Gloeomyces subcerussatus S.H. He & Ghob.-Nejh., 2025

Gloeomyces subcerussatus S.H. He & Ghob.-Nejh. , sp. nov. MB 843410 View Materials . Figs 8 View Fig , 9 View Fig .

Etymology: The species epithet “ subcerussatus ” refers to the morphological similarity to A. cerussatus .

Typus: China, Jilin Province, Antu County, Changbaishan Nature Reserve , on branches of dead standing planted angiosperm tree, 9 Sep. 2011, M. Ghobad - Nejhad, Ghobad-Nejhad 2360 (holotype BJFC 012135 About BJFC ; isotypes in ICH) .

Basidiomes annual, resupinate, effused, closely adnate or loosening with age, inseparable from substrate or easily detached with age, coriaceous, at first as small patches, later confluent up to 4 cm long, 1 cm wide, 80–400 µm thick in section. Hymenophore smooth, pale orange (5A3), light orange [5A(4–5)] to greyish orange [5B(3–5)], slightly darkening in KOH, not cracked when juvenile, densely and deeply cracked when mature; margin thinning out, indistinct, concolourous with hymenophore. Hyphal system monomitic, all hyphae with clamps. Subiculum indistinct; hyphae colourless, thin- to slightly thick-walled, smooth, loosely interwoven, more or less parallel to substrate, moderately branched and septate, 2–5 µm diam. Subhymenium thickening, composed of vertically arranged hyphae, gloeocystidia and acanthohyphidia. Gloeocystidia abundant, variable in shape and size in different stages, narrowly clavate to subcylindrical when mature, slightly thick-walled, 55–95 × 7–10 µm. Acanthohyphidia numerous, colourless, variable in shape and size, hyphoid or arising from a clavate base, mostly branched, with numerous spines, transitional forms from smooth subclavate cystidia-like structures to well-developed acanthohyphidia present, 25–55 × 2–6 µm (spines excluded). Basidia not seen; basidioles rare, scattered among acanthohyphidia, clavate to subcylindrical. Basidiospores ellipsoid, colourless, thin-walled, smooth, amyloid, acyanophilous, 5.8–7.0 × 2.8–4.0 µm, L = 6.7 µm, W = 3.2 µm, Q = 2.1 (n = 10/2), only few spores observed.

Additional specimens examined: China, Beijing, Huairou District, Labagoumen Forest Park, on fallen angiosperm branch, 25 Aug. 2020, S.H. He, He 6847 ( BJFC 033796 About BJFC ); Pinggu District , Xiniujiaoyu Village , on fallen angiosperm branch, 16 Sep. 2020, S.H. He, He 6964 ( BJFC 033913 About BJFC ) .

Notes: Gloeomyces subcerussatus is characterized by clamped generative hyphae, numerous acanthohyphidia, variably shaped and sized gloeocystidia and a habitat on angiosperm branches. In the tree, G. subcerussatus formed a lineage sister to G. bambusinus and G. dextrinoideophyses , both of which differ by having simple-septate generative hyphae and growing on bamboo in subtropical to tropical areas ( Dai et al. 2017b, Tian et al. 2018). Gloeomyces parvisporus is similar to G. subcerussatus by sharing thickened subhymenium, clamped generative hyphae and well-developed gloeocystidia and acanthohyphidia but differs in having subglobose basidiospores 5–6 × 4–5 µm ( Núñez & Ryvarden 1997). Gloeomyces cerussatus differs from G. subcerussatus by having distinctly larger basidiospores (10– 12 × 6–7 µm; Núñez & Ryvarden 1997).