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Page number:252 
Description type:Non-original description 
Description:Aleurodiscus lividocoeruleus (Karst.) Lemke, comb. nov. (Fig. 13) Corticium lividocoeruleum Karst., Not. Sälsk. Faun. et Flor. Fenn. Fbrh. 9: 570. 1868, Bidr. Kdnn. Finl. Nat. Folk 25: 315. 1876, ibid. 37: 151. 1882, ibid. 48: 415. 1889, Icon. Hymen. Fenn. 3: 8. 1889.
Gloeocystidium lividocoeruleum (Karst.) Höhn. et Litsch., K. Akad. Wiss. Wien Nat.-Math. Kl. Sitzungsb. 115: 1554. 1906.
Gloeocystidiellum lividocoeruleum (Karst.) Donk, Fungus 26: 9. 1956. Basidiocarp corticioid, in linear to irregularly effused patches up to 10 cm long and 3 cm wide, confluent; margins determinate, adnate. Fructification 100-230 µm thick in cross section; texture inconspicuous-pruinose to adnatesubceraceous or submembraneous. Hymenial surface continuous, variously colored, often partially pallid to livid, finally partially to completely plumbeous to bluish-black. Context monomitic, composed of branched, conspicuously clamped hyphae, 2-2.5(-3) µm in diameter, with thin to partially thickened walls. Catahymenium consisting of numerous to scattered acanthophyses, embedded pseudocystidia, and basidial elements. Acanthophyses mostly subclavate, (7-)10-18(-20) x (2.5-)3-5(-6) µm, apically pronged. Pseudocystidia (macrocystidia) flexuous-cylindric, (25-)30-80 x (4.5-)5.5-8(-9) µm, often apically moniliform, walls thin to partially thickened; contents faintly yellowish in KOH, darkening in sulphobenzaldehyde. Basidia at maturity subclavate, (15-)20-25(-30) x (4-)4.5-5(-5.5) µm; bearing (two-) four sterigmata up to 5.5 µm long and 1 µm wide at base. Basidiospores ellipsoid to subcylindrical, 5.5-7(-8) x 2.5-3.5(-4) µm, apiculate, rounded at both ends, thin-walled, smooth, amyloid in Melzer's.
Distribution: Ontario, Nova Scotia, Manitoba, British Columbia; New England, New York, Idaho, Wisconsin, Montana, Washington; Europe. Habitat: This species is apparently widespread in Northern conifer forests, where it occurs principally on dry, decorticated coniferous wood. The fungus, unlike most of the Aleurodisci, assumes a truly saprobic habit. On the basis of this habit, A. lividocoeruleus approaches Xylobolus Karst.; but that genus, as currently defined, comprises only dimitic, euhymenial forms.
Discussion: It was keen observation on the part of Eriksson (1954, p. 192) to note the apparent relationship of this species with Aleurodiscus. Eriksson further contends that Gloeocystidiellum Donk, at least in part, is related to Aleurodiscus. Certainly, one could argue strongly for the inclusion of Gloeocystidiellum luridum (Bres.) Boidin and G. leucoxanthum (Bres.) Boidin within Aleurodiscus. It remains to be proved, however, which of the remaining species of Gloeocystidiellum are, likewise, referable to Aleurodiscus. At best, I would consider the type species of Gloeocystidiellum, G. porosum (Berk. et Curt.) Donk, rather remotely related to Aleurodiscus (sensu stricto).
All of the amyloid-spored Aleurodisci which lack acanthophyses possess roughened spores. This condition appears to be generally true for Gloeocystidiellum, for which Eriksson (1954, p. 191) points out the general presence of roughened spores in the amyloid-spored Gloeocystidiella.
The presence of acanthophyses, moniliform pseudocystidia, and smooth, amyloid spores is a combination of characters found only in three generaAleurodiscus (pro parte), Stereum Hill per Gray (pro parte), and Xylobolus Karst. Microscopically, A. lividocoeruleus is a monomitic Xylobolus, and is most closely related to A. cerussatus (Bres. )Höhn. et Litsch. and A. bertii Lloyd. These three species are apparently true saprobes and have relatively small spores for their genus.
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