Agaricus brunneodiscus C. K. Pradeep & C. P. Arya 2022, sp.nov.
Creators: name: Arya, C. P.
name: Kumar, A. Manoj
name: Pradeep, C. K.
name: Parra, Luis A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Agaricus
Agaricus brunneodiscus

description: Agaricus brunneodiscus C.K. Pradeep & C.P. Arya sp.nov. Figs. 2, 3   
MycoBank MB: 840640  
 Diagnosis:—It can be distinguished from the closely related Asian species, Agaricus albosquamosus by the slightly larger basidiomes, white pileus with brown squamules at disc, anise odor, polymorphic large cheilocystidia, larger basidiospores (5.6–7.6 × 3.6–4.5 µm) and distinctive nrITS.   
 Holotype:— INDIA. Kerala State: Thiruvananthapuram District, Palode, JNTBGRI campus, 8.75°N, 77.02°E, elev. 150 m, 16 May 2017, AryaTBGT16727 (CAL1848!). GenBank [ITS]: MZ 437441.   
 Etymology:— brunneodiscus (Latin), refers to the brown pileus disc of the new species.   
 Description:— Pileus 49–81 mm diam., hemispherical in young, becoming convex with a broad obtuse umbo, later plano-convex to applanate with a flat or slightly depressed disc, sometimes uplifted at the margin with a depressed disc in over-mature basidiomes; surface dry, white, off white to creamy white with dark blonde to brown disc (5D4/5E3– 5E5/6D3–6E4) which is entire when young, breaking up into concentrically arranged appressed brownish squamules on a white to brownish background, developing a reddish tinge near the margin in fully mature basidiomes during heavy rain; margin with appendiculate remnants from the partial veil in young basidiomes, entire to variously and deeply incised, not or slightly exceeding the lamellae, when mature. Lamellae free, crowded, up to 8 mm deep intercalated with lamellulae, first pale pink, then bright pink, finally dark brown (5A2/6B2–6F4/7C3–7F8); margin concolorous with face, entire to obscurely denticulate or eroded. Stipe 45–95 × 6–15 mm, centrally attached, cylindrical, curved, stuffed to fistulose, fragile, clavate to sub-bulbous at the base; surface dry, white to off-white, annulate in its upper half, smooth and glabrous above the annulus, finely squamulose below the annulus, vanishing on handling, rarely becoming pale yellowish or brownish on bruising. White mycelial strands and rhizomorphs present at the base. Annulus superous, membranous, cup-like in mature basidiomes later pendent, fragile, persistent or evanescent, white. Context up to 6 mm thick at the pileus disc, fleshy, white not discoloring when cut. Odor of anise. Spore print brown.   
 Macrochemical reactions:—Schäffer’s and KOH reactions negative on fresh basidiomes.   
 Basidiospores 5.6–7.6 × 3.6–4.5 µm, avL = 6.3 ± 0.60, avW= 3.77 ± 0.29, Q = 1.4–2.0, Qm = 1.62, ellipsoid to oblong, brown, thick-walled, without apical pore. Basidia 14–28 × 6–9.5 µm, clavate to broadly clavate, 4–spored, sterigmata up to 3.2 µm long, thin-walled, hyaline. Cheilocystidia abundant, thin-walled, hyaline, simple, or sometimes with two catenulate elements, terminal element polymorphic, usually clavate, ellipsoid, ovoid or fusiform, pedunculate or not, less frequently slightly ampuliform or cylindrical, 12–34 × 10.5–22 µm, antiterminal elements when present ovoid to doliiform, usually smaller than the terminal ones. Pleurocystidia absent. Hymenophoral trama regular, hyphae 1.5–11 µm wide, thin-walled with constricted septa, hyaline. Pileal trama interwoven, branched, septate, hyphae 6–28 µm, inflated, thin-walled, hyaline. Pileipellis a cutis, composed of parallel, cylindrical hyphae 3–10 µm, not or slightly constricted at the septa, thin-walled, with light yellow diffuse pigment. Stipitipellis composed of parallel, hyaline hyphae, cylindrical, not or slightly narrowed at septa 4–9 µm wide, thin-walled, hyaline. Lower surface of the annulus composed of hyaline hyphae, cylindrical, not or slightly narrowed at septa, 2.5–6 µm wide, with disarticulating elements, clavate to subclavate or globose terminal thin-walled elements, 13–24 × 8–11 µm. Clamp connections absent. Oleiferous hyphae present.   
 Habit, habitat and Phenology:—Solitary, scattered or in groups on humus rich soil under palms [Daemonorops verticillaris (Griff.) Mart.] in a palm conservatory and under angiosperm trees in evergreen tropical forest, May–June, August.   
 Additional specimens examined:— India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI campus, 18 May 2016, Arya TBGT 16118; ibid., 10 June 2019, Arya TBGT 17782; ibid., 18 June 2019, Arya TBGT 17829; ibid., 20 August 2019, Arya TBGT 17930; ibid., 8 May 2020, Arya TBGT 18027.
description: Published as part of Arya, C. P., Kumar, A. Manoj, Pradeep, C. K. & Parra, Luis A., 2022, Agaricus brunneodiscus, a new species of Agaricus section Rarolentes from India, pp. 181-193 in Phytotaxa 533 (4) on pages 185-188, DOI: 10.11646/phytotaxa.533.4.1, http://zenodo.org/record/6091244