Hortiboletus campestris (A. H. Sm. & Thiers) Biketova & Wasser

Biketova, Alona Yu., Svetasheva, Tatyana Yu., Taylor, Andy F. S., Simonini, Giampaolo, Gelardi, Matteo, Morozova, Olga V., Polemis, Elias, Muñoz, José A., Albert, László, Saitta, Salvatore, Wasser, Solomon P., Nevo, Eviatar, Zervakis, Georgios I., Vizzini, Alfredo & Dima, Bálint, 2025, Morphological and molecular re-assessment of European and Levantine species of the genus Hortiboletus (Boletaceae), IMA Fungus 16, pp. e 144731-e 144731 : e144731-

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.

Figures

Figure 1. ML phylogenetic tree of Hortiboletus generated from a multilocus (ITS + LSU + tef 1 - a + rpb 2) dataset. BS values ≥ 50 % and PP values ≥ 0.8 indicated at nodes. Thickened branches indicate high statistical support (BS ≥ 70 % and PP ≥ 0.95). Species names of collections follow current identification, except original names of types of Boletus harrisonii and B. rubellus var. flammeus. Hortiboletus species present in Europe and Levant are indicated by light red-coloured fields. Collections with newly-generated sequences are indicated in bold. Two-letter country codes (ISO 3166-1 alpha- 2) denote the origin of specimens. At the end of the annotations to some collections, abbreviations are indicated in brackets: e – epitype, h – holotype, p – paratype, env – environmental sample.

Figure 2. Phylogenetic trees of Hortiboletus from separate ML analyses of each locus: ITS, LSU, tef 1 - a, and rpb 2. BS values ≥ 50 % and PP values ≥ 0.8 are indicated at nodes. Thickened branches indicate high statistical support (BS ≥ 70 % and PP ≥ 0.95). Pie charts underneath each label are the percent of total characters in the alignment that are parsimony-informative.