Agaricus duplocingulatoides Tarafder, A.K. Dutta & K. Acharya, 2018

Tarafder, Entaj, Dutta, Arun Kumar, Sarkar, Jit & Acharya, Krishnendu, 2018, A new species of Agaricus sect. Brunneopicti from Eastern India, Phytotaxa 374 (2), pp. 139-146 : 142

Agaricus duplocingulatoides Tarafder, A.K. Dutta & K. Acharya , sp. nov., Figures 2 & 3

MycoBank MB 826889

Etymology:—Named after its morphological closeness with the taxon Agaricus duplocingulatus . Diagnosis:—Differs from Agaricus duplocingulatus by its smaller pileus (22–32 mm), much smaller stipe (20–25 mm), absence of catenulate cheilocystidia, somewhat longer basidiospores (6–8 × 3.5–4.5 μm), and 11 positions in the entire nrDNA ITS sequences. Holotype:— INDIA. West Bengal: East Midnapur district, Ramnagar, Kasafaltalya, 21°43′29.9″N, 87°31′36.6″E, 10 m elev., 23 June 2016,

E. Tarafder & A. K. Dutta, CUH AM537.

Description:— Fruit -body small to medium-sized, agaricoid. Pileus 22–32 mm diam., convex when young, becoming applanate at maturity with a shallow central depression, surface dry, appressed squamulose, arranged in concentric manner throughout the entire pileus on a white to cream background, surface turns yellow with KOH, negative in Schäffer’s reaction, squammules light brown (6E4) to brownish grey (10D 2, 6E 2) or greyish brown (6E3) towards margin, margin non-striate when young, faintly striate on extreme maturity, incurved, partial veil present, flappy membranous, white (1A1), context white to cream, fleshy, fibrous, unchanging when bruised but turning brownish beige (6E3) with KOH. Lamellae 2–3 mm broad, free, pinkish white (10A2) to pink (12A4) when young, becoming greyish brown (8D3) to brownish grey (8D2) on maturity, dark brown (6F8) to coal black (5H2) on drying, crowded with 2–4 series of lamellulae, edges discolorous, even. Stipe 20–25 × 2–4 mm, tapered at apex, base ca. 7 mm broad, surface white (1A1) when young, grey (5C1-6D1) to brownish grey (5C2-6D2) on age, turns brownish on bruising, silky fibrillose to slightly pruinose, fistulose to hollow, fleshy fibrous, base with white (1A1) rhizomorphs. Annulus present, double edged, the upper one membranous, lower one fugacious, white (1A1). Odour mild phenolic. Taste unknown.

Basidiospores (6–)6.5–7.5(–8) × 3.5–4.2(–4.5) μm [X m = 6.9 ± 0.5 × 4.0 ± 0.3, Q = 1.6–1.9, Q m = 1.7 ± 0.1, n = 30 spores from each of the collected two specimens], ellipsoid, light brown (6D5, 6D6) to brown (6E 6, 6E 7), smooth, amyloid, metachromatic in cresyl blue, thick-walled (up to 1.4 μm). Basidia 14–21 × 6–7 μm, clavate to broadly clavate, smooth, hyaline, 4-spored, sterigmata 1.5–2.5 μm long. Basidioles (11–)13–14(–16) × 5.5–6.5(–7.5) μm, clavate, smooth, hyaline, thin-walled. Lamellae edge fertile with well-developed cheilocystidia. Cheilocystidia 17–25 × 8–11 μm, pyriform, mostly vesiculose, sometimes broadly clavate, hyaline, smooth, thin-walled. Pleurocystidia absent. Pileipellis a cutis, composed of 3.5–13 μm broad, short terminal inflated hyphal elements, cylindrical to palisade in shape, hyaline in KOH, thin-walled. Pileus trama hyphae 7.5–10 μm broad, cylindrical, hyaline, thin-walled. Lamellae trama regular, hyphae 7–12 μm broad, hyaline, thin-walled. Stipitipellis hyphae 2.5–5.5 μm broad, light yellowish with KOH, thin-walled. Stipe trama regular, hyphae 6.5–12 μm broad, cylindrical, thin-walled. Caulocystidia absent. Clamp -connections absent.

Habit and habitat:—solitary or in a group of two, on soil and associated with stone chips, under angiospermous trees.

Additional specimen examined:— INDIA. West Bengal: East Midnapur District, Ramnagar, Kasafaltalya, 21°43′04.8″N, 87°31′38.2″E, 8 m elev, 12 June 2017, E. Tarafder & A. K. Dutta, CUH AM602.

Figures

FIGURE 2. Agaricus duplocingulatoides (CUH AM537). a–b. matured basidiomata at the field showing pileus surface and lamellae side. Scale bars: a–b = 10 mm. Photographed by A. K. Dutta.

FIGURE 3. Agaricus duplocingulatoides (CUH AM537, from Holotype). a. basidiospores; b. basidium; c. cheilocystidia; d. hyphal cells of the pileipellis. Scale bars: a–b = 5 μm; c = 10 μm; d = 15 μm. Drawn by E. Tarafder.