Agaricus indicus C. P. Arya & C. K. Pradeep 2024, sp. nov.
Creators: name: Arya, C. P.
name: Pradeep, C. K.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Agaricus
Agaricus indicus

description: Agaricus indicus C.P. Arya & C.K. Pradeep sp. nov. (Figs. 2, 3)
MycoBank MB: 851576
Diagnosis:—Distinct from the closely related Agaricus purpureosquamulosus by the slightly larger basidiomata, white pileus with rose to grayish red appressed squamules, anise odor, smaller basidiospores [5.6–6.4 (6.8) × 4–4.4 µm] and molecularly by 24 nucleotide positions in nrITS.
Holotype:— INDIA. Kerala State: Thiruvananthapuram District, Palode, JNTBGRI Campus, 8.75°N, 77.02°E, elev. 150 m, 19 May 2016, Arya TBGT (M)16128! GenBank [ITS]: OR661746
Etymology:— indicus (Latin), refers to the type country of the new species.
Description:— Pileus 22–53 mm diam., parabolic in bud, convex to plano-convex when mature and becoming uplifted when old, either with or without a central depression or a small obtuse umbo; surface white with rose to grayish red (11B5/11C5) disc with concolorous appressed squamules throughout when young, becoming greyish brown (8D3) to dark brown with darker disc when old with concolorous squamules, sparse towards the margin, dry; margin straight, become uplifted in old ones, entire to variously incised, striate, appendiculate with remnants from the partial veil, exceeding the lamellae. Lamellae free, pale red (8A3) when young becoming greyish brown to dark brown (6E2/7F4/7F8) when mature, up to 7 mm wide, crowded with lamellulae of different lengths; edge concolorous to the sides. Stipe 30–60 × 3–7 mm, central, cylindric, curved, narrowly hollow, equal to slightly tapering up from a bulbous base; surface white becoming orange gray to grayish brown (5B2/8D3) when mature, white appressed squamules throughout, vanishing on handling, stipe base turns weakly yellowish on bruising, smooth. White mycelial strands present at the stipe base. Context white, up to 6 mm thick at the pileus disc, fleshy, soft. Annulus attached either central or in the upper part, superous, white, fugacious, membranous, easily evanescent. Odor of anise.
Macrochemical reactions:—KOH and Schäffer’s reactions positive on dried basidiomata.
Basidiospores (4.8) 5.6–6.4 (6.8) × 4–4.4 µm, (avL= 5.69 ± 0.476, avW = 3.96 ± 0.174), Q = 1.1–1.6, (avQ = 1.39 ± 0.10), broadly ellipsoid to ellipsoid, smooth, brown, thick-walled. Basidia 12–18.4 × 6–9.2 µm, clavate, tetrasterigmate, thin-walled, hyaline. Lamella edge sterile. Cheilocystidia 14–30 × 8–12 µm, clavate, vesiculose, subglobose, thin-walled, hyaline. Pleurocystidia absent. Hymenophoral trama regular, 4–17.2 µm wide, constricted at septa, thin-walled hyaline. Subhymenium pseudoparenchymatous. Pileal trama composed of cylindrical to inflated hyphae 6–20 µm wide, thin-walled, hyaline. Pileipellis a cutis, hyphae 4–12 µm wide, thin-walled, hyaline. Stipitipellis a cutis, hyphae 4–12 µm wide, thin-walled, hyaline. Annulus composed of cylindrical hyphae, slightly constricted at septa, 3.0–4.2 µm wide, thin-walled, hyaline. Clamp connections absent.
Habitat and phenology:—Solitary or scattered among grass; fruiting in May–July, September.
Additional specimens examined:— India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI Campus, 8.75°N, 77.02°E, elev. 150 m, 24 May 2010, Arya TBGT (M)13257; 31 May 2010, Arya TBGT (M)13275; Kollam District, Chozhiyakode, 8.8°N 76.6 °E 04, elev. 198 m, September 2012, Arya TBGT (M)14243; Thiruvananthapuram District, Palode, JNTBGRI Campus: 01 July 2015, Arya TBGT (M)15735; 18 May 2016, TBGT (M)16119; 19 May 2016, Arya TBGT (M)16132; 17 June 2016, Arya TBGT (M)16344.
Notes: Agaricus indicus is characterized by small to medium basidiomata (22–53 mm), white pileus with rose to grayish red disc becoming dark brown in old basidiomata, appressed squamulose pileus and stipe, central to superior thin fugacious annulus, anise odor, broadly ellipsoid to ellipsoid basidiospores and clavate to vesiculose cheilocystidia. Phylogenetically, BLASTn search utilizing ITS sequence (687bp) showed only 96% sequence identity with A. purpureosquamulosus Tarafder, A.K. Dutta, & K. Acharya (2022: 188) followed by A. glabriusculus S. Hussain (2019: 799) and two other Agaricus spp. with 95% sequence identity. Agaricus purpureosquamulosus differs from A. indicus (OR661746) at 24 nucleotide positions and A. glabriusculus at 25 nucleotide positions (Table 2) in their ITS sequences. These data clearly indicate that A. indicus is distinct from all other species in the sect. Minores. Apart from the molecular differences, A. indicus differs morphologically also with these species. Agaricus purpureosquamulosus, a recently described species from India differs by its purple squamulose pileus and large ellipsoid to elongate basidiospores (7–7.5 × 4.2–4.7 µm). Originally described from Pakistan (Hussain & Sher 2019), A. glabriusculus can be separated by its small basidiomata (12–25mm), pinkish fibrils on the pileus surface, and slightly large basidiospores (6–6.5 × 40–4.5 µm).
Species Variable positions in the final alignment of ITS sequences
287 471 482 483 484 485 487 489 501 518 520 529 530 531 589 591 622 623 635 644 648 655 660 661 A.indicus OR 661744 A T - - - - T G T C A G G G A - G T C C G G C T A.indicus OR 661745 A T - - - - T G T C A G G G A - G T C C G G C T A.indicus OR 661749 A T - - - - T G T C A G G G A - G T C C G G C T A.indicus OR 661746 A T - - - - T G T C A G G G A - G T C C G G C T Agaricus sp. JF727871 A C T T G T T G C C G A G G G T G T T C G T C T A.glabriusculus A T - - - - T A C T G A G A T - - - C G G A T C OL444817
A.glabriusculus - T - - - - T A C T G A G A T - - - C G G A T C MK751852 (T)
Agaricus sp. - T - - - - T A C T G A G A T - - - C C G A T C MK659941
A.purpureosqumulosus - T - - - - C G C C G A A G G T G T T C A T C T OL467541
description: Published as part of Arya, C. P. & Pradeep, C. K., 2024, Agaricus section Minores: New and noteworthy species from India, pp. 255-273 in Phytotaxa 634 (3) on pages 260-263, DOI: 10.11646/phytotaxa.634.3.5, http://zenodo.org/record/13878928