Lepiota stillispora X. Li & J. F. Liang sp. nov.

Fig. 3

Holotype.

China • Guangdong: Dongguan City, Dalingshan Forest Park, 100 m a. s. l., 22°51'47.14"N, 113°45'14.56"E, 8 Jun 2025, X. Li 056 (holotype, RITF 7953). GenBank: ITS = PX 423621; LSU = PX 423622; rpb 2 = PX 913184; mtSSU = PX 423648.

Etymology.

stillispora (Latin), referring to the droplet-shaped basidiospores.

Diagnosis.

Lepiota stillispora can be recognized by its dark brownish umbonate and yellowish-brown squamules on the pileus, droplet-shaped (lacrymoid) basidiospores, clavate cheilocystidia, pileus covering a trichoderm composed of terminal elements that are sometimes swollen in the middle and acuminate at the apex, and clamp connections present in all tissues.

Sectional placement.

Lepiota sect. Helveolae.

Description.

Basidiomata small (Fig. 3 A – C). Pileus 1.6–3.5 cm in diam, campanulate when young, expanding to plano-convex; with a dark brownish (5 C 3–5 C 7) umbo on a dirty-white background; the central region sometimes splitting radially into three lobes at maturity, gradually splitting towards the edge into smaller and yellowish-brown (5 B 3–5 B 6) fibrillose squamules; with floccose velar remnants at the margin, sometimes exceeding lamellae. Lamellae L = 40–60, l = 1–2, moderately crowded, free, whitish, ventricose; edge eroded. Stipe 2.5–3.5 × 0.2–0.4 cm, subcylindrical, thickening towards base, hollow, whitish and smooth above annulus, with brownish (5 A 3–5 A 5) squamules below annulus. Annulus whitish, ephemeral. Odor not distinct. Taste not recorded. Spore print white.

Basidiospores (Fig. 3 D) [40 / 2 / 2] 6.5–9.5 × 3.0–5.0 μm [Q = (1.51) 1.62–2.38 (2.47), Q av = 2.00 ± 0.38], droplet-shaped or lacrymoid in side view, with suprahilar depression or not; adaxial side usually convex, sometimes substraight, abaxial side often not sunken; bullet-shaped or droplet-shaped in front view; colorless, hyaline, smooth, slightly thick-walled, dextrinoid, light red in Congo red, not metachromatic in cresyl blue; apiculus tiny. Basidia 18–31 × 7–10 µm, narrowly clavate or subcylindrical, 4 - spored. Cheilocystidia (Fig. 3 E) 15–35 × 5–11 µm, clavate, colorless, hyaline, thin-walled, often densely arranged into a sterile lamella edge. Pleurocystidia absent. Pileus covering (Fig. 3 F) a trichoderm made up of subcylindrical or narrowly clavate, sometimes swollen in the middle part and acuminate on the apex, terminal elements 126–188 × 6–25 µm, lacking a layer of short elements, with yellow-brownish intracellular pigment; base sometimes with pale yellowish-brown to yellowish-brown extracellular pigment. Clamp connections present in all tissues.

Distribution.

Currently known from Guangdong and Yunnan provinces, China.

Habitat.

Saprotrophic, solitary on the ground in evergreen monsoon rainforest of limestone mountains in summer.

Additional specimens examined.

China • Yunnan: Mengla County, Menglun Town, Lushilin Park, 11 Jul 2006, J. F. Liang 397 (paratype, HKAS 50113).

Notes.

The main characteristics of L. stillispora are small basidiomata, yellowish brown squamules on the pileus, droplet-shaped or lacrymoid basidiospores, clavate cheilocystidia, and a pileus covering that is a trichoderm composed of terminal elements, sometimes narrowing toward the apex, without short elements at the base.

The basidiospores of L. stillispora are similar to those of L. catenariocystidia Han C. Wang & Zhu L. Yang (dist., China: Yunnan), but the latter differs in having dark gray and tomentose squamules, cheilocystidia often in chains, and narrower terminal elements of the pileus covering (Wang and Yang 2005).

Lepiota stillispora shows morphological differences when compared to some related species. Unlike L. himalayensis Khalid & Razaq (dist., Pakistan), which has larger basidiomata, dark brown to blackish squamules on the pileus, and shorter and narrower terminal elements of the pileus covering (Razaq et al. 2012), L. stillispora possesses small basidiomata, yellowish brown squamules on the pileus, and longer and thicker terminal elements of the pileus covering. Lepiota rubella Bres. (dist., Europe) is characterized by narrower terminal elements of the pileus covering, narrowly clavate cheilocystidia, and smaller basidiospores (Vellinga et al. 1998) than L. stillispora. Additionally, L. stillispora differs from L. brunneosquamulosa Jun F. Liang & Zhu L. Yang (dist., China: Yunnan) in that the latter has smaller basidiospores, no cheilocystidia, and a pileus covering with longer terminal elements that taper toward the apex (Liang et al. 2018).

Furthermore, L. brunneoincarnata Chodat & C. Martín (dist., Europe and Asia, including Pakistan and China) and L. stillispora exhibit clear morphological differences. The former differs from the latter by bearing larger basidiomata, grayish brown to blackish brown squamules on the pileus, and wider basidiospores (Liang 2007; Yang et al. 2019).

Phylogenetic analysis confirms the close relationship between L. stillispora and L. revelata (Berk. & Broome) Sacc. Nevertheless, the two species can be readily distinguished by morphological features. Lepiota revelata (tropical and subtropical Asia, including Sri Lanka and China) exhibits pale orange lamellae, subcylindrical basidiospores, and very few cheilocystidia (Berkeley and Broome 1871; Yang et al. 2019).