Short communication
A new edible species of Gomphus (Gomphaceae) from southwestern China
2022 Volume 63 Issue 6 Pages 293-297
Details
2022 Volume 63 Issue 6 Pages 293-297
Gomphus matijun, a new edible species, is described from southwestern China based on phylogenetic and morphological evidence. Phylogenetic analyses of the nrLSU and ITS datasets indicated that G. matijun is related to G. crassipes and G. ludovicianus with weak statistical support in maximum likelihood but strong statistical support in Bayesian analyses. Gomphus matijun is characterized by its gray-blue to blue or blue-purple pileus with a round or irregular outline, relatively smaller basidiospores [9-11(-13) × 6-7(-8) μm], mostly 2-spored basidia, and occurs in subtropical fagaceous forests. A key to the known species of Gomphus is provided.
Gomphus Pers. was introduced by Persoon (1797) and has then undergone many taxonomic and nomenclatural modifications. Giachini (2004), Giachini, Hosaka, Nouhra, Spatafora, and Trappe (2010), and Giachini and Castellano (2011) revealed that Gomphus sensu lato was polyphyletic, and species of the genus were recombined into multiple genera, viz. Gloeocantharellus Singer., Gomphus sensu stricto, Phaeoclavulina Brinkmann, and Turbinellus Earle (Giachini & Castellano, 2011). The pileus of Gomphus is from fan-shaped to slightly funnel-shaped, bright violet, pale olivaceous or brown; its hymenium is wrinkled to almost poroid, violet, vinaceous brown to milky-coffee colored with verrucose basidiospores (Giachini & Castellano, 2011). Gomphus is generally distributed in terrestrial habitats (Giachini, 2004). Five species, G. brunneus (Heinem.) Corner, G. clavatus (Pers.) Gray, G. crassipes (Kuntze) Maire, G. ludovicianus R.H. Petersen, Justice & D.P. Lewis, and G. orientalis R.H. Petersen & M. Zang, are known for the genus, among them G. orientalis is an easily overlooked species described from China and similar to G. clavatus (Zang, 1996).
During a survey of mushroom markets in Guizhou Province, China, we have found a hoof-shaped Gomphus species that is commonly called “matijun” and consumed by local residents. The aim of the present study is to report this new edible Gomphus species and then describe its morphological characteristics and phylogenetic traits since it differs from all other known species.
Morphological characteristics of fresh materials were recorded. All specimens were then dried at 45 °C and deposited in the Herbarium of Cryptogams, Kunming Institute of Botany, Chinese Academy of Sciences (HKAS), Yunnan, China.
Macro-morphological characteristics were described following the methods described by Giachini, Camelini, Rossi, Soares, and Trappe (2012) and Petersen, Hughes, Justice, and Lewis (2014). The dried specimens were sectioned by hand and mounted in 5% of KOH, and observed using a compound microscope (Leica DM2500, Leica Microsystems, Wetzlar, Germany). Twenty basidiospores per collection were measured, and their sizes and shapes were recorded and photographed. The color codes were recorded following Kornerup and Wanscher (1981). Basidiospores were photographed using a Scanning Electron Microscopy (SEM). Basidiospores were taken from the dried hymenium edge with tweezers and pasted with double-sided tape, which was directly mounted on an SEM stub, coated with gold-palladium, and examined and photographed with a JSM-5600LV SEM (JEOL, Tokyo, Japan). The notations [n/m/p] indicated that the measurements were made “n” basidiospores from “m” basidiomata of “p” collections with a minimum of 20 basidiospores. The basidiospore quotient was followed by [Q = L/W], where Q, the quotient of basidiospore length to width (L/W) of a basidiospore in side view and Qm, the mean of Q-values ± SD, was calculated considering the mean value of the lengths and widths of basidiospores. The basidiospore size was measured with and without the myxosporium and given as (a-)b-c(-d) (Tulloss, 2005).
Dried specimens were used to extract DNA. Universal primer pairs of LROR/LR5 (Vilgalys & Hester, 1990) and ITS1F/ITS4 (Gardes & Bruns, 1993; White, Bruns, Lee, & Taylor, 1990) were used for amplifying the large nuclear ribosomal RNA subunit (nrLSU) and the internal transcribed spacers 1 and 2 with the 5.8S rDNA (ITS), respectively. PCR amplification and sequencing followed Liu, Wan, Gong, and Yu (2020). The nrLSU and ITS sequence data obtained in this study were compiled with Gomphus sequences reported by Petersen et al. (2014) and other available sequences in NCBI (https://www.ncbi.nlm.nih.gov/). The newly generated sequences in this study and retrieved from GenBank are shown in Table 1. Two species of Ramaria were used as outgroup.
| Taxon | Voucher | Locality | GenBank accession | |
| nrLSU | ITS | |||
| Gomphus brunneus | BR034190-46 | - | AY574680 | - |
| G. clavatus | OSC 97587 | - | DQ218487 | - |
| G. clavatus | OSC 69447 | - | AF213129 | - |
| G. clavatus | EL 64/03 (GB) | Sweden | EU118628 | EU118628 |
| G. clavatus | AFTOL-ID 725 | - | AY647207 | - |
| G. clavatus | OSC 97588 | - | AY577836 | - |
| G. clavatus | OSC 97616 | - | AY574664 | - |
| G. crassipes | MA:Fungi:79908 | Spain | - | MH322660 |
| G. ludovicianus | TENN 69175 | USA: Texas | KJ655578 | KJ655571 |
| G. ludovicianus | TENN 69161 | USA: Louisiana | NG_059516 | NR_169660 |
| G. ludovicianus | TENN 69174 | USA: Texas | KJ655579 | KJ655572 |
| G. matijun (holotype) | HKAS 122604 | China: Guizhou | OL672986 | OL673002 |
| G. matijun | HKAS 122605 | China: Guizhou | OL672985 | OL673001 |
| G. orientalis | HKAS 90876 | China: Sichuan | OL672987 | - |
| G. orientalis | HKAS 90958 | China: Xizang | OL672988 | OL860986 |
| G. orientalis | HKAS 122603 | China: Yunnan | OL672989 | OL860987 |
| Ramaria conjunctipes var. sparsiramosa | OSC 134658 | - | JX287484 | KF206334 |
| R. rubribrunnescens | OSC 140575 | - | JX269129 | JX310406 |
Sequence datasets were aligned by using MAFFT v.6.8 (Katoh, Kuma, Toh, & Miyata, 2005) and then were manually edited with BioEdit v.7.0.9 (Hall, 1999). Gaps were treated as missing data. Maximum likelihood (ML) analyses were performed using IQ-TREE 1.6 (http://iqtree.cibiv.univie.ac.at/) and the substitution model TIM3+F+G4 for the nrLSU dataset and TN+F+I+G4 for the ITS dataset (Trifinopoulos, Nguyen, Haeseler, & Minh, 2016), which were determined according to the Akaike information criterion (AIC) by IQ-TREE. Clade support for the ML analyses was assessed using the Shimodaira-Hasegawa-like approximate likelihood ratio test (SH-aLRT) with 1,000 replicates (Guindon et al., 2010) and 1,000 replicates of the ultrafast bootstrap (UFB) (Hoang, Chernomor, Haeseler, Minh, & Vinh, 2018). Nodes with support values of both SH-aLRT ≥ 80 and UFB ≥ 95 were considered with supported, nodes with one of SH-aLRT ≥ 80 or UFB ≥ 95 were weakly supported, and nodes with both SH-aLRT < 80 and UFB < 95 were unsupported, and other parameters were used for the default settings. Bayesian Inference (BI) analyses were used to analyze the datasets with MrBayes v. 3.1.6 (Ronquist et al., 2012), and the optimal substitution models for the nrLSU and ITS datasets were determined by using AIC implemented in MrModeltest v. 2.4 (Nylander, 2004). The selected model was GTR+G for the nrLSU dataset, while was GTR+I+G was for the ITS dataset. BI analyses were conducted with generations set to 2 million, with trees sampled every 100 generations.
The average standard deviation of split frequencies (0.01) and effective sample size (ESS) values (> 200) were used to assess convergence. The trees were summarized after omitting the first 25% of trees as burn-in by using the “sump” and “sumt” commands, and the Bayesian posterior probabilities (BPP) of clades were estimated based on the majority rule consensus with the remaining trees. The alignments were deposited in TreeBASE (http://www.tree base.org/treebase/) with submission ID 29274 (nrLSU) and ID 29275 (ITS).
The nrLSU alignment included 17 sequences, including 5 newly generated and 12 retrieved from GenBank, which comprised 915 characters with gaps. The ITS alignment included 11 sequences, including 4 newly generated and 7 retrieved from GenBank, comprising 784 characters. The topologies of phylogenetic trees generated from ML and BI analyses were almost identical with minimal variation in statistical support, and thus only the tree inferred from ML analysis was displayed.
The phylogenetic trees generated from the nrLSU and ITS datasets indicated that the studied collections represented a distinct lineage (Figs. 1, 2). In addition, Gomphus matijun was resolved to be close to G. ludovicianus with a weak statistical support in the Maximum Likelihood analysis but a strong statistical support in the Bayesian analysis (nrLSU: SH-aLRT/UFB/BPP = 91/90/0.99) in the nrLSU phylogenetic tree, while being clustered into a clade with G. crassipes and G. ludovicianus in the phylogenetic tree generated from ITS with weak statistical support in the Maximum Likelihood and strong statistical support in the Bayesian analysis (ITS: SH-aLRT/UFB/BPP = 95/94/0.99).
Taxonomy
Gomphus matijun J. W. Liu & F. Q. Yu, sp. nov. Fig. 3.
MycoBank no.: MB 841963.
Diagnosis: Similar to G. clavatus and G. orientalis, but differs in unipileate fruiting bodies at maturity, ellipsoidal to elongate basidiospores (9-11 × 6-7 μm) and mostly 2-spored basidia.
Type: CHINA, Guizhou Province, Qianxinan Prefecture, Xiangjiaba Market, 24°59′12.34″N, 104°56′17″E, alt 1163 m, 19 Jun 2020, WD001 (HKAS 122604, holotype, GenBank accession No.: ITS = OL673002, nrLSU = OL672986).
Etymology: matijun, named after the local name “matijun” in Guizhou Province.
Basidioma unipileate, clavate, urceiform, or subfusiform when young, then horse hoof-like, up to 14 cm high and 9 cm across. Pileus applanate with down-turned margin at maturity, with a round or irregular outline; Hymenium decurrent, wrinkled and cross-veined, gray-blue (5E1) to blue (16A1-8) or blue-purple (15D5-8) when young, but usually fading to gray (15D1-2) or pale lilac (15D3-4) at maturity. Stipe subclavate, usually approximately 2-7 cm long, 1-3.5 cm wide, lower part whitish (1A1), upper part gray-blue (5E1); context white (1A1), mixed with gray (16B1) to gray-blue tinge (16B4).
Pileipellis composed of thin-walled, scattered, fasciculate to branched hyphae, 2-6 μm wide, tightly interwoven, with common hyphal termini emergent and sometimes forming a pruina-like structure in the hyphal termini, emergent termini cylindrical but irregular in outline, clamp connections present; Stipitipellis of hyaline clamped hyphae 4-6 μm wide. Pileus and stipe context of interwoven, hyaline clamped hyphae 2-6 μm wide. Hymenial trama of thin-walled clamed hyphae. Subhymenial trama slightly thickened, composed of hyaline clamped hyphae 2-5 μm wide, with brown amorphous deposits. Basidia 60-90 × 7-11 μm, long clavate, with 1-3 sterigmata, frequently 2 spored. Hymenial cystidia absent. Basidiospores [40/2/2]9-11(-12) × (5-)6-7(-8) μm, Q = (1.38-)1.40-1.8(-2.0), Qm = 1.65 ± 0.16, ellipsoidal to elongate, finely warted.
Habitat and distribution: Solitary to scattered in fagaceous forests (Information provided by mushroom sellers at Xiangjiaba Market) during summer and autumn. Currently known from southwestern China.
Additional specimen examined: CHINA, Guizhou Province, Qianxinan Prefecture, Xingyi City, Zerong Town, Xiangjiaba market, 24°59′12.34″N, 104°56′17″E, alt 1163 m. 30 Aug 2021, LJW2407 (HKAS 122605, GenBank accession No.: ITS = OL673001, nrLSU = OL672985).
Notes: Gomphus matijun is close to G. crassipes and G. ludovicianus in phylogenetic trees (Figs. 1, 2). However, morphologically G. matijun differs from the latter two by its significantly smaller basidiospores (9-11 × 6-7 μm) and 1-3 spored basidia. Gomphus crassipes and G. ludovicianus have larger basidiospores and 2-4 spored basidia (Petersen et al., 2014). Gomphus matijun share similar characteristics to G. clavatus and G. orientalis, but G. matijun can be distinguished from the latter two by its unipileate basidioma and smaller basidiospores (9-11 × 6-7 μm). Both G. clavatus and G. orientalis have larger basidiospores (Zang, 1996; Giachini et al., 2012). Furthermore, G. clavatus and G. orientalis are associated with Abies and Picea species (Zang, 1996; Giachini et al., 2012), while G. matijun is associated with plants of Fagaceae. According to our phylogenetic analyses, G. clavatus and G. orientalis are also distantly related to G. matijun (Figs. 1, 2). There is close distance between G. orientalis and G. clavatus. According to the description by Zang (1996), G. orientalis differs from G. clavatus by its larger spores (10.3-15.5 × 4.3-7.5 μm vs. 10-15 × 4-7.5 μm), and the ornamentation of warts of basidiospores of G. orientalis are more sparse, despite this, the difference between G. clavatus and G. orientalis in morphological characteristics is negligible. To clarify the relationship thoroughly between G. clavatus and G. orientalis, it is necessary to obtain the DNA sequences of the holotype (R. H. Petersen 56817) and the isotype (HKAS 18144) of G. orientalis then detailed to study in the future.
Key to the species of Gomphus
1a. Basidiomata becoming merismatoid at maturity, pileus fan-shaped...... 2
2a. Basidiospores 10-15 × 4-7.5 μm, Asia, Europe, North America...... G. clavatus
2b. Basidiospores 10.3-15.5 × 4.3-7.5 μm, southwestern China...... G. orientalis
1b. Basidiomata unipileate at maturity, occasionally merismatoid, pileus funnel-shaped to applanate, occasionally fan-shaped...... 3
3a. Basidiospores < 13 μm long...... 4
4a. Basidiospores 7.5-10 × 3.5-5 μm; pileus brown or occasionally rosaceous; wrinkled, reticulate to almost poroid, pale violet to milky-coffee colored; Cameroon, Democratic Republic of Congo, Uganda...... G. brunneus
4b. Basidiospores 9-11 × 6-7 μm, pileus gray-blue to blue or blue-purple; hymenium wrinkled, gray-blue to blue-purple or gray; southeastern China...... G. matijun
3b. Basidiospores > 13 μm long...... 5
5a. Basidiospores 13-15 × 5.5-6 μm; pileus sordid yellow to orangish brown; hymenium wrinkled, violet; Algeria, Morocco, and Spain...... G. crassipes
5b. Basidiospores 14-17 × 5-7 μm; pileus dull “benzo brown”, to “deep Quaker drab”, bruising darker, some pale surface over-center; delicately wrinkled, purple-gray; southeastern United States...... G. ludovicianus
The authors declare no conflicts of interest for this study. All the experiments undertaken in this study comply with the current laws of the People's Republic of China.
We appreciate the kind support given by Professor Kevin D. Hyde, the Center of Excellence in Fungal Research, Mae Fah Luang University, and also Professor Xinhua He, University of Western Australia, for revising the manuscript. Mr. Zhijia Gu, CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, who kindly provided help using the Scanning Electron Microscope. Thanks are also due to the anonymous reviewers for their professional suggestions and comments. This work is supported by the International (Regional) Cooperation and Exchange Projects of the National Natural Science Foundation of China (31961143010) and the Yunnan Province Youth Project of the Applied Fundamental Research Program (2018FG001-082). Thatsanee Luangharn thanks the Thailand Science Research and Innovation (TSRI) for the Fundamental Fund-Basic Research Fund 2565 (652A16009).
