Hymenoboletus luteopurpureus Yan C. Li & Zhu L. Yang, in Wu et al., Fungal Diversity 81: 100 (2016)
Etymology: The epithet ‘‘luteopurpureus’’ refers to the purple stipe with a yellow base and apex.
Pileus 2–4 cm in diam., hemispherical to convex, dark red to brownish red (11D7–8) or dark purplish red (11D5–6) to pinkish red (12C4–4), much paler towards margin; surface tomentose, dry; context white to cream, without discoloration when injured. Hymenophore depressed around apex of stipe; hymenophoral surface white when young, and becoming pinkish (13A2) or pink (12A3–4) when mature; tubes concolorous with hymenophoral surface,color unchanging when injured; pores angular, 1–2/mm; tubes short, up to 5 mm long, without discoloration when bruised. Stipe 3–5 9 0.3–0.5 cm, subcylindrical; surface pink to purple (11B3–5), but yellow (2A7–8) to yellowish (2A4–5) at apex and bright yellow to chrome yellow at base; surface covered with purplish red scabrous dotted-elements, without discoloration when touched; context cream to yellowish, but bright yellow to chrome yellow at base, without discoloration when bruised; basal mycelium bright yellow to chrome yellow. Taste and odor mild.
Basidia 25–30 x 8–10 lm, clavate, 4-spored. Basidiospores (9) 9.5–12 (12.5) x (4.0) 4.5–5 μm [Q = (1.9) 2.1–2.67 (2.78), Qm = 2.3 ± 0.18], subfusiform in side view, narrowly oblong to subfusoid in ventral view, colorless to yellowish, smooth. Hymenophoral trama boletoid; hyphae cylindrical, 3–8 μm wide. Cheilocystidia 30–52 x 6–8.5 μm, fusiform to subfusiform or clavate but with obtuse apex, often containing yellowish pigments, thin-walled. Pleurocystidia 43–69 x 6.5–10 μm, narrowly clavate, lanceolate or subfusiform, with 1–2 constrictions at middle parts, colorless to yellowish, thin-walled. Caulocystidia forming the scabrous squamules over stipe surface, ventricose, clavate, lanceolate or subfusiform with sharp apex. Pileipellis a hymeniform, composed of brownish to yellowish brown cystidioid cells 28–60 x 4–11 μm. Pileal trama composed of interwoven hyphae 5.5–7.5 μm wide. Clamp connections absent.
Habitat: Scattered on soil in tropical forests dominated by Lithocarpus spp. and Castanopsis spp.
Known distribution: Currently only known from southwestern China.
Index Fungorum number: IF818463
Notes: Hymenoboletus luteopurpureus is characterized by the dark red to dark purplish red or pinkish red pileus, the pinkish to pink hymenophore, the pink to purple stipe with yellow base and apex, the white to cream pileal context, the hymeniform pileipellis, the tropical distribution, and the association with tropical fagaceous plants. Hymenoboletus luteopurpureus is somewhat similar to Boletus coccineinanus Corner (Corner 1972), originally described from Malaysia. They share the color of the pileus and hymenophore, and stipe morphology. However, B. coccineinanus is characterized by the tiny pileus which is 0.6–1.2 cm in diam. In addition, its pileipellis is composed of hyphae with 2–4 moniliform cells and the pleurocystidia are absent. These traits differ from those in Hy. Luteopurpureus but are identical with those observed in the sample HKAS 53379 (clade 55 in Wu et al. 2014). Phylogenetically, Hy. luteopurpureus formed a sister group with the genera Harrya and Chiua, with moderate support value. However, Harrya is characterized by a trichodermium pileipellis, while Chiua has a subcutis to trichodermium or hyphoepithelium pileipellis, and a yellow to bright yellow pileal context.