Leucoagaricus thallensis Zaman, A. Izhar & Khalid sp. nov. Figs. 3–4 MycoBank:—MB846996 Etymology:—The specific epithet ‘ thallensis’ refers to the type locality ‘Thal desert’ in Punjab province of Pakistan from where the species is being reported. Diagnosis:— Leucoagaricus thallensis is characterized by its orange-red fibrillose pileus with a white background, the fibrils on the stipe, even edged lamellae due to relatively shorter cheilocystidia, and the occurrence of volva. It differs from La rubrotinctus (Peck) Singer due to its even-edged lamellae, fibrillose stipe, and a distinct volva. Holotype:— Pakistan, Punjab Province, District Khushab, Noorpur Thal, Peelowains (32°01ʹ22.4ʹʹN, 71°59ʹ32.4ʹʹE, 191 m a.s.l.). Gregarious on soil mixed with leaf litter under Dalbergia sissoo and Ziziphus nummularia, 26 July 2022, Zaman Khan & Junaid Khan PW-80 (LAH37619!), ibidem, GenBank no. OP972578 (ITS), OQ568217 (LSU). Description:— Basidiomata 4.8–8.3 cm in total length, medium-sized. Pileus 2.3–4.6 cm diameter, hemispherical or broadly conical to conical and umbonate at first then becoming plane to plano-convex and moderately umbonate with straight margins, dark reddish brown (10R 3/10) at centre; surface covered with radially arranged reddish brown (9D7–9D8) or light orange reddish (6A4) fibrils or squamules whose color washes out and becomes brown or light brown (7.5R 5/16) towards margins on a whitish background; margin entire; context fleshy and white with no change in color upon bruising. Lamellae free, crowded, thin, white to cream (5YR9/2), often with even edges, lamellulae in 1–3 tiers. Stipe 3.5–7.7 × 0.3–0.9 cm, central, cylindrical, hollow, tapering upwards, with sub-bulbous base with mycelial threads, covered over total length with orange-brown or light brown (7.5R5/16) fibrils on shiny white (5YR 9/2) or cream surface, context white. Annulus simple, membranous, a cuff with a small flaring part, thick on edge, white to creamy, concolorous to stipe, in upper part of stipe, easily lost (as shown in the figures). Volva present at base of stipe, white to cream, sheathing. Odor and taste not recorded. Spore print not obtained. Basidiospores [50/3/3], (5.6–)5.7–7.5(–7.7) × (3.5–)3.7–4.7(–4.8) μm, avl × avw = 6.5 × 4.2 μm, Q = 1.51–1.63, avQ = 1.54, oblong ovoid to oblong amygdaliform, broadly ellipsoid to ellipsoid, guttulate, smooth, slightly thickwalled, with prominent apiculus, without a germ pore, hyaline in KOH, dextrinoid. Basidia (14.1–)14.6–19(–20) × (5.6–)5.8–8.6(–9.1) μm, broadly clavate to clavate, smooth, thin-walled, hyaline, sometimes with yellowish refractive contents, 2–4 spored, sterigmata upto 3.5 μm long. Cheilocystidia (10.8–)11.5–18.6(–19) × (5)–8(–8.8) μm, clavate to subclavate, thin-walled, smooth, hyaline. Pileipellis a cutis, hyphae 5.1–11.8 μm in diameter, hyaline, smooth, thin walled, terminal elements cylindrical or wider at center, narrowly fusiform to fusiform or narrowly clavate or narrowly cylindrical with acute apex 45.6–87.3 × 13.2–29.8 μm. Stipitipellis cylindrical to subcylindrical hyphae, 2.7–13 μm in diameter, hyaline, smooth, thin walled, parallel, septate, rarely branched, terminal elements cylindrical to clavate, few are conical. Clamp connections not found. Habit, Habitat and Distribution:—Terrestrial, gregarious on soil mixed with leaf litter under Dalbergia sissoo and Ziziphus nummularia, so far only known from the type locality in Noorpur Thal desert, district Khushab, Punjab, Pakistan. Additional specimens examined:— Pakistan, Punjab Province, District Khushab, Noorpur Thal, Peelowains (32°01ʹ22.4ʹʹN, 71°59ʹ32.4ʹʹE, 191 m a.s.l.), gregarious on soil mixed with leaf litter under Dalbergia sissoo, 29 July 2022, Zaman Khan & Junaid Khan P-197 (LAH37620!), GenBank no:—OP972579 (ITS), OQ568218 (LSU); ibidem, 06 August 2022, P-128 (LAH37621!).

Published as part of Khan, Zaman, Izhar, Aiman & Khalid, Abdul Nasir, 2023, Leucoagaricus thallensis (Agaricaceae; Basidiomycota), a new species from Punjab, Pakistan, pp. 163-177 in Phytotaxa 594 (3) on pages 170-173, DOI: 10.11646/phytotaxa.594.3.1, http://zenodo.org/record/7900684