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

Figs 7 A – C , 12

Etymology.

Derived from Latin ‘ ultra’ (extremely), ‘ putri’ (rotten), and ‘ piceae’ (of spruce), the species epithet “ ultraputripiceae ” characterizes the fungus’s distinctive ecological niche on severely decomposed spruce wood substrates.

Diagnosis.

Pluteus ultraputripiceae is characterized by its brown to light flesh-brown pileus, broadly ellipsoid to ellipsoid basidiospores (avL × avW = 7.7–8.0 × 6.4–6.8 µm), pleurocystidia lacking apical excrescences. It differs from P. dianae by the absence of small apical excrescence structures at the top of pleurocystidia, substrate preference for highly decayed trunks, and distribution in East Asia ( China). The ITS genetic distance is 0.040 (SE = 0.008).

Holotype.

CHINA • Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Jongkushtai village , 42°91'78.66"N, 82°12'56.22"E, alt. 2175 m, 10 July 2023, Z. X. Qi, FJAU 66594 (ITS: PP 516601 , LSU: PP 516653 , tef 1: PP 551608 ) (Collection no.: Qi 1324)

Description.

Basidiomata medium-sized. Pileus 27–47 mm diam; convex to slightly hemispherical when young, brown to dark brown (7.5 YR 5 / 4-10 YR 4 / 6); plano-convex to applanate at maturity, light flesh – brown (2.5 YR 9 / 6) to cinnamon-colored (2.5 YR 8 / 4) and smooth, with slightly translucently striate at the margin, crenulate. Lamellae creamy white (2.5 YR 8 / 6), free, crowded, thick, unequal, slightly ventricose, 6–9 mm wide, edges even; lamellar edge white. Stipe 31–55 × 5–7 mm, cylindrical, fibrous, with white longitudinal striate on the surface (2.5 YR 9 / 4). Odorless. Spore prints pink.

Basidiospores [100, 7, 3] 7.0–8.0 (– 8.5) × 6.0–7.0 (– 7.5) μm, avL × avW = 7.7–8.0 × 6.4–6.8 µm, Q = 1.10–1.41 μm, avQ = 1.14–1.20 μm, broadly ellipsoid to ellipsoid, or ovoid, pale pink, smooth, thin-walled. Basidia 21–29 × 6–10 µm, clavate, thin-walled, 4 - sterigmate, hyaline. Pleurocystidia 54–102 × 20–36 μm, few, scattered, clavate to broadly clavate, or fusiform, apically obtusely rounded, thin-walled, smooth, hyaline. Lamellar edge sterile. Cheilocystidia 41–79 × 18–29 μm, abundant, clustered, fusiform to narrowly clavate to clavate, or broadly clavate, bluntly rounded apically, thin-walled, smooth, hyaline. Pileipellis a trichohymeniderm, with terminal elements 35–64 × 11–25 μm broadly clavate or fusiform, thin-walled, with brown intracellular pigment. Stipitipellis a cutis, hyphae 3–12 µm diam, cylindrical, hyaline, thin-walled. Caulocystidia 30–61 × 10–21 μm, numerous, occurring in clusters, cylindrical to broadly clavate to broadly fusiform, or narrowly utriform, apically obtusely rounded, smooth, thin-walled, with brown intracellular pigment. Clamp connections absent in all tissues.

Habitat.

Solitary to scattered on highly decayed trunks in spruce forests ( P. schrenkiana ).

World distribution.

China.

China distribution.

Xinjiang Uygur Autonomous Region.

Additional specimens examined.

CHINA • Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Jongkushtai village , solitary on rotting wood in spruce forests ( P. schrenkiana ), 42°17'46.35"N, 82°77'54.24"E, alt. 2055 m, 13 July 2023, Z. X. Qi, FJAU 66595 (Collection no.: Qi 1329) (ITS: PP 516602 , LSU: PP 516654 , tef 1: PP 551609 ) . CHINA • Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Jongkushtai village . Scattered on rotting wood in spruce forests ( P. schrenkiana ). 42°97'26.51"N, 82°12'27.25"E, alt. 2192 m, 30 August 2024, Z. X. Qi, FJAU 66611 (Collection no.: Qi 4887) (ITS: PQ 810760 , LSU: PQ 810737 , tef 1: PQ 811047 ) .

Notes.

Pluteus ultraputripiceae is distinguished by its dark brown to pinkish-brown pileus, relatively large basidiospores, and caulocystidia with brown intracellular pigment.

Morphologically, P. ultraputripiceae shares similarities with P. dianae and P. plautus but can be differentiated based on several key features. P. ultraputripiceae is distinguished from P. dianae by its larger basidiospores (avL × avW = 7.7–8.0 × 6.4–6.8 µm), pleurocystidia lacking excrescences, substrate preference for highly decayed trunks ( Picea schrenkiana ), and distribution in East Asia ( China). In contrast, P. dianae produces smaller basidiospores (avL × avW = 7.2 × 5.5 µm), pleurocystidia with excrescences, and primarily inhabits decayed broadleaf trunks in Central and Eastern Europe ( Czechia, Denmark, and Russia) ( Ševčíková et al. 2020). This distinction is further supported by an ITS genetic distance of 0.040 (SE = 0.008) between these taxa. P. ultraputripiceae is separated from P. plautus primarily by basidiomata coloration: P. ultraputripiceae exhibits a dark brown to pinkish-brown pileus with a white stipe, whereas P. plautus features an alutaceous to fuligineous pileus and a velvety brown to blackish-brown stipe with similarly pigmented context ( Weinmann 1836).

The phylogenetic analysis strongly supports the monophyly of P. ultraputripiceae , with three specimens forming a well-supported (MLB = 98, BPP = 1, Fig. 2 ) sister to P. granulatus . These species can be differentiated by basidiomata morphology and geographic distribution: P. ultraputripiceae possesses a light flesh-brown to cinnamon-colored, smooth pileus and occurs in East Asia ( China), while P. granulatus is characterized by a pileus with reddish tinge and distinct granules, occurring in Europe ( Czechia and Italy). The ITS genetic distance between these taxa is 0.008 (SE = 0.003).

Figures

Figure 2. Phylogenetic tree of the / plautus 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 7. Basidiomata features. A – C. Pluteus ultraputripiceae (A. FJAU 66611, B, C. FJAU 66594). D, E. P. hinnuleus (FJAU 66614). A – C. Photos by Zheng-Xiang Qi. D, E. Photos by Di-Zhe Guo. Scale bars: 1 cm.

Figure 12. A. Macroscopic characteristics of Pluteus ultraputripiceae. B. Caulocystidia. C. Basidiospores. D. Basidia. E. Cheilocystidia. F. Pleurocystidia. G. Pileipellis elements. Scale bars: 1 cm (A); 10 µm (B – G).