Cupreoboletus poikilochromus
Cupreoboletus poikilochromus (Pöder, Cetto & Zuccherelli) Simonini, Gelardi & Vizzini, in Gelardi et al., Mycologia 107(6): 1257 (2015)
Basidiomata medium to medium-large. Development gymnocarpic. Pileus (4.6–)7.8–8.0(– 15) cm diam, at first hemispherical then convex and finally pulvinate-flattened to vaguely depressed at center, fleshy, firm at the beginning but progressively softer in age; margin initially involute then progressively expanding and sometimes uplifted, faintly wavy/lobed to regular, extending beyond the tubes up to 2 mm; surface dry but viscid with moist weather, finely tomentose to glabrous, not or only rarely areolate; cuticle pale yellow, primrose yellow to ochraceous yellow (2–3A4), at times with olivaceous shades (2–3B4 to 2–3D4), then ochraceous orange to ochraceous reddish (4–5B8 to 4–5D4) and finally dark copper-red to reddish brown (5–6D8 to 5–6E5) with scattered paler, copper orange hues (7–8D7); discoloring cinnamon orange and eventually fading to tawny red (7–8D8 to 7–8E6); subcuticular layer yellow. Pileus context firm and tough when young, later rubbery, up to 21 mm thick in the central zone, bright yellow (3A7, 3A8), sometimes with pale pinkish flesh hues in age (6–7A2); immediately turning blue throughout after sectioning and finally fading to cinnamon orange (7–8D7); subhymenophoral layer yellow. Hymenophore initially even, later with a convex surface. Tubes usually shorter than the thickness of the pileus context (up to 110 mm long), adnate to depressed around the stipe apex and shortly decurrent with a tooth, bright yellow (3A7, 3A8) to olive yellow (3B8–3D7) and finally orange olivaceous (3E8), bruising blue when cut and irregularly fading copper orange to copper red (5–6B8 to 5–6D6). Pores small at first then gradually wider (up to 1 mm diam), simple, roundish to slightly angular and radially arranged, concolorous with tubes, turning blue when bruised and eventually fading copper brown (8D8–8D6) to drab brown (8–9D8 to 8–9D5), at maturity with russet brown stains at the pore edge. Pores surface uneven and toothed in mature specimens. Stipe (5–)5.5–10.5(–11.5) × 2–3(–5.5) cm, as the same length or a little longer than the pileus diameter at maturity, central to slightly off-center, solid, firm, dry, straight to curved or sinuous, initially ventricose-ovoid to ventricose-fusiform then subcylindrical to cylindrical or rarely attenuate from the apex downward and always tapering at the base, moderately to strongly rooting; surface finely reticulate in the upper half, with meshes longitudinally stretched, smooth elsewhere, bright yellow (3A7, 3A8) but whitish at the base, becoming copper orange or copper red in age (5–6C8 to 5–6D6), bruising blue then cinnamon orange, copper brown (8D8–8D6) or drab brown (8–9D8 to 8–9D5) to blackish when pressed; reticulum first concolorous with the surface then copper red; young and fresh specimens exuding yellowish drops on stipe surface; basal mycelium whitish. Stipe context firm and tough when young then fibrous, bright yellow (3A7, 3A8), sometimes with pale pinkish flesh hues in age (6–7A2), immediately turning blue throughout after sectioning and finally fading to cinnamon orange (7–8D7), yellowish orange to pinkish orange where eaten by slugs or eroded by maggots; dried material with yellowish orange context. Odor strong and persistent, also permeating herbarium material, hard to eliminate from hands after manipulation, reminiscent of propolis, fermented fruit, liquor, dried cinnamon or cottonwood. Flavor mild. Crystal concretions spontaneously exuded on drying, protruding in particular from the hymenophore (FIG. 4F–H) but also from other parts of the basidiomata, easily visible with a hand lens, displaying a glittering appearance when illuminated in the dark and devoid of any fluorescence under UV light (366 nm); crystals iridescent, acicular, needle- or spear-shaped or even ribbonshaped by SEM observation (FIGS. 4F–H, 5C–G), often clumped, yellowish under microscope, soluble in H2O, in 2% acetic acid and in methanol, 5–15 µm broad and up to 200 µm long. Macrochemical reactions: NH4OH: staining yellowish then dark red-brown on pileus, hymenophore and context throughout. KOH and NaOH: orange-red to brownish red on pileus, hymenophore and stipe, bright yellow-orange to orange on context. FeSO4: slowly and weakly olive green then blackish olive throughout. Context in the stipe base inamyloid following Imler’s (1950) procedure (conversely observed as amyloid by Pöder 1987). Spore print olive-brown.
Basidiospores (11.0–)11.9 ± 0.5(–12.4) × (4.5–)4.9 ± 0.3(–5.3) μm, Q= (2.17–)2.42 ± 0.10(– 2.51), V= 154 ± 19 μm³ [316/12/9], (anomalous spores up to 17 × 9 μm), inequilateral, broadly ellipsoidal to less frequently ellipsoid-fusoid in side view, broadly ellipsoid in face view, smooth, with a short apiculus and shallow to moderately marked suprahilar depression, with rounded apex, moderately thick-walled (0.4–0.6 μm), straw yellow to bright yellow in H2O and KOH, having one, two or less frequently three large oil droplets when mature, moderately dextrinoid, cyanophilic and with a faint metachromatic reaction, inamyloid. Basidia (23–)25–51(–55) × 8–13 μm (n = 31), frequent on tube face but nearly absent on margin which appear to be sterile, cylindrical-clavate to truly clavate, rarely cylindrical, moderately thick-walled (0.6–0.9 μm), predominantly four-spored but frequently also one-, two- or three-spored, with relatively long sterigmata (3–8 μm), hyaline to pale yellowish and containing straw-yellow oil guttules in H2O and KOH; basidioles clavate, up to 57 × 12 μm. Cheilocystidia (22–)32–63(–68) × 7–10 μm (n = 43), extremely common, projecting straight to flexuous, fusiform to cylindrical-fusiform or rarely ventricose-fusiform, occasionally subcylindrical, occasionally clavate or sublageniform, smooth, moderately thick-walled (0.5–0.8 μm), hyaline to pale yellowish in H2O and KOH, straw yellow to more frequently reddish orange or reddish brown (inamyloid to moderately dextrinoid) in Melzer’s, without epiparietal encrustations. Pleurocystidia (28–)33–61(–70) × 7–13 μm (n = 55), color, shape and chemical reactions as in cheilocystidia, predominantly ventricose-fusiform, frequent. Pseudocystidia present, rising from the oleiferous hyphae of the lateral stratum, with a bright yellow plasmatic content in KOH, hardly rehydrating (20% KOH must be used), moderately dextrinoid and staining almost blackish in brilliant cresyl blue but vinaceous red when rehydration with 20% KOH is employed before staining, 38–92 × 7–19 μm (n = 46), sometimes with no septa at the base. Pileipellis a trichoderm consisting of strongly interwoven, filamentous and sinuous, often branched hyphae not constricted at septa, tending to be repent in the outermost layer and thus turning into a cutis partially embedded in gelatinous matter; terminal elements (3.0–)4.0–7.0(–11.0) μm (n = 54) wide and up to 140 μm long, cylindrical, occasionally cystidioid, apex rounded-obtuse and enlarged or tapered, moderately thin-walled (up to 0.5 μm), with a bright yellow to ochraceous brown or pale brown plasmatic pigment in H2O and KOH and reddish orange to reddish brown (moderately dextrinoid) in Melzer’s, smooth or rarely ornamented with subtle granular epiparietal encrustations; subterminal elements similar in shape, color and dimensions to the terminal ones. Stipitipellis a texture of subparallel to loosely intermingled and longitudinally running, smooth-walled hyphae, 3–11 μm wide, hyaline in H2O and KOH; the stipe apex covered by a well developed caulohymenial layer consisting of sterile caulobasidioles, fertile spore-bearing caulobasidia mainly two- and threespored, 37–90 × 9–13 μm (n = 9), sterigmata up to 6 μm long and projecting caulocystidia similar in shape, color and chemical reactions to the pleurocystidia, (26–)30–66 × 6–11 μm (n = 16), moderately thick-walled (up to 1.0 μm). Lateral stipe stratum under the caulohymenium present and well differentiated from the stipe trama, of the “boletoid type” (Šutara 2005), at the stipe apex a 40– 80 μm thick layer (up to 350 μm in the ridges of the reticulum) consisting of divergent, inclined and running toward the external surface, loosely intermingled and sparingly branched hyphae remaining separate and embedded in a gelatinous substance; the stratum reducing during development and disappearing at maturity. Stipe trama composed of densely arranged, loosely to strongly interwoven, filamentous, smooth, inamyloid hyphae, 2–17 μm broad, hyaline to bright yellow (oleiferous hyphae) in H2O and KOH. Hymenophore trama divergent of the “Boletus-type” (Singer 1986), with moderately to strongly divergent and loosely arranged, gelatinized hyphae, lateral strata hyphae in transversal section remaining separate and (3–)4–8(–11) μm apart, often branched, hyaline in H2O and KOH, inamyloid in Melzer’s; lateral strata (20–)40–90(–100) μm thick, mediostratum (20–)30–60 μm thick, consisting of a tightly appressed, not gelatinized bundle of hyphae, 2–14 μm wide; in Congo red the mediostratum is darker than the lateral strata; oleiferous hyphae abundant, bright yellow in H2O and KOH and moderately dextrinoid in Melzer’s. Rhizomorphs consisting of unbranched, filamentous, sinuous, inamyloid, smooth-walled hyphae, 2– 12 μm broad, wall up to 2.0 μm thick, hyaline but with a yellowish wall in H2O and KOH. Clamp connections absent. Hyphal system monomitic.
Habit, habitat and distribution: Solitary to gregarious, growing in warm Mediterranean regions on calcareous soils, associated mainly with Quercus spp., also with the presence of Ostrya carpinifolia, Pinus spp. and low-maquis shrubs, from summer to early autumn. Reported from southern Europe, uncommon to rare.
Figure 1. Phylogeny of the Pulveroboletus group based on a Bayesian and maximum-likelihood inference analysis of a matrix of concatenated sequences from four nuclear gene regions (28S, rpb1, rpb2, tef1a). Bayesian posterior probability (BPP) values (in bold) ≥ 0.7 and maximum likelihood bootstrap (MLB) values ≥ 50% are shown on the branches. Thickened branches indicate BPP ≥ 0.95 and MLB support ≥ 70%. Dashed branches indicate BPP ≥ 0.95 and MLB bootstrap support < 70%. Nodes that receive BPP < 0.95 but with ≥ 70% MLB are indicated by small black-filled circles. Clade numbers follow Wu et al. (2014). For the accession numbers of the sequences retrieved from GenBank refer to Wu et al. (2014) and Zhao et al. (2014). Newly sequenced collections are indicated in boldface.
Index Fungorum number: IF812887
Figure 2. ITS phylogeny restricted to the major clade including Cyanoboletus and Cupreoboletus. BPP values (in boldface) ≥ 0.7 and MLB values ≥ 50% are on the branches. Thickened branches indicate BPP ≥ 0.95 and MLB support ≥ 70%. Nodes that receive BPP < 0.95 but with ≥ 70% MLB are indicated by small black-filled circles. Newly sequenced collections are indicated in boldface.
Figure 3. Cupreoboletus poikilochromus. Basidiomata. A. GS 11008, from central-northern Italy, young basidiomata have yellowish olive pileus, with Quercus pubescens. B. GS 10172, from north-central Italy, young and mature basidiomata having reddish cinnamon pileus, with Q. pubescens. C. MG 664a, from central Italy, young and mature basidiomata with yellowish orange pileus, with Q. ilex. D. GS 10171 and GS 10172 from north-central Italy, basidiomata in all stage of development, with Q. pubescens. E. MG 367a. F, G. GS 10171 discoloration and variability of the reticulum on the stipe. H. GS 10171, variability of the hymenophore color. I. GS 10171, uneven pore surface in a mature specimen. Scale bars = 1 cm.
Figure. 4. Cupreoboletus poikilochromus. Microscopic features. A. Basidiospores, in L4, coll. MCVE17271. B. Pseudocystidia, in KOH 20%, coll. MCVE17218. C. Pileipellis, in L4 with interferential phase contrast, coll. GS 10172. D. Pleurocystidium, in KOH 20% + brilliant cresyl blue, coll. MCVE17256. E. Pseudocystidium, in 20% KOH + cresyl blue, coll. MCVE17256. F, G, H. Needle-shaped crystals protruding from the hymenial tissue on drying, observed with the stereomicroscope, coll. GS10171. Scale bars: A–E = 10 µm; F–H = 200 µm.
Figure 5. Additional microscopic features of C. poikilochromus. A, B. (TO HG 10091987) Basidiospores with smooth surface at SEM. C. GS 10172, needle-shaped crystals protruding from the hymenial tissue at optical MS. D-G. GS 10171, morphology of crystals protruding from the hymenial surface at SEM: needle- and spear-shaped crystals, either straight or bent and ribbon-shaped flattened crystals. Scale bars = 50 μm.
Figure 6. Cupreoboletus poikilochromus. Microscopic characters (from MG 367a). A. Basidiospores. B. Basidia. C. Cheilo- and pleurocystidia. D. Pseudocystidium. E. Hymenophoral trama with pseudocystidia. F. Lateral stipe stratum and caulohymenium. G. Pileipellis. Bars: A = 12 μm, B–C = 10 μm, D–G = 20 μm. Drawings by M. Gelardi.
Key reference:
Gelardi, Matteo & Simonini, Giampaolo & Ercole, Enrico & Davoli, Paolo & Vizzini, Alfredo. 2015. Cupreoboletus (Boletaceae, Boletineae), a new monotypic genus segregated from Boletus sect. Luridi to reassign the Mediterranean species B. poikilochromus. Mycologia. 107. 10.3852/15-070.
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