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Research Article
Introduction of two novel species of Hymenopellis (Agaricales, Physalacriaceae) from Thailand
expand article infoAllen Grace T. Niego‡§, Naritsada Thongklang‡, Kevin D. Hyde|‡#, Olivier Raspé‡
‡ Mae Fah Luang University, Chiang Rai, Thailand
§ Iloilo Science and Technology University, Iloilo, Philippines
| Chiang Mai University, Chiang Mai, Thailand
¶ Zhongkai University of Agriculture and Engineering, Guangzhou, China
# Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China

Corresponding author: Olivier Raspé ( Olivier.Ras@mfu.ac.th )

Academic editor: Rui-Lin Zhao
© 2023 Allen Grace T. Niego, Naritsada Thongklang, Kevin D. Hyde, Olivier Raspé.
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: Niego AGT, Thongklang N, Hyde KD, Raspé O (2023) Introduction of two novel species of Hymenopellis (Agaricales, Physalacriaceae) from Thailand. MycoKeys 98: 253-271. https://doi.org/10.3897/mycokeys.98.104517
Open Access

Abstract

Hymenopellis is the most diverse genus in the group of oudemansielloid/xeruloid taxa (Physalacriaceae). This genus has a worldwide distribution with records mostly from Europe and America. Asian taxa are least represented. In this paper on Hymenopellis from Thailand, two novel species are introduced, and a Hymenopellis collection affine to H. orientalis is described. Macro and micromorphological characters are described. Maximum likelihood and Bayesian phylogenetic analyses were performed on combined ITS and nrLSU regions to confirm taxonomical placement and infer the phylogenetic affinities of the studied species. Hymenopellis straminea sp. nov. is straw-yellow, with medium-sized basidiomata, abundant and diverse in form cheilocystidia, few, narrowly lageniform to fusiform pleurocystidia, and clamp connections at the lower part of the stipe. Hymenopellis utriformis sp. nov. has mostly utriform pleurocystidia and 2-spored basidia. In the inferred phylogenies, the new species from this study formed distinct clades well supported by bootstrap proportions and posterior probabilities. The studied specimen affine to H. orientalis produced 2-spored basidia whereas published descriptions of other specimens mention 4-spored basidia. Moreover, the genetic distance between ITS sequences of this specimen and that of a Hymenopellis orientalis specimen from GenBank was 1.30–2.57%. Therefore, the conspecificity of our specimen with H. orientalis is uncertain, and additional specimens are needed to fully confirm its identity.

Key words

2 new species, morphology, macrofungi, phylogeny, Southeast Asia, taxonomy

Introduction

Hymenopellis R.H. Petersen, one of the genera in the Physalacriaceae Corner, was circumscribed by Petersen and Hughes (2010) as a new genus, covering those species with moist to glutinous pileus. It is the largest genus in the oudemansielloid/xeruloid complex and has a worldwide distribution. Hymenopellis species were previously classified in the section Radicatae of Oudemansiella (Clémençon 1979; Pegler and Young 1986; Yang et al. 2009). The presence of a pseudorrhiza separated O. sect. Radicatae from sect. Hygrophoroides (Clémençon 1979). The type species, H. radicata was first described by a British botanist, Richard Relhan, in 1780, under the name Agaricus radicatus, which is also synonymous with Oudemansiella pseudoradicata M.M. Moser, Oudemansiella radicata (Relhan: Fr.) Singer and Xerula radicata (Relhan: Fr.) Dörfelt. There are around 50 species of Hymenopellis (He et al. 2019) of which 13 were first described from Asia (Petersen and Hughes 2010).

Hymenopellis is widely distributed in tropical and temperate regions (He et al. 2019). The majority of the literature on this genus has focused on Europe and the United States, where its taxonomy and distribution have been extensively researched. The most thorough study on Hymenopellis was done by Petersen and Hughes (2010), in which descriptions of all known species were provided. Out of the 50 described species, only 19 have sequences available in GenBank. The majority of sequences found in GenBank are from specimens collected in the eastern United States. Asian taxa are least represented (Petersen and Hughes 2010) with limited studies in this genus from Asian countries. Thirteen species of Hymenopellis have been recorded from Asia, of which 12 were first described from Asian countries. Six species were first described from temperate regions in China and Japan while another six species were described from tropical countries, namely H. altissima (Massee) R.H. Petersen from Singapore (as Collybia altissima), H. bispora (Natarajan & Purush.) R.H. Petersen, H. keralae R.H. Petersen & Manim. and H. raphanipes (Berk.) R.H. Petersen from India, H. endochorda (Berk. and Broome) R.H. Petersen from Sri Lanka (Petersen and Hughes 2010) and H. neuroderma (Pat.) R.H. Petersen from Vietnam (Petersen and Hughes 2010). In Thailand, only two species have been recorded, namely H. raphanipes (Petersen and Nagasawa 2006; Yang et al. 2009), and H. radicata (as X. radicata) (Chandrasrikul et al. 2011). However, the H. radicata recorded in Thailand has no associated sequence available. Thailand has a forested area of around 16.3 million ha (FAO 2020), a thriving habitat for diverse macrofungal species (Hyde et al. 2018). Many macrofungal species have been discovered in this country and many more remain to be introduced to science. Additional collections and further studies are necessary to improve our knowledge of Asian Hymenopellis taxonomy.

In this study, two new tropical species of Hymenopellis are introduced and a Hymenopellis specimen affine to H. orientalis is described from Thailand, adding to the limited number of Asian taxa.

Materials and methods

Sample collection and morphological observations

The specimens were collected from Chiang Rai and Chiang Mai provinces, Thailand during rainy season in June and August 2019. Photographs of the fresh samples were taken on the field, and information about habitat, habit, and other important features (e.g., color of the basidiomata, gills and stipe) of the specimen were noted. The basidiomata were carefully collected and kept in aluminum foil, labeled, and brought to the laboratory. Once in the laboratory, each specimen was photographed, measured, and described. Spore prints were collected on both black and white paper. Specimens were dried using a hot air dryer set to 45–50 °C for 24 hours. They were carefully labelled and stored in zip-lock bags to be used for further analyses. All samples were deposited in the Mae Fah Luang University fungarium (MFLU).

Macromorphological characters of the specimens (i.e., pileus, lamellae, and stipe) were described based on the fresh basidiomata. Naming of original colors was based on Methuen Handbook of Color, 3rd ed. (Kornerup and Wanscher 1978). Preparation of macrofungal samples to describe micromorphological characters was based on the laboratory techniques by Clémençon (2009). Important features were examined using Motic SMZ-171 dissecting microscope and specific features were noted based on the terminology of Vellinga and Noordeloos (2001). Microscopic characters were observed using Nikon Eclipse Nἰ, DS-Ri2 compound microscope with dried samples rehydrated and mounted in water or in 3–5% KOH to retain original color. The prepared slides were stained with ammoniacal Congo Red to bring out hyaline structures. Specific features, i.e., basidiospores, basidia, cystidia and pellis, were drawn by free hand using standard microscopic techniques and described following the glossary of Vellinga and Noordeloos (2001). Dimension of at least 30 basidiospores per collection were measured in side view. The notation [A, B, C] preceding measurements of basidiospores, basidia and cystidia indicates the number (A) of those cells measured from the number (B) of basidiomata in the number (C) of collections. Measurements are presented as (a)b–c–d(e), where ‘a’ and ‘e’ are the extreme values, ‘b–d’ are the 5th and 95th percentiles, and ‘c’ is the average. Q represents the length/width ratio and Q*, the average value.

DNA extraction, PCR and sequencing

DNA was isolated from samples taken from the dried specimens, using the Biospin Fungus Genomic DNA Extraction Kit (Bioer Technology, Hangzhou, China), following the manual’s procedure. The DNA loci amplified by PCR were the ITS region (including ITS1, 5.8S, ITS2) with the primers ITS1-F and ITS4 (White et al. 1990; Gardes and Bruns 1993), and nrLSU, with the primers LR0R and LR5 (Vilgalys and Hester 1990; White et al. 1990). PCR products were purified and sequenced in both directions, using the PCR primers, by Sangon Biological Engineering Technology and Services (Shanghai, China). The quality of each generated sequence read was checked using Bioedit Sequence Alignment Editor version 7.0.9.0 (Hall 1999) and sequence reads were assembled using SEQMan Pro software (DNA Star, Madison, USA).

Phylogenetic analyses

Ten new sequences were generated in this study and were deposited in GenBank (Table 1). Each sequence was compared with sequences in GenBank (National Center for Biotechnology Information, NCBI) with the Basic Local Alignment Search Tool (BLAST). Forty-nine related accessions retrieved from GenBank, including three outgroup taxa, Paraxerula americana (Dörfelt) R.H. Petersen, Strobilurus conigenoides (Ellis) Singer and X. pudens (Pers.) Singer, were used to infer phylogenetic relationships with the newly generated sequences (Table 1). Outgroup taxa were chosen based on the ITS+nrLSU phylogeny in Hao et al. (2016). ITS and nrLSU were the only gene regions used to infer phylogenetic relationships with the newly generated sequences in this study. Other gene regions, especially the protein-coding ones, are very poorly represented in GenBank or non-existent, thus impossible to use for the analysis. The sequences were aligned using MAFFT version 7.450 (Katoh et al. 2019) on the server accessed at http://mafft.cbrc.jp/alignment/server/. TrimAl (Capella-Gutierrez et al. 2009) was used to eliminate ambiguously aligned positions from the alignments, using the strict mode option. The ITS and nrLSU alignments were 655 and 832 bp long, respectively. Phylogenetic tree inference was performed with partitioned maximum likelihood (ML) and Bayesian interference (BI) analyses. The two-character sets were ITS1+ITS2, and 5.8S+LSU. The best-fit nucleotide substitution model for ITS and nrLSU was selected with jModeltest version 2.1.10 (Darriba et al. 2012) based on the corrected Akaike Information Criterion (AICc). For the two gene regions, the HKY+G model was selected as the best model. ML analysis was performed through RAxML-HPC2 version 8.2.10 (Stamatakis 2014) on the web server CIPRES Science Gateway V. 3.3 (Miller et al. 2010) with GTRGAMMA as the model of evolution. The branch support was estimated with 1,000 rapid bootstrap replicates. The final alignment has been submitted to TreeBASE (submission ID 29774). For BI analysis, Markov Chain Monte Carlo (MCMC) sampling was performed using MrBayes v. 3.0b4 (Huelsenbeck and Ronquist 2001). Two runs of five simultaneous MCMC chains were run for 5,000,000 generations with trees and parameters sampled every 1,000th generation, for a total of 10,000 samples. The first 25% of samples were discarded as burn-in phase. The remaining samples were used to calculate the majority rule consensus tree and associated posterior probabilities (PP). The trees were viewed using FigTree v1.4.2 (Rambaut 2012).

Table 1.
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List of sequences used in the phylogenetic analysis from GenBank with geographic origin and accession numbers of gene regions. The sequences newly generated for this study are in bold.

Species Voucher/strain Geographic GenBank Accession No. References
origin ITS nrLSU
Hymenopellis colensoi ZT12902 New Zealand HM005139 HM005119 Petersen and Hughes (2010)
H. colensoi PDD80639 China – AY960989 Unpublished
H. furfuracea HKAS 93109 China KX688223 KX688250 Hao et al. (2016)
H. furfuracea TENN 61671 USA GQ913362 HM005101 Petersen and Hughes (2010)
H. furfuracea AFTOL-ID 538 USA DQ494703 AY691890 Matheny et al. (2006); unpublished
H. furfuracea TM03_474 Canada – EU522838 Porter et al. (2008)
H. furfuracea JM98/155 China AF321484 – Mueller et al. (2001)
H. furfuracea TENN 59876 USA GQ913367 HM005126 Petersen and Hughes (2010)
H. gigaspora NY REH 8676 Australia GQ913357 HM005121 Petersen and Hughes (2010)
H. gigaspora NY REH 8671 Australia GQ913355 – Petersen and Hughes (2010)
H. gigaspora TENN 50056 Australia GQ913358 – Petersen and Hughes (2010)
H. gigaspora TENN 50050 Australia GQ913359 – Petersen and Hughes (2010)
H. hispanica 05110401(SEST) Spain – HM005082 Petersen and Hughes (2010)
H. incognita TENN 58768 USA GQ913424 HM005105 Petersen and Hughes (2010)
H. incognita TENN 60228 USA GQ913419 HM005104 Petersen and Hughes (2010)
H. incognita EIU ASM10044 USA GQ913422 – Petersen and Hughes (2010)
H. japonica HKAS 61674 China KX688225 KX688252 Hao et al. (2016)
H. japonica HKAS 83175 China KX688226 KX688253 Hao et al. (2016)
H. limonispora TENN 59438 USA GQ913406 HM005133 Petersen and Hughes (2010)
H. limonispora TENN 61379 USA GQ913403 HM005134 Petersen and Hughes (2010)
H. limonispora BIOUG24046-A02 Canada KT695313 – Telfer et al. (2015)
H. megalospora DAOM196115 AF042649 unpublished
H. orientalis HKAS 67938 China KX688227 KX688254 Hao et al. (2016)
H. orientalis HKAS 70323 China KX688228 KX688255 Hao et al. (2016)
H. orientalis TMI 2IX2002c1 Japan GQ913396 – Petersen and Hughes (2010)
H. radicata TENN 62837 Sweden GQ913375 HM005125 Petersen and Hughes (2010)
H. radicata TENN 59329 Austria GQ913380 – Petersen and Hughes (2010)
H. radicata TENN 60126 Russia GQ913384 – Petersen and Hughes (2010)
H. radicata TENN 59223 France GQ913392 – Petersen and Hughes (2010)
H. radicata var. bispora TENN 57277 Sweden GQ913379 HM005122 Petersen and Hughes (2010)
H. raphanipes HKAS93070 China KX688248 KX688275 Hao et al. (2016)
H. raphanipes JBZ 2111002 China KX688229 KX688256 Hao et al. (2016)
H. raphanipes HKAS 93073 China KX688231 KX688258 Hao et al. (2016)
H. raphanipes HKAS 42555 China GU980129 HM005108 Petersen and Hughes (2010)
H. raphanipes (2-spored) TENN 59800 Thailand GU980128 – Petersen and Hughes (2010)
H. raphanipes (2-spored) HKAS 42503 China GU980130 – Petersen and Hughes (2010)
H. raphanipes (as O. chiangmaiae) TENN 59791 Thailand KX964658 – Hao et al. (2016)
H. rubrobrunnescens TENN 52479 USA GQ913371 – Petersen and Hughes (2010)
H. rubrobrunnescens TENN 52654 USA GQ913372 HM005112 Petersen and Hughes (2010)
H. rubrobrunnescens TENN 51262 USA GQ913373 HM005113 Petersen and Hughes (2010)
H. rugosoceps TENN 57307 USA GQ913395 HM005116 Petersen and Hughes (2010)
H. rugosoceps TENN 60604 USA GQ913394 HM005117 Petersen and Hughes (2010)
H. sinapicolor S.D. Russell MycoMap 6316 USA MK560120 – Unpublished
H. sinapicolor (holotype) TENN 56566 USA GQ913350 HM005118 Petersen and Hughes (2010)
H. straminea MFLU22-0138 holotype Thailand OP265162 OP265157 this study
H. straminea MFLU22-0139 Thailand OP265163 OP265158 this study
H. superbiens MEL2291946 Australia GQ913360 HM005120 Petersen and Hughes (2010)
H. trichofera MEL2293664 Australia GQ913354 HM005129 Petersen and Hughes (2010)
H. utriformis MFLU22-0140 holotype Thailand OP265164 OP265159 this study
H. utriformis MFLU22-0141 Thailand OP265165 OP265160 this study
H. vinocontusa TMI 7669 Japan GQ913370 – Petersen and Hughes (2010)
H. aff. orientalis MFLU22-0142 Thailand OP265166 OP265161 this study
Paraxerula americana CLO 4746 USA HM005142 HM005094 Petersen and Hughes (2010)
Strobilurus conigenoides TENN 61318 USA GQ892821 HM005091 Petersen and Hughes (2010)
Xerula pudens TENN 59208 Austria HM005154 HM005097 Petersen and Hughes (2010)
“Xerula sp.” BCC56836 Thailand KX755407 KX755408 Sadorn et al. (2016)

Genetic distances between closely related sequences were measured from MAFFT aligned sequences. The genetic distances between ITS sequences were computed based on the combined ITS1 and ITS2 regions, excluding the 5.8S gene. For LSU, the full sequence between the primers LR0R and LR5 was used.

Results and discussion

DNA sequence analyses

The BLAST search results from the sequences of both loci (ITS and nrLSU) all matched with Hymenopellis taxa, thus indicating that all sequences generated from this study belong to this genus.

In the combined ITS and nrLSU phylogeny, the new species H. straminea, represented by the specimens MFLU22-0138 (holotype) and MFLU22-0139, was monophyletic with 99% bootstrap support and 1.00 probability (Fig. 1). The ITS and nrLSU genetic distances between the two accessions were 0.52% (3/573) and 0.44% (4/905), respectively, and therefore are supported as conspecific. Hymenopellis straminea was sister to the clade of H. raphanipes TENN 59800, H. furfuracea JM98-155 and “Xerula sp.” BCC56836 with 75% bootstrap support and a posterior probability of 1 (Fig. 1). The ITS genetic distances between H. straminea MFLU22-0138 (holotype) and the other accessions in the latter clade were 8.81% (49/556) for H. raphanipes TENN 59800, 8.83% (46/521) for H. furfuracea JM98-155 and 9.01% (51/566) for “Xerula sp.” BCC56836. The distance for nrLSU between H. straminea MFLU22-0138 and “Xerula sp.” BCC56836 was 2.73% (25/915).

Figure 1. 

Phylogenetic tree generated from ML analysis of combined ITS and nrLSU data set for Hymenopellis with three outgroup species. Bootstrap support values (≥70%) and posterior probabilities (≥0.9) (BS/PP) are given above the branches. All termini are with species name and voucher ID, with the newly generated sequences from this study in bold.

“Hymenopellis raphanipes” TENN 59800 and “H. furfuracea” JM98-155 were separated from their respective species clades (Fig. 1). Therefore, it is likely that they were not identified correctly. The ITS genetic distance between H. raphanipes TENN 59800 and H. raphanipes TENN 59791 from Thailand was 8.68% (48/553). The ITS genetic distance between H. furfuracea JM98-155 and H. furfuracea HKAS 93109, both specimens from China, was 11.20% (57/509). The ITS genetic distances between specimens are much higher than the highest threshold value (3.0%) of species hypotheses in the Unite database (Nilsson et al. 2019), or the weighted average of the intraspecific ITS variability of Basidiomycota is 3.33% (Nilsson et al. 2008). The distances we observed therefore support separate species. BCC56836, on the other hand, was misidentified as “Xerula sp.” since it is clearly closely related to Hymenopellis species. However, BCC56836 is a culture collection only published for its bioactivity, without a corresponding herbarium specimen. Therefore, its morphology cannot be checked. The ITS genetic distances between “Xerula sp.” BCC56836 and H. raphanipes TENN 59800 and H. furfuracea JM98-155 were 3.91% (22/562) and 3.8% (20/527), respectively, while the ITS genetic distance between H. raphanipes TENN 59800 and H. furfuracea JM98-155 was 2.67% (14/527). It is possible that H. raphanipes TENN 59800, H. furfuracea JM98-155 and “Xerula sp.” BCC56836 are conspecific but further taxonomic studies, especially morphological comparisons among specimens belonging to this clade, are needed to confirm this assumption. Also, a detailed study of the holotypes of H. raphanipes and H. furfuracea is needed to confirm which of the sequenced specimens identified as those two species, if any, actually belong to them.

Hymenopellis utriformis sequences MFLU22-0140 (holotype), MFLU22-0141 separated from the clade of Hymenopellis rubrobrunnescens with 77% bootstrap support and 0.98 probability. The ITS genetic distance between the holotype H. utriformis MFLU22-0140 and H. rubrobrunnescens TENN 51262 is 8.06% (46/571), thus are considered to be separate species. The two sequences of H. utriformis (MFLU22-0140, MFLU22-0141) generated from this study joined together and are well-supported with 100% bootstrap support and 1.00 probability. The ITS and nrLSU genetic distances between the two generated sequences are 0.69% (4/577) and 0.22% (2/890), respectively, thus considered as conspecific.

The Hymenopellis sp. MFLU22-0142 fell into the clade of H. orientalis with 64% bootstrap support and 0.92 posterior probability. The ITS genetic distances between Hymenopellis sp. MFLU22-0142 from this study and H. orientalis TMI-2IX2002c1 and HKAS70323 are 2.57% (14/545) and 1.30% (7/539), respectively.

ITS1 and ITS2 are fast-evolving loci and are very useful in species delimitation in Hymenopellis. The often advocated 3% threshold to separate interspecific and intraspecific ITS genetic distances worked well for the two new species here described, with interspecific distances from their closest relatives being well above this value. However, for the specimen related to Hymenopellis orientalis, while the ITS genetic distance between our specimen and the Japanese specimen was lower than 3%, morphological differences were observed. More specimens related to H. orientalis must be studied to determine if they belong to one or more than one species. The 3% threshold should not be considered as universal. Some Basidiomycota genera have indeed been reported to exhibit lower intraspecific ITS variability such as Amanita muscaria (0.9%) and Boletus edulis (0.3%) (Nilsson et al. 2008).

Taxonomy

Hymenopellis straminea Niego & Raspé, sp. nov.

MycoBank No: MycoBank No: 845750
Facesoffungi Number: FoF12896
Figs 2, 3

Type

Thailand. Chiang Rai Province: Mae Fah Luang District, elevation 1,110 m, tropical hill forest with grass dominated by Castanopsis and Lithocarpus trees, 14 June 2019, A.G. Niego, MFLU22-0138 (holotype); GenBank OP265162-ITS, OP265157-nrLSU.

Etymology

The name refers to the straw-yellow color of the pileus.

Diagnosis

Differentiated from similar Hymenopellis species by the small (< 5 cm), straw-yellow pileus and lamellae without decurrent tooth.

Description

Basidiomata small-sized. Pileus 35–45 mm diam., circular in polar view, in side view convex to applanate, straw-yellow or buff (4B5) evenly colored but darker when young; surface dry to viscid, sticky when wet, non-hygrophanous, rugulose, moderately wrinkled; margin decurved to plane, translucent striate; context white, unchanging when cut, consistency rubber-like. Lamellae 4–5 mm broad, thick, white, ventricose, adnate with no distinct decurrent tooth, spacing > 1 mm; lamellar margin even; lamellulae present, regularly arranged, in 2 (3) tiers. Stipe 65–85 × 3–4 mm, central, cylindrical, mostly equal, thickened at the base, light brown, lighter (5A2) from the pileus becomes yellowish brown (5D5) towards the base, surface dry, appressed squamulose especially towards the base, fistulose; context white, unchanging when cut; pseudorrhiza present. Spore print white. Smell indistinct. Taste mild.

Figure 2. 

Basidiomata of Hymenopellis straminea MFLU22-0138, holotype A, B, D top view of basidiomata C view of lamellae. Scale bar: 3 cm (A–D) Photographs by A.G. Niego.

Basidiospores [60,2,2] (9)10.2–12.8–14.5(15) × (8)8.5–11–11.5(12) µm (Q = 1.0–1.3, Q* = 1.2), subglobose to ellipsoid, thin-walled, hyaline in 5% KOH. Basidia [30,2,2] (35)36–42.8–57(60) × 12–14.3–20 µm (Q = 2.7–3.3, Q* = 3.0), tetrasporic, clavate, without clamp connection; contents grossly granular. Cheilocystidia [30,2,2] (21)26–47–73.5(74) × (6)9.5–12.5–18(21) µm (Q = 2.1–6.2, Q* = 3.8), numerous, grouped together, pedunculate, narrowly lageniform, clavate to broadly clavate, fusiform, smooth, thin-walled, hyaline in 5% KOH. Pleurocystidia [30,2,2] (48.5) 55–87–136 (168) × (15.5) 16–21.5–29 (32.5) µm (Q = 2.5–5.8, Q* = 3.6), mostly narrowly lageniform but can also be fusiform, smooth, thin-walled, hyaline in 5% KOH. Hymenophoral trama irregular, made of thin-walled, hyaline hyphae. Pileipellis an epithelioid hymeniderm with some extended pileal hairs; terminal elements (24.5)25.5–31–36(43) × (12)12.5–14–17(18) µm, with scattered intracellular light brown (6D8) pigment in 5% KOH. Stipitipellis a cutis; hyphae (7.5)8–9.5–11.5(12) µm wide, with intracellular light brown (6D8) pigment in 5% KOH. Clamp connections were seen in the lower part of the stipe.

Figure 3. 

Micromorphological features of H. straminea MFLU22-0138, holotype A basidiospores B basidia C cheilocystidia D pleurocystidia E pileipellis F stipitipellis.

Habitat and distribution

Solitary, in tropical hill forest of Chiang Rai Province, Thailand.

Additional specimen examined

Thailand. Chiang Rai Province: Mae Fah Luang District, elev. 1,100 m, tropical hill forest, 14 June 2019, A.G. Niego, MFLU22-0139; GenBank OP265163-ITS, OP265158-nrLSU.

Notes

Hymenopellis straminea is quite similar to H. megalospora (Clem.) R.H. Petersen, the latter having usually small pileus (<50 mm) but H. megalospora can sometimes reach up to 120 mm diam. The color of H. megalospora may range from disc deep olive brown to “buckthorn brown” (5D6) to pale ochraceous buff (4A2), to nearly white, with or without a darker center. The stipe of H. megalospora, however, is quite longer (70–250 × 2–3 mm), and the lamellae are strongly decurrent, which is not evident in H. straminea. Moreover, H. megalospora has larger basidiospores (15–21 × 8–12 µm) which are finely dimpled or pitted (Petersen and Hughes 2010).

Hymenopellis straminea is also quite similar to some specimens of H. furfuracea (Peck) R.H. Petersen in having a broadly convex to nearly flat pileus with bald and moderately wrinkled surface. Hymenopellis furfuracea basidiomata are more diverse in color (dark brown to gray brown or yellow brown) and size (very small to large). Lamellae also have slight decurrent tooth (Yang et al. 2009; Petersen and Hughes 2010). Hymenopellis straminea on the other hand is consistently small in pileus size (35–45 mm), evenly straw-yellow.

Finally, Hymenopellis raphanipes is different from the new species by having mostly dark colored basidiomata but they can sometimes be “buckthorn brown” (5D6), and also vary in size from small to large (Petersen and Hughes 2010). Strains of H. raphanipes also have 2- and 4- spored basidia. H. straminea basidia, however, are always 4-spored. When compared with H. raphanipes TENN 59800, the herbarium specimen with which H. straminea formed a clade, the morphology is quite different. The most obvious difference is the much bigger basidiospores of H. raphanipes TENN 59800 [(13.7) 14–15.8–17 (18) × (11) 12.5–13.3–14 (15) µm]. The terminal elements of the pileipellis of H. raphanipes TENN 59800 are also larger [(20)23–37–50(70) × (10)11–14.7–17.5(21) µm]. Those morphological differences, together with the high genetic distance in the clade, support that H. straminea is a novel species.

Hymenopellis utriformis Niego & Raspé, sp. nov.

MycoBank No: MycoBank No: 845751
Facesoffungi Number: FoF12895
Figs 4, 5

Type

Thailand. Chiang Mai Province: Mae Taeng District, elev. 400 m, tropical deciduous forest, 09 August 2019, A.G. Niego, MFLU22-0140 (holotype); GenBank OP265164-ITS, OP265159-nrLSU.

Etymology

The name refers to the most common utriform or narrowly utriform pleurocystidia of the type specimen.

Diagnosis

Differentiated from other Hymenopellis species by the moist to viscid, light brown pileus, mostly utriform pleurocystidia and 2-spored basidia.

Description

Basidiomata small-sized to large. Pileus 25–95 mm diam., circular in polar view, in side view broadly convex to plane to slightly depressed, light brown (5C5), moist to viscid, non-hygrophanous, rugose surface, radially wrinkled with age; margin plane to decurved, translucent striate; context cream (1A3) to white, unchanging when cut, consistency rubber-like. Lamellae 4–8mm broad, adnexed, ventricose, white to cream (1A3), spacing > 1 mm; lamellar margin even; lamellulae present, in 2 tiers. Stipe 50–185 mm × 4–12 mm, central, cylindrical, mostly equal, thickened at the base, off-white to light brown (5A2) from the pileus becomes darker (5D4) towards the base, surface dry, appressed squamulose especially towards the base, narrowly fistulose; context white, unchanging when cut; pseudorrhiza present. Annulus and volva absent. Spore print white. Smell indistinct. Taste slightly sweet.

Figure 4. 

A, B basidiomata of Hymenopellis utriformis MFLU22-0140, holotype. Scale bars: Photographs by A.G. Niego.

Basidiospores [60,3,1] (11.7) 12–13.7– 16.7 (17) × (9.3) 10.1–11.4–12.6 (12.7) µm (Q = 1.0–1.5, Q* = 1.2), subglobose to ellipsoid, thin-walled, hyaline in 5% KOH. Basidia [30,3,1] (36) 36.7–38.1–39.2 (39.5) × (9.4) 11.3–11.6–12.8 (13) µm (Q = 3.0–4.0, Q* = 3.3), 2–spored, clavate, without clamp connection. Cheilocystidia [30,3,1] (31) 38–52–64 (67.7) × (8.6) 9–13.2–18 (18.5) µm (Q = 3.1–5.0, Q* = 3.9), numerous, grouped together, pedunculate, narrowly clavate to clavate, conical, narrowly utriform to utriform, smooth, thin-walled, hyaline in 5% KOH. Pleurocystidia [30,3,1] (83) 88–116.3–131 (174) × (22) 22.5–30–35 (37.5) µm (Q = 2.9–5.4, Q* = 3.9) scattered, narrowly utriform to utriform, smooth, thin-walled, hyaline in 5% KOH. Hymenophoral trama irregular, made of thin-walled, hyaline hyphae. Pileipellis an epithelioid hymeniderm; terminal elements 28–52–76 × 11–13.7–17.5 µm with few scattered intracellular light brown (6D8) pigment in 5% KOH. Stipitipellis a trichoderm, terminal elements 28–52–76 × 11–13.7–17.5 µm, with intracellular light brown (6D8) pigment in 5% KOH. Clamp connections not seen.

Figure 5. 

Micromorphological features of H. utriformis MFLU22-0140, holotype A basidiospores B basidia C cheilocystidia D pleurocystidia E pileipellis F caulocystidia.

Habitat and distribution

Solitary to clustered, in soil covered with degrading leaves and other organic matters, in deciduous forest of Chiang Mai Province, Thailand.

Additional specimen examined

Thailand. Chiang Mai Province: Mae Taeng District, elev. 375 m, tropical deciduous forest, 09 August 2019, A.G. Niego, MFLU22-0141; GenBank OP265165-ITS, OP265160-nrLSU.

Notes

Hymenopellis utriformis is similar to H. rubrobrunnescens (Redhead, Ginns & Shoemaker) R.H. Petersen, having small to large but gracile basidiomata. The color is “tawny olive” (5C5) with rugose to rugulose surface.

Hymenopellis radicata (Relhan) R.H. Petersen, as described by Petersen and Hughes (2010), is similar to H. utriformis in having large basidiomata and a mid-brown (5–6D, 5–6E5–8, 5E7, 4E7, 6D3) pileus which is radially wrinkled. Both species are rather moist to viscid. However, H. radicata stipe is longitudinally lined, usually twisted while its cheilocystidia are clavate to subcapitate when young, broadly cylindrical, jar-shaped to occasionally mammillate when mature. The cheilocystidia of H. utriformis were more diverse in shapes. Pleurocystidia of H. radicata are strongly inflated, bluntly rounded to hemispherical apically, narrowly utriform to utriform whereas H. utriformis have narrowly utriform to utriform pleurocystidia only.

Other species similar to H. utriformis found in Asia are H. furfuracea and H. raphanipes, both having medium to large basidiomata but with more diverse pileal colors (Petersen and Hughes 2010). Hymenopellis furfuracea basidia are tetrasporic while those of Hymenopellis raphanipes can be 2-spored, except for the synonymized H. chiangmaiae, which is the tetrasporic form from Asia. Hymenopellis utriformis basidia, however, are strictly 2-spored.

Hymenopellis aff. orientalis (R.H. Petersen & Nagas.) R.H. Petersen

MycoBank No: MycoBank No: 800798
Figs 6, 7

Description

Basidiomata small-sized. Pileus 15 mm diam., convex with an umbo, light brown (4B4) with slightly darker color at the center brown (5C5), paler toward margin, non-hygrophanous, slightly viscid, appressed-squamulose surface, radially wrinkled; margin inflexed, translucently striate; context white to cream (1A3), unchanging when cut, consistency rubbery. Lamellae subventricose, rubbery to rather soft, 3 mm broad, 0.5 mm thick, adnate with slight decurrent tooth, white, subdistant (1 mm apart); lamellar margin finely fimbriate; lamellulae present, in 1–2 tiers. Stipe 67 mm × 2.5 mm, central, cylindrical, tapered upwards, slightly clavate base, whitish to light brown (4A2) from the pileus to slightly darker (4B4) downwards, stuffed to fistulose; surface dry, fibrillose, finely dotted to minutely appressed-squamulose especially towards the base, which is covered with white tomentum; context white, unchanging when cut; pseudorrhiza present, 60 mm long. Annulus and volva absent. Spore print white. Smell indistinct. Taste mild.

Figure 6. 

Basidioma of Hymenopellis aff. orientalis MFLU22-0142 A top view B side view C view of lamellae D side view of context. Scale bar: 1.0 cm (A, D). Photographs by A.G. Niego.

Basidiospores [50,1,1] (13.5) 15–16.4–17.5 (18) × (9.5)–13–13.5 (14.5) μm (Q = 1.2–1.4, Q* = 1.3), broadly ellipsoid to ellipsoid, ovoid, obovoid, thin-walled, delicately puckered, hyaline in 5% KOH. Basidia [30,1,1] (39) 41–48.3–59 (61) × (10)10.5–12–15 (16) μm (Q = 3.1–5.0, Q* = 4.0), bisporic, narrowly to broadly clavate, hyaline in 5% KOH. Cheilocystidia [15,1,1] (49) 53–78.2–110 (118) × (8.7) 12–16.6–23 (26) µm, (Q = 2.9–6.6, Q* = 4.8), numerous, short-pedicellate, conical, fusiform, narrowly clavate, narrowly cylindrical, narrowly lageniform to lageniform, often clamped, smooth, thin-walled, hyaline in 5% KOH. Pleurocystidia [30,3,1] (71) 75–106.7–130 (132) × (24) 24.5–28.5–36 (37.5) µm (Q = 2.8–5.4, Q* = 3.8), fusiform, clavate, narrowly clavate, utriform, narrowly utriform, rounded apex, smooth, firm-walled, hyaline in 5% KOH. Hymenophoral trama irregular, made of thin-walled, hyaline hyphae. Pileipellis a hymeniderm; terminal elements (26.5)27–34.2–42(46) × (12)13–17–22(25.5) µm, with scattered intracellular light brown (6D8) pigment in 5% KOH. Stipitipellis an intricate trichoderm; hyphae (3.3)3.5–5.0–6.0(6.2) µm wide, hyaline in 5% KOH. Clamp connections not observed.

Figure 7. 

Micromorphological features of Hymenopellis aff. orientalis MFLU22-0142 A basidiospores B basidia C cheilocystidia D pleurocystidia E terminal elements of pileipellis F stipitipellis.

Habitat and distribution

Solitary, on the soil covered with litter, in tropical hill forest of Chiang Mai Province, Thailand.

Specimen examined

Thailand. Chiang Mai Province: Mae Taeng District, Ban Pa Daeng, elev. 1,110 m, tropical evergreen hill forest, 08 August, 2019, A.G. Niego, MFLU22-0142; GenBank OP265166-ITS, OP265161-nrLSU.

Notes

The specimen described in this study is morphologically quite similar to H. orientalis, which was first described from Japan (Petersen and Nagasawa 2006). However, it has a smaller pileus (15 mm diam.). It also produces 2-spored basidia whereas those of the holotype are 4-spored. The ITS genetic distances from the two most closely related H. orientalis TMI-2IX2002c1 and HKAS70323 were 2.57% and 1.30%, respectively. Such distances may be compatible with conspecificity. However, some morphological differences were noted, but based only on the single specimen we collected. Therefore, we use the name H. aff. orientalis until additional collections are available from tropical and temperate Asia to ascertain its taxonomic identity and properly describe it if it is confirmed to be a new species different from H. orientalis.

Acknowledgements

The authors would like to thank Dr. Pennycook for confirming the scientific names of the new species, and Dr. Rungtiwa Phookamsak and her projects, Key Research Project Agroforestry Systems for Restoration and Bio-industry Technology Development (Grant no. 2017YFC0505101) and Ministry of Sciences and Technology of China (Grant no. 2017YFC0505100) for providing the ITS and nrLSU sequences.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This paper was supported by Thailand Science Research and Innovation grant “Macrofungi diversity research from the Lancang-Mekong Watershed and surrounding areas (Grant No. DBG6280009), Thailand Research Fund grant “Study of saprobic Agaricales in Thailand to find new industrial mushroom products” (Grant No. DBG6180015), Mae Fah Luang University grant “Survey of edible fungi in dry dipterocarp forests of Chiang Mai Province, Thailand” (Grant No. 641A01003) and the National Research Council of Thailand (NRCT) grant “Total fungal diversity in a given forest area with implications towards species numbers, chemical diversity and biotechnology” (Grant No. N42A650547). Allen Grace Niego offers her profound gratitude to the MFU Thesis/Dissertation Support Grant (Reference No. Oh 7702(6)/49).

Author contributions

Conceptualization: AGTN, OR. Formal analysis: AGTN. Funding acquisition: KDH, OR. Investigation: AGTN. Project administration: KDH, NT, OR. Resources: NT, KDH, OR. Supervision: OR. Writing - original draft: AGTN. Writing - review and editing: OR.

Author ORCIDs

Allen Grace T. Niego https://orcid.org/0000-0001-8125-5061

Naritsada Thongklang https://orcid.org/0000-0001-9337-5001

Kevin D. Hyde https://orcid.org/0000-0002-2191-0762

Olivier Raspé https://orcid.org/0000-0002-8426-2133

Data availability

All of the data that support the findings of this study are available in the main text, or in publicly accessible data repositories, as indicated in the text.

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