Volvariella nodosicystis, 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

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 : 69-71

24. Volvariella nodosicystis F. Caballero, Justo & A. Valverde, sp. nov. ( Fig. 32 ).

MycoBank: MB 856541

Typification:— Holotype: SPAIN. Barcelona: El Prat del Llobregat, in a flower bed (garden area), on the right bank of the river Llobregat towards the sea, in a grassy area between Pennisetum clandestinum , Erodium moschatum , Teucrium fruticans , and Genista umbellata , 17 October 2018, A. Valverde, AH60257!. (Isotype: SFC181017V).

Etymology:—From the Latin “ nodosus ” knotted and the latinized Greek “ cystis ” cystidia, by its cystidia with prominent nodules.

Diagnosis:— Volvariella nodosicystis is characterized by its small size, radially sulcate pileus with a discrete central, grey umbo, a smooth stipe and a saccate, pure white volva, and cheilocystidia with prominent nodules in the upper part.

Description:— Pileus 12–15 mm diam., hemispheric when young, expanding to plano-convex in older specimens, with a central umbo; surface finely fibrillose, radially sulcate, not hygrophanous, pale grey, darker at centre; margin smooth, slightly exceeding the lamellae and irregular. Lamellae relatively crowded, free, broadly ventricose, white when young, becoming salmon pink or pinkish brown with age; edge entire, or irregular, concolourous. Stipe 25–30 × 2–4 mm, cylindrical, slightly widening towards base, straight or slightly curved; surface white, smooth to finely fibrillose. Volva membranaceous, saccate, fragile, pure white, with 2 lobes; rhizomorphs not observed. Context white, thin, with indistinct smell.

Basidiospores (n=155, c=1) 5.4–7.1 × 4.0–5.2 μm, avl × avw = 6.3 × 4.6 μm, Q = 1.15–1.60, avQ = 1.36, broadly ellipsoid to ellipsoid, thick-walled, with barely distinct hilar appendage. Basidia 30–34 × 9–11 μm, tetrasterigmate, clavate, subclavate. Lamella edge heterogeneous. Cheilocystidia common, (40–)49–74(–87) × (13–)19–24(–31) μm, mostly utriform or clavate, often with 2 or 3 round knobs in the upper part. Pleurocystidia scarce, (54–)63–74(–84) × (12–)17–22(–28) µm, scattered, mostly utriform or clavate, without apical knobs. Pileipellis a cutis or an intermediate cutis-trichoderm, with terminal elements 10–16 μm wide, often constricted at the septa, most with hyaline contents. Stipitipellis a cutis with cylindrical hyphae 5–17 μm wide. Volva composed of interwoven, cylindrical hyphae, 5–14 μm wide, with common septa. Clamp connections absent in all parts examined.

Habit, habitat, and phenology:—Subgregarious. Terrestrial, in grassy area, in an urban garden. October.

Distribution:— Spain.

Observations:—This species has been found in a landscaped area, but more collections are needed to establish how constant, and taxonomically significant the habitat is for this species.

Volvariella nodosicystis is a delicate and fragile species that is characterized by its small size, its pileus radially sulcate and a discrete central, grey umbo, its smooth stipe and its saccate, pure white volva. These macroscopic characteristics are common and shared by other taxa of this genus. Its microscopic characters are not unique either, except for the cheilocystidia with prominent nodules in the upper part. If this character proves stable in future collections, it could be used as a diagnostic to differentiate this species from morphologically similar species.

Several small species can easily be confused with V.nodosicystis , including V. pusilla , V. hypopithys , V. neoparvula , and V. latispora . See Tables 1 and 2 for a comparison between these species.

Figures

FIGURE 32. Volvariella nodosicystis. A–B. Basidiomes (AH60257, holotype); C–J. Microscopic characters (AH60257, holotype). C–E. Cheilocystidia; F. Pleurocystidia; G. Spores; H. Pileipellis; I. Volva hyphae; J. Stipitipellis. Bar: (C–G) = 10 µm; (H–J) = 100 µm. Photos by A. Valverde (A–B), F. Caballero (C–J).