Agaricus calolepidotus Linda J. Chen, Enríquez-Bedolla & Llarena-Hernández, sp. nov.
Creators: name: Guzmán-Guillermo, Jorge
name: Chen, Jie
name: Enríquez-Bedolla, José Carlos
name: Ortega, Iván Oros-
name: Zetina-Córdoba, Pedro
name: Núñez-Pastrana, Rosalía
name: Llarena-Hernández, Régulo Carlos
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Agaricus
Agaricus calolepidotus

description: Agaricus calolepidotus Linda J. Chen, Enríquez-Bedolla & Llarena-Hernández sp. nov. (Figs. 2, 3)   
MycoBank: MB854094  
Etymology:—refers to the beautiful (in Greek “calos”) scales (in Greek “lepis/lepidos”) on the pileus.  
 Macroscopic description:— Pileus (3–) 6–12 cm diam., at first hemispherical then plano-convex, finally plane at maturity, entirely covered by brownish orange to light brown appressed fibrillose squamules or scales on beige background, sometimes with an entirely brownish center. Surface dull and dry. Margin not exceeding the lamellae. Lamellae free, straight, intercalated with numerous lamellulae, white for a long time, staining pink to reddish on handling, finally brown at maturity. Stipe 7–10 × 0.5–0.8 cm (up to 2 cm at base), cylindrical and bulbous at base, fistulose, with an annulus in its upper third, above annulus smooth and white, below annulus fibrillose, covered with concolor erected-fibrillose scales towards the base, forming bands, white, becoming reddish orange when bruised. Annulus superous, double, white, membranous, upper surface smooth, lower surface fibrillose-floccose. Context white, firm, becoming reddish orange when exposed. Odor of bitter almonds.   
 Microscopic description:— Basidiospores (4.6–)4.8–5.5 × (3.1–)3.3–3.7 μm, (x = 5.1 × 3.5 μm, Q = 1.32–1.6, Q m = 1.47), ellipsoid, smooth, brown, without apical pore. Basidia 12–16 × 5.5–7 μm, tetrasporic, clavate, hyaline, smooth. Cheilocystidia 17–35 × 7.5–13 μm, abundant, hyaline, simple or septate at the base, frequently clavate to broadly clavate. Pleurocystidia not observed. Lower surface of the annulus composed of hyaline hyphae, cylindrical, not or slightly narrowed at septa, 3–7 μm wide. Inflated elements not observed. Pileipellis a cutis composed of cylindrical and thin-walled hyphae of 3.5–7 μm wide, hyaline or with light brownish membranous pigment, sometimes slightly constricted at the septa. Clamp connections not observed.   
Macrochemical reactions:—Schäffer’s reaction positive, orangish red. KOH reaction positive, yellow.  
Habit and habitat:—gregarious or scattered in soil.  
Material examined:— MEXICO, Veracruz, Cordoba, Sierra del Gallego, 23 July 2019, E. A. Vázquez Rojas, LD201929 (Holotype, XAL); Veracruz, Cordoba, Sierra del Gallego, 17 September 2019, J. C. Enriquez Bedolla, LD201942; Veracruz, Huiloapan de Cuauhtémoc, 8 September 2019, E. A. Vázquez Rojas, LD201949; Veracruz, Cordoba, Sierra del Gallego, 01 November 2019, J. C. Enriquez Bedolla, LD201952.  
 Notes: Agaricus calolepidotus is characterized by its medium to large sized basidiomata, the pileus covered with brownish orange to light brown appressed squamules or scales, lamellae remaining white for a long time, and becoming pink to reddish on handling, the lower surface of stipe covered with concolor erected-fibrillose scales, forming bands, white, discoloring reddish orange when bruised, and the odor of bitter almonds.   
 Within A. subg. Minoriopsis, A. calolepidotus is morphologically very similar to A. globocystidiatus Drewinski & M.A. Neves (2017: 68) and A. guzmanni Linda J. Chen & G. Mata (2019: 95) in the pileus and the lower surface of stipe covered with brownish scales. However, A. globocystidiatus differs by the presence of pleurocystidia, the context exhibiting no change or slightly yellowish when exposed, the stipe tapering at the base and the slightly wider spores, 5.3 × 4.2 μm in average (Drewinski et al. 2017). And A. guzmannii differs by its smaller spores, 4.6 × 3.1 μm in average, and the unchanging context when exposed (Chen et al. 2019). In addition, it has brownish scales on the stipe surface, but never forming bands as observed in A. calolepidotus.
description: Published as part of Guzmán-Guillermo, Jorge, Chen, Jie, Enríquez-Bedolla, José Carlos, Ortega, Iván Oros-, Zetina-Córdoba, Pedro, Núñez-Pastrana, Rosalía & Llarena-Hernández, Régulo Carlos, 2024, Morphological characteristics and phylogenetic analyses revealed two new species of Agaricus subg. Minoriopsis from Mexico, pp. 65-78 in Phytotaxa 655 (1) on page 69, DOI: 10.11646/phytotaxa.655.1.5, http://zenodo.org/record/13217199