Summary:
Features include 1) resupinate growth on wood (mostly hardwood) in waxy to thickly membranous patches, 2) a surface that is whitish, then yellowish to pink-tinted, usually some shade of brown, 3) a characteristic cracking pattern when mature and dry, 4) spores that are broadly elliptic, smooth, and weakly amyloid, 5) basidia over 40 microns long, 6) projecting hyphidia between the basidia, 7) gloeocystidia that are long (>100 microns) tubular, sinuous, and sulfo-positive, and 8) a monomitic hyphal system with clampless septa.

Microscopic:
SPORES 6.8-8.4(9.4) x 5.0-5.6(6.0) microns, nearly round to broadly elliptic, smooth, weakly amyloid, mottled on the inner surface in Melzer''s reagent, thin-walled, "with a rather broad, distinct apiculus which is smoothly molded into the spore wall"; BASIDIA 40-75(100) x 6.0-8.0 microns, clavate, most 4-spored, sterigmata up to 5.0 microns long, a few 2-spored; GLOEOCYSTIDIA numerous, 120-300 x 6-11 microns, "sinuous, tubular, typically broader at the base, apex broadly rounded, thin-walled", the contents colorless to yellowish green in KOH, usually homogeneous, sulfo-positive; HYPHIDIA numerous, 2-3 microns wide, "filiform, some weakly branched at the apex", HYPHAE monomitic; subiculum a layer about 50 microns thick next to substrate, "with hyphae woven, distinct, parallel"; hyphae 2.0-3.6(4.4) microns wide, colorless, inamyloid, thin-walled, lacking clamp connections; subhymenium up to 300 microns thick, compact, indistinct, (Ginns(24)), SPORES 6-7 x 4-4.5 microns, broadly elliptic or nearly round, smooth, amyloid, thin-walled, with granular oily contents or with numerous oil droplets or irregular oil bodies; BASIDIA normally 4-spored, 40-60 x 6-7 microns, basally tapering to a narrow stem-like part, no basal clamp connection, numerous oil droplets or irregular oil bodies in the protoplasm; numerous projecting paraphysoid hyphae between the basidia; GLOEOCYSTIDIA (= pseudocystidia) numerous, 150-200 microns or more long, mostly 8-10 microns wide, tubular, sinuose, "with granular, oily, yellowish contents, which react positively with sulfovanilline", adventitious septations frequent; HYPHAE monomitic: hyphae 1.5-2.5 microns wide, thin-walled, without clamp connections, BASAL HYPHAE arranged in horizontal layer about 50 microns deep, parallel to substrate, SUBHYMENIAL HYPHAE more densely intertwined and oriented more vertically, (Eriksson), SPORES 6-8 x 4-5 microns, elliptic, smooth, amyloid, colorless; BASIDIA (2-)4-spored, 50-60 x 6-7 microns, narrowly clavate, without basal clamp connection; cylindric HYPHIDIA present between the basidia, 60-70 x 2-3 microns; GLOEOCYSTIDIA 100-150 x 6-8 microns, (according to Julich 150-250 x 8-12 microns), cylindric, sinuous, with granular contents, sulfo-positive; HYPHAE monomitic: hyphae 2-4 microns wide, thin-walled, septa without clamp connections, (Breitenbach)

Notes:
Collections were examined from WA, MB, ON, AZ, CA, CT, FL, MI, NY, TN, WI: the species is also reported from BC, OR, NF, PQ, LA, MA, ME, NC, TN, and VT, (Ginns(24)). It occurs in Europe including Scandinavia and the United Kingdom, (Eriksson). It also occurs in Switzerland and Asia, (Breitenbach).

Synonyms and Alternate Names:
Peripherostoma fuscum (Pers.: Fr.) Gray
Sphaeria fusca Pers.