Aleurodiscus subcerussatus S.H. He, Y.F. Cao & Ghob.-Nejh., sp. nov.
MycoBank number: MB; Index Fungorum number: IF; Facesoffungi number: FoF 10785;
Sexual state: Fruiting body – Basidiomata annual, resupinate, effused, closely adnate or loosing with age, inseparable from substrate or easily detached with age, coriaceous, at first as small patches, later confluent up to 4 cm long and 1 cm wide, 80–400 μm thick. Hymenophore smooth, pale orange (5A3), light orange [(5A(4–5)] to greyish orange [5B(3–5)], slightly darkening in KOH, uncracked when juvenile, densely and deeply cracked when mature; margin thinning out, indistinct, concolorous with hymenophore.
Microscopic structures – Hyphal system monomitic, all hyphae with clamps. Subiculum indistinct; hyphae colorless, thin- to slightly thick-walled, smooth, loosely interwoven, more or less parallel to substrate, moderately branched and septate, 2–5 μm in diam. Subhymenium thickening, composed of vertically arranged hyphae, gloeocystidia and acanthophyses. Gloeocystidia abundant, variable in shape and size in different stages, narrowly clavate to subcylindrical when mature, slightly thick-walled, with liquid substances or sometimes empty, 55–95 × 7–10 μm. Acanthophyses numerous, hyaline, variable in shape and size, hyphoid or arose from a clavate base, mostly branched, with numerous spines, transitional forms from smooth subclavate cystidia-like structures to well-developed acanthophyses present, 25–55 × 2–6 μm (spines excluded). Basidia not seen; basidioles rare, scattered in acanthophyses, clavate to subcylindrical. Basidiospores rare, ellipsoid, bearing an apiculus, hyaline, thin-walled, smooth, amyloid, acyanophilous, 6.3–7 × 2.8–4 μm, L = 7 μm, W = 3.3 μm, Q = 2.1 (n = 6/1).
Asexual state: not observed.
Material examined: CHINA, Jilin Province, Antu County, Changbaishan Nature Reserve, on branches of dead standing planted angiosperm tree, 9 September 2011, Ghobad-Nejhad 2360 (BJFC 012135, holotype; isotypes in ICH); Beijing, Huairou County, Labagoumen Forest Park, on fallen angiosperm branch, 25 August 2020, He 6847 (BJFC 033796); Pinggu County, Xiniujiaoyu Village, on fallen angiosperm branch, 16 September 2020, He 6964 (BJFC 033913).
Sequence data: ITS: MH109051 (ITS5/ITS4); LSU: MH109045 (LROR/LR7)
Notes: Morphologically and phylogenetically, A. subcerussatus belongs to the A. cerussatus group that is characterized by having numerous acanthophyses and smooth basidiospores. In the phylogenetic tree, A. subcerussatus clustered with A. canadensis Skolko (Fig. XX). However, the latter species has basidia with two sterigmata and larger basidiospores (12–18 × 9–13 μm, Núñez and Ryvarden 1997). Aleurodiscus parvisporus Núñez & Ryvarden from Japan is similar to A. subcerussatus but differs in having subglobose basidiospores 5–6 × 4–5 μm (Núñez and Ryvarden 1997). Aleurodiscus cerussatus.
Fig. 4. Basidiomata of Aleurodiscus subcerussatus. A Ghobad-Nejhad 2360 (BJFC 012135, holotype). B He 6847 (BJFC 033796). C He 6964 (BJFC 033913). Scale bars: A–C = 1 cm.
Fig. 5. Microscopic structures of Aleurodiscus subcerussatus (BJFC 012135, holotype). a Basidiospores. b Basidioles. c Gloeocystidia. d–e Acanthophyses. f Generative hyphae. Scale bars: a–f = 10 μm.