All specimens have been deposited in the National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control (NIOHP, China CDC). Macro-morphological descriptions were based on field notes and dried specimens. Microscopic features were examined and described in 5% KOH, Congo Red, or Melzer’s reagent and observed under a Nikon Eclipse 80i microscope (Nikon, Tokyo, Japan) with a magnification of up to ×1,000. Thirty basidiospores were measured per collection (excluding apiculus and ornamentation), and the averages (av. X) and quotients (av. Q = L/B) were calculated. Color terms are cited from Anonymous (1969) as well as Kornerup and Wanscher (1978).

A Phire^® Plant Direct PCR Kit (Finnzymes Oy, Finland) was used to obtain PCR products from dried specimens, according to the manufacturer’s instructions and as described previously by Li et al. (2015), with some modifications. The following primer pairs were used to amplify the internal transcribed spacer (ITS): ITS5 (5′‐GGA AGT AAA AGT CGT AAC AAG G‐3′) and ITS4 (5′‐TCC TCC GCT TAT TGATAT GC‐3′) (White et al., 1990). The PCR procedure was as follows: initial denaturation at 98 °C for 5 min, followed by 35 cycles at 98 °C for 5 s, 58 °C for 5 s, and 72 °C for 5 s, and a final extension of 72 °C for 10 min. The PCR products were purified and sequenced by Sangon Biotech, China. The newly generated sequences from this study have been deposited in GenBank and are listed in Table 1 .

New sequences generated in this study and additional sequences retrieved from GenBank ( Table 1 ) were aligned using BioEdit 7.0.5.3 (Hall, 1999) and ClustalX 1.83 (Thompson et al., 1997), followed by manual adjustments. Sequences of Cortinarius bolaris (sect. Bolares) were used as outgroups (Hughes et al., 2009; Dima et al., 2021). The maximum likelihood (ML) and Bayesian inference (BI) methods were used for the phylogenetic analysis. The best-fit model was selected by ModelFinder (Kalyaanamoorthy et al., 2017), adopting Akaike information criterion (AIC). The ML analysis was carried out using RAxML 8.2.12 (Stamatakis, 2006; Silvestro and Michalak, 2012), and the BI tree reconstruction was reconstructed using MrBayes 3.2.5 (Ronquist et al., 2012). Four Markov chains were run for two runs from random starting trees for 10 million generations, and the trees were sampled every 1,000 generations. The burn-in was set to discard 25% of the trees. A majority rule consensus tree of all remaining trees was calculated. The sequence alignment was deposited at TreeBase (submission ID: 30414). Branches that received bootstrap supports for ML and Bayesian posterior probabilities (BPP) greater than or equal to 75% (ML) and 0.95 (BPP) were considered significantly supported.

The ITS dataset comprised 229 fungal collections representing approximately 81 taxa of the genus Cortinarius. ModelFinder suggested that GTR + I + G was the best-fit model of nucleotide evolution for BI. The Bayesian analysis resulted in a concordant topology with an average standard deviation of split frequencies of 0.005575. The ML and BI analyses resulted in nearly identical topologies, and thus only the ML tree is presented with the bootstrap supports for ML and BPP when they were greater than or equal to 50% and 0.90, respectively.

Our phylogeny, which is inferred from ITS sequences ( Figure 1 ), is similar to those of Dima et al (Dima et al., 2016; Dima et al., 2021). The phylogenetic analysis showed five sections, and each section formed separate monophyletic lineages with strong statistical support. Section Anomali formed a distinct highly supported clade (ML = 99 and BPP = 1) and was separated from other sections. Three new species, namely, C. cinnamomeolilacinus (ML = 98 and BPP = 1), C. subclackamasensis (ML = 86 and BPP = 0.99), and C. tropicus (ML = 100 and BPP = 1), nested within the sect. Anomali clade, and formed an independent lineage with high statistical supports, respectively. It is worth noting that collections of C. cinnamomeolilacinus had genetic distances in our phylogeny. However, there were only four base pair differences between them, which were below 1.5% nucleotide differences in the ITS regions. Morphologically, there were no obvious differences of these C. cinnamomeolilacinus collections.

Cortinarius cinnamomeolilacinus Q.Y. Zhang, Jing Si & Hai J. Li, sp. nov. Figure 2 .

MycoBank: 848613

Diagnosis. — This species is characterized by its small basidiomata, more or less hygrophanous, lilac pileal surface with cinnamon buff to brownish cinnamon center, and pale gray to whitish toward margin, subglobose to broadly ellipsoid basidiospores (7−8.5 × 5.8−6.8 μm); it is gregarious on ground dominant with Fagaceae or Pinaceae.

Type. — China, Yunnan Province, Baoshan, Tengchong, Wuhe Town, Lushan, Alt: 1989 m, N: 24°54′06.98″, E: 98°36′30.37″, on ground dominant with Fagaceae, 8 August 2016, TCWH 007 (holotype), and GenBank accession number for ITS: OQ913384.

Etymology. — cinnamomeolilacinus refers to its more or less lilac pileal surface with a cinnamon center.

Habitat and distribution. — Scattered or gregarious on ground dominant with Fagaceae or Pinaceae. Currently, it is only found in tropical Guizhou and Yunnan (nine collections) in summer and autumn.

Macrostructures. — Basidiomata small. Pileus 15−52 mm in diam., hemispheric when young, then convex to plano-convex, some with a low umbo, margin narrowly when young, surface smooth to finely felty, color evenly pale silvery gray to lilac [15A(2−4)], the disc slightly more brownish, cinnamon buff, cinnamon to brownish cinnamon [5B(4−5)], pale gray to whitish (1A1−1B1) toward margin, even to rugulose, hygrophanous. Lamellae adnate with decurrent tooth to slightly adnexed, close, violet (16A4−16A5) when young, then grayish violet [16B4−16C5], pale silvery gray to pale drab gray (16B2−16D2), finally pale brown to cinnamon [6D(4−8)]. Stipe 30- to 70- mm long, apex 4−6 mm in diam., and base 5−10 mm in diam., usually clavate to cylindrical, even or slightly bulbous at base, fragile, shiny, covered with white fibrillose, apex violet [16A(4−5)] when young, later pale brownish (6B2−6D2), other part pale silvery gray [15A(2−3)], pale white veil (1A2) usually sparse, forming yellow [3A(3−4)] floccose-girdles on the stipe, often becoming pale yellow [4B(3−5)], sometimes indistinct, basal mycelium white (1A1). Context in pileus solid, firm, sometimes hollow in stipe, pale silvery gray [16B4−16C5] when fresh, finally pale brown to cinnamon in age [6D(4−8)]. Odor and taste of context strongly fungoid.

Microstructures. — Basidiospores [150/5/5] (6.8−) 7−8.5 (−8.8) × (5.5−) 5.8−6.8 (−7) μm, av. 7.7 × 6.1 μm, Q = 1.22−1.29, av. Q = 1.26, subglobose to broadly ellipsoid, buff to cinnamon-buff, coarsely verrucose, non-dextrinoid. Basidia 4-spored, 29−33 × 6−7 μm, clavate, colorless, or yellowish. Lamella trama hyphae smooth, parallel, 5- to 12- μm wide. Lamellae edge fertile, with some small clavate sterile cells. Pileipellis duplex: Epicutis thin to ± well developed, hyphae ± cylindrical, moderately to strongly interwoven, 5- to 8- μm wide, hyaline or yellowish, smooth to encrusted; hypocutis ± cellular or hyphae more interwoven and radially arranged, cylindrical to enlarged, hyaline to yellowish, smooth to encrusted, (3.5) 4−18 (20) μm wide. Clamp connections present.

Remarks. — Cortinarius albomalus Liimat. & Niskanen and C. cinnamomeolilacinus have similar basidiomata. However, C. albomalus has smaller basidiospores (6.5−7.5 × 5.5−6 µm) and is distributed in North America (Dima et al., 2021; Liimatainen and Niskanen, 2021). Cortinarius pastoralis Soop, H. Lindstr., Dima, Niskanen, Liimat. & Kytöv. and C. cinnamomeolilacinus share pale buff or brownish pilei, but C. pastoralis has larger basidiospores (8.5−9 × 7−8 μm; Dima et al., 2016). Cortinarius albocyaneus Fr. is similar to C. cinnamomeolilacinus with grayish ochraceous to whitish pilei, but C. albocyaneus has larger basidiomata (40−70 mm) and basidiospores (8.5−9.0 × 6.0−7.5 μm), is found in Europe, and is common in northeastern North America (Dima et al., 2021). Cortinarius anomalovelatus Ammirati, Berbee, E. Harrower, Liimat. & Niskanen has grayish-to-white basidiomata and subglobose to broadly ellipsoid basidiospores, which are similar to those of C. cinnamomeolilacinus, but C. anomalovelatus has a heavier universal veil and a grayish-blue to violet pileal surface, and is usually found in western North America (Dima et al., 2021).

Additional specimens (paratypes) examined. — China, Guizhou Province, Liupanshui, Lingshan Temple, on ground of Fagaceae, Alt: 1929 m, N: 26°37′35.94″, E: 104°48′54.95″, October 15, 2016, Li 161015-10; Yunnan Province, Baoshan, Longling County, Longjiang Town, Laohuangtian, on ground dominant with Fagaceae, Alt: 1773 m, N: 24°41′31.01″, E: 98°42′55.24″, 5 August 2017, LLLJ 20170805-002; Longyang District, Wafang Town, Dapingdi, on ground of Pinus yunnanensis, Alt: 1921.9 m, N: 25°21′35.82″, E: 99°4′45.73″, 6 August 2018, LYWF015; Tengchong, Mangbang Town, Hongdoushu, on ground dominant with Fagaceae, Alt: 1772 m, N: 24°54′52″, E: 98°37′59″, 8 August 2018, tcmb 005; Menglian Town, Xiamenglian Village, on ground of mixed forests composed of Fagaceae and P. yunnanensis, 5 August 2014, Li 140805-18; Chuxiong Yi Autonomous Prefecture, Zixi Mountain, near King Baotou, on ground of mixed forest composed of Fagaceae and P. yunnanensis, Alt: 1926 m, N: 25°1′3″, E: 101°24′7″, 25 August 2018, Li 180825-21; Yuxi, Huaning County, on ground dominant with Fagaceae, 8 September 2013, Li 130908-29; Zhaotong, Weixin County, Miaogou Town, Zhashigou Village, on ground dominant with Fagaceae, Alt: 1450 m, N: 27°47′6″, E: 104°49′18″, 22 September 2017, WX 20170922065.

Cortinarius subclackamasensis Q.Y. Zhang, Jing Si & Hai J. Li, sp. nov. Figure 3 .

MycoBank: 848614

Diagnosis. — This species notably has small- to medium-sized basidiomata, buff-yellow and plano-convex pilei, ellipsoid to oblong ellipsoid basidiospores (9.5−10.8 × 5.8−6.8 μm); it is gregarious on ground of Salix or other deciduous trees and distributed in temperate China.

Type. — China, Heilongjiang Province, Huzhong, Huzhong Forest Farm, near Dongfanghong Line 31, on ground of Salix, 18 August 2017, Li 170818-16 (holotype), GenBank accession number for ITS: OQ913394.

Etymology. — Subclackamasensis refers to its morphological similarity to C. clackamasensis.

Habitat and distribution. — Scattered or gregarious on ground of Salix or other deciduous trees. Currently, it is found in Northeast and North China in summer.

Macrostructures. — Basidiomata small to medium sized. Pileus 30−60 mm in diam., hemispheric to subhemispheric when young, becoming plano-convex, then depressed at center and wrinkled, margin sharp sometimes waves; surface moist to hygrophanous when young, with fibrous veil remnants; buff yellow (4A4), to light honey yellow (4/5B4), somewhat lighter olivaceous buff (4C4) at margin, finely radially striate with age. Lamellae adnexed-emarginate, moderately crowded to crowded, vinaceous (9F6) or peach (6A6) when young, somewhat darkening on manipulation, edge even, somewhat lighter. Stipe 40- to 60- mm long, 5- to 10- mm thick above, qual to somewhat clavate, white, and cream with age. Universal veil usually sparse, thin, and somewhat glossy, cream (4A2/3) to light yellow (4A4), flocculose or forming a week girdle on the stipe. Context rather thick, especially in pileus center, brittle, weakly light honey yellow (4/5B4) with age. Odor and taste of context strongly fungoid.

Microstructures. — Basidiospores [90/3/3] 9.5−10.8 (−11) × (5.5−) 5.8−6.8 μm, av. 9.9 × 6.3 μm, Q = 1.56−1.60, av. Q = 1.59, ellipsoid to oblong ellipsoid, weekly to moderately, but distinctly verrucose, indextrinoid to weakly dextrinoid. Basidia 4-spored, 22−25 × 8−11 μm, clavate, colorless or yellowish. Lamella trama hyphae smooth, parallel, 4- to 12- μm wide. Lamellae edge fertile, with some small clavate sterile cells. Pileipellis duplex: Epicutis about 27- to 32 -μm thick, hyphae (6−) 11- to 16- μm wide, in upper part loosely entangled; hypocutis distinct well-developed, colorless or yellowish, irregular, interwoven, with some intracellular pigments, 18−28.5 μm in diam. Clamp connections present.

Remarks. — Phylogenetically, C. latiodistributus Dima, Ammirati, Niskanen, Kytöv., Liimat. & Brandrud, C. clackamasensis Ammirati, Liimat., Niskanen & Dima, and Cortinarius sp. 12 are closely related to C. subclackamasensis. Cortinarius latiodistributus has violet to pallid brown pilei, and shorter basidiospores (7−9.5 μm). Cortinarius clackamasensis has wider basidiospores (9−11 × 6.5−7.5 μm, av. 9.7 × 6.5 μm, Q = 1.4−1.5), grows on the ground under mixed conifers composed of Picea, Pinus, and Abies, and is distributed in the US (Dima et al., 2021). Similar to C. subclackamasensis, C. clintonianus Peck, and C. anomalopacificus Bojantchev, Liimat., Niskanen, Dima & Ammirati have yellowish and plano-convex basidiomata. However, the basidiospores in C. clintonianus and C. anomalopacificus are shorter (6.7−8.1 × 5.6−6.3 μm vs. 6.5−7 × 5−6 μm; Dima et al., 2021).

Additional specimens (paratypes) examined. — China, Beijing, Mentougou District, Xiaolongmen National Forest Park, 30 August 2017, BJMTG20170830-34; Hebei Province, Baoding, Fuping County, Dongxiaguan Town, Zhujiaying Village, Tianshengqiao, 22 August 2019, 20190822-11; Heilongjiang Province, Huzhong, Huzhong forest farm, near Dongfanghong Line 31, on ground of Salix, 18 August 2017, Li 170818-01 and Li 170818-02.

Cortinarius tropicus Q.Y. Zhang, Jing Si & Hai J. Li, sp. nov. Figure 4 .

MycoBank: 848616

Diagnosis. — This species notably has small basidiomata, violet to dark violet pileal surface with fibrillose disc and nearly glabrous, cream to pale violet margin, subglobose to broadly ellipsoid basidiospores (6−8 × 5−6 μm); it is scattered or gregarious on ground dominant with Fagaceae.

Type. — China, Yunnan Province, Baoshan, Tengchong, Qushi Town, Qingqiao Village, Alt: 1490 m, N: 25°17′17″, E: 98°35′26″, on ground dominant with Fagaceae, 6 August 2016, tcqushi 006 (holotype), GenBank accession number for ITS: OQ913379.

Etymology. — tropicus refers to its tropical distribution in Southwest China.

Habitat and distribution. — Scattered or gregarious on ground dominant with Fagaceae. Currently, it is only found in tropical Yunnan (three collections) in summer.

Macrostructures. — Basidiomata small. Pileus 20−45 mm in diam., hemispheric to subhemispheric when young, becoming obtusely conical, conico-convex, broadly umbonate, pale brown [5D(4−5)] at center and gradually paler toward margin when young, violet (17B8) to dark violet (17F8) when mature, disc grayish violet (15E5) to dark violet (17F8), margin cream (4A2/3) to pale violet [16A(2−3)], fibrillose at disc and nearly glabrous near margin, somewhat hygrophanous, margin decurved. Lamellae adnexed-emarginate, subclose, purplish to pale violet lilac [16D(4−6)], finally ± pale brown to cinnamon (16D3-16E3). Stipe 50- to 80- mm long, apex 3 to 5 mm in diam., base 5−10 mm in diam., enlarged, narrowly clavate, surface grayish (16B2) with dark violet [16F(3−4)] streaks or silvery violet (16A3) on upper half and watery brownish below, veil usually sparse, forming floccose-girdles on the stipe, often at first brownish (6B2-6C2) then becoming pale yellow [4A(2-3)], sometimes indistinct, and basal mycelium whitish. Context in pileus solid, firm, violet to silvery violet [16C(4−6)] when fresh, finally pale brown to cinnamon (16D4−16F4) in age. Odor and taste of context strongly fungoid.

Microstructures. — Basidiospores [90/3/3] 6−8 × 5−6 μm, av. 7.4 × 5.9 μm, Q = 1.21−1.29, av. Q = 1.25, subglobose to broadly ellipsoid, buff to cinnamon-buff, coarsely verrucose, non-dextrinoid to slightly dextrinoid. Basidia 4-spored, 30−42 × 7−11 μm, clavate, colorless or yellowish. Lamella trama hyphae hyaline, smooth, parallel, 5- to 13- μm wide. Pileipellis duplex: Epicutis well developed, hyaline or yellow to ochraceous, smooth, cylindrical, radially arranged, ± interwoven, 4−10 μm wide; hypocutis distinct, colorless or yellowish, smooth to slightly encrusted, cylindrical to enlarged, radially oriented, ± interwoven, (4)6- to 15(17)- μm wide. Clamp connections present.

Remarks. — Cortinarius perviolaceus Murrill is easily confused with C. tropicus because of its violet pilei, but C. perviolaceus has smaller basidiomata (8−22 mm vs. 20−45 mm) and wider basidiospores (6−6.5 μm vs. 5−6 μm; Dima et al., 2021). Cortinarius anomalus has similar pilei with blue tinge when young and larger basidiospores (8−9 × 6−7 μm; Dima et al., 2016). Cortinarius anomalovelatus, C. deceptivus Kauffman, and C. harvardensis L. Nagy, Dima & Ammirati formed a sister group with C. tropicus. Compared with the new species, C. anomalovelatus has wider basidiospores (6.3−7 μm vs. 5−6 μm), C. deceptivus produces larger basidiospores (7.8−9.3 × 6−7.4 μm), and C. harvardensis has bluish to violet pileus, lamellae, and stipe, and slightly bigger basidiospores (7.5−8.5 × 5.5−6.5 μm; Dima et al., 2021).

Additional specimens (paratypes) examined. — CHINA. Yunnan Province, Dehong Dai and Jingpo Autonomous Prefecture, Mang City, Jiangdong Town, Daxinzhai, Alt: 1619 m, N: 24°27′54″, E: 98°18′56″, on ground dominant with Fagaceae, 28 July 2015, Li 150728-56 and Li 150728-63.