Aureoboletus rugosus N.K. Zeng, Xu Zhang, L.P. Tang & W.H. Zhang, 2022

Zhang, Xu, Tian, Run, Tang, Li-Ping, Liang, Zhi-Qun, Zhang, Wen-Hao, Jiang, Shuai, Wang, Cheng-Kai & Zeng, Nian-Kai, 2022, Morphological and phylogenetic evidence reveal three new species of Aureoboletus (Boletaceae, Boletales) from China, Phytotaxa 567 (2), pp. 127-148 : 142-143

Aureoboletus rugosus N.K. Zeng, Xu Zhang, L.P. Tang & W.H. Zhang , sp. nov. ( Figs. 3E–I , 6 )

MycoBank: MB841625

Etymology: — Latin “ rugosus ” refers to the wrinkled pileus surface of the new species.

Diagnosis: — Differs from other species of Aureoboletus by small basidiomata, reddish-brown, violet brown, distinctly wrinkled pileal surface, a pileal margin usually with white to subhyaline, gelatinized veil remnants when young, cylindrical basidiospores, and an intricate ixotrichoderm-type pileipellis.

Holotype: — CHINA. Yunnan Province: Jianchuan County, Shibao Mountain Scenic Spot, elev. 2,504 m, 12 September 2019, W. H. Zhang 164 ( FHMU6509 ). GenBank accession number: 28 S = OK327022 , ITS = OK327022 , TEF1 = OK357260 , RPB2 = OM 280448 .

Description: —Basidiomata small-sized. Pileus 3.3–3.5 cm in diam., subhemispherical when young, then broadly convex to applanate; margin usually with white (1A1) to subhyaline, gelatinized veil remnants when young; surface strongly viscid or mucilaginous, brown (7C4) to reddish-brown (7E6), distinctly wrinkled; context 0.3 cm thick in the center of the pileus, white (2A1), unchanging in color when cut. Hymenophore poroid, slightly depressed around apex of stipe; pores 0.5–1 mm in diam., subround, pale yellow (4A2), unchanging in color when cut; tubes approximately 0.7 cm long, pale yellow (4A2), unchanging in color when cut. Stipe 6–7.5 × 0.5–0.7 cm, central, subcylindrical; surface yellowish brown (4A3), strongly viscid when young, with distinct longitudinal streaks; context white, unchanging in color when cut. Basal mycelium white. Odor indistinct.

Basidia 27–31 × 9–10 μm, clavate, thin- to slightly thick-walled (up to 1 μm thick), 4-spored, hyaline or yellowish in KOH; sterigmata 4–4.5 μm long. Basidiospores [150/3/3] 10–13(–14.5) × 4–6 μm, Q = (1.67–) 2–3(–3.25), Qm = 2.45 ± 0.31, cylindrical, moderately thick-walled (up to 1 μm), smooth, yellowish brown in KOH. Cheilocystidia 35–55 × 11–16 μm, fusoid-ventricose or subclavate, moderately thick-walled (up to 1 μm), yellowish-white or hyaline in KOH. Pleurocystidia 32–55 × 9–16 μm, fusoid-ventricose or subclavate, thin- to slightly thick-walled (up to 1 μm), yellowish-white or hyaline in KOH. Hymenophoral trama bilateral, composed of hyphae 4–8 μm wide, moderately thick-walled (up to 1 μm), yellowish in KOH. Pileipellis an intricate ixotrichoderm 150–250 μm thick, made up of hyphae 4–6 μm wide, moderately thick-walled (up to 1 μm), yellowish (1A2) in KOH; terminal cells 27–65 × 5–5.5 μm, narrowly clavate or subcylindrical, with obtuse apex. Pileal trama composed of hyphae 2–12 μm wide, thin- to slightly thick-walled (up to 0.5 μm), hyaline in KOH. Stipitipellis a hymeniderm approximately 250 μm thick, embedded in a gelatinized matrix, made up of hyphae 4–6.5 μm wide, thin-walled, yellowish (1A3) or hyaline in KOH; terminal cells 12–22 × 4–9 μm, clavate, with obtuse apex. Stipe trama made up of parallel hyphae 4–10 μm wide, moderately thickwalled (up to 1 μm), yellowish brown (3B8) in KOH. Clamp connections not observed in any tissue.

Habitat: — Solitary or scattered on the ground in forests dominated by fagaceous trees ( Quercus spp. ), mixed with Pinus yunnanensis Franch.

Known distribution: — Southwestern China (Yunnan Province).

Additional specimens examined: — CHINA, Yunnan Province: Jianchuan County, Shibao Mountain Scenic Spot, elev. 2,542 m, 12 September 2019, G. L. Zhang 078 ( FHMU2766 ); same location and date, L. P. Tang1679 ( FHMU6510 ) .

Notes: Phylogenetically and morphologically, A. rugosus is closely related to

A. thibetanus ( Fig. 2 ). However, A. thibetanus has a distinctly reticulate pileal surface, and outer surfaces of pleurocystidia covered with a 5–8 μm thick layer of a strongly refractive yellow substance ( Yang et al. 2003). Moreover, the phylogenetic distance is 0.036 between our new species A. rugosus and its sister species A. thibetanus ( Fig. 2 ), which also falls within the range of values of 0.012 to 0.42 for the inter-specific variation of Aureoboletus species.

Aureoboletus rugosus is also morphologically similar to Chinese species, A. glutinosus , A. griseorufescens Ming Zhang & T.H. Li (2019: 124) , A. tenuis , and Japanese species, A. viscidipes (Hongo) G. Wu & Zhu L. Yang (2016: 53) . However, A. glutinosus has a smaller pileus (1–2 cm in diam.), and narrower basidiospores (only up to 5 μm in width) ( Zhang et al. 2019); A. griseorufescens has a context more or less greyish-red beneath the pileipellis and browner at the border line adjacent to tubes, gradually changing to greyish-red to greyish-rose when cut, shorter basidiospores [(8–)9–10.5(–11) × (4–)4.5–5(–5.5) μm], and a pileipellis composed of more or less inflated hyphae (12–19 μm wide) ( Zhang et al. 2019); A. tenuis has a yellowish pileal context, and narrower basidiospores (only up to 5 μm wide) ( Zhang et al. 2014); A. viscidipes has a smaller pileus (up to 2.5 cm in diam.), a pileal surface paler in color, and apical surfaces of cystidia covered with a 2 – 3 μm thick layer of a refractive pale yellow substance ( Wu et al. 2016).

Figures

FIGURE 2. Phylogram inferred from a three-locus (28S, TEF1 and RPB2) dataset using RAxML. BS ≥ 70% and PP ≥ 0.95 are indicated above or below the branches as RAxML BS/PP. SW, southwest; SE, southeast; NE, northeast.

FIGURE 3. Basidiomata of Aureoboletus species. A–B A. guangdongensis (FHMU3797, holotype); C–D A. microcarpus (C from FHMU4722; D from FHMU4695); E–I A. rugosus (E from FHMU6509, holotype; F from FHMU2766; G–I from FHMU6510). Bars = 1 cm. A–D photos by N.K. Zeng; E photo by W.H. Zhang; F photo by G.L. Zhang; G–I photos by L.P. Tang.

FIGURE 6. Microscopic features of Aureoboletus rugosus (FHMU6509, holotype).A. Basidiospores.B. Basidia.C. Cheilocystidia. D. Pleurocystidia. E. Pileipellis. Bars = 10 μm. Drawings by X. Zhang.