Mallocybe longquanensis Feng Liu, C. Liu & C.L. Yang

Liu, Feng, Liu, Chao, Zhou, Yi-Jie, Chen, Xiao-Hang, Lan, Zheng-Yong, Xu, Xiu-Lan, Liu, Ying-Gao & Yang, Chun-Lin, 2024, A novel Mallocybe species (Inocybaceae, Agaricales) discovered in the Longquan Mountain of Southwestern China, Phytotaxa 659 (1), pp. 56-66 : 60-63

Mallocybe longquanensis Feng Liu, C. Liu & C.L. Yang , sp. nov. Fig. 2

Index Fungorum: IF556917

Diagnosis:—Differs from M.aurantiodisca by its light brown to yellowish brown pileus with finely tomentose-fibrillose, shorter basidia with a mean Q value <2.0, presence of short cylindric to clavate cheilocystidia, and occurrence on purple clay soils with Quercus glauca . Forming a unique monophyletic group apart from closest relatives including M. aurantiodisca due to unique ITS, LSU and rpb 2 sequences.

Etymology:—Named after Longquan Mountain from where this fungus was collected.

Type:— CHINA. Sichuan Province, Chengdu City, Longquanyi District, Chadian Town, Qianfeng Village, 104°21’58.95”E, 30°34′39.82″N, alt. 534 m, 30 August 2021, C. Liu, LC202108218 (SICAU 22-0164, GenBank accession no.: ITS = OQ434283, LSU = OQ434278, and rpb 2 = OQ569744).

Description:— Basidiomata small-sized. Pileus 1.0– 3.5 cm diam., initially convex, transitioning to a flat shape upon maturity, pileus margin incurved initially, becoming uplifted and wavy with a slight central depression with age, often exhibiting cracks when fully mature; surface dry, appressed tomentose-fibrillose, not at all scaly, ranging from light brown to yellowish-brown, with a darker coloration around the center and a paler hue towards the outer edges. Lamellae 1–3 mm wide, adnate, narrow, dense, elongated, of varying lengths, initially pale white, becoming pale brown, maintaining a uniform coloration. Stipe measures 15–48 × 3–7 mm, centrally positioned, cylindrical and fibrous in texture, solid at first, then becoming hollow, surface fibrillose with appressed velar remnants, dirty white to pale brown. Context creamy white or pale yellowish white in pileus, 1–2 mm thick, maintaining a consistent coloration within the stipe. Odour not distinctive. Taste not recorded.

Basidiospores [100/3/2] (8.1) 8.9–10.5(10.9) × (4.4) 5.2–6.1(6.5) μm, Q = (1.5) 1.7–1.9(2.1), Qm ± SD = 1.77 ± 0.015, ellipsoidal or ovoid, smooth, thin-walled, appearing yellow-brown in 5 % KOH, with a large ellipsoidal oily droplet in the center. Basidia 21.2–27.1 × 7.1–8.6 μm (x = 23.8 × 7.8 μm, n = 50), clavate to narrowly clavate shape, featuring four-spored tops and occasionally two-spored, with short sterigmata measuring 3–5 μm. Pleurocystidia absent. Cheilocystidia of the gills 27.8–43.9 × 10.8–18.6 μm (x = 35.6 × 13.6 μm, n = 50), clavate, cylindrical, or occasionally fusiform, often with rounded or slightly pointed apices, occasionally having tail-like or ventricose shapes, truncate or slightly pointed bases, septate, often constricted at the septa, thin-walled, colorless, and transparent. Hymenophoral trama 85–142 μm, is regular, colorless, with trama elements measuring 13–20 μm wide, inflated or concave, cylindrical, thin-walled, and colorless. Stipitipellis, forming a cutis, accompanying by extending hyphae, cylindrical, appearing yellow when aggregated, 4–10 µm wide, encrusted. Stipe trama densely arranged, light yellowish when aggregated, composed of smooth cylindrical hyphae, colorless, 5–8 μm wide. Clamp connections are found only in the pileus and stipe tissues.

Habitat and distribution:—gregarious or clustered on clay soils under Quercus glauca ; July to September; presently only known from Longquan Mountain, Sichuan province, China.

Additional specimens examined:— CHINA. Sichuan Province, Chengdu City, Longquanyi District, Chadian Town, Longjiawan, 104°23′46.24″E, 30°34′37.87″N, alt. 521 m, under Quercus glauca forest, 30 August 2021, C. Liu, LC202108219 (Paratype, SICAU 22-0165, GenBank accession no.: ITS = OQ434284, LSU = OQ434279, rpb 2 = OQ569745).

Figures

FIGURE 2. Mallocybe longquanensis (SICAU 22-0164) a–f. Fresh basidiomata; g. Basidiospores; h–j Basidia; k–m. Cheilocystidia; n. Hyphae; o. Transverse section of the lamella; Scale bars: a–f = 1 cm; g–n = 10 µm; o = 20 µm.