Leucoagaricus fragilis M. Asif, Niazi, A. Izhar & Khalid, 2021

Niazi, Muhammad Asif Abdul Rehman, Izhar, Aiman, Khalid, Abdul Nasir & Bashir, Hira, 2021, Leucoagaricus fragilis sp. nov. (Agaricaceae) from Punjab, Pakistan, Phytotaxa 501 (1), pp. 140-150 : 144-146

Leucoagaricus fragilis M. Asif, Niazi, A. Izhar & Khalid sp. nov. Figs. 3A–D , 4A–E

MycoBank: MB839737

Etymology:—Specific epithet ‘ fragilis’ (Latin) refers to the fragile basidiomata.

Diagnosis:—This species is characterized by a white, radially fibrillose pileus that rarely splits, a light brown umbonate disk, pinkish brown lamellae at maturity, a white stipe that stains yellow on handling, abundant sphaeropedunculate cheilocystidia, and a pileipellis with broadly clavate elements.

Holotype:— PAKISTAN. Punjab, Haroonabad, District Bahawalnagar , 163m a.s.l., scattered or in small groups on loamy soil along canal bank under Vachellia nilotica , 4 October 2019, BWN 90; Muhammad Asif ( LAH 36797). GenBank accessions: MW 699856 (nrITS), MW 699859 (nrLSU).

Description:— Pileus 0.7–2.5 cm diam.; plane to slightly umbonate; creamy white (2.5YR5/12) becoming brownish (7.3YR7/5.5) when dried; central disk light brown (7.5YR8/4), becoming dark brown (1.9YR4.4/5) in dried specimens; surface radially fibrillose, dry and silky; dentate margin becoming undulate at maturity; rarely splitting radially. Lamellae white (2.5YR5/12) to pinkish brown at maturity; yellowish brown (7.4YR5.4/7.4) in dried specimen; free; distant; edges undulate. Stipe 3.3 × 0.2–0.4 cm diam., creamy white (2.5YR5/12); staining yellow on handling; becoming light brown (2.8YR4.2/8.7) toward apex and dark brown (3.1YR6.7/6.7) toward base in dried specimens; centrally attached; mostly curved; equal; surface smooth, dry and shiny; base slightly bulbous. Annulus inferior; membranous; most often on lower half of the stipe but sometimes on upper half of the stipe; vaguely appendiculate, ring zone visible at maturity in most specimens collected; creamy white (2.5YR5/12); disappearing at maturity. Odor not distinctive.

Basidiospores [80/4/4], (5.8–) 6.3–7.1 (–7.5) × (4.2–) 4.3–4.7 µm, avl × avw = 6.5 × 4.5 µm; Q = 1.07–1.14; Qav = 1.53; subglobose to ellipsoid; thick-walled; smooth with a prominent apiculus; olivaceous droplets present. Basidia (19.98–) 21.1–24 (–25) × (8.1–) 7.4–9.9 (–10.1) µm, avl × avw = 22.4 × 9.1 µm, thick-walled; clavate; frequently trisporic and tetrasporic, rarely bisporic; olivaceous droplets present. Cheilocystidia (17.2–) 17.6–22.2 (–22.3) × (8–) 8.1–9.5 (–9.7) µm, avl × avw = 19.8 × 7.1 µm thin-walled; broadly clavate, often sphaeropedunculate with mostly cylindrical ante-terminal elements; olivaceous droplets present. Pleurocystidia absent. Pileipellis a trichoderm; cylindrical hyphae intermixed with narrow to broader clavate elements; thin-walled; frequently septate; mostly constricted at septa; elements with rounded ends; 4.3–15.8 µm in diam., avw = 9.92 µm. Stipitipellis hyphae thick-walled; septate; irregularly arranged; cylindrical, 4.21–17.61 µm diam., avw = 9.18 µm. Clamp connections absent in all tissues.

Microchemical reactions:—Basidiospores faintly green in 10% ammonia. Cheilocystidia and pileipellis elements not colored in 10% ammonia.

Habitat:—On loamy soil, scattered or in small groups, along the Three R (3R) irrigation canal bank under Vachellia nilotica .

Geographical distribution range:— Known only from the type locality in District Bahawalnagar , Punjab, Pakistan .

Additional material examined:— PAKISTAN. Punjab, Haroonabad, District Bahawalnagar , at 163m a.s.l., scattered or in small groups on loamy soil along the canal bank under Vachellia nilotica , 28 August 2020, AG 74, Muhammad Asif ( LAH 36800!), GenBank accessions; MW 699855 nr( ITS), MW 699858 (nrLSU) ; 5 October 2019, BWN 98, ( LAH 36798!), GenBank accessions; MW 699857 nr( ITS), MW 699860 (nrLSU) ; 25 August 2020, AG 71, ( LAH 36799!) .

Figures

FIGURE 3. A–D Basidiomata of Leucoagaricus fragilis. Photos by: Muhammad Asif

FIGURE 4. A–E. Microscopic characters of Leucoagaricus fragilis (Holotype).A = Basidia, B = Basidiospores, C–D= Cheilocystidia, E = Pileipellis hyphae. Drawings by: Hira Bashir & Muhammad Asif