Agaricus wayanadensis C.P. Arya & C.K. Pradeep sp. nov. (Figs. 5,6)

MycoBank MB: 851578

Diagnosis:—It can be distinguished from A. elongatestipes by orange white to brownish orange pileus with brown squamules, simple clavate to, cylindro-clavate, hyaline cheilocystidia, slightly larger basidiospores (4.8–5.9 × 3.1–3.7 µm) and molecularly by 44 nucleotide positions in the nrITS.

Holotype:— INDIA. Kerala State: Wayanad District, Kuruva Island, 11. 49° N, 76. 55°E, elev. 700 m, 07 June 2022, Arya TBGT (M)18860! GenBank [ITS]: OR661750.

Etymology:— wayanadensis (Latin), refers to the type locality “Wayanad District” of the new species.

Description:— Pileus 30–60 mm diam., plano-convex to applanate with a flat or slightly depressed disc; surface orange white/brownish orange (6B2/6B3) with dark brown disc, brown appressed squamulose throughout, paler and sparse towards margin, dry; margin straight, entire, exceeding the lamellae. Lamellae free, dark brown, up to 6 mm wide, crowded with lamellulae of different lengths; edge concolorous to the sides, entire. Stipe 33–74 × 5–6 mm, central, cylindric, curved, hollow, brittle, tapering up from a clavate base; surface dry, white to off white, becoming light brownish on handling, smooth and glabrous above the annulus, finely squamulose below the annulus, vanishing on handling. White mycelial strands present at the stipe base. Context white, up to 3 mm thick at the pileus disc, fleshy. Annulus superous, white, membranous, skirt like, pendant, evanescent. Odor mushroomy.

Macrochemical reactions:—KOH and Schäffer’s reactions positive on fresh basidiomata.

Basidiospores 4.8–5.9 × 3.1–3.7 µm, (avL = 5.39 ± 0.27, avW = 3.40 ± 0.16), Q = 1.3–1.7, (avQ= 1.58), ellipsoid to oblong, brown, thick-walled, without apical pore. Basidia 14–18 × 6–7 µm, clavate to broadly clavate, tetrasterigmate, thin-walled, hyaline. Lamella edge sterile with crowded cheilocystidia. Cheilocystidia 14.5–25.4 × 8.6–11.6 µm, simple, or sometimes 2-celled, clavate, cylindro-clavate, thin-walled, hyaline. Pleurocystidia absent. Hymenophoral trama regular, hyphae 2.9–14 µm wide, constricted at septa, thin-walled, hyaline. Pileal trama interwoven, branched, septate, hyphae 8.5–20 µm wide, inflated, thin-walled, hyaline. Pileipellis a cutis, composed of parallel, cylindrical hyphae 7.8–10 µm wide, not or slightly constricted at septa, thin-walled, with light brown contents. Stipitipellis composed of parallel, hyphae, cylindrical, not or slightly constricted at septa 3.7–8.8 µm wide, thin-walled, hyaline. Annulus composed of cylindrical hyphae, slightly constricted at septa, 4.1–10.4 µm wide, thin-walled, hyaline. Clamp connections absent.

Habitat and phenology:—Solitary, scattered on soil; fruiting in April, June.

Additional specimen examined:— India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI Campus, 8.75°N, 77.02°E, elev. 150 m, 18 April 2022, Arya TBGT(M)18790.

Notes: Agaricus wayanadensis is characterized by orange white to brownish orange pileus with dark brown appressed squamules, clavate stipe, ellipsoid to oblong basidiospores, simple, clavate cheilocystidia and pileipellis a cutis with brownish contents. In the phylogenetic analysis, A. wayanadensis forms a subclade within clade I and distinct from all other species in the clade by more than 44 nucleotide differences in the nrITS sequences. Agaricus elongatestipes can be distinguished from A. wayanadensis by its ochreous yellow appressed fibrillose pileus, bulbous stipe base, almond odor, small ellipsoid to elongate basidiospores (4.6–5.4 × 3.0–3.5 µm) and clavate, pyriform or capitate cheilocystidia with long narrow stalk and yellow contents. Agaricus luteopallidus is characterized by a pileus covered with pale yellow to light brownish yellow fibrils or with triangular squamules, cheilocystidia simple, rarely in short chains, globose to sphaeropedunculate with yellowish contents, pileipellis hyphae with yellowish pigments and almond odor. Small basidiomata (30–35 mm), yellow pileus with orange flakes, claviform to pyriform cheilocystidia with yellowish contents and pileipellis with yellow vacuolar pigments (Heinemann 1956) distinguishes Agaricus laeticulus. Agaricus cerinupileus can be separated by its large fleshy basidiomata (70–90 mm), flavescent on touching, bruising, or cutting, ochraceous-yellow appressed fibrillose scaly pileus, heavily fibrillose woolly stipe, large basidiospores (5.5–6.5 × 3.5–4.2 µm), and large, capitate cheilocystidia with long narrow stalk with yellow pigments. Grayish yellow to yellow ochre fibrillose squamulose pileus, fibrillose stipe with strongly flavescent on bruising, smaller basidiospores (4.6–5.2 × 2.7–3.3 µm), pyriform to broadly clavate cheilocystidia with yellowish contents and pileipellis hyphae with yellowish brown contents key out Agaricus flavopileatus from A. wayanadensis.