Hygrophorus hedrychii (Helen.) K. Kult, Ceska Mykol. 10(4): 232 (1956)

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 hedrychii (Helen.) K. Kult, Ceska Mykol. 10(4): 232 (1956) Figure 8

Description.

Pileus 10-50 mm broad when dried, subglobose when young, becoming hemispherical, convex to nearly plane when mature; margin incurved when young, even, expanded to sometimes slightly upturned when mature; surface covered with a thick layer of transparent and sticky materials, white, with pinkish (7A2) to yellowish (4A2) tones or cream colour (1A2) on the disc. Lamellae adnate to short decurrent, white at first, changing to pinkish-white (7A2) or pale yellow (4A3) or cream colour (1A2), waxy, with 1-3 lamellulae between two entire lamellae. Stipe 20-85 × 3-10 mm when dried, cylindrical or nearly so, often thinner at apex, usually slightly enlarged at base, uneven, with white short fibrils at apex, sometimes longitudinally lacerated when mature, covered with a layer of transparent sticky materials, white, changing to orange white (5A2, 6A2) where touched. Context thick, white when young, pale to pinkish-yellow when mature, with Cossus smell.

Basidiospores (6)7-8(9) × (3.5)4-4.5(5) µm, Q = 1.5-2(2.3), Qm = 1.8, ellipsoid to subcylindrical, colourless, thin-walled, smooth. Basidia 30-40 × 6-9 µm, Q = 4.1-5.7, clavate, 4-spored; sterigmata 4-5 µm long; basal clamp connections common. Pileipellis an ixotrichoderm, composed of septate hyphae, covered with a gelatinous layer; hyphae thin-walled, 4-5 μm wide. Stipitipellis a trichoderm; hyphae 7-10 μm wide, light yellowish-brown intracellular pigment presented in a few hyphae when immersed in 5% KOH solution. Hymenophoral trama composed of septate, thin-walled and cylindrical hyaline hyphae, size 58-105 × 3-23 μm. Clamp connections present.

Habit, habitat and distribution.

Scattered to gregarious in the north temperate forests dominated by Betula , known from north-eastern China (this study), as well as from Europe where the species was firstly discovered.

Specimens examined.

China, Inner Mongolia Autonomous Region, Chifeng City, Harqin Banner, Wangyedian village, 30 August 2007, T.Z. Liu (CFSZ2851); ibidem, 8 August 2017, T.Z. Liu, Y.Q. Guang & N. Liu (CFSZ18159); Hexigten Banner, Jingpeng Town, 15 August 2017, T.Z. Liu & G.L. Yu (CFSZ18269).

Remarks.

Macroscopically, Hygrophorus hedrychii is a distinctive waxycap, which is relatively easily recognised in the field by its white pileus disc and lamellae changing to pale ochraceous pink when mature and the host association with birch. Microscopically, the Chinese specimens agree with the descriptions by Larsson and Jacobsson (2004) for the Swedish samples and Campo (2015) for the French collections. Molecular phylogenetically, they are also identical to the European species. The Chinese samples from Inner Mongolia are traded as edible fungi at some local markets. The European H. hedrychii was not, however, treated as an edible mushroom (Larsson, personal communication). This difference may indicate different dietary habits in different areas.

Figures

Figure 8. Hygrophorus hedrychii. a Basidiospores b Basidia c Basidiomata (CFSZ 2851) d Basidiomata (CFSZ 18159) e Basidiomata (CFSZ 18269) f Sold at a local market, named as " baizhenmo ".