Volvariella clavocystidiata Kapitonov

Caballero, Fernando, Justo, Alfredo, Parra, Luis A., Angelini, Claudio, Consiglio, Giovanni, Dovana, Francesco, Ferisin, Giuliano, Kaygusuz, Oğuzhan, Knudsen, Henning, Llimona, Xavier, Muñoz, Guillermo, Daniëls, Pablo P., Pérez-De-Gregorio, Miquel À., Ševčíková, Hana, Valverde, Andrés & Vizzini, Alfredo, 2025, Taxonomic and phylogenetic overview of the genus Volvariella (Volvariellaceae), with a focus on European species, Phytotaxa 680 (1), pp. 1-85 : 25-27

3. Volvariella clavocystidiata Kapitonov & E.F. Malysheva in Malysheva, Kapitonov & Malysheva, Phytotaxa 538(2): 144. 2022. ( Fig. 11 )

Typification status:— Holotype: RUSSIA. Tyumen Region, Vagayskiy District, vicinity of Rjabovo village , N57,16051°, E70,29086°,

lowland swamp, 23 July 2020, V . Kapitonov, LE 313639 ( LE-F) .

Description:— Pileus 20–65(–75) mm diam., campanulate when young, expanding to conico-convex, then plano-convex, with a low, broad umbo; surface fibrillose, sometimes arranged in small squamules, sometimes with patches of universal veil, becoming cracked and radially rimose with age, not hygrophanous, grey or grey-brown overall, slightly darker towards centre; margin smooth or slightly striate, slightly exceeding the lamellae and irregular. Lamellae moderately crowded, free, broadly ventricose, white when young, becoming salmon pink or pinkish brown with age; edge fimbriate, concolourous. Stipe 35–80 × 3–5(–8) mm, cylindrical, slightly widening towards base, straight or slightly curved; surface white, densely pubescent. Volva membranaceous, saccate, white to grey-brown, with 2–3 lobes, with rhizomorphs attached to the base. Context white with Pelargonium -like smell.

Basidiospores (n=50, c=2) 4.9–6.2 × 3.6–4.7 μm, avl × avw = 5.6 × 4.15 μm, Q = 1.11–1.56, avQ = 1.35, subglobose to ellipsoid, thick-walled, with barely distinct hilar appendage. Basidia 25–45 × 7–9 μm, tetrasterigmate, broadly clavate. Lamella edge heterogeneous. Cheilocystidia common, 24–65 × 11–26.5 µm, narrowly utriform, narrowly fusiform to broadly fusiform or (broadly) clavate. Pleurocystidia scarce, 24–68 × 11–28 µm, similar to the cheilocystidia. Pileipellis a trichoderm, with terminal elements 15–56 μm wide, often constricted at the septa, hyaline, or with cytoplasmatic brown pigment. Stipitipellis a cutis, with cylindrical hyphae 9–18 μm wide. Caulocystidia 18–22 × 35–65 μm, clavate or narrowly utriform, in the upper part of stipe (not present in all collections). Volva composed of interwoven, cylindrical hyphae, 8–20 μm wide, with few septa; with scattered globose cells, up to 100 μm wide. Hyphae of the rhizomorphs 2–3 μm wide, with clamp connections. Clamp connections absent in all parts examined, except the rhizomorph hyphae.

Habit, habitat, and phenology:—The holotype was growing solitary in waterlogged soil among green mosses and decaying remains of herbaceous plants, in lowland bog (with Carex and Equisetum ). The Slovenian collection was growing gregarious on the edge of a forest road with Quercus sp. and Fagus sp. nearby. May–July.

Distribution:— Russia and Slovenia.

Collections examined:— SLOVENIA. Nova Goriča: Panoveč Park , on the ground, 5 July 2019, G . Ferisin , GDOR 5559 ; ibid., at the edge of a trail, 2 August 2021, G . Ferisin , FG02082021009 .

Observations:—The following characters of our collections differ from the original description of V. clavocystidiata (Malysheva et al. 2002) : pileus up to 75 mm in diameter, variable in colour (white, grey or grey-brown) and the presence of rhizomorphs attached to the volva, with hyphae having clamp connections. Our collections also show greater variability in the morphology of the cheilocystidia: narrowly utriform, narrowly fusiform to broadly fusiform cystidia, and not exclusively clavate as originally described for V. clavocystidiata . The pileipellis elements in our collections have brown intracellular pigment, and are arranged as a cutis-trichoderm.

Phylogenetically, V. clavocystidiata is closely related to a North American collection Volvariella sp. ( OM809177 ) from Indiana ( USA).

Volvariella caesiotincta has a pileus up to 120 mm in diameter, digitate cystidia, and the pigment in the pileipellis elements is granular or vacuolar. Volvariella murinella has larger spores (7.3 × 4.7 μm on average), larger cystidia and lacks rhizomorphs. Volvariella volvacea has larger basidiomes, with darker colours on the pileus, larger basidiospores and larger cystidia often with apical projections.

Figures

FIGURE 11. Volvariella clavocystidiata. A–F. Basidiomes. A–D. (FG02082021009); E–F. (GDOR 5559). G–L. Microscopic characters (GDOR 5559). G. Cheilocystidia; H. Pleurocystidia; I. Spores. J. Pileipellis; K. Volva hyphae; L. Rhizomorph hyphae. Bar: (G–I, K–L) = 10 µm; (J) = 100 µm. Photos by G. Ferisin (A–L).