Volvariella alba Ijaz, Bilal & Jabeen, 2025

Jabeen, Sana, Ijaz, Hira, Ullah, Sadiq, Shahid, Aleena, Sharif, Muhammad Bilal, Aslam, Aqsa, Saeed, Anum, Usman, Muhammad & Khalid, Abdul Nasir, 2025, New and noteworthy Volvariella spp. (Volvariellaceae) from Pakistan, Phytotaxa 691 (2), pp. 151-172 : 156

Volvariella alba Ijaz, Bilal & Jabeen sp. nov. Figs. 2 , 3

MycoBank:—MB#854740

Holotype:— PAKISTAN. Punjab, Bahawalnagar District, Haroonabad , elev. 178 m a.s.l., on soil, 26 July 2023, Bilal Sharif H82 ( UEHF0025 ; GenBank: PQ065600 ).

Etymology:—The specific epithet ‘ alba’ refers to the white color of the pileus.

Diagnosis:— Volvariella alba is characterized by the short smooth stipe, and the bi-lobed, membranous white volva with brown patches making it different from V. nivea which bears a longer stipe and a lobbed white volva.

Description:— Pileus 2.5–2.8 cm diam., broadly conical to convex, surface smooth to slightly fibrillose, context white, margins minutely striate. Lamellae free, close, edges entire, notched at pileal margins, lamellulae frequent, of variable length, light pink (10 RP 8/4). Stipe 2.5–3 × 0.3–0.4 cm, equal, smooth, white. Volva 1.5 cm long, saccate, bi-lobed, membranous, exterior with brown (7.5 YR 3/1) patches on white background, interior off-white. Overall context white.

Basidiospores [20/2/1] (5.7)6.5–7(7.7) × (3.8)4.1–4.6(5) µm, avl × avw = 6.7 × 4.3 μm, Q = 1.3–1.6, Qav = 1.4, ellipsoid, thick-walled; apiculus present, guttulate, inamyloid, hyaline to greenish in 5 % KOH. Basidia (25.4)27.2– 37.6(39.8)×(7.5)7.9–9.2(9.5) μm, clavate to broadly clavate, thin-walled, with 2–4 sterigmata. Cheilocystidia (40.5)44–63.0(64.5)×(14.4)15.8–20.2(20.9) μm, fusiform to broadly fusiform. Pleurocystidia (44.0)46.9– 59.1(60.3)× (12.0)13.5–16.3(16.7) μm, fusoid-ventricose, abundant. Lamellar trama inversely bilateral, hyphae 6.7– 17.8 μm diam. Pileipellis hyphae (8.3)9.3–14.1(15.2) μm diam., branched, septate, thin-walled, colourless. Stipitipellis hyphae (8.2)9.8–17.1(18.9) μm diam., cylindrical, septate. Clamp connections absent. All tissues hyaline and colorless in 5 % KOH.

Habitat and distribution:—Found so far only at the type location in Bahawalnagar District, Punjab, Pakistan, on soil in a hot desert climate dominated by Azadirachta indica , Eucalyptus camaldulensis , and Vachellia nilotica .

Figures

FIGURE 2. Volvariella alba sp. nov. a, b. UEH-F0025 (holotype). Scale bar = 1 cm. Photographs by Bilal Sharif.

FIGURE 3. Volvariella alba sp. nov. UEH-F0025 (holotype). a. Basidiospores. b. Basidia. c. Cheilocystidia. d. Pleurocystidia. Scale bars: = 10 µm. Drawings by Hira Ijaz.