Pluteus jilinensis Z. X. QI, B. Zhang & Y. Li, 2025

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 jilinensis Z. X. QI, B. Zhang & Y. Li sp. nov.

Figs 5 E – G , 10

Etymology.

jilin, for the geographic origin of the type collection.

Diagnosis.

Pluteus jilinensis is separated from P. spaniophyllus by its burnt yellow pileus, with distinct squamules around the center, dense lamellae, and their ITS genetic distance is 0.008 (SE = 0.004), tef 1 genetic distance is 0.008 (SE = 0.004).

Holotype.

CHINA • Jilin Province, Cold Onion Ridge Forest Park ; Latitude and longitude: 43°02'2.06"N, 127°58'44.69"E; Scattered on very rotten decaying wood in broad-leaved forests ( Q. mongolica ); 9 August 2019, G. Rao, FJAU 66616 (Collection no.: Rao 1314) (ITS: PQ 810767 , LSU: PQ 810745 , tef 1: PQ 811051 ).

Description.

Basidiomata small-sized. Pileus 15–21 mm diam; convex or plano-convex, often with a low, broad umbo; burnt yellow (5 YR 8 / 6) to gray-brown (10 YR 8 / 2), transitioning to light brown (2.5 Y 8 / 2) toward the margin; surface rough, with distinct squamules or rugose-venose around the center; margin crenulate, with small rounded or blunt teeth. Context yellowish (2.5 Y 9 / 2). Lamellae free, 3–5 mm wide, crowded, initially white (2.5 YR 9 / 2), pink at maturity (2.5 R 9 / 6), unequal, moderately thick, ventricose, edges even; lamellar edge concolorous to the sides. Stipe 21–45 × 2–4 mm, hollow, fibrous, clavate, slightly expanded at the base, transparent to whitish (7.5 RP 9 / 2) when young, light brown (5 YR 5 / 2) to brown (7.5 YR 5 / 4) at maturity. Spore print unknown.

Basidiospores [60 / 5 / 2] 7.0–8.0 (– 8.5) × 6.0–7.0 (– 7.5) µm, avL × avW = 7.5–7.8 × 6.4–6.8 µm, Q = 1.07–1.25 µm, avQ = 1.15–1.20 µm, subglobose to broadly ellipsoid, smooth, slightly pinkish, thin-walled. Basidia 20–25 × 12–18 µm, broadly clavate, thin-walled, 4 - sterigmate, and hyaline. Pleurocystidia 55–83 × 15–23 μm, rare, scattered, fusiform to broadly fusiform, apically obtuse, thin-walled, smooth, partly containing brown intracellular pigment. Lamellar edge sterile. Cheilocystidia 37–63 × 16–21 μm, abundant, clustered, clavate, subfusiform to broadly fusiform, apically obtuse, with or without mucronate, thin-walled, smooth, hyaline. Pileipellis a hymeniderm, with terminal elements 75–98 × 17–28 μm, subcylindric or subfusiform, some apices with finger-like projections, thin-walled, with brown intracellular pigment. Stipitipellis a cutis, hyphae 5–8 μm diam, cylindrical, hyaline, thin-walled. Caulocystidia 36–55 × 13–19 μm, clustered, more numerous, composed of vesicles, subfusiform, bluntly rounded apically, partly containing brownish intracellular pigment, smooth, thin-walled. Clamp connections absent in all tissues.

Habitat.

Scattered on very rotten decaying wood in broad-leaved forests ( Q. mongolica ).

World distribution.

China.

China distribution.

Jilin Province.

Additional specimens examined.

CHINA • Jilin Province, Quanyang Township, Beigang ; 43°02'2.06"N, 127°58'44.69"E; Scattered on very rotten decaying wood in broad-leaved forests ( Q. mongolica ); 23 August 2021, Z. X. Qi, FJAU 66624 (Collection no.: Qi 401) (ITS: PQ 814290 , LSU: PQ 814291 ) .

Notes.

Pluteus jilinensis is characterized by its smaller basidiomata, burnt yellow pileus, and pleurocystidia with bluntly rounded apices.

Morphologically, P. jilinensis may be confused with P. spaniophyllus and P. depauperatus . P. jilinensis is distinguished from P. spaniophyllus by its denser lamellae and fibrous, harder stipe, in contrast to the sparser lamellae and crumbly, fragile stipe of P. spaniophyllus (Table 3 ). This morphological distinction is further supported by molecular data, with an ITS genetic distance of 0.008 (SE = 0.004) and tef 1 genetic distance of 0.008 (SE = 0.004) between these taxa. P. jilinensis differs from P. depauperatus in several respects: P. jilinensis produces smaller basidiomata (pileus 15–21 mm), with a predominantly burnt yellow, unstriped pileus having a rough surface, and larger basidiospores (avL × avW = 7.5–7.8 × 6.4–6.8 µm). In contrast, P. depauperatus exhibits larger basidiomata (pileus 18–50 mm) with predominantly brown coloration (pale brown, grey-brown, or saffron-brown), distinctly striped margins, sometimes granular center, smaller basidiospores (avL × avW = 6.33 × 5.43 µm), and a distinctive odor ( Kühner and Romagnesi 1956).

Phylogenetically, P. jilinensis and P. aff. semibulbosus form strongly supported sisters. Although both species share similarly sized basidiospores, fusiform pleurocystidia, and subfusiform cheilocystidia, they can be differentiated by several features: P. jilinensis produces smaller basidiomata (≤ 21 mm in diameter) with a more spreading pileus and pileipellis composed of clavate and cylindrical elements, while P. aff. semibulbosus forms larger basidiomata (up to 43 mm in diameter) with a hemispherical pileus and pileipellis consisting of inflated clavate cells. Additionally, the caulocystidia in P. jilinensis have bluntly rounded apices, whereas those in P. aff. semibulbosus possess a papillate apical projection (Table 3 ). These morphological distinctions are reinforced by genetic distances of 0.013 (SE = 0.007) for ITS and 0.004 (SE = 0.003) for tef 1.

Figures

Figure 5. Basidiomata features. A – D. Pluteus tenuipileus (A, B. FJAU 66591, C, D. FJAU 66592). E – G. P. jilinensis (FJAU 66616). H – I. P. spaniophyllus (FJAU 66593). J, K. P. aff. semibulbosus (FJAU 66617). A – K. Photos by Gu Rao. Scale bars: 1 cm.

Figure 10. A. Macroscopic characteristics of Pluteus jilinensis. B. Caulocystidia. C. Basidiospores. D. Pleurocystidia. E. Basidia and Pleurocystidia. F. Cheilocystidia. G. Pileipellis elements. Scale bars: 1 cm (A); 5 µm (C); 10 µm (B, D – F); 20 µm (G).