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Description type:Original description 
Description:Pileus at first hemispherical, then convex to pulvinate, 25–50(–60) mm wide, with pellis red-coloured from youth, e.g. orange-red, bright red, carmine, but also wine-red or dark red, rarely as if slightly greyish powdered in the centre. Pileus margin mostly lighter, pale yellow or rose-pink. Surface dry, matt, when young velutinous, without a fibrillose aspect under a hand-lens, soon cracking near the margin and then becoming conspicuously rimose-areolate overall, exposing the pale yellowish context in the cracks.
Tubes 5–8 mm long, adnate to slightly depressed around the stipe and often shortly decurrent with a tooth, initially light yellow, then vivid yellow, later olivaceous yellow. Pores concolorous with tube-sides, in age angular and relatively large (about 1 mm) as in other species of the Boletus chrysenteron group. Both tubes and pores stain slightly blue or pale blue-greenish when bruised.
Stipe nearly equal, 30–50 x 6–15 mm, light yellow to whitish yellowish, sometimes slightly longitudinally striate, in the middle part at times with a dirty reddish, dirty red-brownish or vinaceous reddish tint; surface with very minute floccose granules, non-reticulate. The floccose granules are more or less concolorous with the background – yellowish on the yellowish parts of the stipe and reddish or brownish on the parts which are reddish or brownish. Stipe base covered with a whitish to pale dirty yellowish tomentum. Partial veil and annulus absent.
Context in the pileus pale yellowish, above tubes more yellow, in the upper and middle part of the stipe pale yellowish, but in the middle part sometimes also wine-reddish and in the lower third usually pale yellow-brownish, when cut slightly bluing, particularly above the tubes and in the upper half of the stipe. Taste mild, smell inconspicuous.
Pileipellis a palisadoderm composed of parallel or subparallel, anticlinally and densely arranged hyphae whose terminal elements reach the same (or approximately the same) level. The hyphae consist of chains of cells which are short to moderately long, subellipsoid or nearly cylindrical, often somewhat constricted at the septa, (5–)8–17(–21) µm wide, containing a dissolved, almost hyaline, pale yellowish content, sporadically also with a granular, honey-brown substance in Melzer’s reagent. Terminal cells (10–)20–40(–60) x (6–)8–15 µm, mostly tapered towards an obtusely rounded top, less often nearly ellipsoid or shortly subcylindrical. When young the palisadodermal hyphae are smooth, later the walls of some palisadodermal elements become faintly roughened with a weak incrustation. This incrustation (particularly when observed in Melzer’s reagent) is distinctly weaker and finer than in B. porosporus, B. chrysenteron and some other species of this group. Thickness of the anticlinally arranged palisadoderm varies in the range (150–)200–350(–450) µm according to age and according to location on the pileus. During growth the initially continuous palisadoderm gradually breaks up into fragments as the pileus gradually expands. Pileus trama composed of loosely interwoven, filamentous or somewhat broadened, 5–16 µm wide, non-amyloid hyphae with dissolved or granular, pale yellowish to honey-brown content in Melzer’s reagent.
Hymenophoral trama in a fully developed state has a structure intermediate between the boletoid and phylloporoid type. This intermediate trama type is best developed in middle-aged or somewhat younger (but not very young) fruit bodies. In very young developmental stages this tramal structure is not yet developed sufficiently and, on the other hand, in a mature or overmature stage it changes into a structure resembling the phylloporoid or a subregular type (for further information concerning the development of the hymenophoral trama in the Boletaceae, see Šutara 2005). Lateral strata in the fully developed state slightly divergent, slightly gelatinous, somewhat lighter and somewhat more loosely arranged than the mediostratum, with hyphae 5–15 µm wide, not touching each other. Distance between the hyphae of the lateral stratum in transverse sections is (1–)2–4(–7) µm. Mediostratum readily staining with Congo-Red, densely arranged, with hyphae 3–9 µm wide, touching each other. Basidia clavate or subcapitate, mostly 4-spored, 26–48(–53) x 11–15 µm, often with a conspicuous, granular content, sometimes also with small globules. Pleurocystidia scattered, smooth and thin-walled, fusiform or elongate fusiform, rarely almost lageniform, 30–52 x 6.5–14 µm. Cheilocystidia similar to the pleurocystidia, smooth and thin-walled, fusiform or elongate fusiform, rarely almost lageniform, 33–54 x 7–14 µm.
Spores smooth, subfusoid, with a distinct suprahilar depression in profile, in maturity mostly truncate to slightly depressed at apex, (10.5–)12.5–15(–19) x (4.5–)5.2–6.2(–7.5) µm, Q (length/width ratio) = (1.9–)2.2–2.7(–3.0), yellow or brownish in Melzer’s reagent. Spore-print not obtained (probably brownish and possibly also with an olivaceous tint as in many other species of the B. chrysenteron group).
An essential part of the stipe is covered with a gradually fragmenting caulohymenium with scattered fertile caulobasidia which produce truncate spores as the basidia of the hymenophore. Caulobasidia 25–46(–52) x 11–15 µm, clavate or subcapitate, mostly 4-spored, often with a granular content, sometimes also with small globules. Caulocystidia 36–73 x 7–15(–19) µm, smooth and thin-walled, fusiform, elongate fusiform, fusiform-ventricose or lageniform, sometimes with a long neck. Stipe base infertile, covered with a tomentum loosely entangled of filamentous, (2–)3–6(–7) µm wide hyphae. A lateral stipe stratum was not found in most specimens. Only in two examined fruit bodies this layer was developed in a very reduced form at the apex of the stipe. This reduced lateral stratum was very thin (not thicker than 20–30 µm) and somewhat loosely arranged, but not gelatinised (for the meaning of the term ‘lateral stipe stratum’, see Šutara 2005). Stipe trama composed of hyphae 4–21 µm wide, densely and more or less regularly arranged, parallel or subparallel with stipe axis, non-amyloid, almost hyaline or pale yellowish in Melzer’s reagent. Trama of both pileus and stipe composed of a monomitic hyphal system with generative hyphae which are thin-walled, exceptionally with walls very slightly thickened (up to 0,6 µm). Clamp connections not found in the fruit body.
Locality and habitat: Czech Republic, north-western Bohemia, less than 1 km from the eastern margin of the town of Teplice, southwest-facing slope of Doubravská hora hill, marginal part of a deciduous, predominantly oak forest, on soil with neutral soil reaction (geological bedrock is phonolite) in fallen leaves under high trees of Quercus robur and small, young trees of Acer platanoides, Acer pseudoplatanus and Fraxinus excelsior, alt. 286 m, 12 July 1992, 28 Aug. 1994, 25 July 2001, 4 Aug. 2003 leg. E. Skála (JŠ 4434, 4435), 11 July 2005, leg. E. Skála and E. Fujdiak (PRM 857255, holotype; JŠ 4433/b, isotype; and JŠ 4433/c), 14. Aug. 2006, leg. E. Skála, J. Šutara and E. Fujdiak (JŠ 4311). In addition to the above-mentioned trees, the following plants were found at the locality: Cornus mas, Ribes grossularia, Symphoricarpus rivularis, Hedera helix and Cephalanthera alba.
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