Steccherinum tenuissimum and S. xanthum spp. nov. (Polyporales, Basidiomycota): New species from China Author Wu, Ya-Xing Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Ministry of Education, Southwest Forestry University, Kunming, P. R. China, & College of Biodiversity Conservation, Southwest Forestry University, Kunming, P. R. China Author Wu, Jian-Rong College of Biodiversity Conservation, Southwest Forestry University, Kunming, P. R. China Author Zhao, Chang-Lin text PLoS ONE 2021 e 0244520 2021-01-13 16 1 1 13 http://dx.doi.org/10.1371/journal.pone.0244520 journal article 10.1371/journal.pone.0244520 1932-6203 PMC7806176 33439872 12631009 Steccherinum tenuissimum C.L. Zhao & Y.X. Wu , sp. nov. Figs 3 and 4 MycoBank No.: MB 837795 Holotype : China . Yunnan Province , Pu’er , Laiyanghe National Forest Park , on fallen angiosperm branch, 30 September 2017 , CLZhao 3153 ( SWFC ). Etymology: tenuissimum (Lat.) : referring to the relatively thin basidiomata. Basidiomata: Annual, adnate, without odour or taste when fresh, becoming membranaceous up on drying, very thin, up to 20 cm long, 3 cm wide, 50–100 μm thick. Hymenial surface odontioid, with round aculei, 3–4 per mm, 0.2–0.5 mm long, white to cream when fresh, turning to cream to olivaceous buff upon drying. Hyphal structure: Hyphal system dimitic, generative hyphae with clamp connections, colourless, thin-walled, branched, interwoven, 1.8–3.5 μm in diameter, IKI–, CB –; skeletal hyphae Fig 3. Basidiomata of Steccherinum tenuissimum . Bars: A = 1 cm, B = 1 mm (holotype). https://doi.org/10.1371/journal.pone.0244520.g003 colourless, thick-walled, unbranched, 2.4–4.5 μm in diameter, IKI–, CB +; tissues unchanged in KOH. Hymenium: Cystidia numerous, colourless, strongly encrusted, 22–39 × 4.5–6 μm; cystidioles absent. Basidia subclavate, with 4-sterigmata and basal clamp connections, 9.5– 19 × 2.5–5.5 μm; basidioles dominant, in shape similar to basidia, but slightly smaller. Spores: Basidiospores ellipsoid, colourless, thin-walled, smooth, with oil drops, IKI–, CB –, 3–5(–5.5) × 2–3.5 μm, L = 4.16 μm, W = 2.86 μm, Q = 1.40–1.52 (n = 120/4). Additional specimens ( paratypes ) examined: China . Yunnan Province , Yuxi , Xinping County , Mopanshan National Forest Park , on fallen angiosperm branch, 16 January 2017 , CLZhao 894 ( SWFC ) ; Xinping County , the Ancient Tea–Horse Road , on fallen angiosperm branch, 13 January 2018 , CLZhao 5100 ( SWFC ) ; Pu’er , Jingdong County , Wuliangshan National Nature Reserve , on fallen branch of Pinus , 5 October 2017 , CLZhao 4294 ( SWFC ) .