Boletus L.
Recent molecular studies have shown that Boletus in its current circumscription is likely an artificial grouping and it is possible that it will be split at some point into smaller genera. Note that Boletus impolitus and Boletus depilatus for practical reasons are retained here, although there is strong evidence that they are closely related to Xerocomus subtomentosus and its allies.
Fruitbody large to medium sized, boletoid, without veil and ring. Stipe solid, with surface usually covered with granules or network. Flesh variously coloured, changing or not when exposed to air. Tubes easily separable from each other, not tearing apart. Pores usually small and rounded.
Boletus rhodoxanthus Kallenb.
Description
Cap up to 15 cm, at first hemispherical, later convex to flat-convex or almost flat, initially finely velvety, then smooth, whitish to greyish, greyish ochraceous or ochraceous, towards the margin or overall with dingy pink or pink tint; cap surface unchanging when bruised. Stipe club-shaped, swollen at the base or cylindrical, at least in the uppermost part but most often almost entirely bright to dark yellow, downwards orange red to red or pinkish red, with fine orange red or red network, stipe surface blueing when handled. Flesh pale yellow in the cap, yellow in the stipe, sometimes with reddish spots in the stipe base, blueing in the cap and remaining unchanged when exposed to air. Tubes yellow, blueing when injured. Pores red to orange, blueing when bruised. Smell not dsitinctive. Taste slightly acid. Spores 10–15.5 × 3.5–5.5 μm, ratio 2.2–3.6. Pileipellis trichodermium of interwoven septate hyphae of cylindrical, finely incrusted cells. Chemical reactions: hyphae of the flesh in the stipe base amyloid with Melzer’s solution.
Habitat. Broadleaf forests, mycorrhizal with oaks (Quercus), beech (Fagus) or sweet chestnut (Castanea).
Distribution. In Europe widespread but uncommon, more often encountered in south.
Similarity. Boletus rhodoxanthus is easily distinguished from the slightly similar Boletus rhodopurpureus, B. rubrosanguineus, B. legaliae and B. satanas by the flesh which blues only in the cap and remains unchanged in the stipe. In the four mentioned species the flesh blues overall.
Photographs
Typical fruitbodies of Boletus rhodoxanthus. (photo M. Mikšík)
Fruitbodies of Boletus rhodoxanthus. Note the blueing pattern. (photo M. Mikšík)
Rich collection of Boletus rhodoxanthus. (photo I. Assyova)
Fruitbodies of Boletus rhodoxanthus. (photo I. Assyova)
Frutbody of Boletus rhodoxanthus. Note the resemblance to Boletus satanas. (photo I. Assyova)
Well developed fruitbody of Boletus rhodoxanthus. (photo B. Assyov)
Fruitbody of Boletus rhodoxanthus. Note the blueing in the cap and the unchanging yellow flesh in the stipe. (photo B. Assyov)
Detail of the stipe surface of Boletus rhodoxanthus. (photo B. Assyov)
Spores of Boletus rhodoxanthus. Scale bar = 10 μm. (photo B. Assyov)
Important literature
Alessio, C.L. 1985. Boletus Dill. ex L. (sensu lato). – In: Fungi Europaei. Vol. 2. Pp. 1–705. Libreria editrice Biella Giovanna, Saronno.
Breitenbach J. & Kränzlin F. 1991. Pilze der Schweiz. Bd. 3(1). Röhrlinge und Blätterpilze. Verlag Mykologia, Luzern.
Engel, H., Krieglsteiner, G., Dermek, A. & Watling, R. 1983. Dickröhrlinge. Die Gattung Boletus in Europa. Verlag Heinz Engel, Weidhausen b. Coburg.
Estadès, A. & Lannoy, G. 2004. Les bolets européens. – Bulletin Mycologique et Botanique Dauphiné-Savoie 44(3): 3–79.
Galli, R. 1998. I Boleti. Atlante pratico-monographico per la determinazione dei boleti. Edinatura, Milano.
Knudsen, H. & Vesterholt, J. [eds.]. 2008. Funga Nordica. Nordsvamp, Kopenhagen.
Lannoy, G. & Estadès, A. 2001. Les Bolets. Flore mycologique d’Europe. Documents Mycologiques Mémoire Hors série no. 6. Pp. 1–163. Association d’Écologie et de Mycologie, Lille.
Muñoz, J.A. 2005. Boletus s. l. – In: Fungi Europaei. Vol. 1. Pp. 1–951. Edizioni Candusso, Alassio.
Pilát, A. & Dermek, A. 1974. Hríbovité huby. Československé hríbovité a sliziakovité huby (Boletaceae – Gomphidiaceae). Veda, Bratislava.
Šutara, J., Mikšík, M. & Janda, V. 2009. Hřibovité houby. Čeled’ Boletaceae a rody Gyrodon, Gyroporus, Boletinus a Suillus. Academia, Praha.