A new species and new records species of Pluteus from Xinjiang Uygur Autonomous Region, China

Specimens and morphological description

Site description

Xinjiang Uygur Autonomous Region is located in the hinterland of the Eurasian continent of northwestern China. For example, there are distinctive landforms, including the world’s second-highest peak. It is surrounded by high mountains, resulting in early dryness and precipitation varies significantly among regions. There are continental cold temperate zone cold climate, temperate zone continental monsoon climate, temperate zone continental arid climate, and alpine climates from north to south (Yao et al., 2022).

In this study, the specimens of the genus Pluteus were collected from Kelan River Valley in Altay City (47°50′14.66″N, 88°13′23.41″E). Altay Region with an altitude of about 577 m, Wolong Bay in Kanas (48°65′77.01″N, 87°03′82.11"E). Altay Region with an altitude of 1,333 m, and Shuimogou in Regiment 74 (43°12′50.69″N, 80°13′18.44″E). Zhaosu County, Ili Kazakh Autonomous Prefecture with an altitude of 1,764 m. See Fig. 1 for details.

Collection and morphological studies

Photos of fresh basidiomata were taken in the field, scientifically fully reflecting the growth environment and the characters, including the shape of the pileus, the color of lamellae, and color codes followed by Munsell Soil Color Charts (Munsell, 2009). The size of basidiomata was measured when fresh, and detailedly recorded the macroscopic characteristics, such as shape, size, and color of the pileus, odor, color, and density of lamellae. A small portion of fresh context and lamellae was dried on silica gel and used for DNA extraction. Fresh basidiomata were dried at 40–50 °C using an electric drier and preserved at the Herbarium of Mycology of Jilin Agricultural University (HMJAU). The observation of microstructure characteristics were based on dry specimens. The dry specimens were rehydrated in 94% ethanol for microscopic examination and then mounted in 3% potassium hydroxide (KOH), 1% Congo Red, and Melzer’s Reagent, using a light microscope (ZEISS, DM1000, Oberkochen, Germany). The morphological descriptions follow Largent, Johnson & Watling (1977). As previously described in Rao et al. (2021b), data were collected. Specifically, the following symbols were used in the description: [n/m/p] indicates that ‘n’ randomly selected basidiospores from ‘m’ basidiomata of ‘p’ collections were measured, ‘avl’ means the average length of basidiospores, except for the extreme values, ‘avw’ refers to the average width of the basidiospores, except the extreme values, ‘Q’ represents the quotient of the length and width of a single basidiospore inside view, ‘Qm’ refers to the average Q value of all basidiospores ± standard deviation. Dimensions for basidiospores are given as (a)b–c(d). The range of b–c contains a minimum of 90% of the measured values. Extreme values (i.e., a and b) are given in parentheses.

Research methods of molecular systematics

Nomenclature

The electronic version in Portable Document Format (PDF) will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants. Hence the new names contained in the electronic version are effectively published under that Code from the electronic edition alone. In addition, new names contained in this work have been submitted to MycoBank from where they will be made available to the Global Names Index. The unique MycoBank number can be resolved and the associated information viewed through any standard web browser by appending the MycoBank number contained in this publication to the prefix “http://www.mycobank.org/MycoTaxo.aspx?Link=T&Rec=.”. The online version of this work is archived and available from the following digital repositories: PeerJ, PubMed Central, and CLOCKSS.

Phylogenetic analyses

In the dataset, 111 sequences derived from two gene loci (ITS and TEF1-α) from 35 samples were used to build phylogenetic trees; nine of these were newly generated, with six ITS sequences and three TEF1-α sequences. The phylogenetic construction performed via ML and BI analysis for the two combined datasets showed a similar topology (Figs. 2 and 3).

In the present study, six sequences of P. aletaiensis were gathered into a single branch along with high support (100/1). Pluteus aletaiensis is classified into the section Celluloderma, and sisters to P. siccus E.F. Malysheva, P. parvicarpus E.F. Malysheva, P. vellingae Justo, Ferisin, Ševčíková, Kaygusuz, G. Muñoz, Lebeuf & S.D. Russell, P. sublaevigatus (Singer) Menolli & Capelari and P. globiger Singer,. with a very high support rate (Fig. 2). The sequence of P. brunneidiscus and P. hongoi from Xinjiang Uygur Autonomous Region were gathered into the sect. Pluteus and formed independent clades with high support (Fig. 3).

Taxonomy

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

MycoBank No. MB 840297

(Figs. 4A–4E and 5)

Etymology. The epithet “Aletaiensis” refers to the Aletai Region, the location of the holotype.

Holotype. CHINA. Xinjiang Uygur Autonomous Region, Aletai Region, Aletai City, Cran River Valley, 47°50′14.66″N, 88°13′23.41″E, ASL 577 m, 14 September 2021, Z.X. Qi (HMJAU 60207), GenBank: OM992247.

Diagnosis. Pluteus aletaiensis differs from P. romellii by its bright brownish yellow, dark brownish-yellow in the middle of pileus, surface cover with white punctuations stipe, brittle texture. Microscopically, narrower pleuro- and cheilo-cystidia, a hymeniderm pileipellis, with globose to short-clavate, containing dark brown intracellular pigment.

Description

Basidiomata tiny to small size. Pileus 5–22.5 mm broad, initially paraboloid to hemispherical, later oblong hemispherical with an umbo, brownish-yellow when young (2.5YR 4/10), bright brownish yellow at maturity (7.5Y 6/12-7.5Y 8/14), dark brownish-yellow in the middle (7.5Y 5/8), not striated, with varying degrees of dehiscence at the margin at maturity. Context yellow, 0.5–1 mm thick. Lamellae close, bright yellow to yellowish (2.5Y 8/6-2.5Y 9/8), edges white (2.5Y 9/6), free, unequal, ventricose, 2–6 mm wide, entire. Stipe 4.5–25 mm long and 1.5–3 mm wide, central, slender, clavate, slightly thick and slightly curved at base, brittle, bright yellow to yellowish (2.5Y 8/6-2.5Y 9/8), with longitudinal striation, white punctuations, and white pruinose mycelium at the base. Spore print unknown.

Basidiospores [100, 12, 3] (5.5)6.0–7.5(8.0) × 5.5–6.5 (7) μm, avl = 7.0 μm, avw = 6.0 μm, Q = (1.08)1.09–1.20(1.24), Qm = 1.16 ± 0.05, globose, subglobose to broadly elliptical, slightly pinkish, thick-walled, smooth, non-dextrinoid, partially containing one droplet or irregular inclusions. Basidia 27–43 × 7–12(13) μm, fusiform to clavate, usually 4-sterigmate, 2–3 sterigmate occasional, thin-walled, and hyaline in KOH. Pleurocystidia 51–75(80) × (11)13–22(23) μm, abundance, subfusiform to vesicular, with short pedicels to broadly lageniform to obtuse at apices, thin-walled, and hyaline in KOH. Cheilocystidia 25–40 × (11)12–20 μm, abundant, clustered, vesiculose or pyriform to broadly fusoid-ventricose with pedicels short necks, with obtuse at apices, thin-walled, and hyaline in KOH. Pileipellis a hymeniderm, cells 15–43 × 10–34(35) μm, composed of globose to short-clavate cells, thin-walled, and hyaline in KOH, containing dark brown intracellular pigment, cells tightly adhering one to another. Stipitipellis a cutis of cylindrical hyphae, elements 5–17 μm wide, thin-walled, hyaline in KOH, septate, without apparent contents. Clamp connections absent in all tissues.

Ecology and distribution. Scattered on the ground in the broad-leaved forest (Populus alba var. pyramidalis Bge). Known from Xinjiang Uygur Autonomous Region of China.

Additional specimens examined. China. Xinjiang Uygur Autonomous Region, Aletai Region, Aletai City, Cran River Valley, 47°50′14.56″N, 88°13′23.45″E, ASL 580 m, 15 September 2021, Z.X. Qi, D.M. Wu, N. Gao & B.K. Cui, HMJAU 60208 (OM991943); Xinjiang Uygur Autonomous Region, Altay Region, Altay City, Cran River Valley, 47°50′14.69″N, 88°13′23.47″E, ASL 576 m, 16 September 2021, Z.X. Qi, D.M. Wu, N. Gao & B.K. Cui, HMJAU 60209 (OM992249).

Note. In our phylogenetic tree (Fig. 2), P. aletaiensis clustered with similar species of section Celulloderma and together with P. siccus P. parvicarpus, P. vellingae, P. sublaevigatus, and P. globiger with high support (Fig. 2). On phylogenetic trees, P. siccus display a close relationship to P. aletaiensis; morphologically, they are distinctly different, P. siccus (Ševčíková et al., 2022) is distinguishable from P. aletaiensis due to its slightly velvety pileus with a greenish hue, and smaller basidiospores (about 4.6–6.0 × (3.5–)4.5–5.5 µm), the polymorphic cheilocystidia, and grows on decaying wood and geographically distributed in the Russian Far East. P. parvicarpus (Ševčíková et al., 2022) could be distinguished from P. aletaiensis by its sulcate-striate at the margin of pileus, smaller basidiospores (about 4.5–6.0 × 4.2–5.5 µm), solitary on fallen branches of deciduous trees, and geographical distribution in the Russian Far East. P. aletaiensis and P. vellingae (Ševčíková et al., 2022) are both with yellow-brown to brown pileus and similar basidiospores. P. vellingae has broadly clavate to clavate or ovoid pleurocystidia, and it grows on coniferous or deciduous wood. P. sublaevigatus (Menolli, Asai & Capelari, 2010) differs from P. aletaiensis with its slightly rugulose at the center of the pileus, and translucently striate at the margin, free to subfree lamellae with lamellulae, and gregarious on decaying wood. P. aletaiensis and P. globiger (Singer & Digilio, 1952; Dias & Cortez, 2013) are both smaller pileus (diameter not more than 23 mm), but the lamellae of P. aletaiensis are bright yellow to yellowish, while P. globiger are greyish orange; on the other hand, P. globiger has ventricose of the cheilocystidia.

Morphologically, we excluded some relatively names species that are highly similar to P. aletaiensis, such as P. fulvibadius Murrill, P. romellii (Britzelm) Lapl., P. sternbergii Velenovský, and P. sulphureus Velenovský.

P. fulvibadius Murrill is also similar to P. aletaiensis. P. fulvibadius, which is widely distributed in the United States, has been reported by many mycologists (Murrill, 1917; Minnis, 2008; Minnis & Sundberg, 2010). P. fulvibadius differs from P. aletaiensis by its bigger pileus, which reaches 15–50 mm broad, slight to strongly rugose around the center, and translucently striate at the margin. In microfeatures, the pleurocystidia of P. fulvibadius are cylindrical-clavate; the pleurocystidia and the cheilocystidia are covered with an apical cap of amorphous mucilaginous material (Minnis, 2008; Minnis & Sundberg, 2010; Ševčíková et al., 2022).

P. romellii is easily confused with P. altaiensis due to its highly similar morphology, and a synonym of P. romellii is P. lutescens (Singer, 1956; Vellinga & Schreurs, 1985; Orton, 1986; Minnis, 2008). However, the pileus of P. aletaiensis is oblong hemispherical with an umbo, bright brownish yellow, dark brownish-yellow in the middle, while the color of P.romellii variable (date-brown, umber, or snuff-brown), glabrous, venation-like protrusions, and with translucent-striate at the margin; on the other hand, pleuro- and cheilo-cystidia of P. romellii are broader (52–62 × 14–30 μm and 23–61 × 12–36 μm respectively) than P. altaiensis (51–75(–80) × (11–)13–22(–23) μm and 25–40 × (11–)12–20 μm respectively) (Singer, 1956; Orton, 1986; Vellinga, 1990; Minnis, 2008). In the phylogenetic tree, P. romellii and P. altaiensis are not clustered in the same branch.

Ševčíková et al. obtained the molecular sequence of P. sternbergii (ON864116) and verified the position of P. sternbergii in the phylogenetic tree, not in the romellii clade, but in the cinereofuscus clade, therefore, selected collection PRM 154258 as the epitype of P. sternbergii. (Ševčíková et al., 2022). Morphologically, the basidiospores, basidia, pleurocystidia, and stipitipellis of P. aletaiensis and P. sternbergii are similar, while P. sternbergii grows in the stump of Populus.

For P. sulphureus, Ševčíková considers the specimens preserved in herbarium PRC (Velenovský no. 95!) as not belonging to the genus Pluteus (Ševčíková et al., 2022).

Pluteus brunneidiscus Murrill, N. Amer. Fl. (New York) 10(2): 131 (1917).

Syn.: Pluteus washingtonensis Murrill, N. Amer. Fl. (New York) 10(2): 135 (1917).

(Figs. 4F–4G and 6)

Description

Basidiomata large-sized. Pileus 68 mm broad, surface shiny and smooth, grayish brown to brownish brown (10.0YR 4/10-10.0YR 3/6), margin spreading to partially collapsed, uneven, entire, partly collapsed. Lamellae close, dirty white (10.0YR 9/2), turning dark brown at maturity (5.0YR 5/4), free, thick, unequal, slightly umbo. Stipe 79 mm × 8.5 mm, central, clavate, slightly wider at the base, fibrous, with longitudinal brownish (5.0YR 4/10) ciliate stripes, denser toward the base. Spore print unknown.

Basidiospores [60, 1, 1] (7.0)7.5–8.0(9.0) × 5.0–6.0 μm, avl = 8.0 μm, avw = 5.5 μm, Q = 1.16–1.50(1.60), Qm = 1.45 ± 0.10, broadly elliptical, oval to ovoid, slightly pinkish, slightly thick-walled, smooth, non-dextrinoid. Basidia 24–33 × 7–11(12) μm, clavate, 4-sterigmate, sterigmate short, less than 1 μm, thin-walled, and hyaline in KOH. Pleurocystidia 49–75(78) × (13)15–26 μm, mass, scattered, fusiform or narrowly fusiform to narrowly utriform, with 2–4 apical hooks (commonly entire), without small lateral hooks, hyaline, smooth, neck thickness up to 2–3 μm. Intermediate cystidia fusiform, poke-shaped, with pointed or flatter apices, without apical hooks, smaller than the pleurocystidia, thick-walled, hyaline. Cheilocystidia 38–60 × (11)12–15 μm, crowded, grouped to clustered, clavate or narrowly clavate to capitate, with obtuse at apices, thick-wall, and hyaline in KOH. Lamellar edge sterile. Pileipellis a cutis, with terminal elements 80–146 × 6–18 μm, individual elements cylindrical, some strongly tapering towards apex, mostly filled with brown intracellular pigment, thin-walled, smooth. Stipitipellis a cutis, hyphae 5–25 μm wide, cylindrical, hyaline or brown intracellular pigment, smooth, and thin-walled. Clamp connections absent in all tissues.

Ecology. Solitary or gregarious, growing on decayed wood (Betula, Umbellularia, Populus) or the humus layer under hardwoods or conifers in summer.

Distribution. Canada, Russia, USA, Turkey (Justo et al., 2014; Kaygusuz et al., 2021), and China (Xinjiang Uygur Autonomous Region)

Specimens examined. CHINA. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Zhaosu County, Shuimogou in Regiment 74, 43°12′50.69″N, 80°13′18.44″E, ASL 1764 m, 1 August 2021, Z.X. Qi, D.M. Wu, N. Gao & Y. Wang, HMJAU 60206 (OM991893, OM943513).

Note. Pluteus brunneidiscus and P. washingtonensis Murrill were first reported from USA (Murrill, 1917). However, Singer (1956), and Banerjee & Sundberg (1995) suggested that these two species may be the same. Singer (1986) cited P. washingtonensis as “probably conspecific with P. brunneidiscus” and with only one difference in the size of spores; besides, the spores of P. washingtonensis (about 6.5–9.6 × 5.3–7.1 µm) are slightly larger. Banerjee & Sundberg (1995) described the terminal elements on the pileipellis of P. brunneidiscus and P. washingtonensis as “versiform.” However, Justo & Castro (2007a) believe that the terminal elements were difficult to observe in the type collections. In modern collections, the shape of these elements was variable within the same basidiocarp and with the same range of variation observed. Therefore, they treated P. washingtonensis as synonymous with P. brunneidiscus. P. brunneidiscus in Europe was firstly described by Justo & Castro (2007a). In our study, P. brunneidiscus is reported as a new record in China.

In our phylogenetic analysis, P. brunneidiscus gathered into sect. Pluteus, with two other species—P. shikae Justo and E.F., P. kovalenkoi E.F.—in clade brunneidiscus. These three species can be distinguished from molecular data. Morphologically, many of their characters are rather variable, such as basidiospores and pleurocystidia with developed apical hooks. However, P. kovalenkoi can also be distinguished from P. brunneidiscus by the shape of pleurocystidia (Justo et al., 2014). We also compared other characters, as detailed in Table 2 (Justo et al., 2014; Kaygusuz et al., 2021).

The type specimen of P. brunneidiscus (Murrill, 1917) collected in Connecticut has a high similarity growth environment to our specimens, both in a temperate climate and autumn. We provide a detailed description of the morphological characteristics of P. brunneidiscus, which enriches Murrill’s (Murrill, 1917) report, such as the color variation of the pileus and the size range of the spores. At the same time, there are some differences. For example, the pileus of margin of our specimens has slightly sticky umbilical protrusions. They sometimes have translucent stripes at the pileus margin, while clamp connections are absent.

Pluteus hongoi Singer, Fieldiana, Bot. 21: 95 (1989).

Syn.: P. major Singer, Fieldiana, Bot. 21: 96 (1989);

Syn.: P. albineus Bonnard, Mycol. helv. 11(2): 131 (2001);

Syn.: P. nothopellitus Justo & M.L. Castro, Mycotaxon 102: 222 (2007).

(Figs. 4H–4I and 7)

Description

Basidiomata medium-sized. Pileus about 36.6 mm broad, flattened hemispherical, surface smooth and shiny, dark brown at the disc (7.5YR 4/2-7.5YR 6/2), becoming lighter toward the margin, margin transversely folded. Lamellae close, free, dense, folded, gray-white to earthy yellow (7.5YR 9/6-7.5YR 9/4), and slightly ventricose. Stipe 40 mm × 5.2 mm, central, subterete, fibrous, slightly expanded downward, white (7.5YR 9/2), smooth, with white longitudinally ciliate at the base. Spore print unknown.

Basidiospores [60, 1, 1] (7.0)8.0–9.5(10.0) × 5.5–6.5 μm, avl = 9.0 μm, avw = 6.0 μm, Q = 1.33–1.60(1.66), Qm = 1.50 ± 0.10, oval, pink, thin-walled, smooth, non-dextrinoid. Basidia 26–38 × 8–11 μm, clavate, usually 4-sterigmate, thin-walled, and hyaline in KOH. Pleurocystidia 55–83 × 14–23 μm, crowded, covering the whole side of the lamellae, flask-shaped to fusiform with 2–5 apical hooks (usually bifid), thick-walled, neck thickness up to 2–3 μm, hyaline in KOH. Cheilocystidia 29–57 × 12–20 μm, abundant, clavate or broad clavate to capitate, obtuse apices, hyaline, thick-walled. Pileipellis a cutis, with terminal elements 69–153 × 5–17 μm; individual elements cylindrical, some strongly tapering towards apex, mostly filled with brown intracellular pigment, smooth, and thin-walled. Stipitipellis a cutis, hyphae 5–19 μm wide, cylindrical, hyaline or brown intracellular pigment, smooth, and thin-walled. Clamp connections absent in all tissues.

Ecology. Solitary or scattered on rotten wood in mixed forests in summer and autumn.

Distribution. Japan, Spain, Russia, USA, Germany, Czech Republic, Slovakia, Republic of Korea, Turkey (Justo et al., 2014; Ševčíková, 2016; Kaygusuz et al., 2021), and China (Heilongjiang, Sichuan, Xinjiang Uygur Autonomous Region) (Xu, 2016).

Specimen examined. CHINA. Xinjiang Uygur Autonomous Region, Aletai Region, Aletai City, Wolong Bay in Kanas, 48°65′77.01″N, 87°03′82.11″E, ASL1333 m, 16 September 2021, Z.X. Qi, D.M. Wu, N. Gao & B.K. Cui, HMJAU60205 (OM302007).

Note. Singer (1989) first described P. hongoi and P. major Singer. Later, P. hongoi is recognized by Justo et al. (2014), because the original description of this taxon is more complete than P. major. Compared with our specimen, the type specimens (Singer, 1989) have smaller basidiospores, and the apical hook’s structure was often dehiscent.

Justo et al. (2014) studied the species belong to section Pluteus in the Holarctic region. They combined the molecular data based on type specimens of P. major, P. albineus Bonnard (Bonnard, 2001), and P. nothopellitus Justo & Castro (2007b) indicate that all these species represent different morphological variants of P. hongoi.

Pluteus hongoi was easily confused with P. cervinus. The pileus of P. cervinus (Murrill, 1917; Justo et al., 2014) was very variable in colors (brown, gray-brown, orange-brown, white), aspect of the pileus (with or without conspicuous squamules and radial fibrils) the stipe often had longitudinal and brown, or gray-brown fibers or scales, and the apical hooks structure (commonly entire) of the pleurocystidia. However, these features are variable and cannot be easily expressed on a basidiocarp (Justo et al., 2014). But they can be distinguished by sequences analyses.

Key to the reported species of Pluteus in Xinjiang Uyghur Autonomous Region

• 1. Metuloid cystidia...............................................................................................................................................2

• - Non-metuloid cystidia.........................................................................................................................................5

• 2. Pleurocystidia apical hooks commonly entire...................................................................................................3

• - Pleurocystidia apical hooks usually bifid..............................................................................................P. hongoi

• 3. With intermediate cystidia.................................................................................................................................4

• - Without intermediate cystidia...............................................................................................................P. pellitus

• 4. Stipe has longitudinal brown stripes, basidiospores (7.0)7.5–8.0(9.0) × 5.0–6.0, pleurocystidia 2–4 apical hooks..........................P. brunneidiscus

• - Stipe has continuous longitudinal brown fibrillose, basidiospores 5.5-8(-9) × 4.5-7, pleurocystidia 3–5 apical hooks....................................P. cervinus

• 5. Pileipellis a trichoderm.....................................................................................................................................6

• - Pileipellis a non-trichoderm................................................................................................................................7

• 6. Pileus black-brown.........................................................................................................................P. umbrosus

• - Pileus golden to dull or brownish yellow............................................................................................P. leoninus

• 7. Pleurocystidia and cheilocystidia with tapered apices....................................................................P. thomsonii

• - Pleurocystidia and cheilocystidia without tapered apices................................................................P. aletaiensis