Hortiboletus hershenzoniae Biketova & Wasser, 2025

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 hershenzoniae Biketova & Wasser sp. nov.

Figs 3 c, d , 8 , 13 , 14 , 15

Diagnosis.

Basidiomes pileate-stipitate, xerocomoid, epigeal, small to medium-small-sized. Young basidiomes usually have a red pileus and yellow stipe, but with age, the colour of the pileus can fade to various tints of brown or greyish-brown and the stipe surface develops a dark-red tint (red scales or fibrils on a yellow background). Pileus up to 10 cm in diam., dry, finely tomentose, sometimes alveolate-rugose or with small cracks. Tubes adnate to slightly decurrent, initially pale yellow to lemon yellow and becoming olivaceous-brown with age, slightly bluing when cut. Pores angular, uneven and denticulate in mature basidiomes, concolourous with tubes, only weakly bluing when bruised. Stipe up to 12 cm long, central or slightly off-centre, usually slender especially in young basidiomes, cylindrical, curved, somewhat tapering towards the base and slightly rooting. Context firm to soft in the pileus, fibrous and brittle in the stipe; pale yellow to lemon yellow, sometimes from pale pink to vinaceous underneath the pileus surface in old basidiomes, usually with minute dots of orange-red or vermilion-red pigment in the stipe base (sometimes dots are absent in young basidiomes); only erratically and slightly bluing when exposed to air. Basidiospores 11.4–13.9 × 6.0–6.6 µm, Qm = 2.02 ± 0.17, broadly elliptical to broadly fusiform, smooth. Pileipellis a palisadoderm, of long, parallel, smooth or sometimes encrusted hyphae; terminal elements 20.0–48.2 × 9.0–13.8 μm, mostly cylindrical and somewhat tapering towards the apex.

Etymology.

Named in honour of the late Zehara Avizohar-Hershenzon, who was one of the pioneers of the mycological science and investigations of macrofungi in Israel.

Holotype ( MTB 10011371 ).

ISRAEL • Sharon Plain: Zikhron Ya’akov , 32°34'28"N, 34°58'33"E, under Quercus calliprinos , 01. 12. 2012, leg. R. Kuznetsov, K-M 001435594 (AB B 12-071 – collector’s number), GenBank: ITS + LSU – PV 030528 , tef 1 - α – PV 088300 , and rpb 2 – PV 088311 .

Description.

Basidiomes pileate-stipitate, xerocomoid, epigeal, small to medium-small-sized. Sometimes basidiomes grow fused together, forming one common pileus originating from two different stipes. Ontogenetic development gymnocarpic.

Pileus 1.9–10 cm diam., initially nearly hemispherical, then convex, applanate to almost flattened, slightly depressed at centre, sometimes irregularly shaped, dry, finely tomentose, sometimes alveolate-rugose or with fine or coarse cracks especially in dry weather, with cream or yellowish (basidiomes with red pileus) or also vinaceous-red (basidiomes with brownish pileus) context in the cracks; pileus surface very variable in colour, initially with different tints of red (blood red, cherry red, rose red, vinaceous-red: BFF 41; OAC 600–605, 607, 621–623) and then usually slowly fading to various tints of brown or greyish-brown and ochraceous (hazel, clay buff, sepia, milky coffee, cigar brown, greyish-ochraceous: BFF 16, 17, 26 - 8, 32; OAC 770, 771, 778, 736, 743, 745), especially in dry weather; cap margin slightly inrolled in young basidiomes and then straight, acute, sometimes obtuse gibbous-corrugate, somewhat (sometimes significantly) paler than the central part of the pileus in young basidiomes.

Tubes up to 15 mm long, at first adnate, later emarginate or slightly decurrent with a tooth, initially straw yellow, lemon yellow or greenish-yellow (BFF 50, 54, 57, 64; OAC 1, 3, 896, 897), later greenish-yellow, citrine olivaceous to olive brown (OAC 801, 817, 832, 838, 894); slightly bluing when injured.

Pores angular, uneven and denticulate in mature basidiomes, pale yellow, lemon or greenish-yellow (BFF 54, 57, 64; OAC 3, 856, 894, 896, 897) in young basidiomes and citrine olivaceous to olive brown with rusty tint (OAC 804, 848, 825, 839, 838, 785) with age, only weakly bluing when bruised.

Stipe 4–11.5 × 0.7–3.7 cm, versiform, central or slightly off-centre, usually slender especially in young basidiomes, cylindrical, curved, somewhat tapering towards the base and slightly rooting, dry, initially smooth or slightly fibrillose and straw or lemon yellow throughout (BFF 50; OAC 1, 3, 853, 855, 856, 898) in wet weather, then becoming ornamented with vinaceous-red and brownish-red scales or fibrils (BFF 17, 19, 20; OAC 657, 635, 601, 602, 622) in the upper or middle part of the stipe and sometimes towards the base especially in dry conditions. Basal mycelium yellow or dirty yellow (OAC 1, 3-5, 853, 856, 847).

Context firm to soft in the pileus, fibrous and brittle in the stipe; pale yellow, sulphur yellow to lemon yellow (BFF 55; OAC 1, 858), slowly fading on drying especially in the pileus, sometimes from pale pink to vinaceous (BFF 76, OAC 578, 599, 611) underneath the cuticle in old basidiomes, usually with minute dots of red-orange or orange-red (OAC 630, 649, 677) pigment in the stipe base that is mostly visible only under a stereomicroscope and sometimes absent in young basidiomes; sometimes only slightly bluing in the pileus and / or in the upper and middle part of the stipe (in wet weather) when exposed to air.

Spore print olive brown (OAC 831, 832).

Odour inconspicuous. Taste mild.

Macrochemical spot-test reactions: Melzer’s reagent: a weak fleeting-amyloid reaction on the hymenophoral trama and on the stipe and pileus context of fresh and dry basidiomes; 25 % NH 4 OH: fading of pinkish pigment of the pileus context under cuticle; 10 % FeSO 4: olivaceous (BFF 62; OAC 866, 868, 832, 882) to bluish-grey on the context in the stipe base and pale olivaceous (OAC 850) to olivaceous-black (OAC 36, 37) on the pileus context; 10 % H 2 SO 4: sienna to light yellow ochre and (OAC 706, 707, 810–813) on pileus surface, yellow ochre (OAC 810–812) on pores, and olive-ochraceus to yellow ochre (OAC 803, 811, 818, 825) on the stipe context.

Basidiospores [336 / 10 / 10] (10.8 –) 12.4 ± 0.9 (– 13.9) × (5.5 –) 6.2 ± 0.3 (– 6.6) µm, Qm = (1.90 –) 2.01 ± 0.08 (– 2.22), Vm = 251 ± 40 µm 3, broadly elliptical to broadly fusiform, smooth, with a weak suprahilar depression in profile, yellowish ochraceous, with 1–3 large guttules when mature. Basidia 28–42 × 9–13 μm, generally four-spored, clavate, hyaline to yellowish, guttulate, without basal clamp.

Basidia [51 / 2 / 2] (32.5 –) 48.4 ± 8.2 (– 74.0) × (11.8 –) 14.2 ± 1.9 (– 19.5) μm, subclavate to clavate, predominantly 4 - spored, sterigmata (2.5 –) 3.2 ± 1.7 (– 6.7) μm long, hyaline to yellowish in 5 % KOH and containing concolourous oil guttules, without basal clamps; basidioles subcylindrical to faintly clavate, smaller than basidia.

Cheilocystidia [11 / 2 / 2] (45.0 –) 52.7 ± 6.3 (– 65.0) × (8.2 –) 12.4 ± 2.9 (– 16.2) μm, slender, ventricose-fusiform, often with elongated neck, with rounded tip, smooth, mostly hyaline to pale yellowish, some with intracellular yellowish oil content, in water and 5 % KOH. Pleurocystidia [30 / 2 / 2] (38.0 –) 56.5 ± 8.1 (– 70.0) × (10.0 –) 13.6 ± 2.2 (– 19.5) μm, slender, ventricose-fusiform, often with elongated neck, with rounded tip, smooth, mostly hyaline to pale yellowish, some with intracellular yellowish oil content, in water and 5 % KOH. Pseudocystidia not observed.

Hymenophoral trama bilaterally divergent, intermediate between the “ Phylloporus - type ” and the “ Boletus - type ”: lateral strata consisting of poorly divergent, tightly arranged, non-gelatinous hyphae almost touching each other, hyaline to very pale yellow in water and 5 % KOH; mediostratum consisting of tightly adpressed, non-gelatinous, parallel running hyphae; in Congo red, the mediostratum is slightly darker than the lateral strata.

Pileipellis a palisadoderm of long, parallel, septate, smooth or encrusted (by granular pigment) hyphae; terminal elements [322 / 10 / 10] (25.2 –) 32.6 ± 5.9 (– 44.2) × (7.3 –) 10.9 ± 2.1 (– 13.9) μm, Qm = (2.32 –) 3.03 ± 0.43 (– 3.61), encrusted, mostly cylindrical and somewhat tapering towards the apex, obtusely triangular, acorn-shaped.

Stipitipellis consisting of slender, subparallel, smooth walled, round tip, pale-yellow in 5 % KOH hyphae, (3.0 –) 3.5–4.5 (– 6.5) μm broad. Bundles of a caulohymenium, constituted of clavate caulobasidioles (23.0 –) 31.0–35.2 (– 42.5) × (8.0 –) 9.3–12.1 (– 14.5) μm, hyaline to pale yellow in 5 % KOH are observed in the upper part of the stipe; fertile caulobasidia not observed. Confused, intermixed, sometimes ramified 4.4–6.0 μm hyphae from which caulobasidioles arise were observed, not constituting a true lateral stratum.

Stipe trama consisting of parallel running, (5.5 –) 6.7–7.1 (– 8.0) μm broad, sometimes restricted to septa hyphae, hyaline in 5 % KOH, inamyloid; infrequent, versiform thromboplerous hyphae are observed here and there.

Clamp connections absent in all tissues.

Ecology and phenology.

Solitary, in small groups, or caespitose, in Mediterranean thermophilous forests, growing with Quercus calliprinos ( Sleiman et al. (2021), as H. engelii, GP ; pers. observ., GP), possibly also with Q. ithaburensis on calcareous soil, common in its habitat. There are some molecularly unconfirmed data referring to a putative association with Pinus halepensis . The main fruiting period starts after the first prolonged and heavy rains and goes from late October to December, sometimes continuing until the last rains in April.

Known distribution (see Fig. 5 b).

So far known from Israel (this study, GP) and Lebanon ( Sleiman et al. (2021), as H. engelii, GP ). It likely grows in other countries of the eastern Mediterranean region.

Additional examined material.

ISRAEL • Carmel Mount: Mt. Carmel National Park, Nahal Oren valley, Henyon Ha’Agam , 32°43'26"N, 35°00'55"E, 260 m, under Q. calliprinos , four from young to mature basidiomes, 13. 11. 2012, leg. Y. Cherniavsky & O. Godorova, det. A. Biketova, K-M 001435678 (AB B 12-024, GP) ; • the same locality, two aged basidiomes, 17. 11. 2012, leg. O. Godorova & A. Biketova, det. A. Biketova, K-M 001435686 (AB B 12-046) ; • Mt. Carmel National Park, near the crossroad Damon , 32°44'03"N, 35°02'22"E, 505 m, under Q. calliprinos , several from young to mature basidiomes, 30. 10. 2015, leg. S. Tam, Y. Gruntman, N. Bar, Y. Segal, T. Schlesinger, E. Baum, Y. Ingel & A. Biketova, det. A. Biketova, K-M 001436710 (AB B 15-261; GP) and K-M 001435695 (AB B 15-263) ; • Dereh Nof HaCarmel , under Q. calliprinos , two mature basidiomes, 20. 11. 2014, leg. Y. Cherniavsky, det. A. Biketova, K-M 001435698 (AB B 14-217, GP) ; • ibid., under Q. calliprinos , 09. 12. 2014, three mature basidiomes (two infected by Hypomyces cf. chrysospermus ), leg. R. Kuznetsov, det. A. Biketova, K-M 001435700 (AB B 14-235) ; • Nesher, not far from the University of Haifa, near the road 672, close to the Cave , 32°45'23.1"N, 35°01'39.6"E, under Pistacia lentiscus with P. halepensis in vicinity, one mature basidiome, 28. 10. 2015, leg. A. Biketova & A. Berqi, det. A. Biketova, K-M 001435702 (AB B 15-252) ; • Lower Galilee: HaSolelim Forest Reserve, near the intersection of highway 77 and the road to Hoshaya , 32°46'07"N, 35°17'38"E, in Q. calliprinos and Q. ithaburensis forest, one to two mature basidiomes in each specimen, 14. 12. 2012, leg. Z. Shafranov & A. Rotenberg, det. A. Biketova, K-M 001435681 (AB B 12-112), K-M 001435683 (AB B 12-113), K-M 001435685 (AB B 12-114), K-M 001435687 (AB B 12-117), and K-M 001435689 (AB B 12-118) ; • Sharon Plain: Zikhron Ya’akov, near Israel National Trail , 32°34'29"N, 34°58'33"E, under Q. calliprinos , one mature basidiome (infected by Hypomyces cf. chrysospermus ), 20. 11. 2014, leg. R. Kuznetsov, det. A. Biketova, K-M 001435704 (AB B 14-218, GP) ; • ibid., 32°34'28.5"N, 34°58'33.2"E, under Q. calliprinos and Q. ithaburensis , two mature basidiomes (one infected by Hypomyces cf. chrysospermus ), 07. 04. 2014, leg. R. Kuznetsov, det. A. Biketova, K-M 001435703 (AB B 14-189) ; • ibid., 32°34'13.0"N, 34°58'26.9"E, under Q. calliprinos , one mature basidiome, 05. 12. 2014, leg. R. Kuznetsov, det. A. Biketova, K-M 001435708 (AB B 14-228, GP) ; • Zikhron Ya’akov, near Israel National Trail, near the ravine , 32°34'29.3"N, 34°58'32.4"E, under Q. calliprinos , 05. 12. 2014, leg. R. Kuznetsov, det. A. Biketova, K-M 001435706 (AB B 14-227, GP, one mature and one aged basidiome) and K-M 001435707 (AB B 14-229, two mature basidiomes), respectively ; • Zikhron Ya’akov, Ramat Menashe, near Israel National Trail , one immature basidiome, under Q. calliprinos and Q. ithaburensis , one very young basidiome, 10. 01. 2014, leg. R. Kuznetsov, det. A. Biketova, K-M 001435696 (AB B 14-238) ; • the forest near Zikhron Ya’akov , under Q. calliprinos , four young to mature basidiomes, 22. 04. 2015, leg. R. Kuznetsov & Y. Cherniavsky, det. A. Biketova, K-M 001435710 (AB B 15-248; GP) ; • Upper Galilee: Goren Park , 33°03'22"N, 35°13'48"E, under Q. calliprinos , two mature basidiomes, 01. 12. 2012, leg. Z. Shafranov, det. A. Biketova, K-M 001435693 (AB B 12-067) ; • ibid., under Quercus sp. , one mature basidiome, 11. 12. 2014, leg. B. Gal, det. A. Biketova, K-M 001435692 (AB B 14-237) ; • Hanita Forest , 33°04'44"N, 35°09'57"E, 160 m, under Q. calliprinos , five mature to old basidiomes, 18. 05. 2013, leg. Z. Shafranov, det. A. Biketova, K-M 001435701 (AB B 13-153) ; • Shomera , 33°04'47.1"N, 35°16'45.3"E, under Q. calliprinos , near P. lentiscus and Laurus nobilis , one mature basidiome and two primordia, 26. 10. 2015, leg. Y. Segal, det. A. Biketova, K-M 001435699 (AB B 15-260, GP) .

Notes.

In the present study, a new species, H. hershenzoniae is described. It is very similar to H. engelii and H. rubellus , but well distinguished from them based on morphology, phylogeny (Fig. 1 ), ecology, and distribution (Figs 4 , 5 ). Basidiomes of these three species are very variable in colour. Young specimens of H. hershenzoniae usually have a red pileus and yellow stipe, but with age, especially in dry conditions, the colour of the pileus usually fades to various tints of brown or greyish-brown and the stipe surface develops a dark-red tint (red scales or fibrils). Such transition of red pigments causes a high chromatic variation, which is also a common feature in H. engelii . We can call this phenomenon “ migration of red pigments from the pileus surface to the stipe surface ”. In contrast, H. rubellus usually has a red-coloured stipe surface even in young basidiomes with red pileus, which is not observed in the specimens of H. hershenzoniae . Hortiboletus hershenzoniae has orange-red or vermilion-red dots in the context of the stipe base, but they are mostly visible only under a stereomicroscope or are totally absent in young basidiomes (see Figs 13 b , 14 b – d ), unlike the clearly visible vermilion-red dots of H. engelii and H. rubellus (see Figs 6 h , 11 h ) ( Engel et al. 1996; Taylor et al. 2002; Hills 2008; Muñoz et al. 2008).

The basidiospores of H. hershenzoniae are significantly broader (average width 6.2 μm, Qm = 2.01) than those of H. engelii (average width 5.1 μm, Qm = 2.35), H. rubellus (average width 5.0 μm, Qm = 2.31), and H. bubalinus (average width 4.8 μm, Qm = 2.46) (Fig. 8 a ). Terminal elements of the pileipellis are encrusted, mainly cylindrical, somewhat tapering towards the apex, and sometimes obtusely triangular. Their size and shape are more similar to those of H. engelii (Fig. 8 b ). The current phylogenetic analysis shows that H. hershenzoniae clusters in a strongly-supported clade in our multilocus analysis (BS = 91; PP = 1.00) and it is closely related to H. engelii (see above and Fig. 1 ). Sleiman et al. (2021) reported this species in Lebanon under the name H. engelii (T 1-1). Based on a BLASTn analysis of the ITS sequence MZ 088076 with those of our Israeli specimens (99.6–99.9 % similarity), as well as on the current phylogenetic reconstruction, the Lebanese specimen unequivocally belongs to H. hershenzoniae .

Key to the European and Levantine species of Hortiboletus

Extralimital taxa

Species presented in this section are from North America and their study was not included in the main tasks of our current research.

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 3. Scanning electron micrographs of Hortiboletus basidiospores: a H. rubellus (MCVE 31743, epitype); b H. engelii (K-M 000170238); c, d H. hershenzoniae (K-M 001435594, holotype). Photos: (a) A. Yu. Biketova and Y. Pollak; (b) A. Yu. Biketova and B. Dobrić; (c, d) A. Yu. Biketova and M. Kalina.

Figure 4. Distribution map of a H. rubellus and b H. bubalinus, based on the current study and sequence data from public repositories and associated publications.

Figure 5. Distribution map of a H. engelii and b H. hershenzoniae, based on the current study and sequence data from public repositories and associated publications.

Figure 6. Hortiboletus rubellus basidiomes: a epitype collection MCVE 31743; b MG 781; c DB- 2022-06 - 29 - 3; d AL 13-125, e LE F- 316026; f K-M 001435677; g basal mycelium of Vgy- 2018-07 - 21 - 1; h orange-red dots in the stipe base context of GK 6705. Photos: (a) G. Simonini; (b) M. Gelardi; (c) B. Dima; (d) L. Albert; (e) A. I. Ivanov; (f) A. Yu. Biketova; (g) G. Vrba; (h) G. Konstantinidis.

Figure 8. Size distributions of a spores and b terminal cells of pileipellis in Hortiboletus using the “ isoprobability ellipse ” method. The distributions of average spore sizes in collections are shown with one standard deviation.

Figure 11. Hortiboletus engelii basidiomes: a JAM 0547; b epitype collection MCVE 18563; c MCVE 18267; d GS 10273; e GS 10848; f AL 21-73; g TUR-A 209577; h orange-red dots in the stipe base context of GK 6124. Photos: (a) J. A. Muñoz; (b) A. F. S. Taylor; (c) G. Simonini; (d) A. Mua; (e) M. Raumi; (f) L. Albert; (g) S. Saitta; (h) G. Konstantinidis.

Figure 13. Hortiboletus hershenzoniae basidiomes: a, b holotype collection K-M 001435594; c K-M 001435695; d K-M 001435706; e, f pileus surface of collections: e K-M 001435695 and f K-M 001435706. Scale bars: 2 mm. Photos: (a, b) R. Kuznetsov; (c – f) A. Yu. Biketova.

Figure 14. Details of macroscopical features of H. hershenzoniae: a uneven, denticulate hymenophoral surface of collection K-M 001436710; b – d context of the stipe base: b without orange-red dots in a young basidiome (K-M 001436710), c with sporadic orange-red dots in young basidiome (K-M 001435695), and d collapsed and dispersed orange-red dots throughout the whole stipe base context of a mature basidiome (K-M 001435695); e stipe surface with reddish fibrils on light-yellow ground in a brown-pileus basidiome of K-M 001436710; f stipe surface with light-yellow ground in a red-pileus basidiome of K-M 001435695. Scale bars: 2 mm (a, e, f); 1 mm (b – d). Photos: A. Yu. Biketova.

Figure 15. Microscopical features of H. hershenzoniae: a basidiospores of collection K-M 001435693 in L 4; b basidia in Congo red, left collection K-M 001435710, right – K-M 001435695; c pileipellis in Congo red, left collection K-M 001435693, centre – K-M 001435686, right – K-M 001435594 (holotype); d pleurocystidia in Congo red, from left to right collections K-M 001435710, K-M 001435695 – twice, and K-M 001435710; e cheilocystidia in Congo red of K-M 001435710. Scale bar: 10 μm. Photos: G. Simonini.