Boletales » Boletaceae » Cupreoboletus

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–)7.88.0(– 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 (23A4), at times with olivaceous shades (23B4 to 23D4), then ochraceous orange to ochraceous reddish (45B8 to 45D4) and finally dark copper-red to reddish brown (56D8 to 56E5) with scattered paler, copper orange hues (78D7); discoloring cinnamon orange and eventually fading to tawny red (78D8 to 78E6); 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 (67A2); immediately turning blue throughout after sectioning and finally fading to cinnamon orange (78D7); 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 (3B83D7) and finally orange olivaceous (3E8), bruising blue when cut and irregularly fading copper orange to copper red (56B8 to 56D6). 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 (8D88D6) to drab brown (89D8 to 89D5), at maturity with russet brown stains at the pore edge. Pores surface uneven and toothed in mature specimens. Stipe (5–)5.510.5(–11.5) × 23(–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 (56C8 to 56D6), bruising blue then cinnamon orange, copper brown (8D88D6) or drab brown (89D8 to 89D5) 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 (67A2), immediately turning blue throughout after sectioning and finally fading to cinnamon orange (78D7), 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. 4FH) 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. 4FH, 5CG), often clumped, yellowish under microscope, soluble in H2O, in 2% acetic acid and in methanol, 515 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 Imlers (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 (0.40.6 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–)2551(–55) × 813 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 (0.60.9 μm), predominantly four-spored but frequently also one-, two- or three-spored, with relatively long sterigmata (38 μm), hyaline to pale yellowish and containing straw-yellow oil guttules in H2O and KOH; basidioles clavate, up to 57 × 12 μm. Cheilocystidia (22–)3263(–68) × 710 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 (0.50.8 μm), hyaline to pale yellowish in H2O and KOH, straw yellow to more frequently reddish orange or reddish brown (inamyloid to moderately dextrinoid) in Melzers, without epiparietal encrustations. Pleurocystidia (28–)3361(–70) × 713 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, 3892 × 719 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–)4.07.0(–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 Melzers, 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, 311 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, 3790 × 913 μm (n = 9), sterigmata up to 6 μm long and projecting caulocystidia similar in shape, color and chemical reactions to the pleurocystidia, (26–)3066 × 611 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 4080 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, 217 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–)48(–11) μm apart, often branched, hyaline in H2O and KOH, inamyloid in Melzers; lateral strata (20–)4090(–100) μm thick, mediostratum (20–)3060 μm thick, consisting of a tightly appressed, not gelatinized bundle of hyphae, 214 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 Melzers. Rhizomorphs consisting of unbranched, filamentous, sinuous, inamyloid, smooth-walled hyphae, 212 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.