Coprinopsis pusilla2021.

Coprinopsis pusilla G. Rao, B. Zhang & Y. Li, sp. Nov2021.

MycoBank No: 840298

Holotype: MZ398014 (ITS nrDNA), MZ398069 (LSU nrDNA)

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Morphological description

Sexual morph: Basidiomata very small to small. Pileus 21–29 mm broad, bellshaped to hemispherical when young, then convex, flat to slightly reflexed at edges, with inconspicuous bulge at the middle, grey or greyish-white when dry, no record when wet, densely covered with flocculent hairs, sometimes central with blackish-grey squamous tapering to the edges, not slime, sometimes the edges crack, hygrophanous no record, veil remnants dense at edges, triangular, subtriangular or massive, not easily disappearing. Lamellae close or crowded, subwhite, greyish-white o flesh blond after drying, sinuate or adnexed, sometimes with vertical teeth, edges slightly toothed, concolorous, not deliquescent. Stipe 35–57 × 3–7 mm, cylindrical, subcylindrical, subequal or a little rough towards the base, white, cream white, hollow, a little fragile, not easy to detach from the cap, densely covered with white and flocculent hairs, brown, brownish-grey to brownish-yellow near the base, veil present at the stalk and cap joints, easily disappearing, no ring, the base with white mycelium. Spore print without record. Basidiospores [90, 4, 3] 8–12 × 5–6.5 (6.8) µm, avl = 9.8 µm, avw = 5.8 µm, Q = 1.45–2.2 (2.24), Qm = 1.70 ± 0.18 µm, oval, elliptic to long elliptic, subcolourless in 5% KOH and aqueous solution, surfaces verrucose, thin wall, no pores, not amyloid. Basidia (18) 19–32 (33) × 9–11 (12) µm, clavate, 4-sterigmate up to 3–4 µm long, 2-sterigmate occasional, without pseudoparaphyses. Pleurocystidia absent. Cheilocystidia (25) 27–53 (55) × (11) 13–21 µm, variable-shaped, subcylindrical, utriform, lageniform, reverse gourd-shaped and subcapitate, sphaeropedunculate elements present on gill edges, smooth, hyaline, thin wall to thick wall. Pileipellis a cutis, terminal hyphae (30) 31–84 (98) × (7) 8–17 (18) µm, with light brown pigment, mostly thick wall in the outer hyphae, present dark encrusting pigment, terminal hyphae present small cylindrical protrusions, about 3 × 3 μm. Veil hyphae (26) 27–100 (113) × (9) 10–19 (20) µm, without encrusting pigment, thick wall, colourless to yellowish, cylindrical, subcylindrical, clavate or irregular. Stipitipellis a cutis, hyphae (21) 22–87 (88) × (9) 10–19 (20) µm, encrusting pigment not observed, colourless to light yellow, cylindrical, subcylindrical, clavate or irregular, terminal hyphae present small cylindrical protrusions. Clamp connections present in  all tissues.

Asexual morph: Undetermined

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Cultures:

Habitat: On the dead and rotten wood of broad-leaved forest or coniferous and broad-leaved mixed forests in autumn.

Distribution: China. Red Leaves Valley in Hanchongling, Dunhua City, Yanbian Korean Autonomous Prefecture, Jilin Province

GenBank Accession:  (HMJAU 58779, HMJAU 58780).

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Notes: Coprinopsis pusilla has a variable macromorphology, but stable micromorphology, which is characterised by small basidiomata, greyish-white pileus, thick and distinct veil remnants at edges, subcolourless and verrucose basidiospores, no pore, the habitat on the decaying wood of broad-leaved trees. C. pusilla forms a stronglysupported independent clade in both ITS and LSU phylogeny trees (Figs 1, 2). Morphologically and phylogenetically similar to Coprinopsis pusilla, C. melanthina is characterised by larger brown pileus, fibrous 

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veil at edges, longer basidiospores (avl = 10.5 µm) (Kits van Waveren 1985). C. uliginicola is characterised by large basidiomata, brown-black basidiospores, pore present (Smith 1972). C. cineraria is characterised by fibrous veil at the edges easily disappearing, smaller basidiospores (6.5–8.5 × 4–5 µm), pileipellis an epithelium (Takahashi 2000).

Reference: [1] Rao, G. ,  Dai, D. ,  Zhao, H. N. , &  Zhang, B. . (2021). Two new psathyrelloid species of coprinopsis (agaricales, psathyrellaceae) from china. MycoKeys.

 Basidiomata and microscopic features of Coprinopsis pusilla A collection HMJAU 58780 B  collection HMJAU 58781 C collection HMJAU 58779 D basidiospores E basidia and basidioles F cheilocystidia G pileipellis. Scale bars: 5 mm (A–C); 10 µm (D–G).

 Scatter plot of basidiospores size in Coprinopsis pusilla.