Agaricus porphyropos L. A. Parra, Angelini & B. Ortiz 2018, sp. nov.
Creators: name: Parra, Luis A.
name: Angelini, Claudio
name: Ortiz-Santana, Beatriz
name: Mata, Gerardo
name: Billette, Christophe
name: Rojo, Carlos
name: Chen, Jie
name: Callac, Philippe
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Agaricus
Agaricus porphyropos

description: Agaricus porphyropos L.A. Parra, Angelini & B. Ortiz, sp. nov. (Fig. 12)   
 MycoBank: MB823281.   
 Etymology: Because the pileus resembles a purple (in Greek “pophyros”) eye (in Greek “ops, opos”).   
 Original description, Macroscopic description: Pileus (2.5–)3.0–5.0(–5.5) cm diam., hemispherical when young, then plano-convex, finally completely plane, sometimes slightly depressed at center with a broad and low umbo, whitish, partially or entirely covered with reddish purple scales with an entire dark purple vinaceous center. Surface smooth, fibrillose, dull and dry. Margin thin, slightly exceeding the lamellae or more or less fimbriate, sometimes obscurely striate on the upper surface after raining. Lamellae free, straight or slightly ventricose, intercalated with numerous lamellulae, white for a long time (resembling at first glance a species of Leucoagaricus), staining bright pink on handling, and finally dark grayish brown with paler and even edge. Stipe 6.0–7.0 × 0.4–0.8 cm, cylindrical or slightly bulbous at base, straight, sometimes flexuose, fistulose, hollow at base, with an annulus in its upper third, above annulus smooth and whitish, below annulus whitish cream, fibrillose and floccose, yellowing on handling, especially at the base which is covered by white felted mycelium and fine white mycelial strands. Annulus superous, double, white, up to 1.5 cm broad, membranous but fragile, upper surface smooth, lower surface fibrillose-lanose or with large floccose scales in concentric bands toward the margin. Sometimes present only in fragments. Context slightly dense, when cut at first white becoming pink over time, but orange brown around the worm holes, with odor of anise.   
 Microscopical description: Spores 4.12–4.70–5.36 × 3–3.43–3.91 μm, Q=1.22–1.37–1.55, broadly ellipsoid to ellipsoid, smooth, brown, without apical pore. Basidia 10–16 × 6.5–9 μm, tetrasporic, clavate or slightly truncated at the apex, also very abundant and doliiform on the lamellae edge, sterigmata up to 2 μm long. Cheilocystidia abundant, hyaline or with internal diffuse brown pigment, simple or septate at the base, terminal elements versiform, most frequently clavate (sometimes slightly narrowed in the middle), pyriform, ovoid or cylindrical, sometimes fusiform, utriform, rarely rostrate or capitulate, 11–30(–42) × 7–14 μm, anteterminal elements in those septate more or less cylindrical, 4–18 × 3–7 μm. Pleurocystidia not observed. Lower surface of the annulus composed of hyaline hyphae, cylindrical, not or slightly narrowed at septa, 3–10 μm wide. Inflated elements not observed. Pileipellis a cutis, hyphae cylindrical or narrowed at septa with fusiform elements. In water, hyphae from the disc 3–10 μm wide, hyaline, or with abundant purplish pink diffuse pigment or in some elements with purple granular pigment, with abundant terminal elements cylindrical or progressively attenuated with rounded apex; hyphae outside of the disc of 3–8 μm wide, similar to those of the disc but with more elongated and cylindrical elements, and with more hyaline elements. Clamp connections not observed.   
 Macrochemical reactions: Schäffer’s reaction positive, reddish brown, difficult to read in the Dominican material. KOH reaction positive, color orange yellow.   
 Habit, habitat, occurrence and distribution: Solitary or in small groups of 2–5 basidiomata, in all types of broadleaf forests. Common. Recorded from the Dominican Republic and the United States Virgin Islands.   
  Species-specific ITS markers in A. subg. Minoriopsis:  tatttCatcag@141, gctccTgagtc@232, atacaCtacac@249, gggctTtctat@288, agctcTCctgaa@556–557, with a T insertion at position 288.   
 Note: The original description is based on the Dominican collections although two additional collections were made in the United States Virgin Islands. All of these collections share similar macro- and microscopic characters, but the ones from the United States Virgin Islands differ in their greater spore length (4.8–6.4 × 3.2–4.0 μm in STJ-392 y 4.8–5.6 × 3.2–4 μm in STJ-314), although overlapping with the size of the Dominican collections, and in that their Schäffer’s reaction is bright orange in dried material. The collections from the United States Virgin Islands will be fully described in a future work in preparation. This species is characterized by its small-medium size, growing in broadleaf forests, a strongly fibrillose pileus with the center strongly colored vinaceous purple and the whitish margin, the stipe is long and flexuose off-white becoming yellow on handling and the fragile annulus, undeveloped, sometimes incomplete and present only in fragments.   
 Material examined: DOMINICAN REPUBLIC, Puerto Plata, Sosúa, at the garden of Hotel Villa Mar, 31 December 2009, JBSD126493 (LAPAM5); Puerto Plata, Sosúa, beach, in a secondary broadleaf forest, 10 December 2013, JBSD126494 Holotypus (LAPAM34, Isotypus). UNITED STATES VIRGIN ISLANDS, Saint John. Bordeaux Mountain, near Spice Hill, 15 November 1996, collector T. J. Baroni, TJB-8312, STJ-392 (NY); Saint John. Bordeaux Mountain, 18°20’8”N, 64°43’15”W, 15 November 1996, collector S. A. Cantrell & B. Ortiz-Santana, S. A. Cantrell SJ-9601, STJ-314 (NY).   
 Taxonomic comments: Very similar to other species with purple pileus such as A. argenteopurpureus, A. lodgeae or A. martinicensis as noted in their descriptions above.
description: Published as part of Parra, Luis A., Angelini, Claudio, Ortiz-Santana, Beatriz, Mata, Gerardo, Billette, Christophe, Rojo, Carlos, Chen, Jie & Callac, Philippe, 2018, The genus Agaricus in the Caribbean. Nine new taxa mostly based on collections from the Dominican Republic, pp. 219-271 in Phytotaxa 345 (3) on pages 247-249, DOI: 10.11646/phytotaxa.345.3.2, http://zenodo.org/record/13708429