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Species Information
Summary: Features include 1) growth on the bark of recently dead branches on live conifers, primarily fir, 2) disc-shaped or cup-shaped fruitbodies at first 0.0-0.5cm across, sometimes becoming confluent, the surface salmon pink when fresh and producing spores, with a distinct margin ringed with tiny white hairs, the abhymenial surface white, gray, or pale brown and finely hairy or matted, 3) spores large and nearly round to broadly elliptic, with amyloid spines, 4) a hymenium of a) basidial elements, b) hyphidia, c) pseudocystidia (not darkening in sulphobenzaldehyde) typically with 1 to several, successively smaller apical swellings, and d) crystals up to 10 microns wide (which also occur in the context), and 5) a context that is monomitic without clamp connections. A. amorphus is rare to uncommon within the range of Aleurodiscus grantii, a similar common species.
Aleurodiscus amorphus has been found in BC, WA, OR, ID, AB, MB, NB, NF, NS, ON, PE, PQ, SK, YT, AZ, CA, CO, CT, MA, ME, MI, MN, MO, MT, NH, NY, TN, VT, WI, WV, (Ginns(5), who notes that "From the Pacific Coast to the eastern foothills of the Rocky Mountains, the very similar, Aleurodiscus grantii [italicized] is more common"). A. amorphus also found in Mexico, Europe, Russia (Siberia), Japan, and China, (Ginns(16)). It occurs in Switzerland (Breitenbach), and Sweden (Eriksson).
Fruiting body: 1-5cm wide, 0.05-0.1cm thick, flat and rounded, slightly convex and discomycete-like, consistency firm, subcoriaceous (somewhat leathery), upper (spore-bearing) surface ochraceous, pinkish gray to orange-red; margin narrow and distinct, (Eriksson), 0.1-0.7cm wide, disc-shaped to cushion-shaped, also sometimes cup-shaped, usually in small groups or cespitose, "isolated or concrescent, breaking through the bark and broadly attached in the center", margin "fringed-filamentous and often arched upward", consistency waxy, soft; upper surface "pale to red-orange, fading to pink-gray when old"; upper surface smooth, farinose (mealy), dull; margin "somewhat lighter-toned to whitish"; lower surface whitish, tomentose, (Breitenbach), 0.1-0.5cm across, disc-shaped or pezizaeform [cup-shaped like Peziza], typically circular, scattered to gregarious, sometimes confluent, attached by short central base up to 0.05cm x 0.05cm, surface flat to slightly convex; when fresh and producing spores salmon pink, when old or after storage pallid, pinkish orange, or olive ochraceous; finely granulose; "margin determinate, ringed with white hairs, cottony to fimbriate, sometimes fasciculate and then appearing hirsute", up to 0.1cm long; abhymenial surface white, gray, blackish gray, or pale brown, "matted tomentose to finely hirsute", (Ginns(16)), spore deposit white (Buczacki)
Microscopic: SPORES about 25 x 20 microns, nearly round to broadly elliptic, "densely covered with fine, cylindrical to slightly conical and abruptly cut (not tapering) spines"; BASIDIA 4-spored, about 100 x 25 or even larger, sterigmata 15-25 microns long; PARAPHYSOID HYPHAE "present between the basidia, moniliform (like a string of pearls) and not projecting", HYPHAE "monomitic with simple septate hyphae, 2-4 microns wide, in an open texture of distinct hyphae", (Eriksson), SPORES 25-30 x 22-25 microns, nearly round to oval, with fine blunt spines, colorless, amyloid; BASIDIA 4-spored, 140-180 x 20-30 microns, without basal clamp connection; CYSTIDIA 100-200 x 15 microns, moniliform hyphal ends; HYPHAE monomitic 2-4 microns wide, septa without clamp connections, (Breitenbach), SPORES (22)24-28(32) x (18)20-23(26) microns, broadly elliptic to nearly round, with amyloid spines up to 4 microns long, wall either colorless and thin or pale yellow and thickened, acyanophilic, apiculus broad and blunt; BASIDIA 4-spored, about 200 x 22-28 microns, tapering to a narrow (4-5 microns) base, basal septum without clamp connection, sterigmata 30-40 microns long and up to 7.5 microns wide at base; HYPHIDIA scattered, (2)3-5 microns, cylindric or some irregularly swollen, "straight to wavy, some with one or two branches"; PSEUDOCYSTIDIA usually numerous, "typically with 1 to several, successively smaller, acropetal, apical swellings" up to 10-11 microns wide (moniliform), acyanophilic, inamyloid, not darkening in sulphobenzaldehyde; CRYSTALS: hymenium and context with few to numerous, small to large (up to 10 microns in diameter) crystals scattered throughout; HYPHAE monomitic, generative hyphae in context 3-5 microns wide, colorless, simple-septate, thin-walled to rather thin-walled, "the exterior surface of the walls swelling in 2% KOH, with few to numerous segments crystalline incrusted", branched, inamyloid, acyanophilic; ''external hyphae, including those forming the "hairs" around the hymenial surface and those of the abhymenial surface, hyaline, pale yellow or some on the abhymenial surface yellow-brown, thin- to rather thin-walled, septate, rarely branched'', the branches arising as an apical dichotomy, encrusted with few to numerous (up to 5 microns), roughed or angular crystals (3)4-6.5 microns in diameter, (Ginns(16))
Habitat / Range
apparently "an early invader of dead or nearly dead branches in the lower crown, primarily on Abies spp., basidiomes produced on bark of recently dead limbs and stems; parasitic, causing cankers on branches of suppressed trees, main stems and often killing suppressed saplings", associated with a white rot; Abies, Larix, Picea, Pinus, Pseudotsuga, Thuja, Tsuga, (Ginns(5)), on dead wood still with bark, principally of Abies (fir), more rarely on Picea (spruce), "on trunks and branches, both fallen and standing or attached respectively", (Breitenbach for Europe), Abies, Picea abies, usually "grows on nearly or recently dead, but still attached lower branches", annual, developing during humid periods, (Eriksson), all year (Buczacki)
Similar Species
Aleurodiscus grantii also has a discoid or pezizoid fruitbodies with large, spiny, amyloid spores, but 1) has clamp connections at about 10% of the septa on the context hyphae, and at the base of nearly all mature basidia, whereas A. amorphus lacks clamp connections, 2) has slightly larger spores (typically has some spores over 30 microns, whereas in A. amorphus it is unusual to find spores over 28 microns long), 3) lacks pseudocystidia, whereas A. amorphus has broad, apically moniliform pseudocystidia (in A. grantii some hyphidia in some specimens have the apical part strangulated to form irregular to moniliform swellings, and these strangulated hyphidia resemble the pseudocystidia of A. amorphus, but they never produce swellings that are as uniformly globose [spherical] or as broad (up to 11 microns) as those of A. amorphus), (Ginns(16)). See also SIMILAR section of Aleurocystidiellum disciformis.
