Lepiota ochraceosquamea J. F. Liang & Zhu L. Yang 2025, sp. nov.

Lepiota ochraceosquamea J. F. Liang & Zhu L. Yang, sp. nov. Fig. 3 Holotype. China • Xizang: near Yikang County, 23 July 2004, alt. 3500 m, Yang 4173 (HKAS 45559). Etymology. ‘> ochraceosquamea’ refers to the color of squamules on the pileus surface. Diagnosis. Lepiota ochraceosquamea is characterized by whitish pileus covering with dark yellowish-brown to light ochre squamules, smooth stipe possessing fine and brown squamules at the base, broadly fusiform or oblong basidiospores (8.5–11.0 × 5.0–6.5 μm), diverse cheilocystidia (clavate, fusiform, or falcate), pileus covering a trichoderm consisting of long, erect elements, without basal short elements. Description. Basidiomata small. Pileus 1–3 cm in diam, initially campanulate, extended gradually, accompanied by development, plano-convex, surface covering with dark yellowish-brown to light ochre (6 D 7–6 D 8) squamules on a whitish surface, with blunt and brown (6 D 8) umbonate center. Context whitish, thin. Lamellae L = 40–60, l = 1–2, free, whitish, then turning dirty white, moderately crowded, ventricose, length unequal. Stipe 1.5–3.5 × 0.2–0.4 cm, tapering upwards, nearly brown, glabrous, with fine and brown (6 D 6–6 D 7) squamules at the base. Annulus whitish, margin nearly brown, and evanescent (Fig. 3 A). Smell not distinct; taste not recorded. Basidiospores (Fig. 3 B) [67 / 3 / 3] (8.0) 8.5–11.0 (11.5) × 5.0–6.5 μm [Q = (1.45) 1.50–2.00, Q = 1.68 ± 0.14], broadly fusiform or oblong in side view, without suprahilar depression, adaxial side convex, apex blunt-round, oblong in front view; colorless, hyaline, smooth, slightly wall-thickened, dextrinoid, congophilous, not metachromatic in cresyl blue. Basidia 24–30 × 9–12 μm, clavate, mostly 4 - spored and occasionally 2 - spored, sterigmata up to 7 μm long. Cheilocystidia (Fig. 3 C) 15–32 × 5–9 μm, diverse, clavate, fusiform, or falcate with flexuous apex, colorless, hyaline, wall-thinned, light pink in Congo red. Pleurocystidia absent. Pileus covering (Fig. 3 D) a trichoderm composed of subcylindrical, narrow to apex, mostly flexuous, slightly wall-thickened, terminal elements 70–240 × 6–18 µm, base rarely with short elements, and with yellow to yellow-brownish intracellular pigment. Clamp connections present in all tissues. Distribution. Known only from the Xizang Autonomous Region and Sichuan Province, China. Habitat. Solitary or in small groups, saprotrophic and terrestrial on moist grasslands. Additional specimens examined (paratypes). China • Xizang: Jiangda County, Jila Mountain, 1 August 2008, alt. 4250 m, Yang 4256 (HKAS 45635); Sichuan: Daocheng County, alt. 4000 m, 1 July 1998, Yang 1957 (HKAS 32150). Notes. The main characteristics of L. ochraceosquamea are ochre-yellow squamules on the pileus, broadly fusiform basidiospores with a blunt-rounded apex, diverse shapes of cheilocystidia, and a trichodermal pileus covering with terminal elements gradually narrowing toward the apex, rarely with short elements at the base. Phylogenetic analysis showed that L. ochraceosquamea clustered with several sequestrate and agaricoid species. Distinct from L. ochraceosquamea, the former species displays distinctly different characters, viz., sequestrate fruiting habit and globose basidiospores. The latter, comprising L. albofloccosa, L. nigrosquamosa, and L. kuehneriana, have distinct morphological features that differentiate them from L. ochraceosquamea. Lepiota albofloccosa has larger basidiomata, snow-white to milky white squamules on the pileus, longer [(11.5 –) 14.7–18.5 (– 21) × (5.5 –) 6.1–7.2 (– 8) μm] fusiform basidiospores, and a pileus covering with short elements at the base (Ahamed et al. 2023). L. nigrosquamosa differs in its medium-sized basidiomata, black-brownish to black squamules on the pileus, longer [(12) 13–16 × 5–7 μm] basidiospores, and a pileus covering with basal short elements (Liang and Yang 2012). Lepiota kuehneriana possesses whitish, flocculent veil remnants on the margin of the pileus, longer basidiospores, and a pileus covering with terminal elements gradually narrowing toward the apex and short elements at the base (Liang 2007; Yang et al. 2019). In addition, L. aspericeps Murrill also has yellowish-brown squamules on the pileus without striations; however, its longer (10.5–15.5 × 4.0–6.0 μm) basidiospores and a pileus covering with short elements at the base distinguish it from L. ochraceosquamea (Murrill 1951; Liang 2007).