Dichostereum boidinii S.H. He & S.L. Liu

Liu, Shi-Liang & He, Shuang-Hui, 2018, Taxonomy and phylogeny of Dichostereum (Russulales), with descriptions of three new species from southern China, MycoKeys 40, pp. 111-126 : 116-119

Dichostereum boidinii S.H. He & S.L. Liu sp. nov. Figs 2b, 4, 6b

Typification.

CHINA. Hubei Province, Wufeng County, Breeding base of Magnolia , on angiosperm stump, 14 Aug 2017, He 5026 (holotype, BJFC 024544, ITS GenBank accession number: MH538324; isotype in CFMR).

Etymology.

" boidinii " (Lat.), named to honour Dr. Jacques Boidin (Lyon, France) for his contribution to the taxonomy of Dichostereum .

Basidiomata.

Perennial, resupinate to effused-reflexed with slightly elevated margin, closely adnate, inseparable from substrates, coriaceous to soft corky, up to 8 cm long, 4 cm wide, 1.5 mm thick. Hymenophore surface smooth, greyish-orange [6B(3-4)], brownish-orange [6C(4-6)] to light brown [6D(4-6)], not cracking; margin abrupt, concolorous or darker than hymenophore surface.

Microscopic structures.

Hyphal system dimitic. Context thickening, compact, composed of generative hyphae, dichohyphae, embedded basidiospores and scattered crystals. Generative hyphae rare, with clamp connections, hyaline, thin-walled, 2-3 µm in diam. Dichohyphae dominant, hyaline to yellow, distinctly thick-walled, dextriniod. Catahymenium composed of dichohyphae, gloeocystidia, basidia and basidioles. Dichohyphae in this layer abundant, similar to those in the context, but strongly dextrinoid, more frequently branched with short terminal branches, 20-40 μm across, 2-4 µm wide at lowest part. Gloeocystidia abundant, fusiform to subulate, hyaline, slightly thick-walled, with solidified contents, 20-60 × 7-12 µm. Basidia subclavate to subcylindrical, hyaline, thin-walled, with 4 sterigmata and a basal clamp connection, 25-40 × 5-7 µm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores subglobose with a distinct apiculus, hyaline to pale yellowish-brown in KOH, thick-walled, strongly amyloid, (5-) 5.5-6.5 (-7) µm in diam.; walls ornamented with warts and crests.

Additional specimens examined.

CHINA. Anhui Province, Huangshan County, Huangshan Nature Reserve, on fallen angiosperm trunk, 21 Oct 2011, He 462 (BJFC 012101); Hainan Province, Lingshui County, Diaoluoshan Nature Reserve, on rotten wood of Dacrydium , 13 Nov 2015, Dai 16117 (BJFC 020210); Jiangxi Province, Anyuan County, Sanbaishan Forest Park, on fallen angiosperm trunk, 15 Aug 2016, He 4410 (BJFC 023851); Yunnan Province, Kunming, Xishan Park, on angiosperm stump, 17 Jul 2013, He 1662 (BJFC 016129).

Remarks.

Dichostereum boidinii is widely distributed in southern China and mainly characterised by the thick, brownish basidiomata and relatively small basidiospores with large warts and crests. Dichostereum pallescens is similar to D. boidinii but differs in having slender dichohyphae and smaller and sparser ornamentations of basidiospores ( Boidin and Lanquetin 1980, Fig. 6). Dichostereum orientale Boidin & Lanq. resembles D. boidinii by sharing short terminal branches of dichohyphae, but differs in having smaller basidiospores (5-5.5 µm in diam.) and a distribution in Africa ( Boidin and Lanquetin 1980). The ornamentation of basidiospores of D. boidinii is similar to D. austrosinense , but the latter species has larger gloeocystidia, basidia and basidiospores.