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

Figs 14 , 15

Etymology.

The species resembles Suillus luteus and “boleti-” indicates its smooth and regular hymenium like species in Boletinus .

Diagnosis.

Suillus boletoluteus has smooth and regular hymenium. The pores and stipes usually change color to greenish blue when cut. This species is in association with Pinus subg. Strobus in southwestern China and subg. Pinus in northeastern China.

Typification.

China: • Inner Mongolia, Hulun Buir, Erguna, Moerdaoga National Forest Park (51°23'16.40"N, 120°45'20.64"E, alt. 1000 m), 27 August 2010, Xiaofei Shi, Shi 633 (holotype, HKAS 63244 ) .

GenBank.

ITS = KU 721499 ; LSU = KU 721374 ; TEFα- 1 = KU 721702

Morphology.

Pileus develops from convex to plane or recurved, margin wavy at maturity, 3–9 cm diameter, surface viscid to glutinous, glabrous, background color yellowish buff (4 B 4), with brownish color streaks (6 D 5,6E 5) underneath the gluten. Younger ones white cap with buff brownish glue (5 C 4). Appendiculated with white and membranous partial veils that fall off with age. Hymenophore adnate to narrowly adnate, yellow (3 B 7). Pores 1–2 per mm, angular, compound. Pore surface covered with brownish cinnamon glandular dots (6 F 4–6 F 7). Change color to greenish blue (24 A 4) when cut or bruised. Tubes 4–7 mm deep. Stipe 6–9.5 × 0.8–1.2 cm, equal or slightly tapering towards apex, solid, cuticle background color greyish white, covered all over with glandular dots that are big and dense in streaks, dots are buff brown (5 B 3, 5 B 4), or cinnamon brown (6 C 4, 6 C 5) in younger ones. A superior gelatinous veil present, white and membranous, fall off at maturity or leave some brownish (6 C 4–6 D 4) membranous traces on the stipe. Context white to yellowish. Sometimes pileus context turn light blue when cut. Spore print brown. Odor and taste indistinctive.

Basidiospores [40 / 2 / 2] 9.5–12.0 (13.5) × 3.5–4.0 μm, Q = (2.38) 2.50–3.43 (3.71), Q sd = 2.81 ± 0.34, 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, 20.0–26.0 × 7.5–8.5 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 130 μm long. Pileipellis a gelatinous layer with some hyphae encrusted by ochraceous granules, some hyphae are not encrusted, most 2–8 μm, up to 11 μm wide. 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.

Solitary to scattered, in association with Pinus sylvestris var. mongolica and Pinus armandii .

Known distribution.

Currently only known from northeastern and southwestern China.

Specimens examined.

China: • Yunnan Province, Jianchuan Town, Lao Jun Mountain (alt. 3400 m), 8 September 2009, Xiaofei Shi, Shi 284 ( HKAS 71797 ) • ibid 12 September 2009, Xiaofei Shi, Shi 289 ( HKAS 71802 ) .

Notes.

This species is sister to North American Suillus acidus . The two sibling species are morphologically very similar. It is interesting that Suillus boletoluteus is in association with Pinus subg. Strobus in southwestern China and subg. Pinus in northeastern China. Host associations of the new species should be further confirmed. In addition, it is possible that S. boletoluteus contains cryptic species as indicated by the long branches in the TEFα- 1, RPB 1 and RPB 2 phylogenies.

Figures

Figure 14. Basidiomata of Suillus boletoluteus (holotype, HKAS 63244). Scale bar: 5 cm.

Figure 15. Suillus boletoluteus (holotype, HKAS 63244). a Basidiospores; b Cheilocystidia and some basidia on tube surface; c Basidia and pleurocystidia. Scale bars: 5 μm (a); 20 μm (b – d).