Dichostereum austrosinense 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 : 114-116

Dichostereum austrosinense S.H. He & S.L. Liu sp. nov. Figs 2a, 3, 6a

Typification.

CHINA. Guangxi Autonomous Region, Jinxiu County, Dayaoshan Nature Reserve, Shengtangshan, on fallen angiosperm trunk, 15 Jul 2017, He 4871 (holotype, BJFC 024390, ITS GenBank accession number: MH538317; isotype in CFMR).

Etymology.

" austrosinense " referring to the distribution in southern China.

Basidiomata.

Perennial, resupinate, effused, closely adnate, inseparable from substrates, coriaceous to soft corky, at first as irregular small patches, later confluent up to 15 cm long, 4.5 cm wide, up to 1 mm thick. Hymenophore surface smooth, greyish-orange [5B(4-5)], brownish-yellow [5C(7-8)] to light brown [6D(4-8)], 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- to slightly thick-walled, 2-3 µm in diam. Dichohyphae dominant, hyaline to yellow, distinctly thick-walled, dichotomously branched with acute tips, weakly dextriniod. Catahymenium composed of dichohyphae, gloeocystidia, basidia and basidioles. Dichohyphae in this layer abundant, similar to those in the context, but strongly dextrinoid, more slender and more frequently branched, 20-50 μm across, 2-4 µm wide at lowest part. Gloeocystidia abundant, subcylindrical to subfusiform, hyaline, slightly thick-walled, with or without solidified contents, 80-130 × 8-15 µm. Basidia narrowly cylindrical, usually slightly sinuous, hyaline, thin-walled, with 4 sterigmata and a basal clamp connection, 50-80 × 5-8 µm; basidioles in shape similar to basidia, but slightly smaller. Basidiospores abundant, subglobose with a distinct apiculus, hyaline to pale yellowish-brown in KOH, thick-walled, strongly amyloid, (7-) 7.3-8 (-9) µm in diam.; walls ornamented with large warts and crests.

Additional specimens examined.

CHINA. Hainan Province, Lingshui County, Diaoluoshan Nature Reserve, on fallen angiosperm trunk, 17 Mar 2016, He 3551 (BJFC 022052); Jiangxi Province, Lianping County, Jiulianshan Nature Reserve, on fallen angiosperm branch, 13 Aug 2016, He 4316 (BJFC 023758).

Remarks.

Dichostereum austrosinense is overall characterised by the relatively large gloeocystidia and basidiospores with large warts and crests. Dichostereum peniophoroides (Burt) Boidin & Lanq. is similar to D. austrosinense but differs in having wider gloeocystidia (7-22 µm), slightly larger basidiospores (7-9 µm) with larger ornamentations and a distribution in Caribbean regions ( Lanquetin 1973; Boidin and Lanquetin 1980). Dichostereum austrosinense is also similar to D. rhodosporum (Wakef.) Boidin & Lanq. which differs in having paler basidiomata, smaller ornamentations of basidiospores and a distribution in Australia and New Zealand ( Boidin and Lanquetin 1980, Figs 2 and 6).