Cortinarius subsalor and C. tibeticisalor spp. nov., two new species from the section Delibuti from China

Abstract

Cortinarius subsalor and C. tibeticisalor, belonging to the section Delibuti, are described from China as new to science. Cortinarius subsalor has been found to be associated with Lithocarpus trees in subtropical China and resembling C. salor, but it differs from the later by having slender basidiomata and the narrower basidiospores. Cortinarius tibeticisalor was collected from eastern Tibetan Plateau, associated with Abies. It differs from other species within sect. Delibuti by having olive tinge of mature or dried basidiomata and bigger basidiospores. The molecular data also support C. subsalor and C. tibeticisalor as new species. The phylogenetic analyses and biogeography of sect. Delibuti are discussed and a key to the species of this section currently known in the world is provided.

Introduction

Cortinarius (Pers.) Gray is an ectomycorrhizal fungal genus, associated with a wide host range of plants, such as Betulaceae, Caesalpiniaceae, Cistaceae, Dipterocarpaceae, Fagaceae, Myrtaceae, Pinaceae, Rhamnaceae, Rosaceae, Salicaceae and some herbaceous plants (Frøslev, Brandrud & Jeppesen, 2006; Niskanen, 2008). The genus is distributed worldwide with nearly 3,000 species (Niskanen et al., 2018; Ammirati et al., 2021; Bidaud et al., 2021). Even though it is the largest genus among macrofungi, its species diversity is still unclear. Most of Cortinarius species were originally discovered from Europe and America but rarely in Asia and Africa (Horak, 1983; Garrido-Benavent et al., 2020; Xie et al., 2020). Several systems of subgenus and sections in Cortinarius are erected based on the macromorphology of geographically limited samplings, but these are not supported by phylogenetic studies (e.g. Fries, 1838; Trog, 1844; Orton, 1955; Bidaud, Moënne-Loccoz & Reumaux, 1994; Garnica, Weiß & Oberwinkler, 2003; Garnica et al., 2005; Harrower et al., 2011; Stensrud et al., 2014; Niskanen et al., 2015; Garnica et al., 2016; Soop et al., 2019). For example, Garnica et al. (2005) proposed natural classification system in Cortinarius involving the taxonomic rearrangement of the species into eight informal clades. Soop et al. (2019) presented a section-based taxonomy of Cortinarius based on four loci of a large global sampling.

Cortinarius sect. Delibuti (Fr.) Sacc. with characteristics of viscid pileus and stipe, have usually been considered as a section in subg. Myxacium (Fr.) Trog (Trog, 1844; Earle, 1902; Orton, 1955; Brandrud et al., 1989; Consiglio, Antonini & Antonini, 2003). Delibuti species can easily be distinguished by the anomaloid appearances, mild taste and subglobose basidiospores from other myxacioid species (Orton, 1955; Soop, 2014). Section Delibuti was also considered to belong to subg. Phlegmacium (Fr.) Trog (Bidaud, Moënne-Loccoz & Reumaux, 1992; Bidaud, Moënne-Loccoz & Reumaux, 1994). Recently, Soop et al. (2019) treated sect. Delibuti among anomaloid sections, not in myxacioid sections based on the shared characters of sect. Delibuti and sect. Anomali Konrad & Maubl., together with support in the phylogenetic analyses. In the past, numeral species were assigned to section Delibuti (Fries, 1838; Earle, 1902; Bidaud, Moënne-Loccoz & Reumaux, 1992; Soop, 2013; Soop, 2014); however, most species have been confirmed not to belong to this section (Orton, 1955; Consiglio, 2012; Dima et al., 2016; Soop et al., 2019). Soop et al. (2019) defined only ten species in sect. Delibuti, but the phylogenetic studies showed that the species diversity of this section is still unrevealed (Harrower et al., 2011; Garnica et al., 2016; Soop et al., 2019).

In China, over 237 Cortinairus species, including several new species, have been described from China (Wei & Yao, 2013; Xie et al., 2019; Xie et al., 2020; Xie et al., 2021; Yuan et al., 2020; Luo & Bau, 2021). Four species within sect. Delibuti, C. betulinus J. Favre from Heilongjiang, C. delibutus Fr. from Heilongjiang, Jilin, Qinghai, Sichuan and Yunnan, C. illibatus Fr. from Ningxia, and C. salor Fr. from Heilongjiang, Jilin, Liaoning and Inner Mongolia, were reported (e.g. Teng, 1963; Yuan & Sun, 1995; Shao & Xiang, 1997; Li & Azbukina, 2011; Xie, 2018; Wang et al., 2020), but the occurrence of species in China is controversial due to the lack of voucher specimens.

In this study, we have conducted taxonomic and phylogenetic studies of Cortinairus in China. Some glutinously violet Cortinarius specimens resembling C. salor were found during the intensive field work but during the identification process they turned out to be new species which we describe here based on morphological and ecological characteristics, as well as phylogenetic analyses evidences. We also discuss the phylogenetic relationship and biogeography of sect. Delibuti. A key is provided the species of sect. Delibuti.

Materials & methods

Specimens and morphological description

Specimens were collected from Zhejiang Province and Tibet Autonomous Region, respectively. The collection sites in Zhejiang are the subtropical areas with the evergreen broadleaf forests dominated by Lithocarpus brevicaudatus. Meanwhile, the collection sites in Tibet are the plateau-alpine areas with coniferous forests dominated by Abies georgei var. smithii. Fresh basidiomata were photographed in the field. Dried specimens were deposited in the Herbarium of Mycology, Jilin Agricultural University (HMJAU), Changchun, China. Macroscopic characteristics were measured and recorded for every basidiomata and color codes followed Kornerup & Wanscher (1978). Microscopic features were examined and described in 5% KOH, Congo Red or Melzer’s reagent and observed using a Zeiss AX10 light microscope. Thirty to forty mature basidiospores were measured (excluding apiculus and ornamentation) per collection. Q = variation in the L/W ratios between the specimens studied. X_av. and Q_av. = average value of basidiospores of per specimen.

Phylogenetic reconstruction

DNA extraction, PCR amplifications, and sequencing methods followed Xie et al. (2019) and Guan & Zhao (2020). The primers ITS1F and ITS4 were used amplification of nrDNA ITS region (White et al., 1990; Gardes & Bruns, 1993). The newly generated ITS sequences were submitted to GenBank. The ITS sequences for the phylogenetic analyses were selected based on results of BLASTn (>90% identity) in GenBank and UNITE and followed the publication by Garnica et al. (2016) and Soop et al. (2019). Two species in section Cyanites Nespiak were chosen as outgroup followed Xie et al. (2021).

Sequences (Table 1) for the phylogenetic analyses were aligned and edited with BioEdit 7.1.3.0 and Clustal X (Thompson et al., 1997; Hall, 1999). For phylogenetic analyses, Bayesian Inference (BI), Maximum Likelihood (ML) and Maximum Parsimony (MP) methods were implemented in this study. MrModeltest 2.3 was used to calculate the best model (HKY+I+G) for BI analysis (Nylander et al., 2008). The BI analysis was performed with MrBayes 3.2.6 (Ronquist & Huelsenbeck, 2003). Four Markov chains were run for 500,000 generations until the split deviation frequency value < 0.01, and sampled every 100th generation. The posterior probability values were estimated from the samples after discarding the first 25% (1,250) generations. A 50% majority rule consensus tree of all remaining trees were calculated. RAxML v. 1.5, implemented in raxmlGUI, were used to construct a ML tree, with a rapid bootstrapping algorithm involving 1,000 replicates (Silvestro & Michalak, 2012; Stamatakis, 2014). All parameters in the ML analysis were kept as defaults except for GTRGAMMA were chose as the model. The MP analysis was conducted in MEGA X (Kumar et al., 2018). The most parsimonious tree with length = 1,012 is shown. The consistency index is (0.442350), the retention index is (0.708912), and the composite index is 0.355860 (0.313587) for all sites and parsimony-informative sites (in parentheses). The bootstrap test was performed 1,000 replicates (Felsenstein, 1985). The MP tree was obtained using the Tree-Bisection-Regrafting (TBR) algorithm (Nei & Kumar, 2000) with search level 3 in which the initial trees were obtained by the random addition of sequences (10 replicates). The phylogenetic trees were visualized in FigTree 1.4.3. The Bayesian posterior probabilities values (BPP) ≥ 0.95, ML bootstrap values (ML) ≥ 75% or MP bootstrap values (MP) ≥ 75% are shown on the branches at the nodes (BPP/ML/MP).

Table 1. ITS sequences used in the phylogenetic analyses.

Species	Voucher	Locality	Accession No.	References
C. acutovelatus	F16388 (UBC)	Canada	FJ039609	Harrower et al. (2011)
C. albocyaneus Epitype	CFP1177 (S)	Sweden, Jämtland	KX302206	Dima et al. (2016)
C. alpinus	HMJAU44407	China, Inner Mongolia	MW911727	This study
C. anomalus Neotype	CFP1154 (S)	Sweden, Ångermanland	KX302224	Dima et al. (2016)
C. basipurpureus	PERTH 04259629	Australia	AY669607	Garnica et al. (2005)
C. bolaris	TUB 0118524	Germany	AY669596	Garnica et al. (2005)
C. boreicyanites Holotype	CFP931 (S)	Sweden, Jämtland	NR130214	Liimatainen et al. (2014)
C. calaisopus	60224 (OTA)	New Zealand	MN846380	GenBank
C. calaisopus Holotype	PDD 94050	New Zealand, Dunedin	NR157880	GenBank
C. camphoratus	DAVFP26155	Canada	EU821659	Harrower et al. (2011)
C. camphoratus	SMI193	Canada	FJ039626	Harrower et al. (2011)
C. carneoroseus	EN76 (CORD)	Argentina	JX983157	GenBank
C. collinitus	IB 19940257	Sweden	AY033096	Peintner et al. (2002)
C. croceocoeruleus	TUB 011833	Germany	AY669590	Garnica et al. (2005)
C. cyanites Neotype	AT2005069 (UPS)	Sweden, Uppland	NR130233	Liimatainen et al. (2014)
C. cypripedi Holotype	PDD 107723	New Zealand, Otago	KT875199	Soop (2016)
C. cystidiocatenatus	HO A20518A6	Australia, Tasmania	AY669651	Garnica et al. (2005)
C. delibutus	F17048 (UBC)	Canada	FJ717515	Harrower et al. (2011)
C. delibutus	SAT01-301-12	USA	FJ717513	Harrower et al. (2011)
C. durifoliorum Holotype	PDD 101829	New Zealand, Westland	KJ635210	Soop, Wallace & Dima (2018)
C. eunomalus	PDD 107706	New Zealand	KT875201	GenBank
C. illibatus	HMJAU48760	China, Heilongjiang	MW911735	This study
C. illibatus	AT2004220 (UPS)	Sweden	UDB002173	UNITE
C. illitus Holotype	IB 19630414	Argentina	AF389128	Peintner, Moncalvo & Vilgalys (2004)
C. illitus	MQ19-CMMF003109	Canada, Quebec	MN751331	GenBank
C. illuminus Neotype	F44877 (S)	Sweden	KP866156	Niskanen et al. (2015)
C. khinganensis Holotype	HMJAU44507	China, Inner Mongolia	MT299952	Xie et al. (2021)
C. microglobisporus Holotype	IB 20110123	Italy	NR153027	Peintner et al. (2014)
C. obtusus	SAT00-298-30	USA	FJ717550	Harrower et al. (2011)
C. phlegmophorus	Typus-M3	India	AY083186	Peintner et al. (2003)
C. pluvius	HMJAU44391	China, Inner Mongolia	MW911726	This study
C. porphyroideus	61406 (OTA)	New Zealand	JX178612	Teasdale et al. (2013)
C. pseudocandelaris	F17165 OC93 (UBC)	Canada, BC	GQ159908	Harrower et al. (2011)
C. psilomorphus Holotype	PDD 103885	New Zealand	KF727393	Soop (2016)
C. putorius Holotype	TN 07-411 (H)	USA	NR153038	Ariyawansa et al. (2015)
C. pyrenaicus	JB-8573/15	Spain, Gisclareny	KX239900	Cadiñanos, Gomez & Ballarà (2016)
C. rattinoides Holotype	PDD 88283	New Zealand	JX000375	GenBank
C. rotundisporus	PERTH 05255074	Australia	AY669612	Garnica et al. (2005)
C. rotundisporus	G12	Australia	AF136738	Sawyer, Chambers & Cairney (1999)
C. salor	IB 19940297	Austria	UDB001066	Peintner et al. (2001)
C. salor	TUB 011838	Germany	AY669592	Garnica et al. (2005)
C. salor II	TUF106868	Estonia	UDB011268	UNITE
C. salor II	TAAM128516	Estonia	UDB015945	UNITE
C. septentrionalis	ARAN Fungi03516	Sweden, Harjedalen	KX239915	Cadiñanos, Gomez & Ballarà (2016)
C. spilomeus Neotype	TEB CFP1137 (S)	Sweden	KX302267	Dima et al. (2016)
C. stillatitus	TUB 011587	Germany	AY669589	Garnica et al. (2005)
C. subsalor	HMJAU48758	China, Zhejiang	MW911733	This study
C. subsalor Holotype	HMJAU48759	China, Zhejiang	MW911734	This study
C. subsalor	MHHNU 30409	China, Hunan	MK250915	GenBank
C. suecicolor Holotype	PDD 74698	New Zealand	JX000360	GenBank
C. tabularis Epitype	CFP949 (S)	Sweden	KX302275	Dima et al. (2016)
C. tasmacamphoratus	HO A20606A0	Tasmania	AY669633	Garnica et al. (2005)
C. tessiae	PDD 94054	New Zealand, Dunedin	JQ287698	GenBank
C. tessiae	PDD 72611	New Zealand	HM060317	GenBank
C. tibeticisalor	HMJAU48761	China, Tibet	MW911731	This study
C. tibeticisalor	HMJAU48762	China, Tibet	MW911732	This study
C. tibeticisalor	HMJAU48763	China, Tibet	MW911730	This study
C. tibeticisalor Holotype	HMJAU48764	China, Tibet	MW911729	This study
C. vanduzerensis	VMS28	Canada	FJ717562	Harrower et al. (2011)
C. vibratilis	IB 19970078	USA	AF325584	Peintner et al. (2001)
C. sp.	CSU CO 2476	Colombia, Antioquia	MF599228	GenBank
C. sp.	FLAS-F-60161	USA	MF153022	GenBank
C. sp.	YM714	Japan, Hokkaido	LC175538	GenBank
C. sp.	1780	Italy	JF907917	Osmundson et al. (2013)
C. sp.	SWUBC500	Canada	DQ481723	Wright, Berch & Berbee (2009)
C. sp.	PDD 72685	New Zealand	MH101524	GenBank

Note:

New species is in bold.

Nomenclature

The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Code of Nomenclature for algae, fungi, and plants, and 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.

Results

BLASTn results

The BLASTn against GenBank and UNITE databases taked the holotype specimens as the examples. The BLASTn results showed that these two new species distinct from other members of Cortinarius and close to sect. Delibuti. The ITS sequence of C. subsalor (MW911734, holotype) has 99% identity with C. salor (MK250915). Here we addressed it as C. subsalor. The percent identity of C. subsalor with C. salor s.l. (AY669592, UDB015945) and C. delibutus (FJ717515) are 96% and 95%, respectively. The ITS sequence of C. tibeticisalor (MW911729, holotype) has 93%, 91%, 90% identity with Cortinarius sp. (LC098750), C. delibutus (FJ717515) and C. tessiae (JQ287698), respectively.

Phylogenetic analyses

The matrix contained 66 ITS sequences with 767 nucleotide sites is available from TreeBASE under S28399 (https://www.treebase.org/treebase-web/search/study/summary.html?id=28399). The BI, ML and MP results showed similar topologies and ML tree was selected as the backbone phylogeny (Fig. 1). The phylogenetic analyses showed 11 sections including one singleton species from Argentina, and two singletons from New Zealand. Every section formed separate monophyletic lineages with strong statistical support. Section Delibuti formed a distinct clade (BPP = 0.96) separate from other sections. Section Delibuti split into five main clades based on the analyses of ITS sequences. Clade A and B consist of Australasian species. Clade C is a clade including our new species from the Tibetan Plateau. Clade D consist of the species distributed in Europe, Asia and North and South America. Clade E represents species in the Northern Hemisphere. Cortinarius subsalor (BPP/ML/MP = 1.00/100%/100%, clade E) and C. tibeticisalor (BPP/ML/MP = 1.00/100%/100%, clade C) formed a dinstinct lineages with high statistical support, respectively. Furthermore, C. subsalor formed a sister relationship with the European C. salor (BPP = 0.97, clade E).

Figure 1. ML phylogram inferred from nrDNA ITS sequence data.

The tree is rooted with sect. Cyanites. The Bayesian posterior probabilities (BPP) ≥ 0.95, ML bootstrap values (ML) ≥ 75% and MP bootstrap values (MP) ≥ 75% are shown on the branches (BPP/ML/MP). New species is marked by blue bold.

Taxonomy

Cortinarius subsalor M.L. Xie, T.Z. Wei & Y. Li, sp. nov.

MycoBank No. MB839320

(Fig. 2)

Figure 2. Cortinarius susalor.

(A) HMJAU48759 (Holotype). (B) HMJAU48758. (C, E) Basidiospores (HMJAU48759). (D, F) Pileipellis (HMJAU48759). (Photo credits: (A) Jun-Liang Chen; (B)–(F) Meng-Le Xie).

Etymology. The name refers to its affinity to Cortinarius salor.

Holotype. CHINA. Zhejiang: Baishanzu Mountain, Qingyuan county, on moist soil under Lithocarpus brevicaudatus (Fagaceae) forest with scattered Theaceae and Rhododendron, 27°45′44″N, 119°11′50″E, ASL 1,510 m, 20 July 2020, Jun-Liang Chen, QY-0235(1192-1198) (HMJAU48759), GenBank: MW911734.

Diagnosis. Pileus hemispherical to plane, violet, glutinous; lamellae violet at first, then turning pale grayish violet; stipe slender, pale violet, then brown; glutinous veil violet. Basidiospores on average 8.0–8.3 × 6.9–7.0 µm, subglobose to broadly ellipsoid. Differing from other species in sect. Delituti by the violet color of basidiomata, the distribution of subtropical China and association with Lithocarpus brevicaudatus.

Description

Pileus 20–50 mm, hemispherical at first, then convex to applanate; bluish violet (18B6-18C7) at first, purple (15B6-15C7) to purplish red (14A6-14B7) at the centre, then grayish violet (17B4-17C5), pale violet (19A3) at the margin; surface glutinous. Lamellae emarginate; moderately crowded; violet (17B6) when young, then grayish violet (17B4-17C5) to pale grayish violet (15B1-15C2); edge almost even. Stipe slender, 35–65 mm long, 3–7 mm thick, clavate at base (up to 14 mm); pale violet to grayish violet (19A3-19B5), later whitish, lightly brown to brown (7D6-7E7); surface with viscid universal veil, basal mycelium white with bluish tinge. Universal veil viscid, violet, remnants forming a girdle on the upper part of the stipe, disappearing with age. Context whitish at the pileus, slightly with yellowish tinge at the center, pale violet tinge extend outward, hygrophanous near lamellae; white with pale violet tinge at the apex of the stipe, yellow at the lower part; somewhat hollow within stipe. Odor not significant, taste mild.

Basidiospores 7.7–9.5 (10.6) × 6.2–7.7 (8.7) µm, Q = 1.10–1.29 (holotype), X_av. = 8.0–8.3 × 6.9–7.0 µm, Q_av. = 1.20, subglobose to broadly ellipsoid, moderately coarsely verrucose, moderately dextrinoid. Basidia 4-spored. Lamellar edges fertile. Pileipellis: epicutis strongly gelatinous, about 180–250 µm thick, with hyphae 2–7 µm wide, yellowish to colorless in 5% KOH, some hyphae with small encrusted granules. Hypodermium present; hypodermial hyphae 4–10 µm wide, cylindrical, almost colorless in 5% KOH, smooth. Clamp connections present.

Exsiccatae. Pileus grayish violet (19B3-19C4) at the margin, light brown to dark brown (6D6-6F8) at the centre; lamellae rust brown (6E8); stipe brown (6D7-6E7), lighter downwards, yellowish white (4A2) at base.

ITS sequence. The ITS sequence of the holotype is distinct from other members of sect. Delibuti and deviating from them by at least 22 substitutions and indel positions.

Ecology and distribution. In subtropical evergreen broadleaf forests, associated with Lithocarpus brevicaudatus (Fagaceae). Known from Zhejiang and Hunan province of China.

Additional specimens examined. CHINA. Zhejiang: Baishanzu Mountain, Qingyuan county, on moist soil under Lithocarpus brevicaudatus (Fagaceae) forest with scattered Theaceae and Rhododendron, 27°45′55″N, 119°11′0″E, ASL 1500 m, 20 August 2020, Meng-Le Xie, 20xml12101 (HMJAU48758), GenBank: MW911733.

Cortinarius tibeticisalor M.L. Xie, T.Z. Wei & Y. Li, sp. nov.

MycoBank No. MB839321

(Fig. 3)

Figure 3. Cortinarius tibeticisalor.

(A) HMJAU48764 (Holotype). (B) HMJAU48762. (C, E) Basidiospores (HMJAU48764). (D, F) Pileipellis (HMJAU48764). (Photo credits: Meng-Le Xie).

Etymology. The name refers to the Tibetan Plateau, the type locality, and its similarity to C. salor.

Holotype. CHINA. Tibet Autonomous Region: Sejila Mountain, Linzhi city, on moist soil in Abies forest with scattered Rhododendron, 29°35′26″N, 94°35′53″E, ASL 4120 m, 5 September 2020, Meng-Le Xie, 20xml12416 (HMJAU48764), GenBank: MW911729.

Diagnosis. Pileus hemispherical to applanate, violet, glutinous, margin wavy, somewhat olive when mature; lamellae for a long time violet, then pale grayish violet to violet gray; stipe robust, bluish gray to brown with olive tinge; veil glutinous, violet. Basidiospores on average 10.3–10.8 × 8.7–8.9 µm, subglobose to broadly ellipsoid, rarely ellipsoid. Differing from other species in sect. Delituti by the olive tinge of basidiomata and the large basidiospores.

Description

Pileus 50–85 mm, hemispherical at first, then convex to plane, sometimes slightly depressed, wavy at margin of mature basidiomata, violet (17C7) at first, especially at the centre, paler violet towards the margin, then grayish orange (5B5) to brown (5D6-5E7) with olive tinge, dark at the centre; surface glutinous. Lamellae emarginate, moderately crowded, persistently violet (17C7), then grayish violet (19B4-19C6) to violet gray (19B2); edge uneven, slightly serrate. Stipe 85–120 mm long, 10–15 mm thick, clavate at base (up to 23 mm); surface with viscid bluish gray (19B2) universal veil remnants, then becoming yellow to brown with olive tinge (4B6-4D7), grayish violet (19B4-19C6) at the apex; basal mycelium white. Universal veil viscid, violet, remnants forming a girdle on the upper part of the stipe, dispearing with age. Context white with marbled violet tinge at first, slightly yellowish from the center of the pileus, then yellow at the stipe, especially at the middle. Odor weak when fresh, somewhat like honey when old or dry. Taste mild.

Basidiospores 9.7–10.9 (12.6) × 7.7–9.0 (10.0) µm, Q = 1.13–1.30 (holotype), X_av. = 10.3–10.8 × 8.7–8.9 µm, Q_av. = 1.20–1.23, subglobose to broadly ellipsoid, rarely ellipsoid, moderately coarsely verrucose, weakly dextrinoid. Basidia 4-spored. Lamellar edges fertile, with narrow clavate cells. Pileipellis: epicutis strongly gelatinous, about 300–410 µm thick, hyphae 3–8 µm wide, with yellowish intracellular pigment in 5% KOH, smooth. Hypodermium present, hyphae 7–15 µm wide, irregular, almost colorless in 5% KOH, smooth. Clamp connections present.

Exsiccatae. Pileus olive brown (4E6-4F7) at margin, yellowish brown (5D7-5E8) at centre; lamellae dark bluish gray (19E2-19F2); stipe bluish white at apex, light brown (6D6-6E7) to dark brown (6F4-6F8), white at base.

ITS sequence. The ITS sequence of the holotype is distinct from other members of sect. Delibuti and deviating from them by at least 40 substitutions and indel positions.

Ecology and distribution. In plateau-alpine coniferous forests, associated with Abies (Pinaceae) trees. Known from Tibetan Plateau of China.

Additional specimens examined. CHINA. Tibet Autonomous Region: Sejila Mountain, Linzhi city, on moist soil under Abies forest with scattered Rhododendron, 29°35′25″N, 94°35′55″E, ASL 4170 m, 28 August 2019, Meng-Le Xie, 19xml10976 (HMJAU48761), GenBank MW911731, 19xml10981 (HMJAU48762), GenBank MW911732; Sejila Mountain, Linzhi city, on moist soil under Abies forest with scattered Rhododendron, 29°35′26″ N, 94°35′53″E, ASL 4120 m, 5 September 2020, Meng-Le Xie, 20xml12395 (HMJAU48763), GenBank: MW911730.

Key to species of sect. Delibuti

• 1 Distributed in Northern Hemisphere 2

• - Distributed in Southern Hemiphere 9

• 2. Pileus usually yellowish to ochraceous without blue 3

• - Pileus more or less violet to blue when young, sometimes partly yellow 4

• 3. Lamellae usually blue when young, veil yellowish C. delibutus

• - Lamellae pinkish ochraceous clay, veil not yellowish C. illibatus

• 4. Pileus frankly blue when young, stipe bluish, veil violet 5

• - Pileus grayish blue to olive brown, stipe pale, veil different 7

• 5. Basidiomata usually small, lamellae violet, then grayish to brownish, stipe usually slender (< 10 mm), base white with bluish tinge, basidiospores on average 8.0–8.3 × 6.9–7.0 µm, subglobose to broadly ellipsoid, distributed in subtropical China, associated with Lithocarpus brevicaudatus C. subsalor

• - Basidiomata usually bigger, lamellae persistently lilaceous or bluish, stipe usually more robust (> 10 mm thick) 6

• 6. Pileus usually staining buff or fading from the centre, stipe base usually grayish brown, basidiospores 7–9 × 6–8 µm, globose to subglobose, distributed in Europue, associated with deciduous and coniferous trees C. salor

• - Pileus usually olive brown when mature, stipe base usually white, basidiospores 10.3–10.8 × 8.7–8.9 µm, subglobose to broadly ellipsoid, rarely ellipsoid, distributed in Tibetan Plateau of China, associated with Abies C. tibeticisalor

• 7. Basidiomata small, pileus yellow to olive-ochre at the centre, grayish blue towards the margin, soon fading, veil yellow, basidiospores 7.5–9.5 × 6.5–7.5 µm, subglobose, associated with Betula . C. betulinus

• - Basidiomata robust, associated with coniferous forests 8

• 8. Pileus usually olive brown with a violet margin, veil olive brown, basidiospores 8–10 × 7–8 µm, globose, associated with Picea C. transiens

• - Pileus not olive brown, but prefer orange tinge, basidiospores 7.5–9.5×6.5–7.5 µm, subglobose, usually associated with Abies, rarely occur in Picea forests C. largodelibutus

• 9. Associated with Nothofagus 10

• - Associated with Myrtaceae trees 11

• 10. Pileus viscid, blue-green to aerugineous, stipe blue green, basidiospores 6.5–8.5 × 6–7 µm, subglobose, destributed in Australasia C. tessiae

• - Pileus glutinous, greyish yellow to greyish orange, stipe violet, then becoming white to pale brownish, basidiospores ellipsoid, destributed in North and South America C. illitus

• 11. Basidiomata distinctly viscid to glutinous, mainly greyish blue-green, basidiospores 7–9 × 7–8 µm, globose to subglobose C. rotundisporus

• - Basidiomata weakly viscid, stipe often dry, mainly yellow-green to olive, Veil orange to ochraceous, basidiospores 6–7.5 × 5.5–6.5 µm, subglobose C. calaisopus

Discussion

Cortinarius subsalor is similar to C. betulinus, C. salor and C. transiens (Melot) Soop due to the bluish tinge of the basiodiomata. However, C. betulinus is usually grayish blue at the margin of the pileus and soon fading, the stipe is often pale and the veil usually is yellow (Kibby, 2005; Niskanen et al., 2008; Soop, 2014). The pileus of C. transiens has a violet tone towards the margin, while the centre is more olive gray to yellowish brown even in young specimens, the stipe is pale, and the gelatinous veil is olive brown (Soop, 1990, 2014). In China, sometimes some bluish myxacioid species have been misidentified as C. salor (MHHNU30409, GenBank: MK250915), collected from Hunan Province. Our phylogenetic analyses showed that this sequence belong to the new species C. subsalor. Cortinarius salor has persistently lilaceous lamellae, the stipe is more robust (>10 mm thick) and the base is more grayish brown, the basidiospores are rounder (7–9 × 6–8 µm), and it occurs in European woodlands (Orton, 1955; Consiglio, Antonini & Antonini, 2003; Soop, 2014). Based on these features, C. salor can be distinguished from the Asian C. subsalor.

Cortinarius tibeticisalor is characterized by the basidiomata usually violet when young, then grayish orange to brown with an olive tinge, larger basidiospores and a restricted distribution in the Tibetan Plateau. Cortinarius tibeticisalor is similar to C. salor in young stage, however, the basidiospores (7–9 × 6–8 µm) of C. salor are significantly smaller and rounder, and the basidiomata never have olive tinge (Orton, 1955; Consiglio, Antonini & Antonini, 2003; Soop, 2014).

According to our phylogenetic analyses, sect. Delibuti demonstrates a widely distributed lineage of Cortinarius, in both the Northern and Southern Hemispheres. This bihemispherical distribution is also seen in several other lineages in Cortinarius, such as Anomali, Bolares, Camphorati, Defibulati, Illumini, and Vibratiles, this is concordant with other studies (e.g. Harrower et al., 2015; Garnica et al., 2016; Soop et al., 2019). The nrDNA ITS region is not suitable to draw conclusions for comprehensive phylogenetic evaluation, however, there are some interesting patterns indicated in sect. Delibuti to be further discussed. The basal lineages (clade A and B) of Delibuti are solely distributed in the Australasia showing a presumable origin of this section in Australasia. Interestingly, clade D contains species from multiple continents in the Northern and Southern Hemispheres. Some species are distributed in Asia (Cortinarius sp., LC175538), in Europe (Cortinarius sp., JF907917), and South America, like Cortinarius sp. (MF599228) from Colombia and C. illitus Moser & Horak (1975) originally described from Argentina, but also found in North America (according to the sequences in GenBank).These patterns could explain that the evolution of sect. Delibuti is limited to the ectomycorrhizal host specificity, as well as geographic barriers (Wang & Qiu, 2006; Brandrud, 1996; Wilson, Hosaka & Mueller, 2017; Feng et al., 2016). The evolution and origin of sect. Delibuti, including the genus Cortinarius will be a subject for future research.

Funding Statement

This study was supported by the China Agriculture Research System (No. CARS20), Overseas Expertise Introduction Project for Discipline Innovation (No. D17014), National Natural Science Foundation of China (No. 31270072), the Special Funds for the Young Scholars of Taxonomy of the Chinese Academy of Sciences (No. ZSBR-001), the National Key Research and Development program of China (No. 2019YFC1604703). The work of Bálint Dima was supported by the ELTE Thematic Excellence Program 2020 (TKP2020-IKA-05) financed by the National Research, Development and Innovation Office. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.