Hygrophorus griseodiscus 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 griseodiscus C.Q. Wang & T.H. Li sp. nov. Figure 7

Typification.

China, Sichuan Province, Jiuzhaigou, elev. ca. 3100 m, 11 September 2012, X.L. He (SAAS462, Holotype!), ITSMN378338.

Etymology.

" griseo -": grey, "- discus ": pileus. The species epithet " griseodiscus " (Lat.) refers to the grey disc of the pileus.

Diagnosis.

Hygrophorus griseodiscus is distinguished from H. brunneodiscus by the greyish pileus with a darker grey pileus disc and larger basidiospores measuring (7)8-10(10.5) × (4)4.5-6(6.5) µm.

Description.

Pileus 20-45 mm broad, convex, obtusely umbonate at disc, grey to light grey (1C1, 1D1), medium to dark grey or olive grey (1E1, 1F1-4) at disc, white to pale grey (1B1) at margin, glutinous when wet; margin even, slightly involuted to extended. Lamellae emarginate with decurrent tooth or subdecurrent, white, thick, subcrowded, unequal, with 1-3 lamellulae between two entire lamellae. Stipe 40-70 × 4-6 mm, cylindrical, white to pale grey (1B1), covered with transparent glutinous materials when wet. Context slightly thick, white.

Basidiospores (7)8-10(10.5) × (4)4.5-6(6.5) µm [mean length = 9 µm, mean width = 5.2 µm], Q = 1.4-2.1, Qm = 1.74, ellipsoid, oblong to subcylindrical, smooth, hyaline. Basidia 29-56.5 × 7-11 µm, Q = 3.05-6(6.9), Qm = 4.39, clavate to cylindrical, thin-walled, 4-spored, with sterigmata up to 6 µm long. Pileipellis an ixotrichoderm, covered with a gelatinous layer; hyphae thin-walled, 2.5-6 μm wide. Hymenophoral trama divergent, composed of septate, thin-walled and cylindrical hyphae; hyphal cells 5.5-20 μm in width, hyaline. Clamp connections present.

Habit, habitat and distribution.

Scattered, on the ground of subalpine coniferous forest dominated by Abies and Picea , often surrounded by mosses, so far only known from Sichuan Province in Southwest China.

Remarks.

Hygrophorus griseodiscus is characterised by its convex and grey pileus with a dark grey to olive grey disc, emarginate to subdecurrent lamellae. The Asian subalpine coniferous habitat may be a helpful character for its identification.

Morphologically, H. brunneodiscus is distinguished from H. griseodiscus by the brownish pileus disc and smaller basidiospores (6.5-9.5 × 4-5 µm). Hygrophorus cossus differs in the greyish-white lamellae with a cream yellow tint and a thicker stipe (6-20 mm wide) ( Candusso 1997, Campo 2015). Hygrophorus discoxanthus can be separated by the pure white pileus when young and rusty brown lamellae when mature ( Candusso 1997, Campo 2015). Hygrophorus eburneus is different by the white pileus and the wider basidiospores (8-10 × 4.5-5.5, Qm = 1.78-1.82) ( Candusso 1997). Hygrophorus glutiniceps is separated by the white pileus with cream or light yellow to orange tint at the disc, shorter basidiospores [(5)6-8.5(10) × (3.5)4-6 µm] and subtropical to tropical distribution. Hygrophorus hedrychii is distinguished by the presence of a pale orange tint on the pileus disc and an orange-pink tint on the lamellae ( Larsson and Jacobsson 2004). Hygrophorus scabrellus is readily distinguished from H. brunneodiscus by its smaller basidiomata (pileus 2.4-2.8 cm broad), dark green tint on pileus and much smaller basidiospores (6.5 × 3.84 µm) ( Naseer et al. 2019).

Figures

Figure 7. Hygrophorus griseodiscus (SAAS 462, Holotype). a, b Basidiomata c Basidiospores d Basidia e Elements of pileipellis.