Volvariella hypopithys (Fr.) Shaffer, Mycologia

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 : 29-31

5. Volvariella hypopithys (Fr.) Shaffer, Mycologia 49(4): 572. 1957. ( Fig. 13 )

≡ Agaricus hypopithys Fr., Hymenomycetes Europaei : 183. 1874 [basionym]

≡ Volvaria hypopithys (Fr.) P. Karst., Bidrag till Kännedom av Finlands Natur och Folk 32: 251. 1879

No original specimens have been located. However, Fries in the protologue stated that A. hypopithys was also described under the name “ A. parvulus B.” on page 261 in Monographia Hymenomycetes Sueciae ( Fries, 1857). In this work Fries cited an unpublished illustration, in “Ic. Nostra in Mus. Ac. Sc. Holm.”, that is preserved in the Swedish Museum of Natural History. Therefore, according to Art. 9.4 this illustration is original material.

Typification status:— Lectotype, designated here: [icon] “2. Agaricus (Volvaria) parvulus . Fr.” kept at the Swedish Museum of Natural History with number S1309 b of Strid’s (1994) catalogue. MycoBank type: MBT 10023147.

Description:— Pileus 10–35 mm diam., ovoid or convex when young, expanding to conical, conico-campanulate or plano-convex, without umbo; surface radially fibrillose when young, with fibrils grouped to form small squamules covering the surface, becoming smoother in older specimens; white, sometimes with yellow, ochre yellow tones at centre; dry, not hygrophanous; margin not striate, slightly irregular and exceeding. Lamellae crowded, free, broadly ventricose, white when young, becoming salmon pink or pinkish brown with age; edge white and floccose, or concolorous and more or less even. Stipe 30–60 × 4–6 mm, cylindrical, slightly widening towards the base (up to 15 mm diam.), straight or sinuous; surface white, pubescent, becoming smooth in older specimens. Volva membranaceous, saccate, white, sometimes with pale ochre tones, with 2–3 lobes; rhizomorphs rare, only observed in one collection. Context white, thin, with indistinct smell.

Basidiospores (n=194, c=3) 6.1–7.8 × 4.6–5.7 μm, avl × avw = 7.0 × 5.1 μm, Q = 1.15–1.60, avQ = 1.37, broadly ellipsoid to oblong; thick-walled, with barely distinct hilar appendage. Basidia 22–25 × 8–9 μm, tetrasterigmate, clavate. Lamella edge sterile. Cheilocystidia common, 46–100(–124) × 15–60 μm, mostly lageniform, with elongated neck, some with (sub)capitate or tibiiform apex, more rarely utriform or fusiform. Pleurocystidia scarce, 40–77 × 11– 24 μm, utriform or lageniform, but without elongated neck. Pileipellis a cutis or an intermediate cutis-trichoderm, with terminal elements 9–29 μm wide, commonly constricted at the septa; hyaline, sometimes with oleaginous cytoplasmatic content, that might form globose to subglobose exudates outside the hyphae. Stipitipellis a cutis or a cutis-trichoderm in the upper part of the stipe, with cylindrical hyphae 8–33 μm wide, with very abundant thromboplerous hyphae, 16–78 μm wide. Volva composed of interwoven, cylindrical hyphae, 5–19 μm wide, with common septa. Hyphae of the rhizomorphs, densely packed, composed of three different types (intermixed): multiseptate hyphae up to 2.5–8.0 µm wide, with clamp connections; multiseptate hyphae up to 6.0–10.0 µm wide, with porose cell wall, without clamp connections; barely septate hyphae, up to 1.4–3.0 µm wide, with slightly thickened wall, with dark brown intracellular pigment. Clamp connections absent in all parts examined, except in some hyphae of the rhizomorphs.

Habit, habitat, and phenology:—Solitary or gregarious. Terrestrial, collected under Fagus , Quercus , Pinus , and Salix . October–November.

Distribution:—Examined collections from Europe and Turkey. Available sequences point to a wider distribution, including North America (see observations).

Additional collections examined:— ESTONIA. Tartu maakond, Meeksi vald, no date, V. Liiv, TUF118303 (as Volvariella pusilla ). FRANCE. Nouvelle-Aquitaine: Tarnos-Le Métro, on sandy soil under Pinus pinaster , 22 October 2008, J.M. Lekuona, ARAN-Fungi A8200367. ITALY. Sardinia: Oschiri, Olbia-Tempio. among grasses, 11 November 2000, M. Contu, TOAV139; Stazzo Montesu, Olbia-Tempio, under Quercus suber , 26 November 2002, M. Contu, TOAV137; Trentino Alto Adige: San Vigilio di Marebbe (Alpe di Fanes), alpine meadow, elev. 2200 m, 1 September 2020, E. Bizio, J. Ferrari. F. Padovan, EB01092020. SPAIN. Balearic Islands: Mallorca, Escorca- Menut, elev. 600 m, in a Quercus ilex forest, 14 October 2018, J. C. Salom, JCS1593-B; Navarra, Zilbeti, between fallen leaves of Fagus sylvatica , 2 October 2011, L.M. García-Bona, LMGB4697 (AH60259). SLOVENIA. Hrpelje-Kozina: Obrov, near Picea abies and Quercus robur , 26 July 2014, G. Ferisin, M. Olivi, FG26072014. SWEDEN. Västergötland, 15 August 2014, A. Stridvall & K.A. Johansson, GB0180210. TURKEY. Karabük: in Yenice Forests, on decayed wood of Fagus orientalis , elev. 230 m, 7 October 2012, O. Kaygusuz, OKA-TR1014; ibid., on wood and fallen branch of F. orientalis , elev. 225 m, 10 October 2015, O. Kaygusuz, OKA-TR1024. UNITED KINGDOM. Wales: Anglesey, Newborough Warren, in sand, under Salix cinerea , 28 August 2012, C.E. Aron, K(M)187337; ibid., in grass on limestone ledge, C.E. Aron, K(M)257372.

Observations:—The above description is based exclusively on the collections examined by us. Additional sequences retrieved from GenBank and UNITE, some under the name Volvariella pusilla , represent in all likelihood V. hypopithys as accepted here. This includes sequences from Canada (Quebec) and USA (Arkansas, California, New York, Pennsylvania), making V. hypopithys one of the few species of Volvariella confirmed to occur both in Europe and North America.

The sample JCS1593-B has small rhizomorphs with clamped hyphae. Since we found only one sample with this character, we are reluctant to add this characteristic as a stable character for the species.

According to the original description, this species is characterized by a small, conical to campanulate white and silky (sericeous) pileus, pubescent stipe and a membranaceous volva. Volvariella glaucocephala is recovered as the sister taxon to V. hypopithys , as part of a more inclusive clade with V. reidii , V. surrecta , and V. strangulata . Volvariella glaucocephala differs from V. hypopithys in the grey-blue colours of the pileus, the relatively narrower spores (avQ = 1.36 in V. hypopithys ; avQ = 1.54 in V. glaucocephala ), and the habitat under Cedrus atlantica , likely associated with mycelium of Agaricus arvensis Schaeffer (1774: 310) . Volvariella neoparvula has a white to greyish white pileus, shorter cystidia (36–67 × 13–33 µm) and clamped hyphae on rhizomorphs. Volvariella pusilla has a smooth, glabrous stipe, lageniform cystidia with shorter neck and pileipellis without globose to vesiculose elements. Volvariella reidii has shorter spores (4.8 × 3.7 µm on average) and its pileipellis lacks globose to vesiculose elements.

Volvariella sylvipraticola has a pileus that is pure white to white with greyish shades, shorter cystidia (48–90 × 12–35 µm) and a pileipellis without globose to vesiculose elements. Volvariella latispora is a smaller species with a pileus of 10–14 mm, larger spores (7.7 × 5.2 µm on average), hymenial trama with globose, sphaerocyte-like elements (15–22 × 15–20 µm) smaller cystidia (46–70 × 18–27 μm) and a pileipellis without globose to vesiculose elements. Volvariella nodosicystis has smaller basidiomes with pale greyish pilei of 12–15 mm, with different cystidia, sometimes with 2–3 nodules at the top and the pileipellis lacks globose to vesiculose elements. Volvariella globifera has smaller spores (5.8 × 3.9 µm on average), and shorter cystidia (33–69 × 8–30 µm); this species has a pileipellis with globose to broadly fusiform, pyriform or allantoid hyphae constricted at the septa, measuring 63–121 × 28–55 µm.

Figures

FIGURE 13. Volvariella hypopithys. A–C. Basidiomes. A. (JCS-1593B); B–C (LMGB 4697). D–J. Microscopic characters. D–E. Cheilocystidia (JCS-1593B); F. Pleurocystidium (K187337); G. Spores (A8200367); H. Pileipellis (A8200367); I. Volva hyphae (LMGB4697); J. Rhizomorph hyphae (JCS-1593B).Bar: (D–J) = 10 µm. Photos by J. C. Salom (A), L.M. García-Bona (B–C), F. Caballero (D–J).