Hortiboletus campestris Biketova & Wasser

Hortiboletus campestris (A. H. Sm. & Thiers) Biketova & Wasser, Index Fungorum 257: 1 (2015) ≡ Boletus campestris A. H. Sm. & Thiers, Boletes of Michigan: 266 (1971) = Boletus harrisonii A. H. Sm. & Thiers, Boletes of Michigan: 267 (1971) Examined material. USA • Michigan: Washtenaw Co., Ann Arbor, 42°16'31"N, 83°43'51"W, gregarious on lawn, 16. 07. 1966, leg. & det. A. H. Smith, MICH 4999 (A. H. Smith 72961 – collector’s number, holotype), GenBank: ITS – PV 036230, LSU – PV 036235, tef 1 - α – PV 106168, and rpb 2 – PV 106172; • Washtenaw Co., Ann Arbor, 42°16'31"N, 83°43'51"W, gregarious on lawn near Picea sp., 01. 07. 1967, leg. K. A. Harrison, det. A. H. Smith, MICH 10011 (K. A. Harrison 9504 – collector’s number, holotype of Boletus harrisonii), GenBank: ITS – PV 036229, LSU – PV 036234, tef 1 - α – PV 106169, and rpb 2 – PV 106173). Notes. Conspecificity of H. campestris and B. harrisonii was proven by phylogenetic multilocus and four single-locus analyses of their holotypes MICH 4999 and MICH 10011, respectively (Figs 1, 2). In the phylogenomic tree of Tremble et al. (2024), they also cluster together in one species-level clade. In the current multigene phylogeny, H. campestris occupies a rather isolated position in the crown clade of Hortiboletus and forms a strongly-supported terminal clade (BS = 100; PP = 1.00). There is a lot of confusion in field recognition and identification of this species. Based on the sequence data from INSDC and connected collection data from publications (Frank et al. 2020; Kuo and Ortiz-Santana 2020), as well as iNaturalist (2024), all specimens identified as H. campestris (MICH KUO- 08240502 (based on the tef 1 - α sequence MK 721094 and rpb 2 – MK 766302), F: PRL 5991 MAN, F: PRL 5879 MAN, and iNaturalist 66900805), Hortiboletus sp. ‘ campestris ’ (DD 614), or B. harrisonii (MICH KUO-09071204 and PBM 4097) actually belong to Hortiboletus flavorubellus (see below). Moreover, the LSU sequence of the MICH KUO- 08240502 collection identified as H. campestris, actually belongs to another collection and species – Xerocomus tenax Nuhn & Halling. Additionally, there are no H. campestris collections represented by their ITS sequences in INSDC, which are correctly identified to the species level (see Fig. 1 and Suppl. materials 1, 3). Further studies on the morphology and distribution of H. campestris are really needed.