Gerronema angustum Ming Zhang & W. X. Zhang, 2025

Zhang, Wei-Xin, Deng, Wang-Qiu, Chang, Chang-Qing, Zhou, Ping, Lin, Min & Zhang, Ming, 2025, Three new species of Gerronema (Agaricales, Basidiomycota) from southern China, MycoKeys 114, pp. 239-258 : 239-258

Gerronema angustum Ming Zhang & W. X. Zhang sp. nov.

Figs 2 , 3

Diagnosis.

Distinguished from other Gerronema species by the combination characters, including caespitose habit, greenish green pileus, narrow and close lamellae, slender stipe, baidiospores measuring (4) 4.5–5.5 × 2.5–3.5 μm, mainly clavate to narrowly utriform cheilocystidia.

Holotype.

China • Guangdong Province: Shaoguan City, Nanling National Forest Park ; 24°53'54"N, 113°2'24"E; 210 m asl.; 7 July 2022; Bin Song, Guo-Rui Zhong, and De-Chun Xie ( GDGM 88662 ).

Etymology.

angustum (Latin), referring to the narrow lamellae of this species.

Description.

Basidiomata small-sized. Pileus 10–18 mm broad, infundibuliform, umbilicate to deeply umbilicate at center, greyish brown to brown (6 E 3–4) when young, greyish green (30 B 3–4, 30 C 2–3) when old, greyish green (30 E 5–6) at center, surface moist, glabrous, margin inflexed, radially striped with greenish grey to dull green (30 B 4–5, 30 D 4–5) lines. Lamellae decurrent, close, narrow, arcuate, even, white (30 A 1) to greenish grey (30 B 2), with 1–3 lamellulae. Stipe 45–60 × 2–5 mm, slender, centric, cylindrical, hollow, fragile, grey to greyish green (30 C 1–3), covered with white (30 A 1) fibrils. Odor and taste not recorded.

Basidiospores (4) 4.5–5.5 × 2.5–3.5 μm, L m = 4.88 ± 0.51 µm, W m = 2.96 ± 0.32 µm, Q = (1.33) 1.43–1.83, Q m = 1.66 ± 0.18, ellipsoid to oblong, smooth, thin-walled, hyaline, guttulate, inamyloid. Basidia 18–26 × 5.5–7 μm, clavate, thin-walled, hyaline, 4 - spored, with sterigmata 2.3–4.4 µm long. Cheilocystidia 26–45 × 6–9.5 μm, clavate, fusiform to narrowly utriform, thin-walled, hyaline. Pleurocystidia not seen. Lamellar trama regular to subregular, hyphae 3–22 μm wide, cylindrical, thin-walled, hyaline. Pileipellis a cutis, hyphae 1.5–24.5 μm wide, smooth, hyaline; pileocystidia 22.5–65 × 8–15.5 µm, oblong to utriform, thin-walled, greyish brown to light brown pigmented in KOH. Pileus trama subregular, sarcodimitic. Stipitipellis a cutis, hyphae 3.5–25 μm wide, sometimes upturned hyphae, smooth, thin-walled, hyaline; caulocystidia 56–72 × 10.5–20.5 µm, narrowly cylindrical to oblong, thin-walled, hyaline. Stipe trama regular, sarcodimitic. Clamp connections present in all tissues.

Habit and distribution.

Caespitose on the rotten wood in broad-leaved forests. Currently only known from the type locality in China.

Additional specimen examined.

China • Guangdong Province: Shaoguan City, Nanling National Forest Park ; 24°55'39"N, 113°3'20"E; 225 m asl.; 7 July 2022; Bin Song, Guo-Rui Zhong, and De-Chun Xie ( GDGM 88663 ) .

Figures

Figure 2. Basidiomata of Gerronema angustum A collection GDGM 88662, holotype B collection GDGM 88663. Photographed by Bin Song. Scale bars: 10 mm.

Figure 3. Microscopic features of Gerronema angustum (GDGM 88662, holotype) A Basidiospores B Basidia C Cheilocystidia D Pileipellis E Stipitipellis. Scale bars: 10 μm (A – C); 50 μm (D – E).