Aleurodiscus subroseus S.H. He & Y.C. Dai

Tian, Yan, Ghobad-Nejhad, Masoomeh, He, Shuang-Hui & Dai, Yu-Cheng, 2018, Three new species of Aleurodiscus s. l. (Russulales, Basidiomycota) from southern China, MycoKeys 37, pp. 93-107 : 99

Aleurodiscus subroseus S.H. He & Y.C. Dai sp. nov. Figs 2 d–e, 5

Diagnosis.

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.

Holotype.

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).

Etymology.

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

Basidiomata.

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.

Microscopic structures.

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).

Additional specimens examined.

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).

Remarks.

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).