ITS: Internal Transcibed Spacer. Als spacer DNA wird nicht codierende DNA bezeichnet, die zwischen bestimmten Untereinheiten von rRNA-Genen lokalisiert ist. 
28s rDNA: ribosomale DNA; jene Abschnitte der DNA, die die Gene für die rRNA (ribosomale RNA, RNA der Ribosomen) enthalten. Ribosomen: Zellorganellen, in denen die Synthese der Eiweiße (Translation) stattfindet. 28s rDNA kommt nur bei Lebewesen mit echtem Zellkern (z.B. Pilz, Pflanze, Mensch) vor, nicht aber bei Bakterien. Die 28s rDNA von Organismen wird, wie auch ITS, häufig für phylogenetische Studien verwendet. Phylogenie: Lehre von der Stammesgeschichte – und damit der Verwandtschaftsverhältnisse zwischen verschiedenen Organismen. 
IF550508
Habitus robustissimarum Boletacearum typicus. A gen. Rubroboletus differt pileo tacto caeruleo- dein nigro maculoso, contextum in stipites basi rubropurpureo. Stipes robustum, totaliter reticulato atque flavo-purpurascens. Pori minuti, primitus lutei vel rubri, tacto cærulescentibus. Caro compacta, odore fortis, flavo-sulphurea, virescens deiunque fracta caerulescens; rubra stipite basi.
Holotype: Boletus torosus Fr. 1835.
Phylogenetic results based on ITS and 28S rDNA sequences reveal that the three species cited above belong to a monophyletic lineage, not characterized in earlier works (Nuhn et al. 2013, Fungal Biology 117: 479-511 ; Arora & Frank 2014, Mycologia 106(3): 464-480 ; Gelardi et al. 2014, Mycologia 106(6): 1168-1187 ; Simonini & Vizzini 2014 , Mycol. Progr. 13(1): 95-109 ; Wu et al. 2014, Fungal Diversity on line, DOI: http://dx.doi.org/10.1007/s13225-014-0283-8; Wu et al. 2015, Fungal Diversity on line,
 
DOI: 10.1007/s13225-015-0322-0). The three species identified in this clade are all European, known from broadleaved forests on calcareous soils. This group is characterized by a unique combination of features:
·       yellow to reddish-orange reticulate stipe,
·       staining dark purplish red from base with age,
·       a typical blue to blackish staining on pileus surface when touched, and
·       an intense blueing reaction of the context when cut.
Pores are either yellow, red or purplish with a high chromatic variability of all parts of basidiome in I. rhodopurpureus.
The taxonomic status of these variants, as well as of Boletus xanthocyaneus Romagn., requires further studies.
Phylogenetic results supporting this publication (ITS and 28S ML phylogenetic trees) are accessible online at http://boletales.com/phylogenetics/. Acknowledgements : to Paul Pirot for verification of the Latin diagnosis, and to the members of the web forum Mediterranean Fungi, from which this project originated.
Etymology: Imperator (Lat., Emperor) in honour of the impressive and prestigious Boletus torosus, and its smaller but equally remarkable relatives. 
Imperator luteocupreus (Bertéa & Estadès) Assyov, Bellanger, Bertéa, Courtec., Koller, Loizides, G. Marques, J.A. Muñoz, N. Oppicelli, D. Puddu, F. Rich. & P.-A. Moreau, comb. nov.
IF550510
Basionym: Boletus luteocupreus Bertéa & Estadès, Docums Mycol. 20 (no. 78): 10 (1990) 
Imperator rhodopurpureus (Smotl.) Assyov, Bellanger, Bertéa, Courtec., Koller, Loizides, G. Marques, J.A. Muñoz, N. Oppicelli, D. Puddu, F. Rich. & P.-A. Moreau, comb. nov.
IF550511
Basionym: Boletus rhodopurpureus Smotl. C.C.H. 29(1-3): 31 (1952) 
Imperator torosus (Fr.) Assyov, Bellanger, Bertéa, Courtec., Koller, Loizides, G. Marques, J.A. Muñoz, N. Oppicelli, D. Puddu, F. Rich. & P.-A. Moreau, comb. nov.
IF550512
Basionym: Boletus torosus Fr., in Fries & Hök, Boleti, Fungorum generis, illustratio: 10 (1835)
 
Der Wörterseher meint:
“Wir wollen unser´n alten Kaiser Boletus wiederhaben!“
…und lassen uns nicht kampflos den Butterboleten vom Brot nehmen!