Volvariella murinella (Quél.) M.M. Moser ex Dennis, P.D. Orton & Hora, Transactions

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 : 33-36

7. Volvariella murinella (Quél.) M.M. Moser ex Dennis, P.D. Orton & Hora, Transactions of the British Mycological

Society 43, suppl.: 167. 1960. ( Fig. 15 )

≡ Volvaria murinella Quél., Comptes Rendus de l’Association Française pour l’Avancement des Sciences11: 391. 1883 [basionym].

Typification status:— Lectotype, designated here: [icon] Volvaria murinella in Quélet, Comptes Rendus de l’Association Française pour l’Avancement des Sciences 11: Tab. XI, Fig. 6 . 1883. MycoBank type: MBT 10023148.

Description:— Pileus 20–70 mm diam., hemispherical when young, expanding to convex or conico-convex, later plano-convex, without umbo; surface finely fibrillose or covered with fibrils grouped into small squamules; quite variable in colour, white, off-white, grey, brown, in different combinations and predominance, usually darker at centre and much paler towards the margin, not hygrophanous; margin not striate or striate when dry, straight or slightly irregular and exceeding the lamellae. Lamellae crowded, free, broadly ventricose; white when young, becoming salmon pink or pinkish brown with age; edge slightly irregular, white and floccose, or concolorous and more or less even. Stipe 40–80 × 0.5–11 mm, cylindrical, slightly widening towards the base (up to 13 mm diam.), straight or sinuous; surface white or with pale yellow tones in older specimens, smooth, fibrillose or irregularly pubescent. Volva membranaceous, saccate, white, white with grey tones, or entirely brown, with 2–4 lobes; rhizomorphs not observed. Context white, thin, with smell like leaves of Pelargonium or indistinct.

Basidiospores (n=606, c=9) 5.7–9.5 × 3.8–5.8 μm, avl × avw = 7.3 × 4.7 μm, Q = 1.16–2.1, avQ = 1.57, broadly ellipsoid to cylindrical, thick-walled, with barely distinct hilar appendage. Basidia 21–29 × 8–10 μm, tetrasterigmate, clavate, subclavate to subcylindrical. Lamella edge sterile or heterogeneous. Cheilocystidia common, 35–94(–118) × 9–36(–43) μm, clavate, fusiform, lageniform, (sub)cylindrical, sometimes with apical projection with rounded or subcapitate apex, some with 1–2 apical lobes. Pleurocystidia scarce, 50–95 × 10–45 µm, scattered, broadly clavate, lageniform, fusiform or more rarely utriform. Pileipellis a cutis or an intermediate cutis-trichoderm, with terminal elements (17–) 25–100(–120) × (7–)11–21(–25) μm, commonly constricted at the septa, in the lower layer with slightly broader elements, 25–39 μm wide, hyaline, or with diffuse, intracellular, olive brown pigment, especially at centre of pileus. Stipitipellis a cutis or a cutis-trichoderm in the upper part of the stipe, with cylindrical hyphae, 9–23 μm wide. Volva composed of interwoven, cylindrical hyphae, 4–23 μm wide, with common septa, with distinct terminal elements, broader towards the round apex. Clamp connections absent in all parts examined.

Habit, habitat, and phenology:—Often solitary or subgregarious. In various habitats, often among grass under various trees ( Castanea , Fraxinus , Liquidambar , Pinus , Populus , and Ulmus ). Mostly collected in spring (March– May) but also in autumn (October).

Distribution:—Known with certainty from Europe and Turkey.

Additional collections examined:— ITALY. Grosseto: Principina a Mare, in a mixed forest of Pinus pinea and P. pinaster , 18 March 2004, G. Consiglio and G. Spisni, AMB19318; ibid. 19 April 2004, G. Consiglio and G. Spisni, AMB18875. SPAIN. Barcelona: La Floresta, Can Busquets, under Quercus ilex and Pinus pinea , 19 April 2008, M. Tabarés, SFC080419; ibid., 17 May 2017, M. Tabarés, SFC170517-T2; ibid., 18 May 2017, M. Tabarés, SFC170518- T1. La Rioja: Autol, bank of the Cidacos river, sandy soil, under Populus nigra , P. alba and riverside vegetation, 18 April 2006, G. Muñoz, GM475; ibid., 25 April 2010, G. Muñoz, GM1824; ibid., 2 April 2010, G. Muñoz, GM1830; Valladolid:Tudela del Duero, mixed forest, under Quercus ilex , 28April 2007, A. García-Blanco, AVM2087; Valladolid, bank of the Pisuerga river, under Alnus sp. , 7 May 2008, A.G. Blanco, AVM2237; ibid., bank of the Pisuerga river, under Populus sp. , 14 May 2017, A.G. Blanco, AVM3343; Zaragoza: bank of the Cidacos river, sandy soil, under Populus nigra , P. alba , Ulmus sp. and riverside vegetation, 11 April 2015, G. Muñoz, GM2888. TURKEY. Burdur: Bucak district, Karacaören, in Kargı Village Sweetgum Forest Nature Protection Area, on soil, Mediterranean forest dominated by Liquidambar orientalis , elev. 280 m, 16 March 2018, O. Kaygusuz, OKA-TR2322; ibid., on soil, under L. orientalis , elev. 267 m, 5 April 2019, O. Kaygusuz, OKA-TR2474; ibid., on soil, associated with L. orientalis , elev. 274 m, 10 April 2020, O. Kaygusuz, OKA-TR2472; ibid., on soil, associated with L. orientalis , elev. 281 m, 22 October 2022, O. Kaygusuz, OKA-TR2207. Muğla: Köyceğiz district, in DöğüŞbelen town, on soil, under L. orientalis , elev. 272 m, 18 April 2021, O. Kaygusuz, OKA-TR2473; ibid., on soil, under L. orientalis , elev. 269 m, 7 March 2022, O. Kaygusuz, OKA-TR2471. Isparta: in Gelincik, on soil under Castanea sativa , elev. 1025 m, 24 March 2017, O. Kaygusuz, OKA-TR2153; ibid., on soil, associated with C. sativa , elev. 1046 m, 18 March 2020, O. Kaygusuz, OKA-TR2539; ibid., on soil under C. sativa , elev. 1055 m, 26 March 2021, O. Kaygusuz, OKA-TR2538.

Observations:—The above description is based exclusively on the collections examined here considered to represent V. murinella . Other collections included in the phylogeny, originally identified as V. murinella , are considered here to represent separate taxa ( Figs. 2 , 3 ).

The original diagnosis of V. murinella ( Quélet 1883) , describes a small species (pileus up to 2–3 cm diam.) with velvety surface and grey colour, glabrous and striate stipe, small, white volva of 3–4 lobes and ellipsoid, 6–8 μm long spores. Subsequently, other mycologists have expanded the knowledge about the species ( Saccardo 1887, Lange 1936, Moser 1980, Boekhout 1986, 1990, Antonín 2010). Thus, among the morphological characteristics that are added to the original description, we can highlight a larger size for the pileus, up to 70 mm diam., grey to white colour, smell of Pelargonium and detailed description of microscopic characters. Volvariella murinella is considered a terrestrial saprophytic species, adapted to different ecosystems and habitats. According to our observations, it has a predilection for riverbanks, at least in Mediterranean habitats, especially fruiting in spring. Although it has been reported on practically all continents, it is very difficult to know its distribution; all the collections assigned to V. murinella in our study have been collected in southern Europe and Turkey.

Volvariella taylorii has macroscopic and microscopic characters that widely overlap with those of V. murinella , and for an unequivocal identification of these two species it is necessary to resort to molecular characters. Volvariella taylorii shows a strong association with coastal dunes, and, to our knowledge, does not exhibit a white pileus. Some other small to medium species with white or grey pileus surface can be confused with V. murinella as well. Volvariella dunensis differs in its occurrence in dune ecosystems, consistently grey (never white) basidiomes, up to 315 µm long terminal elements in the pileipellis, and the presence of caulocystidia. Volvariella terrea differs in the more fibrillose pileus and stipe surface, larger and more polymorphic cystidia (33–130 × 24–32 μm), caulocystidia that are clavate, fusiform or lageniform, 53–64 × 11–18 μm, and the granular intracellular pigment in the pileipellis. Volvariella volvacea differs in the habitat in greenhouses and tanneries, larger spores (8.5 × 5.8 μm on average), and dark brown granular or vacuolar intracellular pigment in the pileipellis elements. Volvariella caesiotincta has larger basidiomes (pileus 25–120 mm diam.), with more intense grey colours, longer and wider pileipellis hyphae (28–500 × 8.5–37(–57) μm) with vacuolar or granular, dark olive green, or dark brown, almost black intracellular pigment, and some terrestrial basidiomes have rhizomorphs with clamp connections.

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

FIGURE 6. Best tree from the Maximum Likelihood analysis of the ITS dataset of Volvariella: detailed view of the lineage including V. izmirensis and related taxa. BS ≥ 70 % and PP ≥ 0.90 are shown on or below the branches. Newly described taxa are highlighted in red.

FIGURE 15. Volvariella murinella. A–D. Basidiomes.A. (GM1830); B. (SFC170517-T2); C. (GM475); D. (GM1824). E–I. Microscopic characters. E. Cheilocystidia (AVM2237); F. Pleurocystidium (AVM2087); G. Spores (AVM3343); H. Pileipellis (GM1824); I. Volva hyphae (GM1824). Bar: (E–G) = 10 µm; (H–I) = 100 µm. Photos by G. Muñoz (A, C–D), M. Tabarés (B), F. Caballero (E–I).