Caballero, Justo & García-Blanco, 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 : 54

16. Volvariella cryptica F. Caballero, Justo & García-Blanco , sp. nov. ( Fig. 24 ).

MycoBank: MB 856533

Typification :— Holotype: SPAIN. Valladolid: Valladolid city, among grasses in a garden, 26 August 2011, A. García-Blanco, AH60258! (Isotype: AVM2584 ).

Etymology:—From the Greek kryptike, hidden, for the difficulty in identifying this species without DNA data.

Diagnosis:— Volvariella cryptica is very similar to the closely related V. neoparvula , differing in the slightly smaller spores with lower avQ values (avl × avw = 6.4 × 4.2 μm, avQ = 1.52). The nrITS sequences of V. cryptica differ from those of V. neoparvula in 19 individual changes, including a four base pair indel exclusive to V. cryptica .

Description:— Pileus 10–25 mm diam., convex or convex-campanulate when young, expanding to plano-convex, with or without a low, broad umbo; surface smooth to finely fibrillose; fibrils sometimes grouped in small squamules; not or slightly hygrophanous, white or off-white overall; 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 slightly irregular, concolourous. Stipe 20–45 × 3–7 mm, cylindrical, slightly widening towards the base, straight or slightly curved; surface white, sometimes with pale brown tints, smooth. Volva membranaceous, saccate, fragile, off-white, with 2–4 lobes; rhizomorphs not observed. Context white, thin, with pleasant but not distinctive smell.

Basidiospores (n=101, c=2) 5.0–8.2 × 3.7–4.8 μm, avl × avw = 6.4 × 4.2 μm, Q = 1.32–1.92, avQ = 1.52, ellipsoid to oblong, thick-walled, with barely a hilar appendage. Basidia 25–40 × 7–9 μm, tetrasterigmate, clavate or subcylindrical. Lamella edge heterogeneous. Cheilocystidia common, (36–)50–78(–86) × (13–)19–22(–30) μm, (broadly) clavate, utriform. Pleurocystidia scarce, 39–64 × 17–28 μm, scattered, similar to cheilocystidia. Pileipellis a cutis or cutis-trichoderm, with hyaline terminal elements (3–)6–21(–33) μm wide, often constricted at the septa. Stipitipellis a cutis, or a cutis-trichoderm, with cylindrical hyphae, 6–14 μm wide. Volva composed of interwoven, cylindrical hyphae, 2–11 μm wide, with few septa. Clamp connections absent in all parts examined.

Habit, habitat, and phenology:—Gregarious. Terrestrial, among grass in urban gardens. August–September.

Distribution:— Spain.

Additional collection examined:— SPAIN. Barcelona: Sant Fost de Campsentelles (Barcelona), among grass in a community garden, 22 September 2019, F. Caballero, SFC 190922.

Observations:— Volvariella cryptica is morphologically very similar to other small, white species of Volvariella . This species was collected in the same garden area as many collections of the taxon here considered to represent V. pusilla , but about 120 m away from it.

Volvariella pusilla has slightly larger basidiomes (pileus up to 50 mm diam.), although there is variability in this character, and the hyphae on the pileipellis are wider (15–50 µm). Volvariella neoparvula has often grey tones on the pileus, larger basidiospores (7.0 × 4.2 µm on average), and has rhizomorphs with clamped hyphae. Volvariella hypopithys differs in the slightly larger basidiospores (6.9 × 4.7 µm on average), larger cystidia 46–124 × 9–30 µm, and the presence of (sub)globose elements in the pileipellis. Volvariella latispora differs in smaller basidiomes (pileus 10–14 mm diam.) and larger basidiospores (7.7 × 5.2 µm on average).

V. cryptica is closely related to V. neoparvula ( Fig. 5 ). The nrITS sequences differ in 19 individual positions, including a four-bp indel present in all sequences of V. neoparvula but not in V. cryptica .

Figures

FIGURE 5. Best tree from the Maximum Likelihood analysis of the ITS dataset of Volvariella: detailed view of the lineage including V. caesiotincta and related taxa. 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 24. Volvariella cryptica. A–B. Basidiomes. A. (AH60258, holotype); B. (SFC190922). C–H. Microscopic characters. C. Cheilocystidia (SFC190922); D. Pleurocystidium (AH60258, holotype); E. Spores (AH60258, holotype). F. Pileipellis (AH60258, holotype); G. Volva hyphae (SFC 190922). H. Stipitipellis (AH60258, holotype). Bar: (C–H) = 10 µm. Photos by A. García-Blanco (A), F. Caballero (B–H).