Hygrophorus glutiniceps 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 glutiniceps C.Q. Wang & T.H. Li sp. nov. Figures 5 , 6

Typification.

China, Guangdong Province, Guangzhou City, Tianluhu Forest Park, on the ground of a forest dominated by Castanopsis fissa , elev. ca. 250 m, 23°13'39"N, 113°25'53"E, 6 September 2012, M. Zhang (GDGM42188, Holotype!), ITSMN378313.

Etymology.

" glutini -": glutinous, "- ceps ": pileus. The species epithet " glutiniceps " (Lat.) refers to the glutinous surface of pileus.

Diagnosis.

Hygrophorus glutiniceps differs from H. discoxanthus by the subtropical to tropical distribution, the darker lamellae and the thinner stipe (3-6 mm broad).

Description.

Pileus 8-40 mm broad, hemispherical to convex, often with an inconspicuous umbo and a usually involute margin when young, broad-convex to depressed with a slightly incurved to rarely uplifting margin when mature, covered with a layer of gelatine-like or transparent gluey materials when wet, white with cream or light yellow to orange tint (4A2-4) at disc, becoming light to yellowish-brown (5E8) with age (especially at margin and in wounded area), usually brownish-orange (5C5) to brown (6E8) when exsiccated. Lamellae broadly adnate or with decurrent tooth when young, short to moderately decurrent when mature, white when young, then changing to ochraceous or even brown (6E8), waxy when wet, with 25-30 complete lamellae reaching to stipe and 1-3 lamellulae between two entire lamellae. Stipe 25-60 × 3-6 mm, equal but often thinner at the base, cylindrical but usually curved, white, occasionally with yellowish tint (2A2), covered with transparent glutinous materials when wet. Context thin, white when young, changing to brown when old.

Basidiospores (5)6-8.5(10) × (3.5)4-5.5(6) µm [mean length = 7.1 µm, mean width = 4.7 µm], Q = (1.2)1.3-1.77(2), Qm = 1.52, ellipsoid to oblong, smooth, hyaline. Basidia 35-47 × 5-8.5 µm, Q values usually more than 5, clavate, thin-walled, 4-spored, with sterigmata up to 7.5 µm long, hyaline. Pileipellis an ixotrichoderm, composed of septate hyphae, usually covered with a gelatinous layer; hyphae thin-walled, 3-5 μm wide, with yellowish gluten in KOH. Stipitipellis an ixotrichoderm, hyphae 3-5 μm wide, similar to those of pileipellis. Hymenophoral trama divergent, composed of septate, thin-walled and cylindrical hyaline in 4-17 μm diam. Clamp connections present.

Habit, habitat and distribution.

Gregarious to scattered, on the ground of subtropical broad-leaf forest dominated by Castanopsis , currently only known from subtropical to tropical areas of China.

Additional specimens examined.

China, Guangdong Province, Guangzhou City, Tianluhu Forest Park, 6 September 2012, M. Zhang (GDGM42217); ibidem, 6 September 2012, J. Xu (GDGM42140). Hainan Province, Changjiang County, 3 July 2013, M. Zhang (GDGM45220); Baisha County, Yinggeling National Nature Reserve, elev. ca. 600 m, 1 August 2015, N.K. Zeng 2452 (FHMU1578); Ledong County, Yinggeling National Nature Reserve, elev. ca. 650 m, 4 June 2017, N.K. Zeng 3052 (FHMU2013).

Remarks.

Hygrophorus glutiniceps is macro-morphologically characterised by its subtropical-tropical distribution, white and sticky pileus and stipe, darkening lamellae when mature or wounded. The size of basidiospores [(5)6-8.5(10) × (3.5)4-5.5(6) µm] and basidia [35-47 × 5-8.5 µm] can be used to confirm the recognition. The association with Castanopsis fissa is also helpful for its identification.

Hygrophorus glutiniceps can be morphologically distinguished from closely-related species by the following differences. Hygrophorus cossus looks different from H. glutiniceps in the different ectomycorrhizal connection (with Quercus ), the temperate distribution, the longer basidiospores [(7-9.5 μm long in Candusso (1997), 7-9 μm long in Larsson and Jacobsson (2004)] and the higher ratio of length to width [Qm = 1.7-1.75 in Candusso (1997)]. Hygrophorus eburneus differs in the different host-connection (with Fagus ), thicker stipe (7-10 mm in width) and larger basidiospores (8-10 × 4.5-5.5 μm) with larger Qm (1.78-1.82); H. discoxanthus differs in the different host-connection (with Fagus ), the more rusty brown tint on pileus and lamellae and the thicker stipe (5-12 mm in width); H. hedrychii differs in the different host-connection (with Betula ) and larger pileus (30-60 mm broad); H. laurae Morgan has a much larger basidioma (with pileus 20-40 mm broad) and a wash of red or brown on the disc; and H. laurae var. decipiens Peck, described from New York, USA, differs in the absence of the pileus discolouration when dry and the nearly unchangeable lamellae ( Morgan 1883, Peck 1905, Candusso 1997, Larsson and Jacobsson 2004).

Figures

Figure 5. Basidiomata of Hygrophorus glutiniceps. a, b GDGM 42140 c GDGM 42154 d GDGM 42188 (Holotype) e GDGM 42217 f GDGM 45220. Scale bars: 2 cm.

Figure 6. Macro- and microscopic features of Hygrophorus glutiniceps. a Basidiomata (GDGM 42217) b Basidiospores (GDGM 42188) c Basidia (GDGM 42188) d Terminal cells of pileipellis (GDGM 42188).