Pluteus aesontiensis Ferisin, Justo & Dovana 2022, sp. nov.
Creators: name: Dovana, Francesco
name: Justo, Alfredo
name: Ferisin, Giuliano
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Pluteaceae
Pluteus
Pluteus aesontiensis

description: Pluteus aesontiensis Ferisin, Justo & Dovana, sp. nov. Figs. 2–3
MycoBank no.: MB841413
Etymology:—Refers to an ancient name for the Isonzo river that flows near the growth site of P. aesontiensis.
Diagnosis:— Pluteus aesontiensis is characterized by small-sized basidiomes with brown, red-brown to deep yellowish brown pileus darker in the centre; cylindrical, sub-bulbous, white pubescent stipe; globose to ellipsoid spores, a hymenidermal pileipellis composed of typically sphaeropedunculate to clavate terminal elements; utriform to broadly fusiform cheilocystidia, fusiform to broadly fusiform pleurocystidia, and caulocystidia only in the upper part of the stipe.
Holotype:— ITALY. Farra d’Isonzo, Isonzo (Soca) river, on trunks of broadleaved tree (trees present in the area: Fraxinus angustifolia Vahl, Populus spp., Robinia pseudoacacia L., Salix spp. and Ulmus minor Mill.) on the ground, 17 June 2017, G. Ferisin; Holotype MCVE30112!; GenBank: MZ412508.
Description: —Pileus 20–30 mm diam., at first convex or broadly conical, then applanate to plano-concave, nonumbonate to sub-umbonate, margin translucently striate or sulcate; brown (2.5 Y5/2–5/4), red-brown (10YR 3/2–3/4– 3/6) to deep yellowish brown (2.5Y 4/2–4/4–4/6), darker at centre (10YR 2/4–1/2); surface glabrous and rugulose at centre, sometimes with irregular cracks in surface that reveal whitish flesh, non-hygrophanous. Lamellae free, crowded, up to 4 mm broad, thin, whitish in youth, later pink with flocculose edge. Stipe 25–40 × 2–3 mm, cylindrical, sub-bulbous, pubescent, white all over. Context in pileus and stipe white. Smell indistinct, taste not recorded.
Basidiospores [160/4/4](5.5–)6.1–6.6–7.1(–7.8)×(4.6–)5.0–5.6–6.2(–7.2)µm,Q=(1.00–)1.10–1.18–1.26(–1.34), subglobose to broadly ellipsoid, rarely globose or ellipsoid, guttulate, hyaline, smooth, thick-walled, cyanophilous, and inamyloid. Basidia 22–27 × 8–10 µm, clavate, 4-spored, hyaline, with granular contents. Pleurocystidia 50– 75 × 18–34 µm, thin-walled; variable in shape from fusiform to broadly fusiform with round apex, rarely obovoid, hyaline or with oily contents observed in ammonia solution. Cheilocystidia 50–80 × 20–34 µm, variable in shape from utriform, broadly fusiform with round apex to clavate or ovoid, with oily contents. Pileipellis a hymeniderm made up of sphaeropedunculate to clavate elements, 40–70 × 25–38 µm, with light brown to brown intracellular pigment. Stipitipellis a cutis of cylindrical, 4–10 µm wide, light brown hyphae. Caulocystidia 40–60 × 18–22 µm, clavate, in small clusters, in the apical part of the stipe. Clamp connections absent in all examined structures.
Habit, habitat and distribution:—In groups, on broadleaved trees (trees present in the area: ashes, black-locust, elm, poplar and willow trees). So far, it is known only from northeastern Italy.
Additional collections examined of P. aesontiensis:— ITALY. Farra d’Isonzo, 04 July 2015, G. Ferisin (MCVE 31601!, GenBank MZ 412509); ibid. 17 June 2017, G. Ferisin (FG1706201714!, GenBank: MZ 412507); ibid. 06 July 2017, G. Ferisin (FG0607201710!, GenBank: MZ 412506).
description: Published as part of Dovana, Francesco, Justo, Alfredo & Ferisin, Giuliano, 2022, Pluteus aesontiensis (Agaricales, Pluteaceae) a new species in sect. Celluloderma, pp. 149-157 in Phytotaxa 533 (2) on pages 150-153, DOI: 10.11646/phytotaxa.533.2.4, http://zenodo.org/record/6036375