Agaricus dolichocaulis R.L. Zhao & B. Cao, sp. nov. 2020
Fungal Names: FN 570668
Holotype: CHINA. INNER MONGOLIA: Hulun Buir, Genhe (50°44′31″N, 121°12′20″E; 740 m asl), scattered on ground in coniferous forest, 25 Aug 2017, Zhilin Ling ZRL20170590 (holotype HMAS 255457).
Morphological description
Pileus 65–125 mm wide, at first broadly parabolic or hemispherical, then convex with broadly umbonate, and finally applanate, at times slightly depressed in the middle; surface dry, at first white throughout, then light purple tone at the disc; edge slightly exceeding, at times appendiculate with remnants of the universal vein. Lamellae free, up to 5–6 mm broad, crowded, with intercalated lamellulae, at first pink or light purple, finally dark brown. Stipe 100–205 × 10–25 mm, cylindrical and clavate, hollow, surface white, smooth above the annulus and squamulose- floccose below the annulus when young, becoming yellowish when bruised. Annulus superior, membranous, smooth and white on the upper surface and floccose, white with light brown flakes on the lower surface. Context white on cutting, unchanging or becoming yellowish toward the stipe base with time. Odor of almond. KOH reaction yellow; Schäffer’s reaction reddish orange on pileus and stipe.
Basidiospores (5.5–)6–7(–8) × 4–5(–5.5) μm [x¯= 6.4 × 4.6 μm, Q = 1.3–1.5(–1.6), Qm = 1.4, n = 30], ellipsoid or ovoid, smooth, thick-walled, brown. Basidia 17–23 × 8–9.5 μm, 4-spored, clavate or slightly truncate at the apex, hyaline, smooth. Cheilocystidia 11–26 × 10–14 μm, hyaline, simple or sometimes catenulate, consisting of ellipsoid, globose, or pyriform elements. Pileipellis a cutis of cylindrical hyphae, 3.5–11 μm wide, not or slightly constricted at septa, hyaline.
Habitat: on ground in coniferous (Pinus) or mixed (Betula and Pinus) forest.
Distribution: northeast China.
GenBank Accession: ITS/LSU MK748199; β-tubulin gene MN896026; EF-1α MN896074; calmodulin gene MN896102
Notes: Agaricus dolichocaulis is represented by 24 specimens from Inner Mongolia in a well-supported clade (92/1.0 BS/PP) (FIG. 1). Agaricus dolichocaulis is similar to A. sylvicola, but the latter has a shorter stature and bulbous stipe base (Parra 2013; Kerrigan 2016).
Reference: Bin Cao , Mao-Qiang He , Zhi-Lin Ling et al. (2020): A revision of Agaricus section Arvenses with nine new species from China.
Agaricus dolichocaulis (ZRL20170590, holotype). A. Basidiomes. B. Basidiospores. C. Cheilocystidia. D. Basidia. E. Pileipellis hyphae. Bars: A = 2 cm; B–E = 5 μm.
