5-3.5 microns, subfiliform, "sickle-shaped or sigmoid to almost straight", ends pointed, colorless or pale yellowish, 1-4-celled; conidiophores 15-30 x 1.5-2.0 microns, cylindric, colorless, septate, simple or branched; microconidia 7-12 x 1.0-1.5 microns, "bacilliform, straight or slightly curved", colorless, 1-celled

Notes:
Collections were examined from NS, ON, PQ, NH, NY, and PA, (Groves). A collection from BC is at the Pacific Forestry Centre determined by A. Funk.

Synonyms and Alternate Names:
Descomyces albellus (Massee & Rodway) Bougher & Castellano
Hymenogaster albellus Massee & Rodway