Suillus phylosubaureus R. Zhang, X. F. Shi, G. M. Mueller & P. G. Liu, 2025

Shi, Xiaofei, Zhang, Shiru, Mueller, Gregory M., Liu, Peigui, Yu, Fuqiang & Senanayake, Indunil C., 2025, A subgeneric revision of the genus Suillus (Suillaceae, Boletales) and novel taxa from Eastern Asia based on morphology and multigene phylogenies, IMA Fungus 16, pp. e 144260-e 144260 : e144260-

Suillus phylosubaureus R. Zhang, X. F. Shi, G. M. Mueller & P. G. Liu sp. nov.

Figs 20 , 21

Etymology.

This species is sister to Suillus subaureus and identified first by molecular phylogeny.

Typification.

China: • Yunnan Province, Jianchuan City, Lao Jun Mountain (alt. 3400 m), 8 September 2009, Xiaofei Shi, Shi 285 (holotype, HKAS 71798 ) .

GenBank.

ITS = KU 721174 ; LSU = KU 721369 ; TEFα- 1 = KU 721696 .

Morphology.

Pileus develops from hemispherical to plane, margin wavy at maturity, 3–8 cm diameter, surface viscid in moist, appressed blackish brown scales (6 F 6, 6 F 7) underneath the glue, becoming patched and almost glabrous when old. Hymenophore subdecurrent to decurrent, younger ones bright yellow (4 A 7, 4 A 8), turn to brownish yellow with age (4 B 7). Do not change color when bruised. Pores 1–2 per mm, angular, compound, arranged as if inconspicuously lamellate, smaller towards the margin. Tubes 3–6 mm deep, concolorous with pores. Stipe 5–10 × 0.8–1.5 cm, equal to slightly clavate, solid, no veil, white background, yellow at apex, covered with small glandular dots that are yellow (4 A 4, 4 A 5) when young, become brown (6 E 4) when old. Mycelia white, do not change color when bruised. Context yellowish white in pileus, slightly blue around worm holes. In stipe pallid yellow, turn blue (23 A 4) when cut. Spore print unknown. Odor and taste indistinctive.

Basidiospores [40 / 2 / 2] 8.0–9.0 × 3.5–4.0 μm, Q = 2.25–2.57, Q sd = 2.35 ± 0.11, smooth, oblong in face view, narrowly inequilateral with a hilar appendage in profile view, brown or ochraceous in KOH, tawny yellow in Melzer’s. Basidia 4 - spored, clavate, bulbous top, 24.0–28.0 × 7.0–8.5 μm, hyaline yellow or brown in KOH, tawny yellow in Melzer’s. Hymenophoral trama divergent, wrinkled or smooth, thin-walled, hyaline and mostly 3–8 μm wide. Pleuro- and Cheilocystidia in fascicles, abundant, clavate, content brown or hyaline, surrounded by brown amorphous materials in KOH, up to 70 μm long. Caulocystidia abundant in all part of the stipe, morphologically similar with pleuro- and cheilocystidia, fascicle base encrusted by profuse brown pigments in KOH, up to 90 μm long. Pileipellis a layer of scale hyphae, not encrusted, ochraceous, smooth, half of each hypha (4–9 μm) shrink into a thinner strand (1–2 μm). Stipitipellis mostly composed of interwoven hyphae, covered by brown amorphogous pigments, about 3–10 μm wide. Context trama hyaline, smooth, thin-walled, interwoven, similar for pileus and stipe, mostly 3–30 μm, up to 40 μm wide at stipe base. Clamp connections absent.

Habitat.

Scattered to gregarious, grows in mixed forest and probably associates with Pinus armandii .

Known distribution.

Currently only known from subalpine region of Yunnan Province, China.

Specimens examined.

China: • Yunnan Province, Jianchuan City, from Li Cha village to Lao Jun Mountain (alt. 3400 m), 2 September 2009, Bang Feng, Bang-Feng 763 ( HKAS 57492 ) ; China: • Yunnan Province, Jianchuan City, Lao Jun Mountain (alt. 3400 m), 8 September 2009, Xiaofei Shi, Shi 288 ( HKAS 71801 ) ; China: • Yunnan Province, Deqen, Shangri-la Town, Haba snow Mountain (alt. 4900 m), September 2008, Yanchun Li, Yanchun-Li 1476 ( HKAS 56316 ) .

Notes.

This new species is sister to North American Suillus subaureus . The two species differ slightly in morphology including colors of the cap. Host association of this species needs to be further studied. As for Suillus subaureus , five needle pines are requisites for the establishment of seedlings. But it is unknown about the host species of S. phylosubaureus and whether five needle pines are required in any of its developmental stages.

Figures

Figure 20. Basidiomata of Suillus phylosubaureus (holotype, HKAS 71798). Scale bar: 5 cm.

Figure 21. Suillus phylosubaureus (holotype, HKAS 71798). a Basidiospores; b Cheilocystidia; c Hymenium with basidia; d Pileipellis (mature specimens). Scale bars: 5 μm (a); 20 μm (b – d).