Pluteus leoninus (Schaeff.) P. Kumm.

Qi, Zheng-Xiang, Wang, Li-Bo, Qian, Ke-Qing, Shi, Li-Li, Hu, Jia-Jun, Tuo, Yong-Lan, Rao, Gu, Samwel Jacob, Muharagi, Liu, Rui-Peng, Liu, Ming-Hao, Guo, Di-Zhe, Liu, Ya-Jie, Zhang, Bo, Li, Xiao & Li, Yu, 2025, Integrating morphology, phylogeny, substrate, and distribution: clarifying the major phylogenetic framework of Pluteus sect. Hispidoderma (Agaricales, Pluteaceae) and describing 18 species, IMA Fungus 16, pp. e 154329-e 154329 : e154329-

Pluteus leoninus (Schaeff.) P. Kumm. , Führ. Pilzk. (Zerbst) (1871: 98)

Figs 25 F – H , 29

Description.

Basidiomata medium-sized. Pileus 20–31 mm diam; convex to plano-convex, often with a low, broad umbo; egg-yellow (5.0 Y 9 / 12), black-brown in the center (2.5 YR 5 / 8), with white pruinose on the surface, margin usually translucently striate. Lamellae flesh pink (2.5 YR 8 / 6), free, slightly crowded, thick, unequal, slightly ventricose, 3–5 mm wide. Stipe 37–48 × 4–7 mm, cylindrical, hollow, partly spirally twisted, base slightly thick, fibrous, surface smooth. Odorless. Spore prints pink.

Basidiospores [150, 5, 3] 6.0–7.0 (– 7.5) × 5.0–6.0 (– 6.5) μm, avL × avW = 6.5–7.0 × 5.5–5.8 µm, Q = 1.15–1.40 μm, avQ = 1.18–1.26 μm, subglobose to broadly ellipsoid, ellipsoid or ovoid, slightly pinkish, smooth, thin-walled. Basidia 24–29 × 7–10 μm, clavate, thin-walled, 4 - sterigmate, hyaline. Pleurocystidia 50–86 × 20–26 μm, numerous, scattered, fusiform to utriform, apically obtusely rounded, commonly provided with 1–4 digitiform excrescences at apex, slightly thick-walled, smooth, hyaline. Lamellar edge sterile. Cheilocystidia 35–72 × 13–25 μm, similar in form to pleurocystidia, numerous, narrowly fusiform to utriform, with 1–2 digitate or mucronate apically, thin-walled, hyaline. Pileipellis a trichoderm with radial hyphae, with terminal elements 43–157 × 13–31 μm, hyphae at the center extending outwards, with cylindrical or fusiform elements, thick-walled, with slightly yellowish intracellular pigment. Stipitipellis a cutis, hyphae 4–11 µm diam, cylindrical, hyaline, non-incrusted, non-gelatinous, and thin-walled. Caulocystidia absent. Clamp connections absent in all tissues.

Habitat.

Solitary to scattered on decaying wood ( Quercus , Picea ) in broad-leaved or mixed forests.

World distribution.

Europe ( Rea 1922; Vellinga and Schreurs 1985; Orton 1986; Vellinga 1990; Breitenbach and Kränzlin 1995; Krieglsteiner 2003; Boccardo et al. 2008; Heilmann-Clausen 2008), Asia ( Takehashi and Kasuya 2007), North America ( Murrill 1917; Kauffman 1918; Singer 1956) and North Africa ( Malençon and Bertault 1970).

China distribution.

It is distributed in all provinces of China ( Xu 2016).

Additional specimens examined.

CHINA • Heilongjiang Province, Heihe Stewardship Station ; On rotting wood in mixed solitary forests; 29 July 2021, Z. X. Qi, FJAU 66580 (Collection no.: Qi 522) (ITS: PP 516612 , LSU: PP 516662 , tef 1: PP 551596 ) . CHINA • Heilongjiang Province, Shuanghe National Nature Reserve ; Scattered on decaying wood in mixed forests; 13 July 2019, D. Z. Guo, FJAU 66581 (Collection no.: Guo 385) (ITS: PP 516611 , LSU: PP 516661 , tef 1: PP 551597 ) . CHINA • Heilongjiang Province, Shuanghe National Nature Reserve ; Scattered on decaying wood in mixed forests; 19 July 2019, D. Z. Guo, FJAU 66582 (Collection no.: Guo 070) (ITS: PP 516610 , LSU: PP 516660 , tef 1: PP 551598 ) .

Notes.

The primary distinguishing characteristics of Pluteus leoninus include a bright yellow to orange-yellow pileus that is rugose in the middle, a slightly yellowish or yellowish-white stipe, most subglobose to broadly ellipsoid, a few globose or ellipsoid.

P. leoninus displays a range of pileus colors, including yellowish brown, yellowish orange, yellow, or lemon yellow in young and mature specimens, which may lead to confusion with sect. Hispidoderma or even sect. Celluloderma, including P. roseipes , P. fenzlii , P. chrysaegis , P. chrysophlebius , and P. luteomarginatus . P. leoninus can be differentiated from the pinkish to pale reddish pileus of P. roseipes by its yellow or yellowish-brown pileus ( Ludwig 2007). P. leoninus can be distinguished from P. fenzlii by its stipe lacking an annulus, a less squamulose pileus, and by examining the structure and dimensions of both the pleurocystidia and the pileipellis ( Malysheva et al. 2007). P. chrysaegis differs from P. leoninus by possessing short pileipellis elements extending up to 40 μm ( Pradeep et al. 2012; Lezzi et al. 2014). P. chrysophlebius is characterized by a shorter stipe and pileus, with an unveined bright yellow pileus lacking brownish shading ( Vellinga 1990). On the other hand, P. luteomarginatus features a pileus with brownish shading, particularly prominent at the center and with a bright yellow margin, along with more subglobose basidiospores (7.5 × 6 μm) ( Takehashi and Kasuya 2007).

The phylogenetic tree results were consistent with the morphological results. Specimens from China in P. leoninus clustered in the same branch as Russia, France, USA, and Turkey with high support (MLB = 100, BPP = 0.99, Fig. 4 ).

Figures

Figure 4. Phylogenetic tree of the / leoninus clade of the sect. Hispidoderma. The best tree from the ML and BI analysis of the ITS + tef 1 dataset. The two values of internal nodes respectively represent the Maximum Likelihood bootstrap (MLBP) / Bayesian posterior probability (BIPP). Nodes with a bootstrap probability (BP) ≥ 80 and a Bayesian posterior probability (PP) ≥ 0.80 are indicated in the phylogram. This study species is in bold and red font.

Figure 25. Basidiomata features. A – E. Pluteus ussuriensis (A, B. FJAU 66576, C, D. FJAU 66577, E. FJAU 66578). F – H. P. leoninus (F. FJAU 66581, G, H. FJAU 66580). A – D. Photos by Gu Rao. E. Photos by Ming-Hao Liu. F. Photos by Di-Zhe Guo. G, H. Photos by Zheng-Xiang Qi. Scale bars: 1 cm.

Figure 29. A. Macroscopic characteristics of Pluteus leoninus. B. Pileipellis elements. C. Cheilocystidia. D. Basidiospores. E. Pleurocystidia. Scale bars: 1 cm (A); 10 µm (B, C, E); 20 µm (D).