Steccherinum tenuissimum C.L. Zhao & Y.X. Wu, 2021

Wu, Ya-Xing, Wu, Jian-Rong & Zhao, Chang-Lin, 2021, Steccherinum tenuissimum and S. xanthum spp. nov. (Polyporales, Basidiomycota): New species from China, PLoS ONE (e 0244520) 16 (1), pp. 1-13 : 7-9

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

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) .

Steccherinum xanthum C.L. Zhao & Y.X. Wu , sp. nov. Figs 5 and 6

MycoBank No.: MB 837796

Holotype: China. Yunnan Province, Pu’er, Jingdong County, Wuliangshan National Nature Reserve , on fallen angiosperm branch, 6 October 2017, CLZhao 4479 ( SWFC).

Etymology: xanthum (Lat.) : referring to the buff hymenial surface of the type specimen.

Basidiomata: Annual, resupinate, adnate, without odour or taste when fresh, becoming membranaceous up on drying, up to 10 cm long, 4 cm wide, 100–200 μm thick. Hymenial surface odontioid, with round aculei, 5–6 per mm, 0.1–0.3 mm long, white to cream when fresh, turning buff to yellow upon drying.

Hyphal structure: Hyphal system monomitic, generative hyphae with clamp connections, colourless, thin-walled, branched, covered by crystals, interwoven, 2–4.5 μm in diameter; IKI–, CB –; tissues unchanged in KOH.

Hymenium: Cystidia numerous, strongly encrusted in the apical part, 35.5–125 × 5–9 μm; cystidioles absent. Basidia clavate, with 4-sterigmata and basal clamp connections, 10–

19.3 × 3–5.2 μm, basidioles dominant, in a shape similar to basidia, but slightly smaller.

Spores: Basidiospores ellipsoid, colourless, smooth, thin-walled, with oil drops, IKI–, CB –, 2.7–5(–5.6) × 2–3.9(–4.4) μm, L = 3.48 μm, W = 2.63 μm, Q = 1.25–1.41 (n = 240/9).

Additional specimens (paratypes) examined: China. Yunnan Province, Pu’er, Zhenyuan County, Heping town , Jinshan Forest Park, on fallen angiosperm trunk, 12 January 2018, CLZhao 5024, 5032, 5044 ( SWFC) ; 21 August 2018, CLZhao 8124 ( SWFC) ; on fallen angiosperm branch 12 January 2018, CLZhao 5030 ( SWFC) ; Jingdong County, Wuliangshan National Nature Reserve , on fallen angiosperm trunk, 6 October 2017, CLZhao 4381 ( SWFC) .

Figures

Fig 3. Basidiomata of Steccherinum tenuissimum. Bars: A = 1 cm, B = 1 mm (holotype). https://doi.org/10.1371/journal.pone.0244520.g003

Fig 4. Microscopic structures of Steccherinum tenuissimum (drawn from the holotype). A: Basidiospores. B: Basidia and basidioles. C: Cystidia. D: A section of hymenium.Bars: A = 5 μm, B–D = 10 μm. https://doi.org/10.1371/journal.pone.0244520.g004

Fig 5. Basidiomata of Steccherinum xanthum. Bars: A = 1 cm, B = 1 mm (holotype). https://doi.org/10.1371/journal.pone.0244520.g005

Fig 6. Microscopic structures of Steccherinum xanthum (drawn from the holotype). A: Basidiospores. B: Basidia and basidioles. C: Cystidia. D: A section of hymenium.Bars: A = 5 μm, B–D = 10 μm. https://doi.org/10.1371/journal.pone.0244520.g006