Pyrrhulomyces pileocystidiatus J. Huang & E. Tian, 2025

Lei, Chunyu, Deng, Guiyin, Huang, Jiahui, Shen, Yalun, Yan, Wenbo, Tian, Enjing & Fu, Yongping, 2025, New species and newly recorded species of the family Strophariaceae (Agaricomycetes, Agaricales) in China, MycoKeys 124, pp. 309-329 : 309-329

Pyrrhulomyces pileocystidiatus J. Huang & E. Tian sp. nov.

Figs 4 , 5

Etymology.

Referring to the presence of pileocystidia.

Diagnosis.

Characterized by the bright orange-red to ochraceous brown pileus with an obtuse umbo, bitter taste, blackening basidiomata, the pleurocystidia as chrysocystidia, and the presence of broadly clavate and orange-red pileocystidia.

Holotype.

China • Jilin, Changbai Mountain Ancient Tree Park ; 42°01'16"N, 128°03'42"E; on decaying wood in coniferous and mixed forests; 17 September 2024; Jiahui Huang, 37436 ( holotype: HMJAU!) .

Description.

Pileus 30–50 mm in diam, hemispherical to obtusely conical, becoming nearly plane but with a broad low umbo, margin undulate, adorned with fibrillose veil remnants, surface viscid when moist, glabrous or with appressed fibrils, ground color champagne (4 B 4), the central part appears light brown to agate (7 E 8) when fresh, hygrophanous in appearance, fading to dark gray (1 F 1) at maturity. Context light yellow (4 A 4), thin to moderately thick. Lamellae adnate to sinuate, absinthe yellow (3 C 5) to caput mortuum (8 F 7), moderately broad, L = 49–57, I = 1–3, crowded, with paler edges and fimbriate ornamentation. Stipe 40–50 mm long, 3–6 mm wide, central, cylindrical, typically curved at base; surface dry, fibrillose or with scattered fibrillose squamules, ash gray (1 B 2), base brownish orange to feuille morte (5 C 6–6 D 7) dark. Veil evanescent, dark brown (6 F 7) to pale (2 A 2), sometimes forming an arachnoid annulus, stipe hollow.

Basidiospores 6–8 × 4–5 µm, Q = 1.30–1.70, Qm = 1.48 ± 0.10, ellipsoid to ovoid or subovoid in face view, subamygdaliform to inequilateral in side view, wall smooth and slightly thickened, without a germ pore, chamois (4 C 5) in KOH, paler in Melzer’s reagent. Basidia 22–30 × 6–8 µm, 4 - spored, narrowly clavate, hyaline to pale yellow (2 A 3) in KOH. Pleurocystidia abundant, as chrysocystidia 38–50 × 10–15 µm, typically clavate or mucronate-clavate, hyaline or light yellow (3 A 5), containing a refractive amorphous inclusion, thin-walled, smooth. Cheilocystidia 40–70 × 5–8 µm, slightly inflated at the base or subbase, with a slender neck (2.5–5 µm wide), apex obtuse to slightly pointed, thin-walled and smooth, hyaline to pale yellow (2 A 3) in KOH. Caulocystidia not observed. Gill trama of parallel hyphae hyaline to pastel yellow (2 A 4) in KOH, subparallel hyphae with inflated cells up to 20 µm in diameter, thin-walled and smooth; subhymenium not gelatinized. Pileipellis a ixocutis, hyphae 2.5–5 µm wide, smooth-walled, hyaline or light yellow (3 A 5). Pileocystidia 22.5–42 × 12–18 µm, scattered, clavate, containing small vacuolar inclusions, light orange (5 A 5) in KOH. Clamp connections present in all tissues.

Habitat.

Scattered on decaying wood in coniferous or mixed forests, preferring humid environments, in summer and fall.

Additional materials examined.

China • Guizhou, Bijie City, Nayong County, Shimuzhu Village , on decaying wood in coniferous forest, 21 July 2020, Enjing Tian 37437 ( HMJAU) .

Comments.

This species is characterized by a bright orange-red to ochraceous brown pileus with an obtuse umbo, bitter taste, blackening basidiomata, pleurocystidia as chrysocystidia, and broadly clavate and orange-red pileocystidia.

Pyrrhulomyces pileocystidiatus is similar to the only two known species of the genus Pyrrhulomyces , Py. astragalinus and Py. amariceps . Py. pileocystidiatus differs from Py. astragalinus mainly by the presence of orange-red and clavate pileocystidia, and the latter lacks these special types of end cells of the pileipellis ( Smith and Hesler 1968; Tian and Matheny 2021). Furthermore, it is easy to distinguish Py. pileocystidiatus from Py. amariceps based on the features of pleurocystidia and pileocystidia. The former has only one typically clavate or mucronate-clavate pleurochrysocystidia and orange-red and clavate pileocystidia. In contrast, the latter has two types of pleurocystidia (clavate or mucronate-clavate chrysocystidia with a refractive amorphous inclusion and fusiform-ventricose cystidia with a homogeneous content) and smaller pileocystidia (23–27 × 4–9 µm) with various shapes ( Tian and Matheny 2021).

In the phylogenetic analyses, Py. pileocystidiatus clustered in the genus Pyrrhulomyces clade with high statistical support but represented a relatively independent lineage (Fig. 1 ). Pyrrhulomyces pileocystidiatus differs from Py. amariceps by ITS (4–5 %) and 28 S (4–5 sites) genetic divergence and Py. astragalinus by ITS (1–2 %) and 28 S (0–1 sites) genetic divergence.

Therefore, this species is proposed as a new Pyrrhulomyces species based on morphological examination and phylogenetic analyses.

Figures

Figure 1. Bayesian inference (BI) phylogram of Agrocybe, Pholiota and Pyrrhulomyces based on dataset (ITS + nrLSU). PPs> 0.95 and bootstrap values > 70 % are shown. Types are indicated in green, and the new species and the species newly recorded in China in this study are in red.

Figure 4. Basidiomata of Pyrrhulomyces pileocystidiatus A, B. (HMJAU 37436, holotype). Photos by Jiahui Huang. Scale bars: 1 cm.

Figure 5. Microcharacters of Pyrrhulomyces pileocystidiatus (HMJAU 37436, holotype). Drawings by Chunyu Lei. A. Basidiospores; B. Basidia; C. Pileocystidia; D. Cheilocystidia; E. Pleurocystidia. Scale bars: 10 µm (A – E).