Summary: Features include 1) a discoid fruitbody (or subpileate from a reduced base), growing on live conifer bark, 2) a spore-bearing surface that dries cream-buff with grayish tints, 3) a thick determinate margin, 4) spores that are oval to broadly elliptic, amyloid, and minutely verruculose in Melzer''s reagent, the wall thickening up to 2 microns, 5) a catahymenium composed of large basidial elements, scattered hypha-like paraphysoids, and skeletal encrusted paraphysoids (cystidiohyphidia), and 6) a dimitic context mostly of thick-walled skeletal hyphae, (differing microscopically from Aleurodiscus species).
Microscopic: SPORES (12)15-18(20) x (10)11-15(16) microns, ovoid to broadly elliptic, flattened adaxially, minutely verruculose in Melzer''s reagent, amyloid, wall thickened up to 2 microns, apiculate; BASIDIA 4-spored, 55-90(110) x 8-12 microns, flexuous-cylindric to subclavate when mature, sterigmata slender up to 14(16) microns long and 2-3 microns wide at base; simple PARAPHYSOIDS scattered, 3-4 microns wide, thin-walled; skeletal paraphysoids 3.5-5(6) microns wide, cylindric, aseptate, walls thickened, smooth to wrinkled, the cystidiohyphidia "generally apically incrusted, with the incrustation dissolving in KOH"; CONTEXT dimitic, mostly of skeletal hyphae (2)3.5-4.5(6) microns wide, aseptate, colorless to yellowish in KOH, thick-walled, generative hyphae scant, 1.5-3.5(4) microns wide, irregular, branched, with scattered clamp connections, (Lemke)
Notes: Aleurocystidiellum subcruentatum has been found in BC, WA, OR, NS, ON, PQ, AK, CA, NH, and NY, (Ginns), and China and Japan, (Lemke).
Habitat and Range
SIMILAR SPECIES
Aleurodiscus spp. share catahymenial organization, large basidia, and amyloid spores, but the diagnostic cystidiohyphidia present in Aleurocystidiellum subcruentatum are foreign to Aleurodiscus, and it lacks the sterile elements (acanthophyses, pseudocystidia) typically found in Aleurodiscus; furthermore, Aleurocystidiellum subcruentatum is decidedly dimitic, (Lemke).
Habitat
on conifer bark "of live trees, sometimes on bark lesions on suppressed trees"; Abies grandis (Grand Fir), Picea glauca (White Spruce), P. rubens (Red Spruce), P. sitchensis (Sitka Spruce), Pseudotsuga menziesii (Douglas-fir), (Ginns), primarily on bark of Picea (spruce) in North America, occurring in Europe on Pinus, reported from Japan on Tsuga diversifolia (Japanese Hemlock), Thuja sp., and Cryptomeria japonica (Japanese-cedar), and from China on Abies (fir), (Lemke)