Lulesia umbrinomarginata Y.Q. Xiao, L.Q. Huang & Z.M. He

Xiao, Ying-Qun, Xu, You-Di, Chen, Zuo-Hong & He, Zheng-Mi, 2024, Lulesia umbrinomarginata (Entolomataceae, Agaricales), a newly discovered species from Southern China, Phytotaxa 650 (1), pp. 60-72 : 67-69

Lulesia umbrinomarginata Y.Q. Xiao, L.Q. Huang & Z.M. He , sp. nov. ( Figs. 2–4 )

MycoBank: MB851831

Etymology:— ‘ umbrinomarginata ’ (Latin), referring to the wood brown pileus margin.

Diagnosis:—This species exhibits a brown-hued, zonate, depressed pileus, pale yellow-brown decurrent lamellae, a whitish eccentric stipe with basal rhizoids, white decurrent lamellae, and angular basidiospores. Similar to L. mundula , but differs by its relatively larger basidiospores (6.0–7.0 × 5.0–6.0 μm), which are almost always broadly ellipsoid.

Type:— CHINA. Guangdong Province: Huidong County, Xunliao Bay, on leaf litter of Acacia confusa Merr. , alt. 20 m, at 22°42'0.07''N, 114°45'3.33''E, 30 June 2023, Z.M. He 22, MHHNU 20022 (holotype!).

Gene sequences ex-holotype:—PP060629 (ITS); PP059604 (LSU); PP158701 (RPB2); PP158693 (TEF1); PP158697 (ATP6).

Description:— Fruitbody small-sized to medium-sized, clitocyboid. Pileus 20–40 mm in diam, applanate with a depressed center; surface dry, greyish brown (4B2-3) to wood brown (5E6-8), zonate, concentric cracked at disc; margin much darker in color, always reflexed to involute, shallowly grooved, undulate to lobate, faintly white (1A1) pubescent at very margin; context thin (1–2 mm thick), whitish (2A1). Lamellae decurrent, crowded and often furcate (L = 40–60, I = 1–3), pale yellow-brown (3A2), narrow (about 2 mm high); edges smooth. Stipe 18–23 × 2.5–5 mm, somewhat eccentric, enlarged towards apex and base, often slightly flexuous; surface dry, whitish (2A1), more or less darker in color near apex; base inflated, with many white (1A1) rhizoids; context whitish (2A1). Odor farinaceous. Chemical spot test: surface of dried pileus and stipe produces a red reaction to 5% KOH.

Basidiospores [60/3/2] 6.0–7.0 × 5.0–6.0 μm, Q = (1.13–)1.17–1.31(–1.40), Qm = 1.23 ± 0.05, broadly ellipsoid, angular, undulate-pustulate, with acute apiculus (0.7–1.0 μm across), thin-walled, inamyloid, cyanophilic, some of them occurring in tetrads. Basidia 23.0–28.0 ×7.3–9.0 μm, clavate, hyaline, thin-walled, 4-spored; sterigmata up to 5.0 μm long. Pleurocystidia and cheilocystidia absent. Lamellar trama irregular, composed of interwoven, thin-walled, cylindrical hyphae (3.0–)4.0–6.0(–8.0) µm wide. Pileipellis a cutis, composed of parallel to slightly interwoven, slightly thick-walled (up to 0.8 μm), cylindrical hyphae (2.0–)3.0–5.0(–8.0) μm wide, producing a brown intracellular pigment. Stipitipellis a cutis, composed of parallel to subparallel, thin- to slightly thick-walled (up to 0.8 μm) hyphae (3.0–)4.0–6.0(–8.0) μm wide. Clamp connections absent in all tissues.

Ecology:—Gregarious, on decaying fallen leave, in subtropical regions; summer.

Distribution:—Only known from Southern China.

Additional specimen examined:— CHINA. Guangdong Province: Huidong County, Xunliao Bay, on leaf litter of Acacia confusa , alt. 20 m, at 22°41'59.33''N, 114°45'4.32''E, 30 June 2023, Z.M. He 23, MHHNU 20023.

Figures

FIGURE 2. Lulesia umbrinomarginata. a, b Fresh basidiomes, MHHNU 20022 (holotype); c Dried basidiomes, MHHNU 20023. Bars = 1 cm, photographed by Zheng-Mi He.

FIGURE 3. Microscopic features of Lulesia umbrinomarginata (MHHNU 20022, holotype). a Basidiospores; b Basidia; c Pileipellis. Bars = 10 μm, drawn by Ying-Qun Xiao.

FIGURE 4. Basidiospores of Lulesia umbrinomarginata (MHHNU 20022, holotype) under SEM. Bars = 1 μm, photographed by Jian- Feng Zou.