An integrated taxonomic approach refines the Imperator torosus species concept and reveals the cryptic I. occultus sp. nov. (Boletales, Boletaceae)
Imperator torosus is a polymorphic, critical Friesian bolete, originally described from Central Europe, but with a convoluted taxonomic history which caused much uncertainty in delimiting it from similar-looking species. Previous molecular phylogenetic analyses confidently indicated that I. torosus , as presently circumscribed, is a polyphyletic species in need of taxonomic revision. Based on a two-locus (ITS and LSU) phylogeny, pairwise distance and percent nucleotide similarity analyses, as well as morphological and ecological evidence, I. torosus s. str. is defined and Imperator occultus described as a novel species. Besides unravelling the intricate taxonomic history of I. torosus s. l., detailed macro- and micro-morphological descriptions based on well-documented collections are provided for both I. torosus s. str. and I. occultus , accompanied by colour photographs taken in their natural habitats and line drawings of their main microscopic features. A comprehensive and circumstantial discussion upon the reasons why the recent epitypification of B. torosus is deemed untenable is presented. Morphological comparisons with xanthoid phenotypes of Imperator rhodopurpureus ( I. rhodopurpureus f. xanthopurpureus and I. xanthocyaneus ), as well as their taxonomic placement within the genus Imperator are also elucidated and discussed.
Authors
- Boris Assyov (ORCID: https://orcid.org/0000-0002-7365-2443)
- Pierre‐Arthur Moreau (ORCID: https://orcid.org/0000-0003-4783-3643)
- Alfredo Vizzini (ORCID: https://orcid.org/0000-0001-8390-6446)
- Michal Mikšík (ORCID: https://orcid.org/0000-0003-4415-7184)
- Andrin Gross (ORCID: https://orcid.org/0000-0002-2489-8105)
- Bálint Dima (ORCID: https://orcid.org/0000-0003-2099-3903)
- Günter Saar (ORCID: https://orcid.org/0000-0002-6365-7929)
- Jean‐Michel Bellanger (ORCID: https://orcid.org/0000-0001-9289-2349)
- László Albert (ORCID: https://orcid.org/0000-0003-4505-3010)
- Artemis D. Treindl (ORCID: https://orcid.org/0000-0001-7347-2891)
- Alona Yu. Biketova (ORCID: https://orcid.org/0000-0003-0801-0660)
- Marco Cartabia (ORCID: https://orcid.org/0000-0002-1986-3178)
- Jacques Guinberteau
- Matteo Gelardi (ORCID: https://orcid.org/0009-0008-0903-852X)
- Eva Zupan
- Marko Požnjak
- Neven Ferenčak
Institutions
- Eötvös Loránd University (HU)
- Centre National de la Recherche Scientifique (FR)
- Inserm (FR)
- École Pratique des Hautes Études (FR)
- Université de Lille (FR)
- Bulgarian Academy of Sciences (BG)
- Royal Botanic Gardens, Kew (GB)
- Swiss Federal Institute for Forest, Snow and Landscape Research (CH)
- ETH Zurich (CH)
- Centre d'Écologie Fonctionnelle et Évolutive (FR)
- Institute of Biodiversity and Ecosystem Research (BG)
- Institut de Recherche pour le Développement (FR)
- Laboratoire de Génie Civil et Géo Environnement (FR)
- University of Turin (IT)
- University of Haifa (IL)
Publication Details
- Journal
- MycoKeys
- Published
- 2026-11-02
- DOI
- https://doi.org/10.3897/mycokeys.142.208955
- Primary Topic
- Plant and Fungal Species Descriptions
- Type
- article
- Field-Weighted Citation Impact
- 0.00