Amoenoboletus brachysporus Ming Zhang, T. Li & T.H. Li, 2024

Li, Ting, Zhong, Guorui, Li, Taihui, Deng, Wangqiu & Zhang, Ming, 2024, Amoenoboletus brachysporus (Boletaceae), a new species from Southern China, Phytotaxa 633 (1), pp. 51-59 : 54-57

Amoenoboletus brachysporus Ming Zhang, T. Li & T.H. Li , sp. nov. ( Figs. 2 , 3 , 4 )

MycoBank: 845370

Diagnosis: Distinguished from other Amoenoboletus species by the combination characters of the larger basidiomata (pileus up to 8.5 cm broad), pale yellow pileus surface covered with yellowish brown to reddish brown appressed squamules, red to dark red stipe surface with dense, coarse, fibrillose-appressed belts or squamules, and the shorter basidiospores.

Etymology: The epithet “ brachy -” means short, “- sporus ” means spores, “ brachysporus ” refers to the new species with shorter basidiospores

Holotype: CHINA. Guangdong province, Guangzhou, Baiyun Mountain , at 23°11′ N, 113°17′ E, alt. 100 m, 17 June 2021, coll. Ming Zhang ( GDGM85730 !).

Description: Basidiomata medium to large sized. Pileus 4–8.5 cm broad, subhemispherical to convex when young, expanding to plano-convex to applanate in age; background colour pale yellow, covered with greyish yellow, yellowish brown to reddish brown (3B5–5E 5, 4E 6–5E 6, 9E 5–9E8), conspicuous patches or coarse fibrillose-appressed squamules, cracked from centre to margin; margin slightly uplifted in age; surface dry. Context 0.6–1 cm thick at the centre of pileus, yellowish white to pale yellow (2A2–3A2, 2A3–3A3), unchanging upon bruising. Tubes 0.4–0.6 cm deep, depressed around stipe, pastel yellow to greyish yellow (1A4–2A4, 1B4–2B4) in age, unchanging when bruised; Pores angular, 1–2 per mm, orange red, greyish red to red (8A7–11A7, 8B5–10B5) when young, gradually fading from pastel red to greyish yellow (8A3, 4B5) in age, unchanging or slightly bluish white (22A2) when bruised. Stipe 4–9 × 1.2–2.2 cm, central, subcylindrical or clavate, solid, equal or slightly enlarged downwards, background concolorous with the pileal context, surface densely covered with red to vivid red (9A7–11A7) granular-punctate, fibrillose-appressed belts or coarse squamules, unchanging when bruised or in age; pale yellow (2A2–3A2) at base; basal mycelium white to yellowish white (1A2). Stipe context yellowish white to pale yellow (2A2–3A2, 2A3–3A3), unchanging or slightly bluish white (22A2) upon exposure. Odour indistinct. Taste mild.

Basidiospores [80/5/3] (7–)7.5–8.5(–9) × (5–)5.5–6(–6.3) μm, Q = (1.17–)1.3–1.41(–1.5), Q m = 1.35±0.09, broadly ellipsoid to ellipsoid, barely inequilateral in profile, smooth, greyish yellow to butter yellow (2B5–4B5) in 5% KOH, inamyloid, thin-walled. Basidia 27–38 × 10–13 μm, clavate, hyaline and containing scattered straw-yellow (3B4) oil guttules in 5% KOH and light yellow (4A4) in Melzer’s reagent, inamyloid, 4-spored, sterigmata 3–6 μm long, basal clamps absent. Cheilocystidia 18–30 × 6–13 μm, sparse, fusiform, thin-walled, yellowish white (1A2) to nearly hyaline in 5% KOH. Pleurocystidia 45–58(–63) × 6–12 μm, sparse, irregularly cylindrical or cylindrical-fusiform, on average usually slightly narrower than cheilocystidia, colour and chemical reactions similar to cheilocystidia. Hymenophoral trama subparallel to somewhat bilateral, yellowish (1A2) to hyaline in 5 % KOH, light yellow (4A4) in Melzer’s reagent, composed of 4–8 μm wide branching hyphae, yellowish (1A2) to hyaline in 5 % KOH, yellowish brown in Melzer’s reagent, thin-walled. Pileipellis made up of loosely entangled hyphae, occasionally branched, smooth, thin-walled, hyaline, sometimes outer surface covered with brown granular pigment. Stipitipellis composed of broadly clavate inflated hyphae 10–30 × 6–10 μm, pale yellow (1A3) to hyaline in 5 % KOH. Caulocystidia 15–28 × 6–12 μm, cylindrical or cylindrical-fusiform, thin-walled. Stipe trama composed of longitudinally arranged cylindrical hyphae 4–12 μm wide, thin-walled, branched, smooth, yellowish white (1A2) to hyaline. Clamp connections absent.

Known distribution: Currently only known from Guangdong province, Southern China.

Habit and habitat: Solitary to scattered on soil in broadleaf forest mainly dominated by Fagaceae trees, and mixed with other broadleaf trees as Acacia auriculiformis A. Cunn. ex Benth. , Schima superba Gardner & Champ.

Additional specimens examined: CHINA. Guangdong province, Guangzhou, Baiyun National Forest Park, at 23°11′ N, 113°17′ E, alt. 155 m, 21 June 2021, coll. Xiaoqing Huang GDGM 87379 ; Guangzhou, Baiyun National Forest Park, at 23°11′ N, 113°17′ E, alt. 132 m, 7 July 2023, coll. Guorui Zhong GDGM 92249 .

Figures

FIGURE 2. Basidiomata of Amoenoboletus brachysporus. a–c, e: GDGM 85730 (holotype); d: GDGM 87379; f–h: GDGM 92249. Bars: a, b = 50 mm; c, e = 20 mm; d, f–h = 10 mm. Photographed by Ming Zhang and Guorui Zhong.

FIGURE 3. Microscopic features of Amoenoboletus brachysporus(GDGM 85730,holotype).a. Basidiosporesb.Basidium withbasidioles. Bars: a, b = 10 μm. Photographed by Ting Li.

FIGURE 4. Microscopic features of Amoenoboletus brachysporus (GDGM 85730, holotype). a. Basidiospores b. Pileipellis. c. Pleurocystidia d. Cheilocystidia. e Stipitipellis with caulocystidia. Bars = 10 μm. Line drawings by Ting Li.