The definition of the generic limits of Xerocomus s. l. and particularly the delimitation of this genus from Boletus is very unclear and controversial. During his study of European species of the Boletaceae, the author has come to the conclusion that Xerocomus in a wide concept is a heterogeneous mixture of several groups of species. These groups are separated from each other by different anatomical and some other characters. Also recent molecular studies show that Xerocomus s. l. is not a monophyletic group. In agreement with these facts, the European species of Xerocomus s. l. whose anatomy was studied by the present author are here classified into the following, more distinctly delimited genera: Xerocomus s. str., Phylloporus, Xerocomellus gen. nov., Hemileccinum gen. nov. and Pseudoboletus. Boletus badius and Boletus moravicus, also often treated as species of Xerocomus, are retained for the present in the genus Boletus. The differences between Xerocomus s. str., Phylloporus, Xerocomellus, Hemileccinum, Pseudoboletus and Boletus (which is related to this group of genera) are discussed in detail. Two new genera, Xerocomellus and Hemileccinum, and necessary new combinations of species names are proposed.

The paper deals with Boletus roseogriseus and Boletus fuscoroseus, two closely related species of the genus Boletus, section Appendiculati. B. roseogriseus is described as a new species based on a morphological and molecular study of collected material. B. fuscoroseus, validly published by Smotlacha in 1912, has been often incorrectly named Boletus pseudoregius. This name, however, does not have priority because B. pseudoregius was validly published as late as 1988. In order to contribute to clarification of some controversial questions concerning B. fuscoroseus, the authors have selected a neotype for this species. Descriptions of B. roseogriseus and B. fuscoroseus are accompanied by results of a molecular study (ITS and LSU rDNA sequences) and a discussion of characters distinguishing these species from other representatives of section Appendiculati.

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One of the characteristic features of European species of genera Boletus s.str. and Butyriboletus is a conspicuous development of their cheilocystidia covering their pores in youth. The development of this type of cheilocystidia is partly supported by the growth of hyphae of the hymenophoral trama under the cheilocystidia. This special arrangement of cheilocystidia is an important diagnostic character distinguishing European species of the above-mentioned genera from other groups of boletes in Boletaceae. The microscopical structure of this type of pores is described in detail.

A new species, Boletus kluzakii, which was found in southern Bohemia (Czech Republic), is described. Typical characters of this bolete are: pileus when young whitish or pallid, sometimes with a slight pinkish tint, then more or less rose-pink or purplish pink, at times even purple-reddish in some places; pileus surface conspicuously reddening when handled or bruised; hymenophore yellow, bluing when bruised; stipe yellow with a yellow reticulation; context under pileus cuticle red or purplish red but in other parts of the pileus and in upper half of the stipe pale yellowish or vivid yellow, turning blue when injured; taste bitter. Characters distinguishing Boletus kluzakii from Boletus radicans (the most closely related species) and from other boletes with a pinkish or reddish shade of pileus (Boletus regius, B. fuscoroseus, B. speciosus, B. pulchrotinctus, B. roseoolivaceus, B. roseopurpureus and B. pulchriceps) are discussed.