Aureoboletus guangdongensis N.K. Zeng, Xu Zhang & Zhi Q. Liang, 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 : 139

Aureoboletus guangdongensis N.K. Zeng, Xu Zhang & Zhi Q. Liang , sp. nov. ( Figs. 3A – B , 4 )

MycoBank: MB841618

Etymology:—Latin “ guangdongensis ” refers to the location Guangdong Province, southern China, where the holotype was collected.

Diagnosis:—Differs from other species of Aureoboletus by a small basidiomata, a brownish-orange, dry pileal surface, short and wide basidiospores, and a trichoderm-type pileipellis composed of more or less inflated hyphae.

Holotype:— CHINA. Guangdong Province: Renhua County, Danxia National Nature Reserve, elev. 360 m, 12 June 2019, N. K. Zeng 4083 ( FHMU3797 ). GenBank accession number: 28 S = OK327021 , TEF1 = OM 321040 , RPB2 = OM 280447 .

Description:— Basidiomata small-sized. Pileus 2.4–4.5 cm in diam., subhemispherical when young, then convex to applanate; surface dry, subtomentose, brownish-orange (5B5) at first, reddish-brown (6C3) to reddish violet (7C2) when mature; context approximately 0.7 cm thick in the center of the pileus, white (1A3), unchanging in color when cut. Hymenophore poroid, depressed around apex of stipe; pores 0.3–0.5 mm in diam., angular to subround, pale yellow (1A3), unchanging in color when cut; tubes approximately 0.7 cm long, pale yellow (4A2), unchanging in color when cut. Stipe 5.5–6 × 0.5–1 cm, central, subcylindrical or subclavate; surface pale brownish-orange (4B3) when young, then pastel reddish violet (7B2), with distinct longitudinal streaks; context white (1A3), unchanging in color when cut. Basal mycelium white (1A1). Odor indistinct.

Basidia 27–31 × 9–10 μm, clavate, moderately thick-walled (up to 1 μm), 4-spored, hyaline or yellowish in KOH; sterigmata 3–5 μm long. Basidiospores [100/2/2] 7–9.5(–11) × (4–)4.5–6 μm, Q = (1.28–) 1.5–1.78(–2), Qm = 1.65 ± 0.18, elongate, moderately thick-walled (up to 1 μm), smooth, yellowish brown (3B8) in KOH. Cheilocystidia 29–40 × 8–10 μm, fusiform or subfusiform, moderately thick-walled (up to 1 μm), yellowish-white or hyaline in KOH. Pleurocystidia 25–35 × 7.5–10 μm, abundant, fusiform or subfusiform, yellowish in KOH, moderately thickwalled (up to 1 μm). Hymenophoral trama bilateral, composed of hyphae 5–10 μm wide, moderately thick-walled (up to 1 μm), yellowish in KOH. Pileipellis a trichoderm 250–500 μm thick, made up of hyphae 4–14 μm wide, slightly inflated to moniliform, yellowish-white or hyaline in KOH; terminal cells 17.5–47 × 4–14 μm, cystidioid, subclavate or subcylindrical, with obtuse, sometimes acute apex. Pileal trama composed of hyphae 5–20 μm wide, moderately thick-walled (up to 1 μm), hyaline in KOH. Stipitipellis a hymeniderm 250–400 μm thick, made up of hyphae 3–8 μm wide, thin-walled, yellowish-white or hyaline in KOH; terminal cells 12–22 × 4–9 μm, broadly clavate, subcylindrical, or subfusiform, with obtuse apex. Stipe trama made up of parallel hyphae 4–10 μm broad, slightly thick-walled (up to 0.5 μm), colorless in KOH. Clamp connections not observed in any tissue.

Habitat:—Solitary on the ground in forests dominated by fagaceous trees ( Lithocarpus spp. ).

Known distribution:—Southern and southeastern China (Guangdong and Fujian Provinces).

Additional specimen examined:— CHINA. Fujian Province: Zhangping County, Xinqiao Town, Chengkou Village , elev. 350 m, 28 July 2013, N. K. Zeng 1310 ( FHMU864 ); same location and date, N. K. Zeng1310-1 ( FHMU6511 ) .

Notes: Phylogenetically and morphologically, A. guangdongensis is closely related to A. catenarius G. Wu & Zhu L. Yang (2016: 42) , A. moravicus (Vaček 1946: 36) Klofac (2010: 142) , A. roxanae ( Frost 1874: 104) Klofac (2010: 143) , and A. velutipes Ming Zhang & T.H. Li (2019: 132) ( Fig. 2 ). However, A. catenariu s, originally described from Yunnan Province, southwestern China, has a larger pileus (3.5–6 cm in diam.), narrower basidiospores (7–9 × 3.5–5 μm), and wider hyphae in pileipellis (up to 27 μm) ( Wu et al. 2016); A. moravicus has a larger pileus (up to 8 cm in diam.), and longer basidiospores [8–11(–12) × 4.5–5.5(–6) μm], and it is distributed in Europe ( Herink 1964; Klofac 2016); A. roxanae has a larger pileus (8–9 cm in diam.), longer but narrower basidiospores [9.5–11(–13) × 3.5–4(–4.5) μm], a pileipellis made up of uninflated hyphae, and it is distributed in Canada, USA, and Mexico ( Frost 1874; GarcíaJiménez et al. 2019); A. velutipes , originally described from Guangdong Province, southern China, has a light yellow to pastel yellow stipe covered with fibrillose to tomentose squamules, and larger basidiospores [10–13 × (4–)5–6(–6.5) μm] ( Zhang et al. 2019). In addition, A. guangdongensis is also affiliated with a Chinese undescribed species voucher GDGM49259 ( Fig. 1 ), and their morphological differences will be investigated in the future.

Figures

FIGURE 1. The collection sites of three new Aureoboletus species.

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 4. Microscopic features of Aureoboletus guangdongensis (FHMU3797, holotype). A. Basidiospores. B. Basidia and cystidium. C. Cheilocystidia. D. Pleurocystidia. E. Pileipellis. Bars = 10 μm. Drawings by X. Zhang.