Volvariella bilobata A.K. Dutta & P. Chattopadhyay, 2022

Chattopadhyay, Pinaki, Talukdar, Mousumi, Beypih, Jeswani, Tayung, Kumananda & Dutta, Arun Kumar, 2022, A new species of Volvariella (Agaricales, Basidiomycota) from West Bengal, India, Phytotaxa 567 (1), pp. 36-48 : 40

Volvariella bilobata A.K. Dutta & P. Chattopadhyay , sp. nov., Figures 1 & 2

MycoBank MB 844749

Etymology:—The specific epithet ‘ bilobata ’ derived from Latin ‘bi’ meaning “two”, and ‘lobatus’, meaning “having lobes”, together referring to the two-lobed volva.

Diagnosis:—Differs from Volvariella volvacea by bilobed volva, smaller basidiospores (4.8–5.5 × 2.7–3.5 µm) and smaller sized basidium (20–23 × 5–7 µm).

Holotype:— INDIA. West Bengal: North-24- Parganas district, Barasat, Jagannathpur , near Kajibari bus stand, 22°44’50.9”N, 88°26’54.7”E, elev. 13.0 m, 21 August 2019, A.K. Dutta, AKD 54/2019 ( GUBH 19922 ).

Description:— Pileus 45–70 mm diam., convex, surface greyish brown (6E3), non-hygrophanous, unchanging on bruising, silky fibrillose, margin translucent striate; context 3–4 mm thick at the center, cream, unchanging on bruising. Lamellae 3–4 mm broad, free, close to crowded with 1–2 series of lamellulae, greyish white (8B1) when young, becoming greyish orange (6B3) when old, concolorous, margin serrated. Stipe 45–60 × 4–10 mm, central, cylindrical, mostly equal, sometimes slightly tapering towards apex, surface greyish white (8B1), fibrillose; context white to cream, solid. Volva 25–40 × 15–30 mm, free from the stipe, bilobed saccate, fleshy, surface greyish brown (6E3) at the outer side and greyish white (8B1) at the inner side, slightly fibrillose. Odour fungus like. Taste not recorded.

Basidiospores (4.8–)5.0–5.2(–5.5) × (2.7–)3.0–3.2(–3.5) µm [X mr = 5.08–5.13 × 3.18–3.28, X mm = 5.10 ± 0.17 × 3.22 ± 0.23 μm, Q mr = 1.57–1.60, Q mm = 1.59 ± 0.09, n = 28 basidiospores per 2 specimens], ellipsoid, often 1–2 guttate, thin- to slightly thick-walled, smooth. Basidia 20–23 × 5–7 µm, clavate, hyaline, thin-walled, 4-spored, sterigmata ca. 2 µm long. Basidioles 14–18 × 3–6 μm, clavate, hyaline, thin-walled. Cheilocystidia 32–83 × 13–30 µm, crowded, clavate to ventricose lageniform, hyaline with KOH, thin-walled. Pleurocystidia 18.5–27.5 × 7–10 µm, abundant, variable in shape, ventricose acuminate to ventricose rostrate, broadly clavate to lageniform, hyaline with KOH, thinwalled. Lamellae trama hyphae 5–10 µm broad, hyaline with KOH, unbranched, thin-walled, often associated with oliferous hyphae, measuring 5–7 μm broad. Pileipellis a cutis-type, hyphae 8–18 µm broad, non-gelatinous, light brown with KOH, thin-walled. Pileus context hyphae 7.5–10 µm broad, often branched, hyaline with KOH, thinwalled. Stipitipellis a cutis-type, hyphae 63–175 × 20–38 µm, regular, cylindrical, hyaline to pale brown with KOH, unbranched, thin-walled. Stipe context hyphae 2.5–10 µm broad, regular, hyaline with KOH, unbranched, thin-walled. Volva composed of hyphae measuring 5–10 µm broad, closely packed, irregular, unbranched, light brown with KOH, thin-walled. Clamp-connection absent in all tissues.

Ecology and distribution:—Solitary, scattered, on soil deposited in the base of a dicotyledonous tree. Known only from Eastern India.

Additional specimen examined:— INDIA. West Bengal: North-24- Parganas district, Barasat, Jagannathpur , near Kajibari bus stand, 22°44’49.1”N, 88°26’56.9”E, elev. 15.0 m, 23 August 2019, A.K. Dutta, AKD 82/2019 ( CUH AM778 ) .

Figures

FIGURE 1. Mature basidiocarps of Volvariella bilobata (GUBH 19922, holotype, photos by A.K. Dutta): A. Fruitbody in natural habitat; B. Mature fruitbody showing bilobed volva; C. Lamellae features of the young and mature basidiocarps. Scale bars:A–C = 10 mm

FIGURE 2. Microscopic features of Volvariella bilobata (GUBH 19922, CUH AM778, Drawing by A.K. Dutta): A. Basidiospores; B. Basidia; C. Basidioles; D. Cheilocystidia; E. Pleurocystidia; F. Hyphal cells in the pileipellis. Scale bars: A–C = 5 μm; D–F = 10 μm.