Stropharia acanthostipitata Angelini & Vizzini, 2017

Stropharia acanthostipitata Angelini & Vizzini , sp. nov. ( Figs. 3–7 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Mycobank MB 822654

Diagnosis:—The species is characterized by a Hypholoma -like habit, a dry, hygrophanous, non-striate pileus surface with only fugacious velar elements towards the margin, brownish lamellae with violaceous hues when mature, a stipe without annulus, a strong radish-like smell, spores with an indistinct germ-pore, chrysocystidia present on lamellar edge and face, and acanthocytes developed overall the stipe.

Type:— DOMINICAN REPUBLIC, Sosua (Puerto Plata)— Loc. Puerto Chiquito , 10 basidiomes growing on woody debris in a man-made deciduous forest, 28 December 2010, C. Angelini, JBSD 127401 , Holotype ( JBSD!) ; ANGE691 , Isotype ( ANGE!) .

Etymology:—The specific epithet, from the Latin words acanthus (bear’s breeches, bear’s-foot) and stipitatus (stipitate) refers to the presence of acanthocytes distributed all over the stipe length.

Description:—Macrocharacters. Habit Hypholoma -like. Pileus 35–60 mm broad, convex, then applanate or slightly depressed, ocher-yellow to brownish [Mu 10YR 8/4 (very pale brown), 10YR 8/6 (yellow)]; margin brownish, purplish, not striate, with very fugacious whitish velar remnants (sometimes appendiculate); surface dry, smooth, glabrous, sometimes minutely squamulose in mature specimens, hygrophanous and without velar remnants. Lamellae moderately crowded, slightly ventricose, emarginate to emarginate with decurrent tooth, lamellulae l = (0) 1–3, brownish [10YR 7/4 (very pale brown)] with gray-greenish and purplish hues; edge eroded, whitish. Stipe 30–70 × 4–8 mm, central, solid, curved or flexuose, cylindrical or slightly expanded at base, (sub)concolorous with the pileus, white toward the base, fibrillose, dry, without a membranous annulus but covered with small white flakes especially at the apex, often with white rhizomorphs. Context pale yellowish, taste and smell strongly radish-like. Spore-print purplish-brown.

Microcharacters. Spores (4.4–) 6.1 ± 0.5 (–7.5) × (3.4–) 3.9 ± 0.3 (–4.5) μm (n = 80), Q = (1.2–) 1.6 ± 0.1 (–1.8), amygdaliform to phaseoliform in side view, ellipsoid to almost ovoid in frontal view, with one or two guttules and indistinct germ pore (reduced to an apical thinning), slightly thick-walled, non-amyloid, non-dextrinoid, pale brown in water. Basidia (16–) 26.7–31.7 × 6–7 (–8) μm, clavate, 4-spored, rarely 2-spored. Marginal sterile elements Cheiloleptocystidia (sub)globose, pyriform (18.4–23.4 × 15–21.7 μm) to sphaeropedunculate (16.7–33.4 × 11.7–28.4 μm), mixed with or covering the basidia, basidioles and cheilochrysocystidia. Cheilochrysocystidia 33.2–70 × 9.3–13.3 μm, lageniform, subfusiform, banana-like or with a shape difficult to define, provided with a yellow or yellow-brownish refractive content partially or completely filling the cells. Face sterile elements Pleurochrysocystidia 45–58.5 × 10– 12.5 μm, quite abundant, shape difficult to define, almost subutriform-fusiform, rarely pyriform, thin-walled with the same refractive content of the cheilochrysocystidia. Pileipellis a xerocutis of interwoven, cylindrical, 3.3–10 μm wide short hyphae, provided with parietal and minutely incrusting pigment. Hypodermium undifferentiated. Stipitipellis about 10 μm thick, consisting of parallel and slender, 3–5 μm wide, hyphae, from which polymorphic, sometimes diverticulate, cauloleptocystidia and caulochrysocystidia emerge. Stpititrama composed of septate, cylindrical and swollen, 9–12 μm wide hyphae. Hymenophoral trama subregular, consisting of swollen and shortly septate, 50–70 × 16–25 μm hyphae. Clamp-connections present everywhere. Acanthocytes present (abundant and crowded in the holotype collection, rare in JLC LD4-120329-01) from the base (including rhizomorphs) to the apex of the stipe; crystals up to 35 μm long.

Habit, ecology and distribution:—Fasciculate or gregarious on the ground among vegetal debris, on decaying or buried wood; so far known only from the Dominican Republic and French Guiana.

Additional collection examined:— FRENCH GUIANA, Matoury ( La Désirée ), on woody debris, 29 March 2012, J-L. Cheype, JLC LD4-120329-01 ( JLC!) .