The species is distinct by having corticioid basidiomata, a compact texture, simple-septate generative hyphae, abundant acanthophyses, basidia with an acanthophysoid appendage and smooth basidiospores 7–10 × 4–6 μm and growing on bamboo.

CHINA. Jiangxi Province, Yifeng County, Guanshan Nature Reserve, alt. ca. 800 m, on fallen culms and branches of bamboo, 10 Aug 2016, He 4261 (holotype, BJFC 023703).

“Bambusinus” refers to the substrate of bamboo.

Annual, resupinate, effused, closely adnate, inseparable from substrate, coriaceous, at first as small patches, later confluent up to 30 cm long and 2.5 cm wide, 180–300 μm thick. Hymenophore smooth, white (4A1) to yellowish-white (4A2) when young, becoming greyish-yellow [4B (3–4)] to brownish-orange [6C (5–8)] with age, uncracked or cracked with age; margin abrupt, indistinct, concolorous with hymenophore.

Hyphal system monomitic; generative hyphae simple-septate, colourless, thin- to thick-walled, scattered near the substrate, 2–4 μm in diam. Subiculum thin to indistinct. Subhymenium thick, with compact texture, composed of acanthophyses and gloeocystidia. Acanthophyses abundant, hyphoid or distinctly swollen in the middle part, colourless, thin-walled, with abundant spines in apex, 30–40 × 3–12 μm. Gloeocystidia abundant, flexuous or slightly moniliform with one to several constrictions, slightly thick-walled, negative in sulphobenzaldehyde, 30–55 × 8–13 μm. Basidia subclavate to subcylindrical, colourless, slightly thick-walled, usually with a lateral acanthophysoid appendage, with four sterigmata and a basal simple septum, 25–35 × 7–9 μm. Basidiospores ellipsoid to broadly ellipsoid, bearing a distinct apiculus, colourless, thin-walled, smooth, amyloid, 7–10 × 4–6 μm, L = 8.7 μm, W = 4.9 μm, Q = 1.6–1.9 (n = 90/3).

CHINA. Jiangxi Province, Yifeng County, Guanshan Nature Reserve, alt. ca. 800 m, on fallen culms and branches of bamboo, 10 Aug 2016, He 4250 (BJFC 023692) and He 4263 (BJFC 023705).

Aleurodiscus bambusinus is morphologically similar and phylogenetically close to A. dextrinoideophyses S.H. He and A. tropicus L.D. Dai & S.H. He that also grow on bamboo in East Asia (Dai et al. 2017a, b). Aleurodiscus dextrinoideophyses differs from A. bambusinus by having apparently dextrinoid acanthophyses and smaller basidiospores (5–7 × 3–4 μm, Dai et al. 2017b). Aleurodiscus tropicus differs from A. bambusinus by having a looser texture and slightly larger basidiospores (9–12 × 5–7.5 μm, Dai et al. 2017a). The ITS similarity between A. bambusinus (He 4261) and A. dextrinoideophyses (He 4105) is 95.6% of 434 base pairs and, between A. bambusinus (He 4261) and A. tropicus (He 3830), is 97.3% of 582 base pairs. Aleurodiscus aberrans G. Cunn. and A. rimulosus Núñez & Ryvarden are also similar to A. bambusinus, but they differ from this new species by having smooth basidia and growing on angiosperm wood outside of Asia (Núñez and Ryvarden 1997).

Figure 2. 

Basidiomata. a–b Aleurodiscus bambusinus (a He 4250 b holotype, He 4261) c A. isabellinus (holotype, KKN-2017-19) d–e A. subroseus (d He 5571 e He 4895). Scale bars: 1 cm.

Figure 3. 

Microscopic structures of Aleurodiscus bambusinus (drawn from the holotype). a Basidiospores; b Basidia c Gloeocystidia d–e Acanthophyses f Generative hyphae.

The species is distinct by having soft, yellow to yellowish-brown and corticioid basidiomata, a loose texture, abundant yellow acanthophyses, simple-septate generative hyphae and smooth basidiospores 6–8.5 × 3–4 μm.

CHINA. Yunnan Province, Dali County, Cangshan Nature Reserve, alt. ca. 2600 m, on fallen decorticated angiosperm branches, 27 Oct 2017, KKN-2017-19 (holotype in CFMR, isotype in BJFC).

“Isabellinus” refers to the yellowish-brown basidiomata.

Annual, resupinate, effused, adnate, inseparable from substrate, soft, membranaceous to coriaceous, at first as small patches, later confluent up to 15 cm long and 1 cm wide, 150–300 μm thick. Hymenophore smooth, light orange [5A(4–5)] , greyish-orange[5B(5–6)], orange [5B(7–8)] to brownish-yellow [5C(7–8)], uncracked or cracked with age; margin thinning out, fimbriate, white (5A1) when juvenile, becoming abrupt, indistinct, concolorous with hymenophore when mature.

Hyphal system monomitic, generative hyphae simple-septate, colourless, thin- to slightly thick-walled, straight, loosely interwoven, frequently branched and septate, 2–4 μm in diam. Acanthophyses abundant, colourless to yellow, thick-walled, hyphoid or arising laterally or apically from a clavate or cylindrical base 30–50 × 5–7 μm, with abundant spines in upper part, some hyphoid ones near substrate with long spines (branches) resembling binding hyphae. Gloeocystidia abundant, embedded, colourless, slightly thick-walled, subcylindrical or slightly moniliform, negative in sulphobenzaldehyde, 35–110 × 5–8 μm. Basidia clavate, colourless, thin-walled, with four sterigmata and a basal simple septum, 40–55 × 6–7 μm. Basidiospores ellipsoid to oblong ellipsoid, bearing a distinct apiculus, colourless, thin-walled, smooth, amyloid, (5.5–) 6–8.5 × (2.8–) 3–4 μm, L = 7 μm, W =3.7 μm, Q = 1.9 (n = 24/1).

CHINA. Yunnan Province, Dali County, Cangshan Nature Reserve, alt. ca. 2600 m, on small dead bamboo, 27 Oct 2017, He 5283 (BJFC 024801) and He 5287 (BJFC 024805); on fallen angiosperm branch, 27 Oct 2017, He 5294 (BJFC 024812); Jingdong County, Ailaoshan Nature Reserve, alt. 2450 m, on fallen angiosperm branch, 4 Oct 2017, C.L. Zhao 3843 (SWFC).

All the studied specimens of A. isabellinus lack a true hymenium and only the holotype has a few basidia and basidiospores. Aleurodiscus isabellinus was nested within the A. cerussatus group (Fig. 1). In this group, Aleurodiscus thailandicus S.H. He is similar to A. isabellinus by sharing the yellow basidiomata and acanthophyses, but differs by having two types of gloeocystida and acanthophyses without a clavate or cylindrical base (Dai et al. 2017a). The ITS similarity between A. isabellinus (He 5283) and A. thailandicus (He 4099) is 93.6% of 578 base pairs. Aleurodiscus thailandicus was described from Thailand based on a fertile specimen on bamboo, but later several sterile specimens on bamboo from south-western China were identified as this species according to the sequence data. Morphologically, the soft and yellow to yellowish-brown basidiomata of A. isabellinus resemble the genus Vararia P. Karst. which belongs to Peniophoraceae according to phylogenetic analyses.

Figure 4. 

Microscopic structures of Aleurodiscus isabellinus (drawn from the isotype). a Basidiospores b A basidium and a basidiole c Gloeocystidia d–f Acanthophyses g Generative hyphae.

The species is distinct by having pinkish and corticioid basidiomata when fresh, clamped generative hyphae, moniliform gloeocystidia, presence of acanthophyses (acanthocystidia) and echinulate basidiospores 16–20 × 11–14 μm.

CHINA. Guangxi Autonomous Region, Xing’an County, Mao’ershan Nature Reserve, alt. ca. 1600 m, on dead but still attached branch of living angiosperm tree, 13 Jul 2017, He 4807 (holotype, BJFC 024326).

“Subroseus” (Lat.) refers to the pinkish basidiomata when fresh.

Annual, resupinate, effused, closely adnate, inseparable from substrate, coriaceous, at first as small irregular patches, later confluent up to 35 cm long and 3 cm wide, up to 300 μm thick. Hymenophore smooth, pinkish-white (12A2), pink (12A3), pale orange (6A3) to light orange (6A4) when fresh, becoming pale orange (6A3), light orange [6A(4–5)], greyish-orange [6B(3–6)] to brownish-orange [6C(5–6)] when dry, uncracked; margin abrupt, white and distinct when fresh, becoming concolorous or darker than hymenophore and indistinct when dry, slightly elevated when mature.

Hyphal system monomitic, generative hyphae with clamp connections. Subiculum thin to indistinct. Subhymenium thickening with age, with embedded gloeocystidia, acanthophyses and crystals. Hyphae in this layer colourless, thin-walled, frequently branched and septate, agglutinated, 2–4 μm in diam. Gloeocystidia abundant, moniliform, with one to several constrictions, smooth, slightly thick-walled, negative in sulphobenzaldehyde, 45–70 × 6–12 μm. Acanthophyses (acanthocystidia) abundant, variable in shape and size, subclavate to subcylindrical, with few to many spines at apex, colourless, slightly thick-walled, 30–60 × 6–20 μm. Hyphidia scattered, thin-walled, colourless, rarely branched. Basidia clavate, slightly sinuous, colourless, thin-walled, smooth, with four sterigmata and a basal clamp connection, 52–80 × 13–17 μm. Basidiospores ellipsoid to broadly ellipsoid, bearing a distinct apiculus, colourless, slightly thick-walled, echinulate, strongly amyloid, 16–20 × 11–14 μm, L = 18.4 μm, W = 12.6 μm, Q = 1.5 (n = 90/3) (spines excluded).

CHINA. Guangxi Autonomous Region, Xing’an County, Mao’ershan Nature Reserve, alt. ca. 1600 m, on dead but still attached branch of living angiosperm tree, 13 Jul 2017, He 4814 (BJFC 024333); Jinxiu County, Dayaoshan Nature Reserve, Yinshan Forest Park, alt. ca. 1500 m, on fallen angiosperm branch, 16 Jul 2017, He 4895 (BJFC 024414). Guizhou Province, Jiangkou County, Fanjingshan Nature Reserve, alt. 1500–2000 m, on dead but still attached branch of living angiosperm tree, 11 Jul 2018, He 5558 (BJFC); 12 Jul 2018, He 5571, He 5577, He 5581, He 5585, He 5589 and He 5593 (BJFC).

Aleurodiscus subroseus is morphologically similar and phylogenetically close to A. wakefieldiae Boidin & Beller (Fig. 1), but the latter differs by having longer basidia (80–180 μm) and larger basidiospores (20–28 × 14–20 μm, Núñez and Ryvarden 1997). Aleurodiscus penicillatus Burt is similar to A. subroseus, but differs by growing on gymnosperm wood and having wider basidiospores (13–17 μm, Núñez and Ryvarden 1997). Aleurodiscus mirabilis (Berk. & M.A. Curtis) Höhn. also has pinkish fresh basidiomata and is widely distributed in southern China. However, it can be easily distinguished from A. subroseus by having basally warted basidia and larger basidiospores (24–28 × 14–17 μm, Núñez and Ryvarden 1997). In the phylogenetic tree (Fig. 1), A. penicillatus and A. mirabilis are distantly related to A. subroseus. Aleurodiscus corticola Gorjón et al. from Argentina on bark of living Nothofagus dombeyi also has moniliform gloeocystidia and similar basidiospores with A. subroseus, but differs by having pulvinate and tuberculate basidiomata and absence of acanthophyses (Gorjón et al. 2013).

Figure 5. 

Microscopic structures of Aleurodiscus subroseus (drawn from the holotype). a Basidiospores; b A basidium and a basidiole c Acanthophyses d Gloeocystidia e Hyphidia f Generative hyphae.