Agaricus palodensis C.P. Arya & C.K. Pradeep, 2024

Arya, C. P. & Pradeep, C. K., 2024, Agaricus section Minores: New and noteworthy species from India, Phytotaxa 634 (3), pp. 255-273 : 264

Agaricus palodensis C.P. Arya & C.K. Pradeep sp. nov. ( Figs. 4 )

MycoBank MB: 851577

Diagnosis:—It can be distinguished from the closely related Agaricus patris by the slightly larger basidiomata, white pileus with violet brown appressed squamules, large, narrowly clavate to cylindro-clavate cheilocystidia, and molecularly by 14 nucleotide positions in nrITS.

Holotype:— INDIA. Kerala State: Thiruvananthapuram District, Palode, JNTBGRI Campus , 8.75°N, 77.02°E, elev. 150 m, 24 May 2018, Arya TBGT (M)17483! GenBank[ITS]: OR661748

Etymology:— palodensis (Latin) , refers to the type locality “Palode” of the new species.

Description:— Pileus 49–80 mm diam., plano-convex, surface white with violet-brown (10E5) appressed squamules throughout with a darker disc (10F8) which is entire, dry; margin straight, appendiculate with the remnants of the partial veil, entire to incised rarely. Lamellae free, reddish brown to grayish brown (8E4/9D3) up to 9 mm wide, crowded with lamellulae of different lengths; edge concolorous to the sides, entire. Stipe 45–76 × 9–10 mm, central, cylindric, narrowly hollow, tapering upwards from a globose base; surface white become light brown on handling with pale brown appressed squamules at extreme base. White mycelial strands present at the stipe base. Annulus superous, white, descending, pendant, evanescent. Context white, up to 6 mm thick at the pileus disc, Odor mild, of almond.

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

Basidiospores 5.2–6.4 × 3.1–4.0 μm, (avL = 5.8 ± 0.3 8μm, avW = 3.5 ± 0.24), Q = 1.4–1.8 μm, (avQ = 1.6 ± 0.11), ellipsoid to oblong, smooth, brown, thick-walled without apical pore. Basidia 15–20 × 6.3–8.8 μm, clavate, tetrasterigmate, thin-walled, hyaline. Lamella edge sterile with abundant cheilocystidia. Cheilocystidia 15–60 × 8–13 μm, simple, narrowly clavate to cylindro-clavate with a long stalk, thin-walled, hyaline. Pleurocystidia absent. Hymenophoral trama regular, 4–8 μm composed of cylindrical hyphae, thin-walled, hyaline. Subhymenium pseudoparenchymatous. Pileal trama composed of multiseptate, cylindrical to inflated hyphae, 4–16 μm wide, constricted at septa, thin-walled, hyaline. Pileipellis a cutis, composed of parallel hyphae, 4–8 μm wide with brown intracellular contents. Stipitipellis composed of parallelly arranged, multiseptate hyphae 3.2–10 μm wide, thin-walled, hyaline. Clamp connections absent.

Habitat and phenology:—Solitary on soil; fruiting in May.

Additional specimen examined:— India, Kerala State, Thiruvananthapuram District, Palode, JNTBGRI Campus, 8.75°N, 77.02°E, elev. 150 m, 06 May 2021, AryaTBGT(M)18550.

Notes: Agaricus palodensis is characterized by medium to large basidiomata, violet brown appressed squamulose pileus, ellipsoid to oblong basidiospores, large, narrowly clavate, hyaline cheilocystidia with a long stalk and odor of almond. Molecularly BLASTn search using nrITS sequence (705bp) showed 97% sequence identity with A. patris from Thailand (KU975118). Agaricus palodensis (OR661748) differs from A. patris at 14 nucleotide positions while the remaining species in clade IV differs by more than 14 positions in their ITS sequences ( Table 3). Agaricus patris though morphologically and phylogenetically related can however, be separated by its medium sized basidiomata, purplish to reddish brown fibrillose scaly pileus and simple, variable, clavate to sphaeropedunculate cheilocystidia with yellowish contents. Originally described from Thailand ( Hyde et al. 2017), A. purpureosquameus M.Q. He & R.L. Zhao (2017:1) differs by its smaller basidiomata (35 mm), slightly larger, ellipsoid basidiospores (5.5–6.6 × 3.6–4.2 μm), and pyriform cheilocystidia with yellow pigments. Agaricus rufuspileus M.Q. He & R.L. Zhao (2017:22) originally described from China ( He et al. 2017) can be distinguished from A. palodensis by its slightly smaller basidiomata (49–60 mm), brown to reddish brown fibrillose pileus, and clavate to broadly clavate cheilocystidia with yellow contents. Agaricus sodalis Linda J. Chen, R.L. Zhao & K.D. Hyde (2015: 175) can be keyed out by its smaller basidiospores (5.0–5.6 × 3.4–3.8 μm), smaller cheilocystidia with yellowish contents along with molecular differences.

Figures

FIGURE 4. Agaricus palodensis (TBGT(M)17483, holotype). A. Habit in-situ B. Basidioma with brown lamellae; C. Basiditum; D. Basidiospores; E. Cheilocystidia; F. Pileipellis; G. Stipitipellis. Scale bar: A–B = 10 mm C–E =10 um; F–G = 20 um. Photos by: C. P. Arya.