Hygrophorus brunneodiscus C.Q. Wang & T.H. Li, 2020

Wang, Chao-Qun, Li, Tai-Hui, Zhang, Ming, He, Xiao-Lan, Qin, Wei-Qiang, Liu, Tie-Zhi, Zeng, Nian-Kai, Wang, Xiang-Hua, Liu, Jian-Wei, Wei, Tie-Zheng, Xu, Jiang, Li, Yue-Qiu & Shen, Ya-Heng, 2020, Hygrophorus subsection Hygrophorus (Hygrophoraceae, Agaricales) in China, MycoKeys 68, pp. 49-73 : 49

Hygrophorus brunneodiscus C.Q. Wang & T.H. Li sp. nov. Figure 3

Typification.

China, Hunan Province, Zhangjiajie City, Zhangjiajie Campus of Jishou University, on the ground of a forest dominated by Quercus fabri and Q. serrata , elev. ca. 220 m, 29°8'24"N, 110°27'42"E, 26 May 2019, W.Q. Qin (GDGM73213, Holotype!), ITSMN378318.

Etymology.

" brunneo -": brown, "- discus ": pileus disc. The species epithet " brunneodiscus " (Lat.) refers to the brown pileus disc of this new taxon.

Diagnosis.

Hygrophorus brunneodiscus differs from H. cossus by the smaller pileus (20-50 mm broad), brownish pileus disc, thinner stipe (4-7 mm wide) and the shorter basidia (32-48 µm long); differs from H. fuscopapillatus and H. griseodiscus by the low elevation distribution and brown pileus disc.

Description.

Pileus 20-50 mm broad, hemispherical or conical with a slightly involute or slightly revolute margin when young, becoming convex with an expanded margin when mature, whitish to brownish as a whole, brownish-orange, light brown, yellowish-brown (5C4-5, 5D4-5, 5E5-8) at the disc (about one fourth part of the radius from the centre to the margin), becoming paler to greyish-yellow (4B3-4), greyish-white (4B1) or whitish outwards and white at the margin or with a white marginal zone of 1-2 mm wide, viscid, covered with a glutinous layer of transparent materials when wet. Lamellae short decurrent to decurrent, white, waxy, with 36-40 complete lamellae and 1-3 lamellulae between two complete lamellae; lamella edge concolorous, entire. Stipe 40-90 × 4-7 mm, cylindrical, hollow, nearly equal to slightly thinner at apex and tapering towards the base; pale yellow to greyish-yellow (4A3, 4B3), white to yellowish-white (4A2) at apex, sometimes white at base; sticky, covered with a layer of transparent materials when wet, easily-sticking debris on the slime layer, usually fibrillose or with scattered white fibrillose dots at apex. Context thin, white to light brown, with slight fishy odour.

Basidiospores (6.5)7-9(9.5) × 4-5.5(6) μm [mean length = 7.6 µm, mean width = 4.6 µm], Q = (1.3)1.4-2(2.1), Qm = 1.68, ellipsoid to oblong, smooth. Basidia 32-48 × 6-8.5 µm, Q = 4.1-6.6, Qm = 5.3, clavate, thin-walled, 4-spored, with sterigmata 5.5-7(9) µm long. Pileipellis an ixotrichoderm, composed of septate cylindrical hyphae, covered with a gelatinous layer; hyphae thin-walled, 2.5-5 μm wide, slightly yellowish and glutinous in KOH. Hymenophoral trama divergent, composed of septate, thin-walled and cylindrical hyphae; hyphal cells 45-70 × 6-10 μm, hyaline. Clamp connections present.

Habit, habitat and distribution.

Solitary to scattered, on the ground of subtropical broad-leaf forest dominated by Quercus , so far only known from Hunan Province in South Central China.

Additional specimens examined.

China, Hunan Province, Zhangjiajie City, Zhangjiajie Campus of Jishou University, 26 October 2018, W.Q. Qin (GDGM75489); ibidem, 30 June 2019, W.Q. Qin (GDGM76934).

Remarks.

Hygrophorus brunneodiscus is characterised by its brown tint on pileus disc, sticky pileus and stipe surface, basidiospores (6.5)7-9(9.5) × 4-5.5(6) μm, basidia 32-48 × 6-8.5 µm and subtropical and low elevation distribution.

Hygrophorus brunneodiscus can be easily recognised within subsect. Hygrophorus for its brownish colour on the pileus disc. Apart from that, H. cossus differs from H. brunneodiscus by having pale ochraceous grey colour at the pileus centre and more slender basidia (48-60 × 7-8.5 μm) ( Larsson and Jacobsson 2004). Hygrophorus discoxanthus differs in the pure white mature basidiomata as young, rusty-brown pileus margin and discolouration of rusty brown at the lamellar edge and different host-association (with Fagus ) ( Candusso 1997, Larsson and Jacobsson 2004). Hygrophorus eburneus differs from it by having more carnose pileus and thicker stipe (4-10 mm wide), forming an ectomycorrhizal relationship with Fagus ( Larsson and Jacobsson 2004). Hygrophorus hedrychii differs from it by having larger and more robust fruit-bodies (pileus 30-80 mm in diam. and stipe 5-10 mm in width), forming an ectomycorrhizal relationship with Betula ( Larsson and Jacobsson 2004, Campo 2015). Hygrophorus scabrellus differs from it by owning smaller (24-28 mm in diam.) and off-white with dark green colour pileus, smaller basidiospores (mean length = 6.5 µm, mean width = 3.84 µm) and distribution in temperate forests under Quercus trees ( Naseer et al. 2019).

Figures

Figure 3. Hygrophorus brunneodiscus. a, b Basidiomata (GDGM 73213, Holotype) c, d Basidiomata (GDGM 75489) e Basidiospores (GDGM 73213) f Basidia (GDGM 73213) g Elements of pileipellis (GDGM 73213). Scale bars: 2 cm (a-d).