Volvariella latispora G. Moreno, A. Sánchez & P. Alvarado, Fungal Systematics

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 : 31-33

6. Volvariella latispora G. Moreno, A. Sánchez & P. Alvarado, Fungal Systematics and Evolution 13: 355. 2024. ( Fig. 14 ).

Typification status:— Holotype: SPAIN. Segovia, Revenga, on grassy soils in a Quercus ilex subsp. rotundifolia stand with Tuberaria guttata , Rumex bucephalophorus and bryophytes, 20 May 2016, A. Sánchez (holotype AH 49362).

Description:— Pileus 10–14 mm diam., hemispherical when young, expanding to plano-convex and eventually with depressed centre in older specimens, with a central umbo; surface smooth to finely fibrillose, radially striate-sulcate, not hygrophanous, white overall, very pale brown at centre; margin smooth, slightly exceeding the lamellae and irregular. Lamellae subdistant, free, broadly ventricose; white when young, becoming salmon pink or pinkish brown with age; edge entire, or irregular, concolorous. Stipe 14–18 × 1 mm, cylindrical, slightly widening towards base, straight or slightly curved; surface white, smooth to finely fibrillose. Volva membranaceous, saccate, fragile, off-white, with 2–3 lobes; rhizomorphs not observed. Context white, thin, with indistinct or pleasant smell.

Basidiospores (n=51, c=1) 6.2–10.4 × 4.3–6.5 μm, avl × avw = 7.7 × 5.2 μm, Q = 1.22–1.80, avQ = 1.44, broadly ellipsoid to oblong, thick-walled, with barely distinct hilar appendage. Basidia 23–47 × 11–13 μm, tetrasterigmate, clavate, subclavate. Lamella edge heterogeneous. Cheilocystidia relatively scarce, 46–70 × 18–27 μm, mostly utriform or clavate, some lageniform, often with 2–3 round knobs in the upper part. Pleurocystidia, scarce, 50–65 × 15–20 µm, scattered, mostly utriform or clavate. Subhymenium composed of oval or spherical elements, 15–22 × 15–20 μm, with hyaline, cytoplasmatic content. Pileipellis a cutis or an intermediate cutis-trichoderm, with terminal elements (6–)13–30(–55) μm wide, often constricted at the septa, most with hyaline contents. Stipitipellis a cutis with cylindrical hyphae, 4–22 μm wide. Volva composed of interwoven, cylindrical hyphae, 5–24 μm wide, with common septa, on the external surface with distinct, terminal, cystidium-like elements, 44–76 ×14–26 µm, lageniform, clavate, utriform or fusiform. Clamp connections absent in all parts examined.

Habit, habitat, and phenology:—Gregarious.Terrestrial, in a clearing on the edge of a road, among moss ( Bartramia sp. ) and Pinus sp. needles, near Quercus ilex and Pinus sp. , on sandy acidic soil (our collection); on grassy soils in a Quercus ilex subsp. rotundifolia stand with Tuberaria guttata , Rumex bucephalophorus and bryophytes (Crous et al. 2024). July (our collection); May (Crous et al. 2024).

Distribution:— Spain. Only known from the locality and collections reported in the original description (Crous et al. 2024) and the collection described in detail here.

Collections examined:— SPAIN. La Rioja, Santa Lucía, terrestrial, in a clearing on the edge of a road, among moss ( Bartramia sp. ) and Pinus sp. needles, near Quercus ilex and Pinus sp. , on sandy acidic soil, 2 July 2006, A. Caballero, AH 60276.

Observations:— Volvariella latispora was recently described based on four collections made in central Spain. The diagnostic characters highlighted in the original description were its small size, whitish grey volva, smooth, ellipsoid to broadly ellipsoid spores measuring 5–8.7(–9) × 4–6.6 μm, fusiform to lageniform cystidia and presence of a velipellis at the apex of the pileus formed by hyaline filaments (Crous et al. 2024). We did not observe a distinct velipellis in our collection, but our observations otherwise agree well with the original description of V. latispora .

Considering the extensive morphological re-characterization of European species presented here, we highlight the following morphological characters of V. latispora : very small size, smooth, striate-sulcate and pure white pileus, subdistant lamellae, smooth or slightly fibrillose and white stipe, membranaceous and whitish or white-grey volva, and the particular morphology of the subhymenium, composed of oval or spherical elements with hyaline cytoplasmic content. The cystidium-like elements of the volva that we found in our collection are also unusual among the European species of Volvariella studied here.

Volvariella latispora appears in the phylogeny ( Fig. 2 ) in a well-supported clade with V. nodosicystis , V. pilosipilea , and two yet-unnamed species from China and USA. Volvariella nodosicystis differs in the grey pileus, smaller spores (6.3 × 4.6 μm on average), and narrower pileipellis hyphae (10–26 μm wide). Volvariella pilosipilea also differs in the smaller spores (6.6 × 5.1 μm on average). Volvariella liliputiana (Henn.) G.C. Rath has even smaller basidiomes (pileus 5–10 mm diam.), and smaller spores (4–5 × 4 μm). This species was originally described from Uttar Pradesh ( India) (Hennings 1901).

Figures

FIGURE 2. Best tree from the Maximum Likelihood analysis of the ITS dataset of Volvariella: detailed view of the lineage including V. murinella and related taxa. BS ≥ 70 % and PP ≥ 0.90 are shown on or below the branches. Newly described taxa are highlighted in red.

FIGURE 14. Volvariella latispora. A. Basidiomes (AH60276). B–H. Microscopic characters (AH60276, holotype). B. Cheilocystidia; C. Pleurocystidia; D. Spores; E. Subhymenium; F. Pileipellis hyphae; G–H. Volva hyphae. Bar: (B–H) = 10 µm. Photos by A. Caballero (A), F. Caballero (B–H).