Panellus microspermus Q.Y. Zhang, Q. Chen & Yuan Yuan, 2023

Chen, Qian, Xu, Zhen-Zhen & Zhang, Qiu-Yue, 2023, Panellus microspermus sp. nov. (Agaricales, Basidiomycota) evidenced by the morphological characters and molecular phylogeny, Phytotaxa 606 (1), pp. 16-28 : 22

Panellus microspermus Q.Y. Zhang, Q. Chen & Yuan Yuan , sp. nov., ( Figs. 2–3 )

MycoBank no.—849346

Etymology:— Microspermus (Lat.): Refers to the species having small basidiospores.

Diagnosis:—Differs from other Panellus species by the cream to pale buff pileus with finely chalky pruinose surface, a thin gelatinous context, and small basidiospores measuring 2.5–3.2 × 1.5–2 μm.

Type:— CHINA. Guizhou Province: Zunyi , Suiyang County, Kuankuoshui Nature Reserve , on fallen angiosperm branch, 7 July 2022, Dai 24286 (holotype, BJFC 039528 ) .

Description:— Basidiomata annual, pileate with a lateral rudimentary stipe base, gregarious, subgelatinous. Pileus 5–15 × 3–9 mm, reniform to flabelliform; pileal surface grayish to grayish brown when fresh and dry, opaque, convex to plane, chalky pruinose; margin incurved when dry, entire; context pale grayish brown, thin, gelatinous. Hymenophore concolorous with the context, lamellate; lamellae radiating from the base of the pileus, adnate, gelatinous, with white chalky-encrusted surface. Stipe base 0.5–2 × 1–3 mm, concolorous with pileal surface or darker, enlarged suddenly into the pileus, with a small disc at the base, pruinose on surface. Odor and taste not distinctive. Luminescence not clear.

Basidiospores (2.2–)2.5–3.2(3.5–) × 1.5–2(–2.1) μm, L = 2.96 μm, W = 1.89 μm, Q = 1.55–1.58 (n = 60/2), ellipsoid, tapering at apiculus, hyaline, thin-walled, smooth, faintly IKI+, CB–. Basidia 18–22 × 4–5 μm, clavate, 4–spored, thin-walled, smooth, sterigmata 3–5 μm long; basidioles 14–20 × 3–4.5 μm, dominant, clavate to fusiform. Pleurocystidia 13–16 × 3–4 μm, present in hymenium, tubular to acerose, thin-walled, smooth. Cheilocystidia 10–35 × 2–5 μm, present at lamellar edge, clavate, fusiform to tubular, thin-walled, some with diverticulate projections. Pileipellis comprising a palisade of abundant dichophysial hyphae and pileocystidia; dichophysial hyphae slightly thick-walled, 2–4 μm in diameter; pileocystidia 25–45 × 4–6 μm, clavate, thin-walled, some with diverticulate projections, and sometimes indistinguishable from the dichophysial hyphae. Pileus hyphae subparallel, thin-walled, 0.5–3 μm in diameter, encrusted with granular matter, forming a thin dense layer, 3–6 μm thick. Tramal hyphae subparallel along lamellae, thin-walled, 2–3 μm in diameter; numerous dichophysial hyphae present at lamellar edge, interspersed between cheilocystidia. Clamp connections present.

Additional specimen (paratype) examined:— CHINA. Guizhou Province: Zunyi, Suiyang County, Kuankuoshui Nature Reserve , on fallen angiosperm branch, 6 July 2022, Dai 24269 ( BJFC039511 ) .

Figures

FIGURE 2. Basidiomata of Panellus microspermus (Holotype, Dai 24286). A Basidiomata soaked in 3% KOH for 30 minutes. B Basidiomata in situ. Scale bars: A, B = 1.0 cm. Photo by: Qiu-Yue Zhang.

FIGURE 3. Microscopic structures of Panellus microspermus (Holotype, Dai 24286). a Basidiospores. b Hyphae from pileus. c A section of lamellar trama, including pleurocystidia, cheilocystidia, basidia, and basidioles. d Dichophysial hyphae and pileocystidia from pileipellis. Drawings by: Qiu-Yue Zhang.