Agaricus martinicensis Pegler, Kew Bull. Addit. Ser.

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, Phytotaxa 345 (3), pp. 219-271 : 243-246

Agaricus martinicensis Pegler, Kew Bull. Addit. Ser. 6: 446. 1983. ( Figs. 10–11 )

Macroscopic description: Pileus 3–6 cm diam., at first hemispherical then plano-convex, finally plane, sometimes with revolute margin, depressed towards the center where it has a broad and low umbo, background whitish partially or entirely covered by reddish purple scales with an entire intensely colored dark reddish purple center. Surface smooth, fibrillose, dry and dull. Margin thin, fimbriate, not or slightly exceeding the lamellae. Lamellae free, crowded, straight or slightly sinuate, intercalated with numerous lamellulae, white for a long time (resembling at first glance in the field a species of the genus Leucoagaricus Locq. ex Singer ), staining orangish pink when handled, and finally dark brown with a paler and slightly eroded edge. Stipe 4.5–6.5 × 0.7–1.0 cm, cylindrical or more enlarged and curved at base, sometimes sinuate, clavate, bulbous or slightly marginately bulbous, fistulose, hollow at base, with an annulus in its upper third, completely white or off-white, above annulus finely fibrillose, below annulus fibrillose or with thick white cottony scales, which sometimes seem like true recurved squamules, becoming pink salmon on handling especially towards the base where is provided with a thick, simple or branched rhizomorph. Annulus superous, double, white, yellowing on handling or with age, up to 1 cm wide, membranous of remarkable thickness, upper surface smooth, lower surface fibrillose-floccose and with finely denticulate margin. Context dense or not, when cut at first white and then white or ochre salmon in the pileus, and ochre salmon in the stipe, rarely with reddish tones in the stipe apex and in the center of the pileus, with odor like almonds.

Microscopic description: Spores (4.24–)4.33–4.91–5.36 × 2.88–3.21–3.61 μm, Q=1.29–1.53–1.72, ellipsoid or ellipsoid elongate, smooth, brown, without apical pore. Basidia 12–16(–21) × 6.5–8.0 μm, clavate or slightly truncated at the apex, sterigmata up to 3 μm long. Cheilocystidia abundant, hyaline and smooth, simple or with a basal septum, terminal elements generally clavate, broadly clavate or pyriform, often also fusiform or rostrate, rarely capitulate, 12–38 × 6.5–13(–16) μm, anteterminal elements of those septate 7–17 x 4–6 μm. Pleurocystidia not observed. Lower surface of the annulus composed of cylindrical hyphae not or narrowed at septa, 2–7(–9) μm wide. Inflated elements not observed. Pileipellis a cutis with a transition to a trichoderm at the squamose disc. At the disc with two types of hyphae, some cylindrical similar to those outside of the disc of 3–7 μm wide and others thicker consisting of doliiform elements with rounded apex of 6–15 μm wide, while outside of the disc predominate cylindrical hyphae with constant diameter, composed of elongated elements of 3–7 μm wide. In water, the hyphae from the disc may have pinkish diffuse pigment or a very fine granular yellow pigment, while the hyphae from the perimarginal area have a finely granulate vinaceous brown pigment. Clamp connections not observed.

Macrochemical reactions: Schäffer’s reaction positive, color dark reddish purple. KOH reaction positive, color orange yellow. Fiard’s original field notes from the holotype point out a positive blood red Schäffer’s reaction in fresh collections.

Habit, habitat, occurrence and distribution: Gregarious, growing in groups of few basidiomata in all types of broadleaf forests. Very common. Recorded from the Dominican Republic and Martinique. From the later, Pegler (1983) designated the holotype (Fiard 820) and two paratypes (Fiard 780A and Pegler 2930).

Note: Very variable species, sometimes robust, fleshy and with a short stipe, other times slender, slightly fleshy and with a long thin stipe. It is characterized by its medium size, the pileus with vinaceous purple scales, always darker at center and with a low umbo, lamellae and stipe staining ochre salmon after handled, the thick, ample and double annulus and by the stipe usually ending in a thick and single rhizomorph.

Material examined: DOMINICAN REPUBLIC, María Trinidad Sánchez, Rio San Juan, road to Payita , in a lowland forest, 3 January 2011, JBSD121929 ( LAPAM10 ) ; Puerto Plata, Sosúa, Puerto Chiquito , 25 November 2011, JBSD123819 ( LAPAM16 ) ; Puerto Plata, Sosúa, Puerto Chiquito , 21 November 2013, JBSD126495 ( LAPAM42 ) ; Puerto Plata, Sosúa, Puerto Chiquito , 29 December 2013, JBSD126496 ( LAPAM43 ) ; Puerto Plata, Sosúa, Puerto Chiquito , 29 December 2013, JBSD126497 ( LAPAM44 ) ; Puerto Plata, Sosúa, Puerto Chiquito , 22 December 2014, JBSD126498 ( LAPAM63 ) ; Puerto Plata, Sosúa , beach, 4 December 2014, JBSD126499 ( LAPAM56 ) .

Taxonomic comments: This species is highly similar to A. argenteopurpureus and A. lodgeae with which it has already been compared (see taxonomic comments of these species).

This species is also macroscopically similar to many species of A. subg. Minores in the pileus completely covered by reddish purple squamules, but it is distinguished by its membranous double annulus that is thicker at the margin with the lower surface fibrillose-squamulose and its dark reddish purple Schäffer’s reaction in dried material, instead of a simple annulus that is fragile and ephemeral and the weak reddish pink Schäffer’s reaction in dried material of A. subg. Minores . In other respects, A. martinicensis is also similar to A. porphyropos , but the latter species is less robust and usually has scales more dispersed towards the pileus margin.

Additional comments: ITS sequences of the seven Dominican studied collections fully match three sequences used in this study, from two collections made by J.-P. Fiard (F2343 and F2815) and one by C. Lechat (CL/ MART 03.055) in the Caribbean island of Martinique.

Figures

FIGURE10.Macroscopic charactersofA.martinicensis.A–H.Basidiomata.A.(JBSD121929);B.(JBSD123819);C,G,H.(JBSD126496); D. (JBSD126499); E. (JBSD126498); F. (JBSD126497). Photos by C. Angelini.

FIGURE 11. Microscopic characters of A. martinicensis. A–J. (A–F, H, J in ammoniacal Congo red; G, I in water).A–D. (JBSD123819), E–J. (JBSD126497). A–C. Cheilocystidia. D. Basidia. E. Spores. F. Hyphae of the lower surface of the annulus. G–J. Pileipellis hyphae (G–H discal area, I–J medial area). Photos by L.A. Parra.