Justo A, Minnis AM, Ghignone S, Menolli Jr. N, Capelari M, Rodríguez O, Malysheva E, Contu M, Vizzini A. 2011. Species recognition in Pluteus and Volvopluteus (Pluteaceae, Agaricales): morphology, geography and phylogeny. Mycological Progress 10:453–479.
Pluteus heteromarginatus Justo, sp. nov. (Fig. 6)
MycoBank 518596
Latin Diagnosis: Pluteo longistriato similis sed differt in pileo brunneo, cheilocystidiis raris, et in spatii interne transcripti sequentia ("ITS").
Etymology. The epithet makes reference to the heterogeneous nature of the lamellar edges, provided with sparse cheilocystidia, basidioles and fertile basidia.
Pileus 20–36 mm, convex to plano-convex, with or without a low, broad umbo; surface radially sulcate almost up to the center, smooth or only slightly rugose-squamulose at center, without conspicuous fibrils, brown (in the range of Mu. 7.5YR 6/6-6/8, 5/6-5/8, 4/6), darker at center and paler towards margin, hygrophanous, pallescent on drying, especially at center. Lamellae crowded, free, ventricose, up to 8 mm broad, white when young, later pink, with concolorous or whitish edges. Stipe 35–50 × 2–4 mm, cylindrical, slightly tapering towards apex; surface white or white-cream (approx. Mu. White Page 2.5Y 9.5/2),glabrous, longitudinally striate, under lens with brown dots all over. Context in stipe and pileus white, slightly cream colored at stipe base. Smell and taste indistinct. Spore print pink (Mu. 5YR 7/4-8/4).
Basidiospores [60, 3, 1] 5.3–7.2 (8.0) × 4.5–6.0 (7.0) μm, avl × avw = 6.2 × 5.3 μm, Q=(1.0) 1.15–1.30 (1.40), avQ = 1.18, broadly ellipsoid, rarely globose or ellipsoid. Basidia 24–34 × 9.5–11 μm, 4-spored, narrowly utriform or clavate. Pleurocystidia 40–65 × 10–17 μm, mostly fusiform or narrowly lageniform, with elongated apex or an apical flexuous excrescence 5–10μm long, more rarely ovoid or(narrowly) utriform, with evenly disolved pale brown intracellular pigment or colorless, with thin, smooth walls,common all over lamellar sides. Lamellar edge heterogeneous, with scattered cheilocystidia, basidioles and fertile basidia near the sides. Cheilocystidia 20–45 × 9.5–15 μm,(narrowly) clavate, narrowly utriform, more rarely obovoid with long peduncle or broadly fusiform, without apical appendages, colorless, with thin, smooth walls, scattered along lamellar edge, sometimes in clusters, not forming a well-developed strip. Pileipellis a trichohymeniderm mostly composed of elements 56–100 × 14–20 μm: individual elements very variable in shape, fusiform, narrowly clavate,lageniform, obovoid, utriform, filled with brown intracellular pigment, with thin, smooth walls. At the base of that elements, a second morphological type occurs: 24–28 × 14–16 μm clavate elements, also filled with brown intracellular pigment. Stipitipellis a cutis; hyphae 5–15 μ mwide, cylindrical, colorless or with brown pigment; with thin, smooth walls. Caulocystidia 45–75 × 7–17 μm, fusiform or lageniform, sometimes with elongated apex, with brown intracellular pigment, with thin, smooth walls, scattered or in clusters. Clamp-connections absent in all tissues. Habit, habitat and distribution. Gregarious, on decayed, unidentified (probably coniferous) wood. Collected in Northern Florida (USA) during summer (August). Collection examined: USA Florida, St. Marks Wildlife Refuge, 26.VIII.2009, D. Floudas, AJ172 (MICH, holotypus).