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 Add this item to the list  821859 Original description
Remarks (public):Volvariella morozovae is characterised by its medium-sized and slender basidiocarps with pale brownish grey and hairy pilei, olivaceous-brown or rusty brown felted volva, small (5–6.2 × 3.3–4.3 µm) elongate-ellipsoid to lacrymoid basidiospores. There are several fairly well known species with small or medium-sized basidiocarps, grey or brown pilei and coloured volva, among them Volvariella cinerascens Bres., V. fuscidula Bres., V. murinella (Quél.) M.M. Moser ex Dennis, P.D. Orton & Hora, V. taylorii (Berk. & Broome) Singer and V. nigrodisca Shaffer. The studied Vietnamese collection does not agree in all respect with the description of any of these species. It lacks 1) the glabrous pileus with striate margin and narrow (3–3.5 µm) basidiospores of V. cinerascens (Boekhout 1986, 1990, Orton 1986); 2) the initially viscid puleus, the blackening stipe, and the larger (6.7–8.2 × 4.7–5.5 µm) basidiospores of V. fuscidula (Shaffer 1963); 3) significantly larger (40–100 × 10–30(50) µm) cheilo- and pleurocystidia, and terrestrial habitats with preference of grasslands of V. murinella (Boekhout 1990); 4) grey-olivaceous pileus, larger (5.6–8.7 × 4–6 µm) subglobose basidiospores, and longer (up to 80 µm) cheilo- and pleurocystidia of V. taylorii (Shaffer 1957; Pegler 1983; Orton 1986); 5) rimose pileus with striate margin and blackish disc, vinaceous-buff lamellae, white volva, and clavate cheilocystidia of V. nigrodisca (Shaffer 1963). Two species, Volvariella heterospora Menolli & Capelari (Menolli & Capelari 2008) and V. leucocalix Sá & Wartchow (Sá & Wartchow 2016), recently described from Brazil and similar to V. morozovae in terms of pileus colouration and morphology of hymenial cystidia, nevertheless significantly differs from it in colour of volva which is never greyish brown, as well as shape and size of basidiospores. Another species from Brazil with brownish basidiocarps, V. nullicystidiata Menolli & Capelari (Menolli & Capelari 2008), is also different based on larger pileus and stipe, basidiospore size (7.5–8.7 × 5–7.5 µm) and lack of cystidia. The new species also resembles in some respects the North American V. lepiotospora Singer but differs according to the original description of the latter in lighter coloured pileus, brownish volva, shape of basidiospores, and the absence of clamp connections (Shaffer 1957). References: Boekhout T. 1986. Notulae ad Floram Agaricinam Neerlandicam – XII: small, saprophytic Volvariella species in the Netherlands. Persoonia 13: 197–211. Boekhout T. 1990. Volvariella, in C Bas, ThW Kuyper, ME Noordeloos, EC Vellinga (eds.). Flora Agaricina Neerlandica 2. Rotterdam, A.A. Balkema. 56-64. Menolli N, Capelari M. 2008. Records and two new species of Volvariella (Pluteaceae, Agaricales) from Brazil. Mycotaxon 106: 385–398. Pegler DN. 1983. Agaric flora of the Lesser Antilles. Kew Bulletin Additional Series 9: 1–668. Orton PD. 1986. Pluteaceae: Pluteus & Volvariella. In: Henderson DM, Orton PD, Watling R. (eds.). British Fungus Flora: Agarics and Boleti, vol. 4. Edinburgh, Royal Botanic Garden. Sá MCA, Wartchow F. 2016. Volvariella leucocalix (Pluteaceae), a new species from Brazilian semiarid region. Mycosphere 7(1): 30–35. Shaffer RL. 1957. Volvariella in North America. Mycologia 49(4): 545–579. Shaffer RL. 1963. Synonyms, new combinations, and new species in Volvariella (Agaricales). Mycologia 54(5): 563–572. Singer R. 1955. New and interesting species of Basidiomycetes. IV. Mycologia 47(5): 763–777. 
Description type:Original description 
Description:Basidiocarps medium-sized. Pileus 30–40 mm, broadly campanulate, later expanded, without umbo; non-hygrophanous; not viscid; sandy brown, cinereous, pale brownish grey, darker at centre – grey-brown or dirty brown, towards margin paler to beige or whitish; radially silky fibrillose to hairy with some short hairs ascending, with slightly serrulated margin fringed with fluffy fibrils. Lamellae crowded to fairly distant, free, hardly ventricose, initially whitish then pink to brownish pink, with concolorous entire edge. Stipe 35–50 × 3–4 mm, cylindrical, not or somewhat broadening towards base, up to 6–7 mm, white or with light ochraceous or buff shades; entirely minutely pubescent. Volva thin, membranous, saccate, sordid grey-brown to olivaceous-brown with rusty brown spots, irregularly lobed, with felted to woolly outer surface. Context white. Smell and taste indistinct. Basidiospores 5–6.2 × 3.3–4.3 µm, Q = 1.30–1.65, Q* = 1.46, elongate-ellipsoid to lacrymoid, some rather ovoid, hyaline in KOH, thick-walled. Basidia 13.5–20 × 7–8.5 µm, 4-spored, broadly clavate with a medial constriction at maturity. Cheilocystidia 40–55 × 13–18 µm, variable in shape, mainly ventricose-lageniform, broadly fusiform, sometimes with apical excrescences or subglobose apex, some proportion utriform, thin- or slightly thick-walled. Pleurocystidia rare, 45–50 × 18–30 µm, utriform or broadly clavate, slightly thick-walled. Pileipellis a cutis, made up of short-celled, slightly thick-walled hyphae, 20–35 µm wide, with intracellular grey-brown pigment; transforming into a trichoderm at centre of pileus, with cylindrical, fusiform or sublageniform terminal elements more than 100 µm long. Stipitipellis a cutis, made up of long, cylindrical, hyaline hyphae, 10–12 µm wide; hairs of stipe cylindrical, up to 150–200 µm long. Clamp connections absent in all parts examined. 
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