E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include 1) growth on twigs and stems of species of Rosaceae, 2) fruitbodies as patches that are palish with orange tinges, thin and leathery, and often pruinose, 3) spores that are oval to oval-elliptic, amyloid, and finely spiny, 4) a catahymenium composed of a) a loose network of basidial elements, b) naked dendrohyphidia (may be covered with crystals), and c) abundant yellowish pseudocystidia (macrocystidia) of a deep origin, and 5) a monomitic context without clamp connections.

Aleurodiscus aurantius has been recorded from BC, ON, and CA, (Ginns). It occurs in Europe including Denmark, Norway, and Sweden, (Eriksson). Collections were examined from BC, CA, France, Germany, Norway, and Sweden, and the range includes South America, Japan, and New Zealand, (Lemke).

Fruiting body:
0.01-0.03cm thick, effused (spread out on substrate), closely attached, consistency subcoriaceous (somewhat leathery); "palish with orange tinges"; usually smooth; without distinct margin, (Eriksson), corticioid, in resupinate patches 0.5-1.5cm wide, 0.015-0.0375cm thick, sometimes coalescing to form wider areas, texture densely pruinose to compact-submembranous; color variable, drying isabelline to cinereous, or even fuscous; drying rimose [cracked] to continuous; margin at first indeterminate [indistinct], adnate [tightly attached], fimbriate [fringed], and lighter in color, becoming more distinct and colored like the rest of the surface, (Lemke), spore deposit white (Buczacki)

Microscopic:
SPORES about 20 x 13 microns, elliptic to nearly round, finely echinulate (spiny), amyloid; BASIDIA 4-spored, about 60 x 15 microns, sterigmata about 15 microns long; DENDROHYPHIDIA numerous, richly branched and covered with crystals; PSEUDOCYSTIDIA "variable in shape, narrowly paraphysoid with rounded apex, or wider and more rounded, tapering basally to a long shaft with a +/- moniliform apex, or even smooth to simply tapering", cell contents yellowish (darken in sulfovanillin), making pseudocystidia easy to separate from basidia; HYPHAE monomitic with hyphae 2.5-4 microns wide, simple-septate, thin-walled, in an open texture, (Eriksson), SPORES (14)16-20(22) x (10)12-15(16) microns, oval to oval-elliptic, "apiculate, flattened adaxially, firm-walled, finely echinulate in Melzer''s, amyloid"; catahymenium composed of a loose network of basidial elements, naked dendrohyphidia, and abundant pseudocystidia (macrocystidia) of a deep origin; BASIDIA 4-spored, (30)50-70(80) x 10-14 microns, cylindric to flexuous-subclavate, sterigmata divergent and up to 20 microns long and 4 microns wide at base; PSEUDOCYSTIDIA embedded, (30)40-60 x 12-20 microns, variable, mostly ampulliform with one to several apical constrictions, contents yellow brown in KOH, PARAPHYSOIDS 2-2.5 microns wide, hypha-like, "without clamps, simple to branched, forming a mass of naked dendrohyphidia at the level of the hymenium"; HYPHAE monomitic, of hyphae 2.5-4 microns wide, simple-septate, thin-walled, branched, (Lemke)