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Research Article
Two new species of Micropsalliota (Agaricales, Agaricaceae) from subtropical regions of China
expand article infoJun-Qing Yan‡§, Zhi-Heng Zeng‡, Ya-Ping Hu|, Cheng-Feng Nie‡, Bin-Rong Ke‡, Sheng-Nan Wang§, Hui Zeng‡
‡ Institute of Edible mushroom, Fujian Academy of Agricultural Sciences, Fuzhou, China
§ Jiangxi Agricultural University, Nanchang, China
| Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment Mountains, Nanjing, China

Corresponding author: Jun-Qing Yan ( yanjunqing1990@126.com )

Corresponding author: Sheng-Nan Wang ( wangshengnan_2003@163.com )

Corresponding author: Hui Zeng ( zenghui@faas.cn )

Academic editor: Zai-Wei Ge
© 2025 Jun-Qing Yan, Zhi-Heng Zeng, Ya-Ping Hu, Cheng-Feng Nie, Bin-Rong Ke, Sheng-Nan Wang, Hui Zeng.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Yan J-Q, Zeng Z-H, Hu Y-P, Nie C-F, Ke B-R, Wang S-N, Zeng H (2025) Two new species of Micropsalliota (Agaricales, Agaricaceae) from subtropical regions of China. MycoKeys 113: 193-208. https://doi.org/10.3897/mycokeys.113.140599
Open Access

Abstract

Micropsalliota is a relatively small genus, with 97 names recorded in previous research. In this study, two new species of Micropsalliota, M. bispora and M. vulgaris, have been identified based on morphological and phylogenetic evidence from subtropical regions of China. Morphologically, M. bispora is characterized by very small basidiomata, cymbiform basidiospores up to 9.0 μm long, white to cream pileus with fawn to dull red center, and tibiiform cheilocystidia; M. vulgaris is recognized by small basidiomata, medium-sized spores, white to cream pileus, covered with reddish brown to dark brown fibrils, various cheilocystidia that are up to 60 μm long, and hyphae of fibrils exhibiting pale brown vacuolar pigmentation. Their distinct taxonomic status is confirmed by the positions of the two new species in 4-locus (ITS, LSU, rpb2, tef-1α) phylogenetic trees. Detailed descriptions and morphological photographs of two new species are presented. To aid in diagnosis, a key to 35 species of Micropsalliota in China is provided.

Key words:

Basidiomycetes, phylogeny, taxonomy, two new taxa

Introduction

Micropsalliota Höhn. was circumscribed by Höhnel in 1914 to accommodate species within Agaricus L. that form small and slender basidiomata (Höhnel 1914). It was once based on inappropriate characteristics and considered a dubious genus. Later, it was amended by Heinemann (1956) and Pegler and Rayner (1969), and subsequently accepted by Singer (1975). Currently, it is a widely accepted view that species of Micropsalliota are usually characterized by small, slender basidiomata, frequently with capitate or subcapitate cheilocystidia, pileipellis hyphae that are incrusted and turn green in ammonia solution when fresh, and, in most species, basidiospores with apically thickened endosporium and lacking germ pore (Heinemann 1977; Zhao et al. 2010).

Micropsalliota spp. generally grow in the tropics and subtropics, but the diversity of known species is not particularly rich. Only 97 names, including synonyms and subspecies, were listed in Index Fungorum and about 87 species are recorded worldwide (Al-Kharousi et al. 2022; Yan et al. 2022; Gao et al. 2024).

Heinemann (1983) divided the genus into four groups based on the stature of the basidiomata, the color of the pileus, and the shape of the cheilocystidia, and devised a method he called the “IG value” for measuring stature. However, Zhao et al. (2010) and Yan et al. (2022) argue that the IG value is not a reliable measure. When comparing numerous individual basidiomes from numerous populations of a single species, the IG value exhibits significant variation and often overlaps with Heinemann’s group designations. In previous molecular systematics studies, Zhao et al. (2010), Yan et al. (2022) and Gao et al. (2024) constructed its phylogeny using two-gene dataset (nrITS and nrLSU), three-gene dataset (nrITS, nrLSU, and rpb2), and four-gene dataset (nrITS, nrLSU, rpb2, and tef-1α), respectively. The study of Gao et al. (2024) shows that the genus is separated into 11 major clades and subclades.

In recent years, China has been a hotspot for the discovery of new species in this genus. Following the discovery of M. pseudoglobocystis Li Wei & R.L. Zhao as a new species, an additional 18 new species have been reported in China, bringing the total number of species to 33. (Wei et al. 2015; Li et al. 2021; Yan et al. 2022; Ji and He 2023; Gao et al. 2024). As part of the study on Chinese macrofungi species, two new species were discovered, during our investigations into subtropical regions of China. This study further elucidates the diversity of Micropsalliota in the area, following our publication of six new species of Micropsalliota from this region in 2022 (Yan et al. 2022). Detailed information on the new taxa is presented in this study.

Materials and methods

Morphological studies

Specimens were collected from Fujian and Zhejiang provinces of China in 2022 and were deposited in the Herbarium of Fungi, Jiangxi Agricultural University (HFJAU). Macroscopic descriptions were based on detailed field notes of fresh basidiomata and photos. Colour codes follow the Methuen Handbook of Colour (Kornerup and Wanscher 1978). Microscopic structures were observed and measured from dried specimens mounted in water and 5% KOH. Congo red was used as a stain when necessary (Horak 2005). At least 40 basidiospores, basidia, and cystidia were measured for each collection. The range of spore size is expressed in the form (a)b–c(d), where “a” and “d” represent the minimum and maximum values, respectively, 90% of the spores fall within the range ‘b–c’. The meanings of the other spore characteristics are as follows: “Q” stands for the ratio of length and width (Yan et al. 2022; Chen et al. 2024).

DNA extraction, PCR amplification, and sequencing

DNA was extracted from dried specimens with the NuClean Plant Genomic DNA kit (CWBIO, China). Four regions (ITS, LSU, rpb2, tef-1α) were selected for the study and were amplified using the primer pairs ITS1/ITS4(White et al. 1990), LR0R/LR7 (Hopple and Vilgalys 1999), bRPB2-6F/bRPB2-7R (Matheny 2005), EF1-983F/EF1-1567R (Rehner and Buckley 2005), respectively. PCR was performed using a touchdown program for all regions: initial 95 °C for 5 min, and then 14 cycles of denaturing at 95 °C for 30 s, annealing at 65 °C for 45 s (-1 °C per cycle), extension at 72 °C for 1 min; then 30 cycles of denaturing at 95 °C for 30 s, annealing at 52 °C for 30 s, extension at 72 °C for 1 min; final extension at 72 °C for 10 min (Wang et al. 2022; Yan et al. 2022). The PCR products were sequenced by Qing Ke Biotechnology Co. Ltd (Wuhan City, China).

Alignment and phylogenetic analyses

Sequence reads were assembled and edited using SEQUENCHER v.5.4 and were deposited in GenBank database. Based on the research by Yan et al. (2022) and Gao et al. (2024), and the similarity of these new species to the most closely related sequences identified in the BLAST results of ITS, 242 nucleotide DNA sequences in NCBI GenBank were downloaded. Agaricus crassisquamosus R.L. Zhao, A. variicystis Linda J. Chen, K.D. Hyde & R.L. Zhao, Hymenagaricus epipastus (Berk. & Broome) Heinem. & Little Flower, H. sp. and Leucoagaricus centricastaneus Y.R. Ma, Z.W. Ge & T.Z. Liu were chosen as outgroup taxa according to the results of Yan et al. (2022) and Gao et al. (2024). A total of 258 sequences including 100 ITS, 82 LSU, 46 rpb2, and 30 tef1 sequences were used in subsequent analyses. Details are presented in Table 1.

Table 1.
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Details of sequences used in the phylogenetic analyses.

Taxa Vouchers ITS LSU rpb2 tef-1α Reference
Micropsalliota alba – EF069420 – – – Gao et al. (2024)
M. albella LE2016123 Holotype MN294514 MN294516 – – He et al. (2020)
M. albofelina LE312536 Holotype OK257212 OK257209 – – Crous et al. (2021)
M. albofelina HKAS70329 OR799877 OR799922 OR962218 OR962180 Gao et al. (2024)
M. albosericea zrl3049 HM436644 – – – Zhao et al. (2010)
M. allantoidea zrl2038 Holotype HM436648 HM436597 – – Zhao et al. (2010)
M. appendiculata HKAS131127 OR799912 OR799956 OR962247 OR962204 Gao et al. (2024)
M. appendiculata LE F-315913 Holotype OR161109 OR161104 – – Ivanova et al. (2023)
M. arginophaea zrl3110 HM436617 HM436577 – – Zhao et al. (2010)
M. arginophaea HKAS60309 OR799878 OR799923 OR962219 OR962208 Gao et al. (2024)
M. bifida zrl3067 Holotype HM436640 HM436591 – – Zhao et al. (2010)
M. bifida HFJAU2998 OM650272 OM650252 OM669858 – Yan et al. (2022)
M. bispora HFJAU3833 PQ345346 PQ345351 PQ358515 PQ358519 this study
M. bispora HFJAU4253 Holotype PQ345347 PQ345352 PQ358516 PQ358520 this study
M. brunneosquamata LD201236 Holotype KP316210 – – – Chen et al. (2016)
M. cortinata zrl2129 HM436630 HM436593 – – Zhao et al. (2010)
M. cortinata HKAS92221 OR799879 OR799924 OR962220 OR962183 Gao et al. (2024)
M. delicatula HKAS54332 OR799880 OR799925 OR962221 OR962209 Gao et al. (2024)
M. delicatula ZRL2015234 Holotype MT671229 – – – Li et al. (2021)
M. dentatomarginata GX20170202 Holotype MT671228 MT671242 – – Li et al. (2021)
M. digitatocystis HKAS123832 OR799883 OR799928 OR962224 OR962185 Gao et al. (2024)
M. digitatocystis ZRL20180564 Holotype MT671239 MT671250 – – Li et al. (2021)
M. ferruginea HKAS 131130 OR799885 OR799930 OR962226 OR962182 Gao et al. (2024)
M. ferruginea HKAS 70562 Holotype OR799884 OR799929 OR962225 OR962181 Gao et al. (2024)
M. fimbriata HKAS 60241 Holotype OR799886 OR799931 OR962227 OR962198 Gao et al. (2024)
M. fimbriata HKAS 60261 OR799887 OR799932 – OR962199 Gao et al. (2024)
M. furfuracea zrl3006 Holotype HM436621 HM436603 – – Zhao et al. (2010)
M. furfuracea HKAS60229 OR799889 OR799934 OR962229 OR962201 Gao et al. (2024)
M. geesterani LAPAG520 KM923965 KM923966 – – Parra et al. (2016)
M. geesterani E.C. Vellinga 2263(L) AF482857 AF482888 – – Parra et al. (2016)
M. gigaspora HKAS131118 OR799890 OR799935 OR962230 – Gao et al. (2024)
M. gigaspora HKAS131119 Holotype OR799891 OR799936 OR962231 – Gao et al. (2024)
M. globocystis 1 HKAS131120 OR799892 OR799937 – OR962186 Gao et al. (2024)
M. globocystis 1 HFJAU1518 OM650277 OM650255 OM669852 – Yan et al. (2022)
M. globocystis 2 HKAS131133 OR799895 OR799940 OR962234 OR962197 Gao et al. (2024)
M. globocystis 2 HKAS92202 OR799894 OR799939 OR962233 OR962196 Gao et al. (2024)
M. globocystis 3 VDW1278 MT304640 – – – Yan et al. (2022)
M. globocystis 4 zrl2049 HM436635 – – – Zhao et al. (2010)
M. globocystis 4 HFJAU2709 OM650278 OM650262 OM669856 – Yan et al. (2022)
M. gracilis zrl2041 HM436647 HM436583 – – Zhao et al. (2010)
M. gracilis HNL503432 MW192914 – – – Yan et al. (2022)
M. inflata LE F-315912 Holotype OR161110 OR161106 – – Ivanova et al. (2023)
M. jiangxiensis THJ20018 ON117420 ON117438 – – Ji and He (2023)
M. jiangxiensis THJ20019A ON117421 ON117439 – – Ji and He (2023)
M. lateritia var. vinaceipes zrl2073 Holotype HM436631 – – – Zhao et al. (2010)
M. lateritia var. vinaceipes HKAS131124 OR799896 OR799941 OR962235 OR962202 Gao et al. (2024)
M. longicystis HKAS131121 Holotype OR799897 OR799942 OR962257 – Gao et al. (2024)
M. longicystis HKAS131126 OR799898 OR799943 OR962258 – Gao et al. (2024)
M. megarubescens zrl2086 Holotype HM436620 – – – Zhao et al. (2010)
M. megarubescens HKAS60253 OR799900 OR799945 OR962237 OR962189 Gao et al. (2024)
M. megaspora zrl3068 Holotype HM436624 – – – Zhao et al. (2010)
M. megaspora HFJAU1255 OM650282 OM650258 OM669876 – Yan et al. (2022)
M. minor HFJAU2796 OM650294 OM650266 OM669865 – Yan et al. (2022)
M. minor HFJAU2812 Holotype OM650293 – OM669864 – Yan et al. (2022)
M. nana HKAS114619 OR799901 OR799946 OR962238 OR962216 Gao et al. (2024)
M. nana HKAS115226 Holotype OR799902 OR799947 – OR962217 Gao et al. (2024)
M. ovalispora HFJAU2010 Holotype OM650295 OM650269 OM669866 – Yan et al. (2022)
M. ovalispora HFJAU3179 OM650296 – OM669867 – Yan et al. (2022)
M. pileocystidiata AMH9975 Holotype MG917970 – – – Patil et al. (2022)
M. pileocystidiata MMH1114 MZ598496 – – – Patil et al. (2022)
M. pleurocystidiata zrl2023 HM436636 – – – Zhao et al. (2010)
M. pseudoarginea HKAS131125 OR799903 OR799948 OR962239 OR962212 Gao et al. (2024)
M. pseudoarginea HFJAU2122 OM650284 OM650260 OM669861 – Yan et al. (2022)
M. pseudodelicatula HKAS131129 OR799905 OR799950 OR962241 OR962213 Gao et al. (2024)
M. pseudodelicatula HFJAU2228 Holotype OM650288 OM650264 OM669863 – Yan et al. (2022)
M. pseudoglobocystis HKAS87127 OR799908 OR799953 OR962244 OR962190 Gao et al. (2024)
M. pseudoglobocystis ZRL2013321 Holotype KM889913 – – – Wei et al. (2015)
M. purpureobrunneola LE2016124 Holotype MN294513 MN294517 – – He et al. (2020)
M. pusillissima zrl3047 Holotype HM436645 HM436594 – – Zhao et al. (2010)
M. repanda LAPAF8 KP739805 KP739804 – – Parra et al. (2016)
M. roseipes HFJAU2494 OM650297 OM650270 OM669870 – Yan et al. (2022)
M. rubrobrunnescens zrl2120 Holotype HM436628 HM436588 – – Zhao et al. (2010)
M. rubrobrunnescens HKAS96929 OR799914 OR799958 OR962249 OR962206 Gao et al. (2024)
M. rubrobrunnescens var. tibiicystis zrl2121 Holotype HM436629 HM436589 – – Zhao et al. (2010)
M. rufosquarrosa HFJAU1208 OM650291 OM650267 OM669868 – Yan et al. (2022)
M. rufosquarrosa HFJAU1236 Holotype OM650292 OM650268 OM669869 – Yan et al. (2022)
M. squarrosa HKA128713 OR799916 OR799960 OR962251 – Gao et al. (2024)
M. squarrosa HKAS128633 Holotype OR799915 OR799959 OR962250 – Gao et al. (2024)
M. subalba zrl2080 HM436646 HM436596 – – Zhao et al. (2010)
M. subalba HKAS105828 OR799917 OR799961 – OR962211 Gao et al. (2024)
M. subarginea zrl2052 HM436612 HM436573 – – Zhao et al. (2010)
M. subarginea zrl2092 HM436611 HM436574 – – Zhao et al. (2010)
M. suricatoides LE F-348071 OR161111 OR161105 – – Ivanova et al. (2023)
M. suricatoides LE F-348072 Holotype OR161112 – – – Ivanova et al. (2023)
M. tenuipes HFJAU1536 Holotype OM650289 – – – Yan et al. (2022)
M. tenuipes HFJAU3180 OM650290 OM650265 – – Yan et al. (2022)
M. umbonata HKAS131131 Holotype OR799920 OR799964 OR962254 OR962194 Gao et al. (2024)
M. umbonata HKAS131132 OR799921 OR799965 OR962255 OR962195 Gao et al. (2024)
M. ventricocystidiata SQUH-ATR004 OM397373 OM630413 – – Al-Kharousi et al. (2022)
M. ventricocystidiata SQUH-GOB002 Holotype OM397374 OM630414 – – Al-Kharousi et al. (2022)
M. vulgaris HFJAU3350 Holotype PQ345344 PQ345349 PQ358513 PQ358517 this study
M. vulgaris HFJAU5707 PQ345345 PQ345350 PQ358514 PQ358518 this study
M. wuyishanensis HFJAU3048 Holotype OM650298 – OM669878 – Yan et al. (2022)
M. xanthorubescens zrl3083 HM436638 HM436598 – – Zhao et al. (2010)
M. xanthorubescens NW1356 MW504965 – – – Yan et al. (2022)
Outgroup
Agaricus crassisquamosus ZRL2012607 Holotype KT951376 KT951510 – – Zhao et al. (2016)
A. variicystis LD201234 Holotype KT951339 KT951517 – – Zhao et al. (2016)
Hymenagaricus epipastus ZRL3045 HM436649 HM436609 – – Zhao et al. (2010)
Hymenagaricus sp. ZRL3103 KM982450 KM982452 – – Li et al. (2021)
Leucoagaricus centricastaneus SYAU FUNGI 076 Holotype OM976855 OM976871 OR962256 OR962207 Gao et al. (2024)

Sequence datasets, containing intron regions, were separately aligned on the MAFFT v.7 (Katoh and Standley 2013). Bayesian Inference (BI) and Maximum Likelihood (ML) phylogenetic analyses of the aligned concatenated dataset were carried out in MRBAYES v.3.2.7a and RAXML 8.2.12, respectively (Ronquist and Huelsenbeck 2003; Stamatakis 2006). The best-fit models of BI were determined by PARTITIONFINDER, based on the Corrected Akaike information criterion (AICc) (Lanfear et al. 2017). The GTRGAMMA model as the best-fit likelihood model for ML analysis with 1,000 replicates and allowing partitions to have different seeds (Silvestro and Michalak 2012). For the Bayesian analysis, four Monte Carlo Markov chains were run for 10 million generations, sampling every 1000th generation, with the first 25% of trees discarded as burn-in. Branches with Bayesian posterior probability (BI-PP) ≥ 0.95 and ML bootstrap support (ML-BP) ≥ 75% are considered statistically supported and are shown in the tree (Fig. 1). All alignments for phylogenetic analyses and the resulting trees were deposited in TreeBASE (ID: 31925, http://purl.org/phylo/treebase/phylows/study/TB2:S31925?x-access-code=2021c0bf9e5d391e2fa622a887e944b3&format=html).

Figure 1. 

Phylogram of Micropsalliota generated by Bayesian inference (BI) analysis based on sequences of ITS(I)+LSU(L)+rpb2 (R)+tef-1α (T). It was rooted with Agaricus spp. Hymenagaricus spp. and. Leucoagaricus centricastaneus. Posterior probabilities (BI-PP) and ML bootstrap values (ML-BP) ≥ 0.95 and ≥75%, respectively, are shown as BP/PP. Black bullet indicates newly described taxa. T indicates Holotype.

Results

A total of 2708 characters from 100 taxa were used in phylogenetic analyses (ITS 774 bp; LSU 752 bp; rpb2 608 bp; tef-1α 574 bp), of which 403, 133, 248, 299 sites were variable and 304, 106, 223, 188 sites were parsimony informative for ITS, LSU, rpb2, tef-1α, respectively. The best models are calculated separately, and the results are as follows: the best models for Bayesian analysis were GTR+I+G for the ITS and LSU, SYM+I+G for the rpb2 and tef-1α. The loglikelihood of the ML consensus tree was -21457.61, and the average standard deviation of split frequencies less than 0.01 after 1.88 million generations in the Bayesian analysis.

As shown in the Bayes tree, the 11 major clades and subclades proposed by Gao et al. (2024) were well reproduced in this study, except for Clade lateritia. Two new species were formed distinct and stable branches, respectively, and group together with M. cortinata (Heinem.) Heinem., with high statistical support in the Bayesian inference (BPP = 1). Details are presented in Fig. 1.

Taxonomy

Micropsalliota bispora J.Q. Yan, S.N. Wang, & H. Zeng, sp. nov.

MycoBank No: 855802
Fig. 2

Etymology.

Name refers to the majority of basidia are 2-spored.

Diagnosis.

Micropsalliota bispora is mainly characterized by very small basidiomata; white to cream pileus, with the center being fawn to dull red; cymbiform basidiospores in profile view, 8.0–9.0(9.5) × 4.0–5.0(5.3) μm; and tibiiform cheilocystidia. It differs from M. albofelina by having bigger spores, which are up to 9.0 μm in length.

Figure 2. 

Morphological structures of Micropsalliota bispora. A–C Basidiomata D spores E basidia F–H cheilocystidia I hyphae of fibrils. All microstructures were observed in 5%KOH, structures of E–H were stained by 1%Congo red. Scale bars: 10 mm (A–C);10 μm (D–I).

Holotype.

China • Fujian Province, Wuyishan National Park, 11 July 2022, Jun-Qing Yan, Cheng-Feng Nie, HFJAU4253.

Description.

Pileus 3.0–5.0 mm in diameter, white to cream, fawn (7E4) to dull red (8C3) at center, plano-convex to plane, surface dry, covered with white well-developed fibrils at early age, gradually disappears with aging. Context less than 0.8 mm thick. Lamellae 0.5–1.0 mm broad, free to short adnexed, distant, white, becoming brownish orange to light brown (7C4–7D4) as mature, edge white, smooth to serrate, with two series of lamellulae. Stipe 10–25 mm long, 0.5–1.0 mm thick, cylindrical, slender, white, surface with white fibrils, gradually disappears with aging. Annulus unobserved.

Basidiospores 8.0–9.0(9.5) × 4.0–5.0(5.3) μm, Q = (1.6)1.7–2.0, cymbiform in profile view, ellipsoid to elongated-ellipsoid in face view, light brown, wall 0.5 μm thick, apically thickened endosporium, without germ pore, inamyloid. Basidia 11–15 × 6.5–8.0 μm, clavate, hyaline, 2-spored, rarely 4-spored. Pleurocystidia absent. Cheilocystidia 35–55 × 6.8–15(17) μm, tibiiform, apex capitate, rarely subacute, 4.0–6.0(7.0) μm in diameter. Fibrils at the center of pileus composed of hyphae, 8.0–15 μm broad, with pale brown membranous pigment, constricted at the septa on some hyphae.

Habit and habitat.

Scattered on soil in broad-leaved forest or mixed coniferous and broad-leaved forests.

Additional specimens examined.

China • Fujian Province, Wuyishan National Park, 25 June 2022, Jun-Qing Yan, Bin-Rong Ke, HFJAU3833.

Note.

Macroscopically, M. bispora is very similar to M. albofelina D.D. Ivanova & O.V. Morozova, with both species having very small basidiomata and well-developed scales or fibrils at an early age. However, the latter has spores that are shorter than 7.5 μm and a white center on the pileus (Crous et al. 2021). Micropsalliota longicystis T. Gao & Z.W. Ge and M. pseudoarginea Heinem. are also similar to M. bispora macroscopically, but M. longicystis has pleurocystidia and its spores shorter than 6.0 μm (Gao et al. 2024), and M. pseudoarginea has broadly clavate or ventricose-clavate cheilocystidia and its spores shorter than 5.0 μm (Zhao et al. 2010). Among the known species of Micropsalliota with a pileus generally less than 10 mm, there are no species like M. bispora with spores longer than 8.0 μm. Based solely on this characteristic, M. bispora can be distinctly differentiated from known species of Micropsalliota.

M. geesterani (Bas & Heinem.) R.L. Zhao & L.A. Parra, M. gigaspora T. Gao & Z.W. Ge, and M. ventricocystidiata Al-Sadi & S. Hussain are similar to M. bispora, with spores up to 9.0 μm, but their pilei are larger than 20 mm. Additionally, M. geesterani has a purple pileus, and fusiform, cylindrical, or narrowly clavate cheilocystidia (Parra et al. 2016), M. gigaspora has clavate cheilocystidia (Gao et al. 2024), and M. ventricocystidiata has ventricose cheilocystidia (Al-Kharousi et al. 2022).

Micropsalliota vulgaris J.Q. Yan, S.N. Wang, & H. Zeng, sp. nov.

MycoBank No: 855803
Fig. 3

Etymology.

Name refers to the fact that many known species in this genus share similar macroscopic characteristics with the new species.

Diagnosis.

Micropsalliota vulgaris is mainly characterized by small basidiomata; white to cream pileus, covered with reddish brown to dark brown fibrillose; elongated-ellipsoid to elongated basidiospores in profile view, (6.3)6.7–8.0 × 3.7–4.4(4.7) μm; various cheilocystidia; hyphae of fibrils have pale brown vacuolar pigment. It differs from M. squarrosa by having various cheilocystidia.

Figure 3. 

Morphological structures of Micropsalliota vulgaris. A–D Basidiomata E spores F basidia G, H hyphae of fibrils I–O cheilocystidia. All microstructures were observed in 5%KOH, except for G, which were observed in water. Structures of F and I–O were stained by 1% Congo red. Scale bars: 10 mm (A–D);10 μm (E–O).

Holotype.

China • Zhejiang Province, Wencheng County, 24 May 2022, Ya-Ping Hu, Jun-Qing Yan, HFJAU3350.

Description.

Pileus 10–35 mm, convex, white to cream, covered with reddish brown to dark brown (9E6–9F6) fibrillose, dense at the center, sparser towards the edge. Context less than 2.0 mm thick, turning brownish red (9C7–9C8) in some areas when bruised or cut. Lamellae 3.0–4.0 mm, crowded, free, with 2–3 series of lamellulae, dull white, edge dull white, slightly serrate. Stipe 50–80 mm long, 3.0–4.0 mm thick, cylindrical, slender, white, surface with white fibrils, gradually disappears with aging. Context of stipe turning brownish red (9C7–9C8) in some areas when bruised or cut. Annulus unobserved.

Basidiospores (6.3)6.7–8.0 × 3.7–4.4(4.7) μm, Q = (1.5)1.6–1.9(2.0), elongated-ellipsoid to elongated, slightly flattened on one side in profile view, ellipsoid to elongated-ellipsoid in face view, light brown, wall 0.5 μm thick, apically thickened endosporium, without germ pore, inamyloid. Basidia 15–19 × 6.0–7.5 μm, clavate, hyaline, 4-spored. Pleurocystidia absent. Cheilocystidia 35–62 × 4.2–11 μm, various, tibiiform, capitate, subhypoid, rarely fork, apex capitate, rarely mucronate, 4.0–8.0 μm in diameter. Fibrils composed of hyphae 8.0–15 μm broad, with pale brown vacuolar pigment.

Habit and habitat.

Scattered on soil in broad-leaved forest.

Additional specimens examined.

China • Zhejiang Province, Wencheng County, 25 May 2022, Zhi-Heng Zeng, Shen-Nan Wang, HFJAU5707.

Note.

Among the known species of the Micropsalliota, few have a similar combination of characteristics as M. vulgaris, that is, a white pileus covered with brown fibrils, lacks pleurocystidia, and has spores up to 8.0 μm. However, they can be clearly distinguished from M. vulgaris: M. endophaea Heinem., M. inflata D.D. Ivanova & O.V. Morozova,and M. megaspora R.L. Zhao, Desjardin, Soytong & K.D. Hyde have pilei that are generally less than 10 mm in diameter, and their cheilocystidia are shorter than 40 μm (Heinemann 1988; Zhao et al. 2010; Ivanova et al. 2023); M. fimbriata T. Gao & Z.W. Ge, and M. gigaspora have clavate cheilocystidia and incrusted hyphae of pileus squamules (Gao et al. 2024); M. geesterani has a purple pileus that can reach up to 200 mm in diameter (Parra et al. 2016); M. squarrosa T. Gao & Z.W. Ge has clavate to clavate-capitate cheilocystidia (Gao et al. 2024); M. ventricocystidiata has ventricose cheilocystidia (Al-Kharousi et al. 2022).

Discussion

In the phylogenetic tree (Fig. 1), M. cortinata groups together with two new species, and is very close to M. vulgaris. In previous studies, the branch where M. cortinata is located was designated as clade cortinata, which is distinguished by cortinate partial veil that leaves remnants only on the pileus margin (Zhao et al. 2010; Gao et al. 2024). The two new species, however, exhibit developed fibrils on the pileus margin, a feature that distinguishes them from clade cortinata. Additionally, the branch where these three species are located was difficult to morphologically characterize. The basidiospores of M. cortinata are shorter than 6.5 μm, and the cheilocystidia are clavate to ventricose, the hyphae of pileipellis have membranous pigments, which allows it to be distinctly differentiated from M. vulgaris (Heinemann 1980; Zhao et al. 2010). M. bispora, with its very small basidiomata, mostly 2-spored basidia, and tibiiform cheilocystidia, can be distinctly differentiated from M. vulgaris. While all three species lack pleurocystidia, this characteristic alone is not sufficient to unite them.

In previous study (Gao et al. 2024), Clade lateritia includes six species: M. inflata, M. lateritia var. vinaceipes R.L. Zhao, Desjardin, Soytong & K.D. Hyde, M. rubrobrunnescens R.L. Zhao, Desjardin, Soytong & K.D. Hyde, M. rubrobrunnescens var. tibiicystis R.L. Zhao, Desjardin, Soytong & K.D. Hyde, M. suthepensis R.L. Zhao, Desjardin, Soytong & K.D. Hyde, and M. wuyishanensis J.Q. Yan. However, stable support was only obtained in the Bayesian inference, and there were no clear shared characteristics. Due to M. suthepensis having only LSU sequences and significant morphological differences with two new species, it was not included in this phylogenetic analysis. In this study, the remaining species did not form stable clades, except for M. lateritia var. vinaceipes and M. wuyishanensis, which grouped together to form a stable clade with good morphological consistency, such as ellipsoid to amygdaliform spores measuring 5–6 μm in length, red-brown squamulose pileipellis, and hyphae of fibrils exhibiting vacuolar pigments. During the research process of this genus, many issues regarding the stability of the branches were not well resolved. However, as more species are discovered, we believe that more well-supported clades will emerge in the phylogenetic tree.

Key to Micropsalliota species distributed in China

1 Pileus white to dirty white 2
– Pileus distinctly coloured or covered with numerous coloured fibrils 16
2 Basidiospores mainly shorter than 5.5 μm 3
– Basidiospores mainly longer than 5.5 μm 7
3 Cheilocystidia bifid with two toe-like subcapitate lobes M. bifida
– Not as above 4
4 Basidiospores ovoid in face view, amygdaliform in profile view M. ovalispora
– Not as above 5
5 Cheilocystidia non-capitate M. pseudoarginea
– Cheilocystidia tibiiform or lageniform, capitate at apex 6
6 Pileus < 5 mm in diameter, hyphae of pileus squamules hyaline M. pseudodelicatula
– Pileus >5 mm in diameter, hyphae of pileus squamules has membranous pigments M. nana
7 Pileus mainly <10 mm in diameter 8
– Pileus mainly >10 mm in diameter 12
8 Cheilocystidia two types, tibiiform or forked with capitate or subacute apex M. minor
– Not as above 9
9 Cheilocystidia utriform M. tenuipes
– Cheilocystidia capitate at apex 10
10 Spores 8.0–9.0 μm M. bispora
–Spores shorter than 8.0 μm 11
11 Stipe less than 20 mm long, and annulus superior membranous M. delicatula
– Stipe up to 30 mm long, and annulus absent M. albofelina
12 Pileus 20–80 mm in diameter M. megarubescens
– Pileus mainly <20 mm in diameter 13
13 Pleurocystidia present M. longicystis
– Pleurocystidia absent 14
14 Pileipellis hyphae with incrusted pigments M. dentatomarginata
– Pileipellis hyphae with vacuolar pigments 15
15 Pileus not stains M. subalba
– Pileus stains reddish brown when bruised or cut M. rubrobrunnescens
16 Pleurocystidia present 17
– Pleurocystidia absent 18
17 Cheilocystidia cylindrical to subclavate M. digitatocystis
– Cheilocystidia pyriform to subglobose M. appendiculata
18 Pileus mainly <10 mm in diameter 19
– Pileus larger than 10 mm in diameter 22
19 Pileus brown to dark brown M. megaspora
– Pileus pink, red to violet-red 20
20 Cheilocystidia hyphoid, often forked, up to 60 μm long M. wuyishanensis
– Not as above 21
21 Stipe dirty white with pink tone, cheilocystidia without deposit M. cf. roseipes
– Stipe white, cheilocystidia covered by light brown deposit M. rufosquarrosa
22 Pileus >20 mm in diameter 23
– Pileus <20 mm in diameter 31
23 Basidiospores less than 6.0 μm long M. pseudoglobocystis
– Basidiospores up to 7.0 μm long or longer 24
24 Stipe less than 30 mm long, cheilocystidia cylindrical to subclavate, 12–33 μm long M. jiangxiensis
– Stipe up to 50 mm long or longer, cheilocystidia not as above 25
25 Basidiospores mainly wider than 4.0 μm 26
– Basidiospores mainly narrower than 4.0 μm 28
26 Spores up to 9.0 μm, cheilocystidia broadly clavate to clavate M. gigaspora
– Spores mainly less than 8.0 μm, cheilocystidia not as above 27
27 Cheilocystidia clavate to clavate-capitate M. squarrosa
– Cheilocystidia various, tibiiform, capitate, subhypoid, rarely fork M. vulgaris
28 Flesh stains red when bruised or cut M. furfuracea
– Flesh stains yellow, reddish-brown or blue when bruised or cut 29
29 Flesh stains blue M. ferruginea
– Flesh stains yellow or reddish-brown 30
30 Pileus has conspicuously obtuse umbo; squamules light brown, yellowish brown, or brown M. umbonata
– Pileus has slightly or not umbonate, squamules purple to purplish brown, greyish brown or reddish-brown M. globocystis
31 Veil cortinate M. cortinata
– Veil membranous 32
32 Basidiomata brown 33
– Basidiomata violet-red 34
33 Spores shorter than 5.5 μm M. arginophaea
– Spores up to 7.5 μm M. fimbriata
34 Cheilocystidia broadly clavate or seldom subcapitate M. lateritia var. vinaceipes
– Cheilocystidia versiform, ventricose to irregularly tibiiform, capitate or subcapitate with long narrow neck M. gracilis

Acknowledgements

Sincere thanks to the anonymous reviewers of the manuscript.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This research was funded by the National Natural Science Foundation of China, grant number 32460326 and 31960008; Jiangxi Provincial Natural Science Foundation, grant number 20224BAB205003; Fujian Provincial Natural Science Foundation, grant number 2023J01379; the Project of FAAS, grant number XTCXGC2021007.

Author contributions

Conceptualization: JQY, ZHZ. Data curation: CFN, ZHZ. Formal analysis: BRK, ZHZ. Funding acquisition: YPH, HZ, JQY, ZHZ. Investigation: ZHZ, JQY, YPH, BRK, CFN. Methodology: SNW. Project administration: HZ. Software: JQY. Supervision: SNW. Validation: SNW. Visualization: ZHZ. Writing – original draft: JQY, ZHZ. Writing – review and editing: HZ, SNW.

Author ORCIDs

Jun-Qing Yan https://orcid.org/0000-0003-1128-5171

Sheng-Nan Wang https://orcid.org/0000-0003-0648-271X

Hui Zeng https://orcid.org/0000-0003-2025-844X

Data availability

All of the data that support the findings of this study are available in the main text.

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Jun-Qing Yan and Zhi-Heng Zeng contributed equally to this work.
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