Hortiboletus rubellus Simonini, Vizzini & Gelardi

Hortiboletus rubellus (Krombh.) Simonini, Vizzini & Gelardi, in Vizzini, Index Fungorum 244: 1 (2015) Figs 3 a, 6, 7, 8 ≡ Boletus rubellus Krombh., Naturgetr. Abbild. Beschr. Schwämme 5: 12 (1836) ≡ Suillus rubellus (Krombh.) Kuntze, Revisio generum plantarum 3 (3): 536 (1898) ≡ Leucobolites rubellus (Krombh.) Beck, Z. Pilzk. 2 (7): 142 (1923) ≡ Tubiporus rubellus (Krombh.) S. Imai, Trans. Mycol. Soc. Japan 8 (3): 113 (1968) ≡ Xerocomellus rubellus (Krombh.) Šutara, Czech Mycol. 60 (1): 50 (2008) = Xerocomus rubellus Quél., Compt. Rend. Assoc. Franç. Avancem. Sci. 24 (2): 620 (1896) [1895] = Boletus versicolor Rostk., in Sturm, Deutschl. Fl., 3 Abt. (Pilze Deutschl.) 5: 55 (1844), nom. illegit., Art. 53.1 (Shenzhen), non Boletus versicolor L., Sp. Pl. 2: 1176 (1753) = Trametes versicolor (L.) Lloyd (1921) [1920] = Versipellis versicolor (Rostk.) Quél., Enchir. Fung.: 158 (1886), nom. illegit., Art. 53.1 (Shenzhen) = Versipellis pruinata var. versicolor Quél., Enchir. Fung.: 158 (1886), replaced synonym of Boletus versicolor Rostk. (1844) ? = Boletus sanguineus With., Syst. Arr. Brit. Pl., Edn 4 4: 313 (1801), nom. illegit., Art. 53.1 (Shenzhen), non Boletus sanguineus L., Sp. Pl., Edn 2 2 (2): 1646 (1763) = Pycnoporus sanguineus (L.) Murrill (1904) ? = Viscipellis sanguinea (With.) Quél., Enchir. Fung. (Paris): 156 (1886), nom. illegit., Art. 53.1 (Shenzhen) ? = Boletus rutilus Fr., in Fries & Hök, Boleti, Fungorum generis, illustratio: 5 (1835) Holotype. CZECHIA • tab. XXXVI, figs 21–24 (Krombholz 1836). Epitype designated here (MBT 10022257). ITALY • Emilia-Romagna: Reggio Emilia, Viano, Pulpiano, 44°30'23"N, 10°33'24"E, 507 m, several young to mature basidiomes growing in a cultivated field beside a track, close to a Quercus cerris and Q. pubescens wood, 19. 06. 2011, leg. & det. G. Simonini, MCVE 31743 (GS 10212 – collector’s number, K-M 001435705 – isoepitype), GenBank: ITS – PV 094851. Description. Basidiomes pileate-stipitate, xerocomoid, epigeal, small to medium-small sized. Ontogenetic development gymnocarpic. Pileus (2 –) 3.5–10 (– 15) cm broad, nearly hemispherical at first, then convex, pulvinate to applanate, also slightly depressed at centre, sometimes irregularly shaped; surface matt, dry, ± finely tomentose to sometimes rugulose, but later smooth, sometimes areolate towards the peripheral zone or with minute to coarse cracks especially in dry weather and showing a yellowish or somewhat pinkish subcuticular layer resembling some areolate Xerocomellus species; margin initially involute then extended, regular to wavy-lobed, acute and slightly exceeding the pileal context; rather variable in colours, but generally with bright red tints, initially blood red, wine red, cherry red, rose red, orange-red, pink, fading in mature basidiomes from ochraceous red, ochraceous pink to reddish-brown, with a margin at the very beginning whitish (due to a narrow band 1–2 mm broad), then gradually concolourous with age, unchanging or becoming slightly darker on handling or when injured. Tubes up to 12 mm long, at first adnate, later emarginate or slightly decurrent with a tooth, initially lemon or chrome yellow, later greenish-yellow to olive brown, slightly bluing when injured. Pores large, wider than 1 mm (up to 1.5–2 mm) in old basidiomes, roundish to angular, concolourous with the tubes, in mature basidiomes with orange-rusty tinges, weakly bluing when bruised and later becoming dirty brownish. Stipe (2 –) 2.5–7 (– 12) × 0.4–2.5 (– 3.5) cm, usually as long as or slightly longer than pileus diameter, central or slightly off-centre, solid, firstly versiform, clavate or somewhat bulbous, later more cylindrical or sometime inflated in the lower part, always tapering at the very base and slightly rooting; surface with fine reddish punctuations or fibrils on an ochraceous yellow background, later often with rather coarse longitudinal striations; surface usually concolourous with the pileus or paler, but yellow or pale yellow at apex; sometimes the stipe can be entirely yellow or entirely red, or a mix of both colours; basal mycelium whitish-yellow. Context rather firm when young, later soft, becoming fibrous in the stipe (up to 1.5 cm in the centre of the pileus); pale yellow, dirty ochraceous yellow in the lower half of the stipe and eventually pale pinkish underneath the cuticle; in the stipe base with a typical orange-red pigment in the form of small dots, which are sometimes scarce and hardly noticeable or conversely abundant and then visible as a large flame-orange area at the stipe base; light blue on exposure, especially in the pileus-stipe connection zone, above the tubes and in the peripheral layers of the stipe, later fading to dirty yellow; discolouration less pronounced in dry and old basidiomes. Spore print olive brown. Odour pleasantly mushroom-like to fruity or inconspicuous. Taste mild. Macrochemical spot-test reactions: Melzer’s reagent: a weak fleeting-amyloid reaction in the stipe context and exceptionally also in the hymenophoral trama of dried basidiomes sometimes occurs, but most collections show a strong dextrinoid reaction in all tissues; 20 % KOH: reddish-brown on pileus and hymenophore, pinkish on pileal context, bright orange on stipe surface and context and progressively darker downwards; 25 % NH 4 OH: negative to pale yellow everywhere; 10 % FeSO 4: sordid green everywhere, particularly on hymenophore. Basidiospores [561 / 19 / 19] (10.3 –) 11.6 ± 0.6 (– 12.8) × (4.7 –) 5.0 ± 0.2 (– 5.5) μm, Q = (2.07 –) 2.31 ± 0.12 (– 2.59), Vm = 155 ± 17 μm 3, inequilateral, broadly ellipsoid or fusiform to ellipsoid-fusiform in side view, ellipsoid to amygdaliform or slightly fusiform in face view, smooth under both light microscope and SEM, apex rounded, with a short apiculus, usually with a weak to pronounced suprahilar depression and with a slightly pronounced adaxial swelling, moderately thick-walled (up to 1 μm), straw yellow to honey yellow in water and 5 % KOH, having one or two large oil droplets when mature, rarely pluri-guttulate, inamyloid and orthochromatic. Basidia [17 / 4 / 4] (24.8 –) 33.9 ± 6.1 (– 46.3) × (7.8 –) 10.8 ± 1.3 (– 12.0) μm, subclavate to clavate, predominantly 4 - spored, sterigmata 3.1–5.0 μm, hyaline to yellowish in 5 % KOH, and containing concolourous oil guttules; basidioles subcylindrical to faintly clavate, similar in size to basidia. Cheilocystidia [17 / 4 / 4] (26.0 –) 33.8 ± 7.0 (– 43.8) × (8.7 –) 9.3 ± 0.4 (– 10.0) μm, relatively common, scattered, slender, ventricose-fusiform, often with elongated straight or flexuous neck, with rounded tip, smooth, hyaline to pale yellowish in water and 5 % KOH, without epiparietal encrustations. Pleurocystidia [10 / 2 / 2] (21.9 –) 37.8 ± 10.2 (– 51.3) × (6.0 –) 8.4 ± 0.7 (– 11.3) μm, infrequent, slender, ventricose-fusiform, often with elongate neck, mostly hyaline, rarely with yellowish content in 5 % KOH. Pseudocystidia not observed. Hymenophoral trama bilaterally divergent, intermediate between the “ Phylloporus - type ” and the “ Boletus - type ”: lateral strata consisting of poorly divergent, tightly arranged, non-gelatinous hyphae almost touching each other, hyaline to very pale yellow in water and 5 % KOH; mediostratum consisting of tightly adpressed, non gelatinous, parallel running hyphae; in Congo red the mediostratum is slightly darker than the lateral strata. Pileipellis a physalo-palisadoderm consisting of moderately long, more or less cylindrical, septate hyphae; terminal elements [539 / 15 / 15] (21.4 –) 25.6 ± 4.2 (– 36.1) × (6.3 –) 8.6 ± 1.7 (– 12.1) μm, Q = (2.03 –) 3.12 ± 0.55 (– 4.19), versiform, mainly broadly cylindrical with rounded apex to cystidioid, sometimes also with elongate neck, but also slender, cylindrical, moderately clavate, slightly tapering towards the tip, lageniform, utriform, acorn-shaped, sometimes bifurcate, apex mainly rounded-obtuse, but sometimes pointed, not encrusted (especially in young basidiomes) or poorly and finely encrusted (fine granular or rarely zebra-like epiparietal encrustations) at base, hyaline to pale yellow in water and 5 % KOH; subterminal elements subcylindrical or somewhat inflated and then broader than terminal ones (up to 18 μm), sometimes branched, more frequently encrusted, pale yellowish-brown in 5 % KOH. Subpileipellis elements usually distinctly encrusted by a fine, pale yellow, granular pigment (5 % KOH). Stipitipellis consisting of slender, subparallel to loosely interwoven, smooth-walled, hyaline to pale yellow hyphae 3–5 μm broad, forming a partially developed caulohymenium; in the upper third of the stipe, bundles of caulohymenium consist of clavate, hyaline to yellow caulobasidia (30–50 × 8–15 μm), caulobasidioles, and broadly ventricose-fusiform or clavate caulocystidia (24–50 × 7–11 μm), with an often extremely elongated neck (to 30 μm long). Stipe texture formed of parallel running, ± hyaline, 2–4 mm broad hyphae; scattered to scarce orange-red crystals (hyphal excretions) dissolving in 5 % KOH found in the stipe base context. Lateral stipe stratum under the caulohymenium poorly differentiated from the stipe trama, consisting of divergent, inclined and running towards the external surface, densely arranged hyphae. Stipe trama inconspicuous, formed of parallel running, filamentous, 4–13 μm broad hyphae, ± hyaline in water and 5 % KOH, inamyloid. Clamp connections absent in all tissues. Ecology and phenology. Solitary, gregarious in small groups (2–3 basidiomes) or even subcaespitose, growing on bare soil, on litter or in the grass, often in anthropogenic environments, such as gardens, urban parks, lawns, meadows, disturbed roadsides, light grassy forest and planting edges, shrublands, sometimes in undisturbed forests, mostly under broadleaved trees including preferably Quercus spp. (Q. cerris, Q. coccifera, Q. faginea, Q. frainetto, Q. petraea, Q. pubescens, Q. pyrenaica, Q. robur), Castanea sativa, Fagus spp. (F. sylvatica, F. orientalis), and