Butyriboletus peckii (Frost) Kuan Zhao, Zhu L. Yang & Halling, 2015

Butyriboletus peckii (Frost) Kuan Zhao, Zhu L. Yang & Halling View in CoL , comb. nov. Fig. 2a–d View FIGURE 2

MycoBank: MB 812757

Basionym: Boletus peckii Frost, Ann. Rep. N.Y. St. Mus. Nat. Hist. 29: 45, 1878

Pileus 2.5–9.5 cm in diameter, convex, becoming broadly convex to nearly plane in age; surface dry, finely tomentose, deep red to dull red or rose red, fading to brownish rose to dull brown or buffy brown from the disc outward, margin retain its color longer than the disc; context whitish to pale yellow, bluing slightly when exposed. Hymenophore surface at first bright yellow to golden yellow, becoming dingy olive yellow to brownish yellow in age, bluing then slowly staining brownish when bruised; pores circular to somewhat elongate, 2–3 per mm; tubes 4–15 mm deep. Stipe 4–9 × 1–1.6 cm, mostly equal, gradually broadening towards base, dry, solid, minutely and densely pruinose, rosy red to dark red or purplish red with yellow at the apex, typically reticulate nearly overall or at least on the upper portion, reticulation usually distinct; basal mycelium whitish to pale yellow. Odor not distinct. Taste unpleasant, typically bitter or somewhat tart ( Smith & Thiers 1971; Bessette et al. 2000).

Basidiospores [40/1/1] 9–13 (14) × 3.5–5 μm [Q = (2.40) 2.44–3.25 (3.67), Q m =2.83 ± 0.31], subfusiform, subhyaline in KOH. Hymenophoral trama boletoid. Basidia 24–35 × 7–10 μm, clavate, hyaline in KOH, 4-spored. Pleurocystidia 26–38 × 8–12 μm, smooth and thin-walled, hyaline in KOH, narrowly lageniform, lageniform to fusoidventricose; cheilocystidia similar to pleurocystidia in shape but smaller. Pileipellis composed of interwoven hyphae 4–6 μm in diameter, smooth, thin-walled, hyaline. Clamp connections absent.

Habitat: Scattered or in groups on the ground in broadleaf forests and mixed woods, especially with beech and oak.

Known distribution: Known from eastern North America.

Material examined: USA. Tennessee, Sevier, Gatlinburg , 06 Aug 1963, TENN 027510 .

Notes: Boletus peckii was transferred to the genus Caloboletus for its bitter taste ( Vizzini 2014b). However, recent phylogenetic analyses indicated that this species nested with Bu. appendiculatus and its allies ( “ regius Clade” in Nuhn et al. 2013; Clade 46 in Wu et al. 2014; this study); Morphologically, its context turns blue when exposed and then becomes light red ( Smith & Thiers 1971; Bessette et al. 2000), which is also different from the bluish color change in Caloboletus ( Zhao et al. 2014a) .