Caballero, Justo, G. Muñoz, Kaygusuz & Knudsen, 2025

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 : 76-79

28. Volvariella sylvipraticola F. Caballero, Justo, G. Muñoz, Kaygusuz & Knudsen , sp. nov. ( Fig. 36 ).

MycoBank: MB 856545

Typification:— Holotype: SPAIN. Zaragoza, Parque Grande José Antonio Labordeta, in grass on soil consisting mainly of sand and gravel, under Pinus halepensis and P. pinea , 18 September 2012, G. Muñoz, AH59938. (Isotype: GM2601).

Etymology:—From the Latin “ sylva ” wood, forest, “ pratum ” meadow and “ cola ” dweller, for its habitat in both woods and meadows.

Diagnosis:— Volvariella sylvipraticola is characterized by small to medium-sized basidiomes with a white or grey, fibrillose pileus that is usually darker at the centre, a white stipe, a brown to grey-brown volva, subglobose to oblong basidiospores (7.0 × 5.1 μm on average), and narrowly utriform to narrowly lageniform pleurocystidia with a broad, obtuse apex.

Description:— Pileus 10–60 mm diam., convex when young, expanding to conico-convex then plano-convex, with a low, broad umbo, sometimes slightly conico-truncate; surface fibrillose, sometimes fibrils grouped in small squamules, rather smooth in older specimens, not hygrophanous, white or grey overall, darker grey at centre, paler towards margin; margin smooth or slightly striate, slightly exceeding the lamellae and irregular. Lamellae crowded, free, broadly ventricose; white when young, becoming salmon pink or pinkish brown with age; edge entire, or irregular, concolorous. Stipe 20–80 × 2–7 mm, cylindrical, slightly widening towards base (up to 9 mm), straight or slightly curved; surface white, or with slight yellow tint, smooth to finely fibrillose. Volva membranaceous, saccate, brown to grey-brown, with 2–4 lobes, with rhizomorphs attached to the base. Context white with Pelargonium -like smell.

Basidiospores (n=516, c=9) (5.2–)5.6–9.3 × (3.7–)4.1–6.2 μm, avl × avw = 7.0 × 5.1 μm, Q = 1.11–1.78, avQ = 1.38, subglobose to oblong, thick-walled, with barely distinct hilar appendage. Basidia 28–43 × 7.5–11 μm, tetrasterigmate, clavate, or subcylindrical. Lamella edge heterogeneous. Cheilocystidia scarce to common (35–)40–90 × 10–38 μm, broadly clavate, broadly cylindrical, fusiform to broadly fusiform, utriform to broadly utriform, thin-walled, hyaline. Pleurocystidia absent or scarce in some collections, common in others, (45–)50–78(–85) × (9.5–)10.5–16.0(–18.0) µm, numerous, most narrowly utriform to narrowly lageniform or narrowly fusiform, pedicellate and with broadly obtuse apex, sometimes with sinuous neck, thin- to slightly thick-walled, hyaline, but absent or rare in some collections. Pileipellis a cutis or an intermediate cutis-trichoderm, with terminal elements 12–42 μm wide, often constricted at the septa, hyaline, or with brown to dark brown diffuse, intracellular pigment. Stipitipellis a cutis or a cutis-trichoderm in the upper part of the stipe, with cylindrical hyphae 5.5–32 μm wide. Caulocystidia 56–59 × 18–20 μm, lageniform or fusiform, scarce, located in the upper part of the stipe (not present in all collections). Hyphae of the rhizomorphs (0.5–)1.3–3.3(–4.4) μm wide, thin-walled, with clamp connections at the septa, hyaline, or with pale olive brown pigment. Volva composed of interwoven, cylindrical hyphae, 3–30 μm wide, with common septa; individual elements often constricted at the septa. Clamp connections absent in all parts examined, but present on rhizomorph hyphae.

Habit, habitat, and phenology:—Gregarious or in groups of few basidiomes, terrestrial. The Spanish collections were fruiting in areas with Mediterranean influence under Pinus halepensis (two collections in landscaped areas in an urban environment and the other two on siliceous sandy soil with decomposing organic matter, in environments near the sea). The Danish and Swedish collections are from fertile grassland, lawns, and in pastures around rubbish heaps. July–November.

Distribution:—Known from Denmark, Spain, and Sweden, based on collections. GenBank sequences also from Pakistan and Germany.

Additional collections examined:— DENMARK. East Jutland: Horsens Nørrestrand, close to Loddentot, in grassland, 5 November 1993, J. Vesterholt, C-F-21086; ibid., 21 September 1994, J. Vesterholt, C-F-25363; East Jutland, close to Skjoldhøjkollegiet, in grass lawn, 5 July 1997, J. & L. Vesterholt, C-F-27378. SPAIN. Balearic Islands: Cabrera, Serra de ses Figueres, in soil under Pinus halepensis , 23 November 1994, J.L. Siquier, JLS C-114-B; Girona: Palafrugell, La Musclera, on siliceous sandy soil rich in organic matter, under Pinus halepensis , 5 October 2010, C. Roqué, CR05102010-1; Zaragoza: Parque Grande José Antonio Labordeta, 9 October 2012, in grass on soil consisting mainly of sand and gravel, under Pinus halepensis and P. pinea, G. Muñoz, GM2608 . SWEDEN. Upland: Bälinge parish, close to Forkarby, in pastureland, 27 August 1951, H. Smith, Fungi Exsiccati Suecici no. 2002, C-F-118194; ibid., Västergötland, Göteborg, just south of Brunnsbo, on almost bare soil amongst sparse grasses on an old rubbish dump, 20 August 1943, F. Karlvall, Fungi Exsiccati Suecici no. 2003, C-F-118193.

Observations:—In the Spanish collections of Volvariella sylvipraticola pleuro- and cheilocystidia were scarce, and sometimes totally absent, while in the Danish and Swedish collections both pleuro- and cheilocystidia were common.

Two GenBank sequences, identified as V. taylorii , from Pakistan (HUP10388) and Germany (GLM-F29463) are considered to represent V. sylvipraticola . These two collections are, in their nrITS sequences, very distant from the collections here interpreted as V. taylorii ( Figs. 1 , 4 ).

Volvariella sylvipraticola appears in the phylogeny ( Fig. 4 ) close to V. cordispora , V. izmirensis , V. lepiotospora Singer (1955: 774) , and V. ptilotricha . Volvariella cordispora differs from V. sylvipraticola by its smaller basidiospores (6.0 × 4.6 µm on average), presence of frequent heart-shaped spores, and the absence of caulocystidia. Volvariella izmirensis is readily distinguished by its white to beige pileus with pale brown to cinereous tints, pubescent stipe, golden brown to ochre brown volva, smaller basidiospores (8.0 × 4.8 µm on average), different cheilocystidia, and longclavate or obovoid caulocystidia. Volvariella lepiotospora has a dark brown to black pileus, arachnoid volva, ovoid, smaller basidiospores (5.5 × 3.3 µm on average), and clavate cheilocystidia ( Shaffer 1957). Volvariella ptilotricha has small basidiomes (up to 15 mm diam.) with pubescence greyish brown pileus, hairy stipe, dark-coloured olive grey or rusty brown volva, smaller basidiospores (5.5 × 4.0 µm on average), and predominantly utriform or lageniform cheilocystidia ( Malysheva et al. 2019).

Many species of Volvariella with white or grey pileus surface can be confused with V. sylvipraticola . For a detailed comparison see Tables 1 and 2.

Identification key to the species treated in this paper

As noted under the individual species, morphological separation of all taxa described here is not always possible, and nrITS sequences are needed for a confident identification. This key is our best attempt at grouping the species based on their macromorphology, micromorpholoy and ecology. New species are in bold.

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6. Growing on decaying basidiomes of other agarics (mostly Clitocybe nebularis ) ............................................................. V. surrecta Habitat different ................................................................................................................................................................................ 2 Habitat lignicolous, growing on living trees or dead wood .............................................................................................................. 3 Habitat terrestrial .............................................................................................................................................................................. 5 Pileus silky-fibrillose, often pure white, sometimes with yellow tinges, rarely bright yellow. Spores avl × avw = 8.5 × 5.9 μm...... ....................................................................................................................................................................................... V. bombycina Pileus grey, or if white not silky-fibrillose. Spores avl × avw <8.0 × 5.5 μm ................................................................................. 4 Pileus grey, grey-brown, bluish grey, olive or greenish grey. Spores avl × avw = 6.9 × 4.9 μm ........................................................ ................................................................................................................................. V. caesiotincta (compare also with V. volvacea ) Pileus white, sometimes with grey or brown tinges. Spores avl × avw = 7.8 × 5.4 μm ........................................... V. mediterranea Growing among (or next to) basidiomes of Agaricus species.......................................................................................................... 6 Habitat different ................................................................................................................................................................................ 7 Pileus grey, grey-brown, 20–80 mm diam. Fruiting among basidiomes of Agaricus xanthodermus .................................. V. terrea -

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Pileus grey, often with a bluish grey tinge, 18–35 mm diam. Fruiting among basidiomes of Agaricus arvensis ............................... ................................................................................................................................................................................. V. glaucocephala Pileus at maturity grey or grey-brown colors ................................................................................................................................... 8 Pileus at maturity white or very pale colors (sometimes darker at center) .................................................................................... 15 In dune ecosystems or sandy soils near the coast ............................................................................................................................. 9 Habitat different .............................................................................................................................................................................. 10 Pileus reaching> 60 mm in diam. ........................................................................ V. dunensis (compare also with V. mediterranea ) Pileus <60 mm in diam. ...................................................................................................................................................................... ........................................ V. ranulicystis , V. siquieri , V. sylvipraticola , V. taylorii (see individual descriptions and Tables 1 and 2) Growing on compost, sawdust, often in greenhouses, associated with accumulations of organic matter ....................... V. volvacea Habitat different .............................................................................................................................................................................. 11 Cheilocystidia utriform, clavate, often with 2–3 round knobs in the upper part ........................................................ V. nodosicystis Cheilocystidia different. ................................................................................................................................................................. 12 Spores avl × avw <6.5 × 4.5 μm .................................................................................................................................................... 13 Spores avl × avw> 6.5 × 4.5 μm .................................................................................................................................................... 14 Spores avl × avw = 5.6 × 4.1 μm, avQ = 1.35 ........................................................................................................ V. clavocystidiata Spores avl × avw = 6.4 × 4.0 μm, avQ = 1.59 ............................................................................................................ V. ranulicystis Spores with avQ> 1.50 ............................................................................................................................. V. murinella (grey forms) Spores with avQ <1.50 ........................................ Grey, terrestrial forms of V. caesiotincta , V. mediterranea and V. sylvipraticola Spores with avQ> 1.50 .................................................................................................................................................................. 16 Spores with avQ <1.50 .................................................................................................................................................................. 19 Spores avl ≤ 7.0 μm........................................................................................................................................................... V. cryptica Spores avl ≥ 7.0 μm......................................................................................................................................................................... 17 Spores often with a distinct median constriction ......................................................................................................... V. strangulata Spores without a distinct median constriction ................................................................................................................................ 18 Spores avl × avw = 8.0 × 4.8 μm, avQ = 1.75 ............................................................................................................... V. izmirensis Spores avl × avw = 7.0–7.3 × 4.2–4.7 μm, avQ = 1.57–1.67 .............................................................................................................. ............................................................................................ V. murinella and V. neoparvula (see observations under those species) Spores avl × avw = 4.8 × 3.7μm ............................................................................................................................................ V. reidii Spores avl × avw ≥ 5.8 × 3.9 μm .................................................................................................................................................... 20 Some spores with a heart-shaped outline ..................................................................................................................... V. cordispora Heart-shaped spores absent ............................................................................................................................................................ 21 Spores avl ≥ 7.5 μm.......................................................... V. latispora and V. mediterranea (see observations under those species) Spores avl ≤ 7.5 μm.............................................................................................................................................................................. Small, white saprotrophic species often growing in grassy areas ( V. deceptiva , V. globifera , V. graminicola , V. hypopithys , V. pilosipilea , V. pusilla , and V. sylvipraticola ). See the individual descriptions and notes under each species, but nrITS data is needed for a confident identification.

Figures

FIGURE 1. Best tree from the Maximum Likelihood analysis of the ITS dataset of Volvariella: general overview with collapsed terminal clades (except V. ranulicystis). BS ≥ 70 % and PP ≥ 0.90 are shown on or below the branches. The length of branches marked with “/” has been reduced to accommodate graphical representation. Newly described taxa are highlighted in red.

FIGURE 4. Best tree from the Maximum Likelihood analysis of the ITS dataset of Volvariella: detailed view of the lineage including V. hypopithys and related taxa. BS ≥ 70 % and PP ≥ 0.90 are shown on or below the branches. Newly described taxa are highlighted in red.

FIGURE 36. Volvariella sylvipraticola. A–D. Basidiomes. A. (GM2608); B. (JLSC114B); C. (AH59938, holotype); D. (CR05102010- 1). E–L. Microscopic characters. E. Cheilocystidia (CR05102010-1); F. Pleurocystidia (CR05102010-1); G. Spores (JLS C-114-B); H. Pileipellis (CR05102010-1); I. Volva hyphae (CR05102010-1); J–K. Rhizomorphs (JLS C-114-B); L. Stipitipellis (CR05102010-1). Bar: (E–G, I–J) = 10 µm; (H) = 100 µm); (K) = 5 µm. Photos by G. Muñoz (A, C), J.L. Siquier (B), C. Roqué (D), F. Caballero (E–L).