Agaricus duplocingulatoides var. brevisporus C.P. Arya & C.K. Pradeep, var. nov.
Index Fungorum number: IF 900408; MycoBank number: MB 900408; Facesoffungi number: FoF 14217; Fig. 1
Etymology – Refers to the small basidiospores of the variety.
Diagnosis – Differs from the type variety Agaricus duplocingulatoides by larger basidiomata, smaller basidiospores and negative KOH reaction.
Macroscopic characters – Pileus 39–78 mm diam., convex to plano-convex, then applanate with an obtuse umbo at the disc; surface dry, dark brown (6F8/7F5/7F7/7F8) appressed squamules dense and smooth at disc, elsewhere almost in concentric rings, scarce towards margin on an off white background, develops reddish white (7A2) tinge here and there during heavy rain; margin straight, appendiculate, white, with remnants from the partial veil, entire, exceeding the lamellae. Lamellae free, crowded, up to 8 mm wide, greyish brown to dark brown (7D3/7F4/7F5/8D3/8E3) intercalated with lamellulae of different lengths; edge concolorous to the sides. Stipe 28–55×6–13 mm, central, cylindric, curved, stuffed to narrowly hollow, tapering slightly upwards from a broad base; surface dry, white to off white become brownish on handling, smooth and glabrous above the annulus, minutely squamulose below annulus, vanishing on handling. Context up to 5 mm thick at the pileus disc, fleshy, white, not discoloring when cut. Annulus superous, pendent, skirt like, white, upper side smooth, lower side floccose, evanescent. White mycelial codons present. Odor of anise.
Microscopic characters – Basidiospores 4.3–5.6×3.2–3.8 µm, (avL=4.9±0.37, avW=3.53±0.19), Q = 1.2–1.6, Qm = 1.41, broadly ellipsoid to ellipsoid, brown, thick-walled, without apical pore. Basidia 14–23×5–7 µm, clavate to broadly clavate, tetrasporic, thin-walled, hyaline. Lamella edge sterile with abundant cheilocystidia, 10–32×6–25 µm, simple or with one basal cell, pyriform, vesiculose, clavate, broadly clavate, thin-walled, hyaline. Pleurocystidia absent. Hymenophoral trama regular, hyphae 3–13.5 µm wide, thin-walled with constricted at the septa, hyaline. Pileal trama interwoven, branched, septate, hyphae 6–26 µm wide, cylindrical, thin-walled, hyaline. Pileipellis an interrupted cutis, composed of cylindrical hyphae with brownish contents, 4–6.5 µm, not or slightly constricted at the septa, thin-walled. Stipitipellis composed of parallel, hyaline hyphae, cylindrical, 4–16 µm wide, thinwalled, hyaline. Lower surface of the annulus composed of cylindrical hyphae, 4–7.5 µm wide not or hardly constricted at the septa with brownish contents in some hyphae. Clamp connections absent. Oleiferous hyphae present.
Macrochemical reactions – Schäffer’s and KOH reactions negative on fresh basidiomata. Holotype: India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI campus, 8.75° N, 77.02° E, elev. 150 m, 23 October 2019, TBGT(M)17998.
Habitat and distribution – solitary, scattered on soil, known only from the type collection in Kerala State, India.
Other materials examined – India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI campus, 8.75° N, 77.02° E, elev. 150 m, 3 November 2017, TBGT(M)17239, ibid. 9 July 2020, TBGT(M)18157; 16 September 2021, TBGT(M)18689, paratypes.
GenBank numbers – ITS: OP520722, OP528741, OP528742, OP520724
Notes – This collection are morphologically very similar and phylogenetically closely affiliated to Agaricus duplocingulatoides Tarafder, A.K. Dutta & K. Acharya which was collected from India (Tarafder et al. 2018). However, Agaricus duplocingulatoides has smaller basidiomata (22–32 mm), a positive KOH reaction and larger basidiospores (6–) 6.5–7.5(–8) × 3.5–4.2 (–4.5) μm while our collection comprises medium-sized basidiomata, white to cream-coloured pileus with brownish squamules, negative Schäffer’s and KOH reactions, fistulose stipe with a broad base, smaller basidiospores, pileipellis an interrupted cutis and presence of pyriform to broadly clavate cheilocystidia. Molecularly, there are five nucleotide differences in ITS locus of our collection with Agaricus duplocingulatoides. Agaricus duplocingulatus Heinem. morphologically similar to our collection in its pileus size, shape, color of pileus and negative Schaeffer’s reaction. However, it differs by larger basidiospores (4.8–5.4–6(–6.6)×3.5–4.5 μm), presence of catenulate cheilocystidia, ochraceous to reddish discoloration when cut or bruised and poor DNA sequence similarity (97.12% identity) in ITS. Thus, we introduce our collection as a new variety viz., Agaricus duplocingulatoides
var. brevisporus (Fig. 1).
Figure 1 – Agaricus duplocingulatoides var. brevisporus (TBGT17998). a Habit. b Gill view. c Sectional view. d Basidiospores. e Cheilocystidia. f Annulus. Scale bars: a–c=10 mm, d–f=10 μm