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

Figs 16 , 17

Etymology.

The epithet indicates the grey color of the pileus.

Typification.

China: • Shaanxi Province, Baoji City, Mei Xian, Yingtou Town, Hao Ping Dali village (alt. 1300 m), 4 September 2010, Xiaofei Shi, Shi 664 (holotype, HKAS 63243 ) .

Diagnosis.

Suillus cinerescens has grey pileus, is in association with Pinus armandii in central and southwestern China.

GenBank.

ITS = KU 721159 ; LSU = KU 721317 ; TEFα- 1 = KU 721740 ; RPB 1 = KU 852278 .

Morphology.

Pileus develops from hemispherical to convex or plane, 4–9 cm diameter, surface viscid to glutinous, glabrous, background color yellowish brown (4 B 4), younger ones with dark olive glue (3 C 4, 3 C 5), discoloring to greyish (3 B 3) when old. Hymenophore adnate to narrowly adnate, younger ones dull cinnamon (5 C 4, 5 C 5), turn to olive yellow (3 B 6, 3 C 6) with age. Do not change color when bruised. Pores 1 per mm, angular, compound. Tubes 4–9 mm deep, concolorous with pores. Stipe 6–10 × 0.9–2 cm, equal or tapering towards apex, solid, no ring, cuticle color yellowish white (3 A 3), covered all over with reddish brown (4 A 6, 4 A 7) glandular dots. Mycelia white, turn to red (6 A 3, 7 A 3) when bruised. Context white to yellowish. Do not change color when exposed. Spore print olive brown. Odor and taste indistinctive.

Basidiospores [40 / 2 / 2] (8.5) 9.0–10 × (3.5) 4.0–4.5 μm, Q = (2.22) 2.25–2.50, Q sd = 2.4 ± 0.13, smooth, oblong in face view, narrowly inequilateral with a hilar appendage in profile view, brown or uncommonly hyaline in KOH, dark ochraceous in Melzer’s. Basidia 4 - spored, clavate, bulbous top, 20.0–25.0 × 7.0–8.0 μm, contain brown pigments or uncommonly hyaline in KOH. Hymenophoral trama divergent, wrinkled, thin-walled, hyaline and mostly 5–11 μm, up to 15 μm. Pleuro- and cheilocystidia in fascicles, abundant, clavate, up to 70 μm long, content brown or hyaline, surrounded by brown amorphous materials in KOH. Caulocystidia abundant, morphologically similar with pleuro- and cheilocystidia, in fascicles with over 10 caulocystidia, surrounded by brown pigments, up to 100 μm. Pileipellis encrusted by fine ochraceous granules, hyphae scattered in yellowish glue in KOH, most 3–7 μm, up to 11 μm wide. Stipitipellis covered by profuse brown amorphous pigments, composed of interwoven hyphae, about 3–9 μm wide. Context trama hyaline, smooth, thin-walled, interwoven, similar in pileus and stipe, mostly 5–50 μm, up to 110 μm wide at stipe base. Clamp connections absent.

Habitat.

Usually gregarious, in association with Pinus armandii .

Known distribution.

Currently known from central and southwestern China.

Specimens examined.

China: • Hubei Province, Shen Nong Jia Forest, Honghua Duo town (alt. 1600 m), 31 July 2011, Xiaofei Shi, Shi 763 ( HKAS 71893 ) ; China: • Yunnan Province, Lijiang City, Xuesong village (alt. 2700 m), 27 August 2009, Gang Wu, GangWu 155 ( HKAS 57687 ) ; China: • Heilongjiang Province, Yichun City, Wuying National Forest Park (alt. 400 m), 17 August 2010, Xiaofei Shi, Shi 558 ( HKAS 63234 ) ; China: • Heilongjiang Province, Da Xing Anling, Huzhong Town, Hua road (alt. 1000 m), associated with Pinus pumila , 21 August 2010, Xiaofei Shi, Shi 588 ( HKAS 63225 ) .

Notes.

Two collections ( HKAS 63234 and 63225) are excluded from the new species description because they are strongly indicated as different species by phylogenetic, morphological and ecological evidence. The collection “ HKAS 63234 ” from northeastern China has strong bluing reaction when the hymenium is bruised and it associates with Pinus koraiensis . Another collection “ HKAS 63225 ” has more reddish cinnamon in pileus color, and it associates with Pinus pumila . However, more collections are needed to confirm these observations and to support the cryptic species. The Suillus cinerescens collections associated with Pinus armandii are morphologically similar with closely related species S. plorans from Europe.

Figures

Figure 16. Basidiomata of Suillus cinerescens (holotype, HKAS 63243). Scale bar: 5 cm.

Figure 17. Suillus cinerescens (holotype, HKAS 63243). a Basidiospores; b Cheilocystidia; c Hymenium with basidia; d Pileipellis (mature specimens). Scale bars: 5 μm (a); 20 μm (b – d).