Summary:
Features include 1) resupinate growth on hardwood, 2) fruitbodies that are tightly attached, waxy, grayish, sometimes with a violet or pink tint, the margin well demarcated, and pubescent when actively growing, 3) spores that are oblong, smooth and inamyloid, 4) obscure dendrohyphidia, 5) cylindric cystidia, and 6) a monomitic hyphal system, the hyphae with clamp connections.

Microscopic:
SPORES 6-8 x 2.5-3 microns, narrowly elliptic-oblong, "more or less obliquely acute towards the apiculus", smooth, inamyloid, acyanophilic, thin-walled; BASIDIA 4-spored, 30-50 x 5-7 microns (when mature), narrowly clavate, with basal clamp connection; DENDROHYPHIDIA "present but often few and difficult to find, not projecting", at the base 2-3 microns wide, lateral branches varying in shape, 1-2 microns wide, as a rule 2-5 microns long; CYSTIDIA "varying in number, sometimes numerous and as a rule easily found, enclosed or somewhat projecting", 50-100 x 5-9 microns, cylindric but tapering toward the base, "apically obtuse, rounded, thin-walled, with continuous, non-granular contents, not reacting to sulfoaldehyde"; HYPHAE monomitic, "hyphae thin or in the basal part with slightly thickened walls", 2-3.5 microns wide, "richly branched and forming a tough context", clamp connections present, "in older parts of fruitbody often hyphal encrustations together with lumps of larger crystals", subhymenium thickening, subiculum usually well developed, (Eriksson), SPORES 5-8 x 2.5-3 microns, oblong, obliquely apiculate and a little flattened laterally; BASIDIA 2-4-spored, 12-45 x 3-7 microns, (Bourdot)

Notes:
Crustomyces expallens has been found in BC, AB, and ON, (Ginns). It has also been found in Denmark, France, and Russia, (Eriksson).

Synonyms and Alternate Names:
Cerocorticium cremoricolor (Berk. & M.A. Curtis) Ginns
Corticium cremoricolor Berk. & M.A. Curtis