Biodiversity Data Journal : Taxonomic Paper
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Taxonomic Paper
Tylocinum is no longer monotypic: Tylocinum brevisporum sp. nov. (Boletales, Boletaceae) from northern Thailand
expand article infoBhavesh Raghoonundon‡,§, Naveed Davoodian|, Monthien Phonemany‡,§, Olivier Raspé§
‡ Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, Thailand
§ School of Science, Mae Fah Luang University, Chiang Rai, Thailand
| National Herbarium of Victoria, Royal Botanic Gardens Victoria, Melbourne, Victoria, Australia
Open Access

Abstract

Background

Tylocinum Y.C. Li & Zhu L. Yang 2016 is a Boletaceae genus belonging in subfamily Leccinoideae. It was described in 2016 from China and, prior to this study, it contained only one species, T. griseolum Y.C. Li & Zhu L. Yang 2016. During our survey of Boletaceae from Thailand, we collected some specimens that could be identified as a Tylocinum species, different from T. griseolum.

New information

The bolete specimens, collected in forests dominated by Dipterocarpaceae and Fagaceae in northern Thailand, are described as Tylocinum brevisporum Raghoonundon & Raspé sp. nov. Macroscopic and microscopic descriptions with illustrations are provided, as well as a 3-gene phylogeny, which confirms the new taxon’s position in Tylocinum. Tylocinum brevisporum differs from the only other known Tylocinum species (T. griseolum) by its brownish-grey colour, greyish-orange to brownish-orange colour change in the hymenophore when bruised, smaller pores (≤ 0.5 mm), longer tubes (up to 6 mm long), shorter and narrower basidiospores, longer and broader basidia and longer pleurocystidia relative to cheilocystidia. T. brevisporum is the second species from the genus Tylocinum and the only one to be found outside China thus far.

Keywords

new species, Boletaceae, Leccinoideae, molecular phylogeny, taxonomy, Thailand

Introduction

Tylocinum Y.C. Li & Zhu L. Yang 2016, is a monotypic genus of ectomycorrhizal (ECM) boletes (Boletaceae, Boletales, Agaricomycetes, Basidiomycota, Fungi). Typical characters of the genus are its dark scabrous stipe surface, white to pallid unchanging context in the pileus and stipe, white to pallid hymenophore, trichodermium pileipellis and smooth basidiospores (Wu et al. 2016). The type species Tylocinum griseolum Y.C. Li & Zhu L. Yang 2016, was originally described from China and was the only species known from this genus at the time. The phylogenetic analyses by Wu et al. (2016) showed that Tylocinum forms a separate clade from all other generic clades in the subfamily Leccinoideae.

The plant family Dipterocarpaceae includes many species of large trees that are often dominant in the tropical and subtropical lowlands of Southeast Asia, where the species diversity of Dipterocarpaceae is highest (Ashton 1982, Hamilton et al. 2019). Many Dipterocarpaceae are well known to be ECM, symbiotically associating with various ECM fungi, including mushroom-forming species (Watling et al. 2002, Yuwa-Amornpitak et al. 2006, Brearley 2012). Several new genera and species of boletes have recently been documented from tropical dipterocarp forest (Desjardin et al. 2009, Neves et al. 2012, Hosen et al. 2013, Halling et al. 2014, Raspé et al. 2016, Wu et al. 2016, Vadthanarat et al. 2019, Chuankid et al. 2019). Members of the Fagaceae, which also form ECM associations, co-occur with dipterocarps in Southeast Asia (Smith et al. 2008), which promotes higher mycodiversity and ECM colonisation in those tropical forest ecosystems (Corrales et al. 2018).

In this study, we describe a new species of Tylocinum from dry dipterocarp forests of northern Thailand, with description, illustrations and molecular phylogenetic analyses of a multi-gene DNA sequence dataset (atp6, tef1 and rpb2).

Materials and methods

Specimens collected

Fresh basidiomata were collected during the rainy season (2019) from Chiang Mai and Chiang Rai Provinces, orthern Thailand. The basidiomata were photographed on-site and wrapped in aluminium foil. The descriptions of the macroscopic features were made on the same day, after which the basidiomata were dried in an electric drier at 45–50°C. Specimens were deposited in the Mae Fah Luang University (MFLU) or CMUB Herbaria.

Ecological, morphological and taxonomic study

The habitat, locality information and macro-chemical reactions on fresh basidiomata were recorded. Spore prints were taken for each collection. Colour codes were given using Kornerup and Wanscher (1978) as a guide. Microscopic characters were studied in the dried specimens. The following mounting solutions were used to observe the tissues: 10% aqueous potassium hydroxide (KOH) or 28–30% ammonium hydroxide (NH4OH) solutions or 1% ammoniacal Congo red solution. The microscopic structures were studied at magnifications of 60× and 100×, photographed with a calibrated Nikon Y-TV55 camera, fitted to a Nikon DIC microscope. A total of 60 basidiospores, 30 basidia, 30 pleurocystidia, 30 cheilocystidia and 30 terminal cells and 30 hyphae for both the pileipellis and stipitipellis were measured. The dimensions of the microscopic features are presented in the following format: (a–) b–c–d (−e), in which c represents the average, b the 5th percentile, d the 95th percentile and a and e the minimum and maximum values, respectively. Q, the length/width ratio for the spores, is presented in the same format. All microscopic features were drawn by free hand, using a drawing tube. Faces of Fungi (Jayasiri et al. 2015) and MycoBank numbers are provided for the new species.

DNA extraction, PCR amplification and sequencing

Genomic DNA was extracted from CTAB-preserved tissues or dry specimens (ca. 10 mg) using a CTAB isolation procedure, adapted from Doyle and Doyle (1990). The atp6, tef1 and rpb2 gene regions were amplified by polymerase chain reaction (PCR). For amplification of atp6, the primers ATP6-1M40F and ATP6-2M were used (Raspé et al. 2016). EF1-983F and EF1-2218R (Rehner and Buckley 2005) were used to amplify tef1 and bRPB2-6F and bRPB2-7.1R (Matheny 2005) were used to amplify rpb2. The PCR amplification, purification and sequencing of atp6, rpb2 and tef1 were used following the procedure from Raspé et al. (2016).

Sequence alignment and phylogenetic analysis

The sequences were assembled using Geneious 8 (Biomatters). The Basic Local Alignment Search Tool (BLAST) (https://blast.ncbi.nlm.nih.gov/Blast.cgi) from GenBank was used to find the closest matches to the sequences. Reference sequences (Table 1) were downloaded and aligned using MAFFT v. 7 (Katoh and Standley 2013; http://mafft.cbrc.jp/alignment/server/). Then, the concatenated three-gene matrix was prepared.

Table 1.

List of collections used for DNA analyses, with origin, GenBank accession numbers and reference(s).

Species

Voucher

Origin

atp 6

tef 1

rpb 2

References

Baorangia major

OR0209

Thailand

MG897421

MG897431

MG897441

Phookamsak et al. (2019)

Baorangia pseudocalopus

HKAS75739

China

KJ184570

KM605179

Wu et al. (2015)

Baorangia rufomaculata

BOTH4144

USA

MG897415

MG897425

MG897435

Phookamsak et al. (2019)

Borofutus dhakanus

OR0345

Thailand

MH614660

MH614709

MH614755

Vadthanarat et al. (2018)

Ionosporus longipes

LEE1180

Malaysia

MT085461

MT085471

MH712031

Khmelnitsky et al. (2019)

Lanmaoa asiatica

OR0228

China

MH614682

MH614730

MH614777

Vadthanarat et al. (2019)

Lanmaoa carminipes

BOTH4591

USA

MG897419

MG897429

MG897439

Phookamsak et al. (2019)

Lanmaoa pallidorosea

BOTH4432

USA

MG897417

MG897427

MG897437

Phookamsak et al. (2019)

Leccinum monticola

HKAS76669

China

KF112249

KF112723

Wu et al. (2014)

Leccinum quercinum

HKAS63502

China

KF112250

KF112724

Wu et al. (2014)

Leccinum scabrum

RW105a

Belgium

KT823979

KT824045

KT824012

Raspé et al. (2016)

Leccinum scabrum

VDKO0938

Belgium

MG212549

MG212593

MG212635

Vadthanarat et al. (2018)

Leccinum schistophilum

VDKO1128

Belgium

KT823989

KT824055

KT824022

Raspé et al. (2016)

Leccinum variicolor

HKAS57758

China

KF112251

KF112725

Wu et al. (2014)

Leccinum variicolor

VDKO0844

Belgium

MG212550

MG212594

MG212636

Vadthanarat et al. (2018)

Leccinellum aff. crocipodium

HKAS76658

China

KF112252

KF112728

Wu et al. (2014)

Lecinellum cf. intusrubens

OR0082

Thailand

MZ803019

MZ803024

MZ824749

This study

Leccinellum crocipodium

VDKO1006

Belgium

KT823988

KT824054

KT824021

Raspé et al. (2016)

Leccinellum cremeum

HKAS90639

China

KT990781

KT990420

Wu et al. (2016)

Leccinellum sp.

HKAS53427

China

KF112253

KF112727

Wu et al. (2014)

Leccinellum sp.

OR0711

Thailand

MH614685

MH614733

MH614780

Vadthanarat et al. (2019)

Octaviania hesperi

KPM-NC 17793

Japan

KC552150

JN378422

Orihara et al. (2016)

Octaviania japonimontana

KPM-NC 17797

Japan

KC552151

JN378425

Orihara et al. (2016)

Octaviania nonae

KPM-NC 17748

Japan

KC552143

JN378403

Orihara et al. (2016)

Octaviania tasmanica

MEL 2341996

Australia

KC552156

JN378436

Orihara et al. (2012), Orihara et al. (2016)

Octaviania zelleri

MES270

USA

KC552161

JN378440

Orihara et al. (2012), Orihara et al. (2016)

Pseudoaustroboletus cf. valens

OR0477

China

MZ803020

MZ803025

MZ824750

This study

Retiboletus brevibasidiatus

OR0570

Thailand

MT085469

MT085476

MT085479

Chuankid et al. (2021)

Retiboletus brunneolus

HKAS 52680

China

KF112179

KF112690

Wu et al. (2014)

Retiboletus fuscus

OR0231

China

MG212556

MG212600

MG212642

Vadthanarat et al. (2018)

Retiboletus fuscus

OR0738

Thailand

MT085462

MT085472

MT085477

Chuankid et al. (2021)

Retiboletus griseus

MB03-079

USA

KT823964

KT824030

KT823997

Raspé et al. (2016)

Retiboletus kauffmanii

OR0278

China

MG212557

MG212601

MG212643

Vadthanarat et al. (2018)

Retiboletus nigrogriseus

BC0179

Thailand

MT085464

MT085474

MT085478

Chuankid et al. (2021)

Retiboletus nigrogriseus

OR049

Thailand

KT823967

KT824000

KT824033

Raspé et al. (2016)

Retiboletus ornatipes

MBsn

USA

MT219514

MT219516

MT219515

Chuankid et al. (2021)

Rhodactina rostratispora

SV170

Thailand

MG212560

MG212605

MG212645

Vadthanarat et al. (2018)

Rossbeevera eucyanea

TUMH-40252

Japan

KC552116

KC552069

Orihara et al. (2016)

Rossbeevera griseovelutina

TUMH-40266

Japan

KC552121

KC552073

Orihara et al. (2016)

Rossbeevera vittatispora

A.W. Claridge 2137

Australia

KC552105

KC552063

Orihara et al. (2016)

Spongiforma thailandica

DED7873

Thailand

MG212563

KF030436

MG212648

Nuhn et al. (2013),

Vadthanarat et al. (2018)

Spongispora temasekensis

ACMF5

Singapore

MZ803018

MZ803023

MZ824748

This study

Turmalinea mesomorpha subsp. mesomorpha

KPM-NC 18012

Japan

KC552139

KC552090

Orihara et al. (2016)

Turmalinea persicina

KPM-NC 18001

Japan

KC552130

KC552082

Orihara et al. (2016)

Turmalinea sp.

Muroi361

USA

DQ218885

DQ219224

DQ219046

Orihara et al. (2016)

Tylocinum griseolum

HKAS50281

China

KF112284

KF112730

Wu et al. (2014)

Tylocinum brevisporum

OR622

Thailand

MZ803021

MZ824751

This study

All analyses were done on the CIPRES Science Gateway (https://www.phylo.org; Miller et al. 2012). Maximum Likelihood (ML) phylogenetic tree inference was done using RAxML-HPC2 v.8.2.10 (Stamatakis 2006), using the GTRCAT model of sequence evolution with 25 categories. Three Lanmaoa species and three Baorangia species were selected as outgroup. Four partitions were defined: atp6, tef1 exons, rpb2 exons and introns. Statistical support of the clades was obtained using 1,000 rapid bootstrap replicates.

Using jModeltest2 (Darriba et al. 2012) on XSEDE via the CIPRES Science Gateway, the best-fit model of substitution for analysis in MrBayes was estimated for each gene, based on the Bayesian Information Criterion (BIC). GTR + I + G for atp6 and introns, SYM + I + G for tef1 exons and K80 + I + G for rpb2 exons were selected as the best fit models. Partitioned Bayesian analysis was performed with MrBayes 3.2.7a (Ronquist et al. 2012). Two runs of four cold and one heated chains were run for 1,000,000 generations and sampled every 200 generations. The average standard deviation of split frequencies was 0.005106 at the end of the runs. The burn-in phase (25%) was estimated by checking the stationarity in the plot generated by the sump command.

Taxon treatment

Tylocinum brevisporum Raghoonundon & Raspé, sp. nov.

Materials    Download as CSV 
Holotype:
  1. kingdom:
    Fungi
    ; phylum:
    Basidiomycota
    ; class:
    Agaricomycetes
    ; order:
    Boletales
    ; family:
    Boletaceae
    ; taxonRank:
    species
    ; genus:
    Tylocinum
    ; specificEpithet:
    brevisporum
    ; country:
    Thailand
    ; stateProvince:
    Chiang Rai Province, Chang Wat, Doi Pui
    ; verbatimElevation:
    730 m
    ; verbatimCoordinates:
    19°48'50"N, 99°51'57"E
    ; eventDate:
    20 August 2019
    ; identifiedBy:
    Bhavesh Raghoonundon
    ; institutionID:
    MFLU 21-0144
    ; institutionCode:
    Mae Fah Luang University Herbarium
    ; collectionCode:
    BR137
Other material:
  1. kingdom:
    Fungi
    ; phylum:
    Basidiomycota
    ; class:
    Agaricomycetes
    ; order:
    Boletales
    ; family:
    Boletaceae
    ; taxonRank:
    species
    ; genus:
    Tylocinum
    ; specificEpithet:
    brevisporum
    ; country:
    Thailand
    ; stateProvince:
    Chiang Mai Province, Mueang District
    ; verbatimElevation:
    450 m
    ; verbatimCoordinates:
    18°48'40"N, 98°56'31"E
    ; eventDate:
    18 May 2015
    ; identifiedBy:
    Olivier Raspé
    ; institutionID:
    CMU-B OR622
    ; collectionID:
    OR622
    ; institutionCode:
    Chiang Mai University Herbaria

Description

Basidiomata pileo-stipitate, small to medium-sized (Fig. 1). Pileus (1.5–)2.0–2.5 cm in diameter, convex when young, becoming plano-depressed with age; margin deflexed to uplifted, surface finely tomentose, dull and dry, at first brown (7E4) to greyish-brown (8E3–8F4), becoming paler (8D3) near the margin with age; context 3–5 mm thick halfway to the margin, soft and fleshy, off-white, slightly browning on exposure. Stipe central, cylindrical, (3.4–)4.9–6.5 cm × 0.6–1.3 cm, surface even, dull and dry, scabrous, covered with granular squamules (dotted-verrucose), brownish-grey (7E2–8E2) when young to reddish-brown (8E5) to dark brown (8F5) with age, no colour change when bruised, basal mycelium off-white; context solid, fleshy, off-white, reddish-brown to dark brown near the stipe base (8F7) and in worm wounds, slightly browning on exposure. Hymenophore tubulate, subventricose, adnexed, slightly depressed around apex of the stipe, greyish-orange to brownish-orange when bruised. Tubes 3–6 mm long halfway to the margin, off-white, easily separable from one another. Pores ≤ 0.5 mm wide at mid-radius, regularly arranged, angular, off-white, turning brown to dark brown (8E5–8F5) when bruised. Odour fungoid. Taste bitter. Spore print not obtained.

Figure 1.  

Photograph of Tylocinum brevisporum sp. nov. a, b Basidioma of specimen OR622; c Basidioma of the holotype (BR 137).

Basidiospores (6.7–)7.5–10–11.7(–11.8) × (3.1–)3.5–4.7–5.8(–5.9) µm (n = 50) Q = (1.7–) 1.79–2.15–2.5 (–2.61), ellipsoid in central view, oblong to subcylindrical in side view, smooth under light microscope, yellowish to brownish in KOH (Fig. 2). Basidia 4-spored, (27–)27–37.4–54(–54) × (9–)9–12.3–19(–19) µm, clavate, yellowish to brownish in KOH, sterigmata up to 3 µm long. Cheilocystidia (19–)19.3–25.5–33(–35) × (4–)4.1–6–8.2(–8.5) µm, frequent, fusiform, thin-walled, yellowish to brownish hyaline in KOH and NH4OH. Pleurocystidia (40­–)41–53–69(–70) × (8–)7.4–12–16.6(–17) µm, thin-walled, fusiform to broadly fusiform with a long pedicel and sharp apex, occasionally containing yellowish inclusions, yellowish to brownish hyaline in KOH and NH4OH. Hymenophoral trama boletoid, elements smooth, cylindrical, hyaline, 5–10 µm wide. Pileipellis a trichodermium, hyphae terminations with 3–4 cells that are 5–11 µm wide and terminal cells 31–48 µm × 6–10 µm, colourless to slightly brownish in KOH. Pileus trama composed of interwoven hyaline hyphae 5–9 µm wide. Stipitipellis a disrupted hymeniderm with hyphae 3.7–7.4 µm wide, colourless to slightly brownish in KOH and caulocystidia (24–)24.5–35–47(–48) × (9–)9.2–12.4–16.9(–17) µm, thin-walled, clavate to broadly clavate with a sharp apex, yellowish to brownish hyaline in KOH and NH4OH. Stipe trama composed of cylindrical, hyaline, interwoven hyphae 3.7–7.4 µm wide. Clamp connections absent.

Figure 2.  

Microscopic features of Tylocinum brevisporum; a Basidiospores; b Basidia; c, d Caulocystidia; e Pleurocystidia; f Cheilocystidia; g Pileipellis. Scale bars: a, b, c, d, f = 10 µm, e = 20 µm, g = 50 µm.

Diagnosis

This species is distinguished from Tylocinum griseolum by its greyish-brown colour, greyish-orange to brownish-orange colour change in the hymenophore when bruised, smaller pores (≤ 0.5 mm) and longer tubes (up to 6 mm long). Additionally, the basidiospores are shorter and narrower compared to T. griseolum and the basidia are slightly longer and broader. Furthermore, the pleurocystidia of Tylocinum brevisporum are longer than its cheilocystidia.

Etymology

Epithet “brevisporum”; from the Latin words brevi (short) and sporae (spores), referring to the shorter spores of this species compared to Tylocinum griseolum.

Distribution

Thus far known only from northern Thailand.

Ecology

Solitary, in tropical forest dominated by Dipterocarpaceae (Dipterocarpus spp. and Shorea spp.), with some Fagaceae (Quercus spp., Lithocarpus spp. and Castanopsis calathiformis).

Notes

Morphologically, Tylocinum brevisporum is similar to Tylocinum griseolum, with which it shares the overall grey colour of the basidiomata and dark scabrous stipe surface. However, Tylocinum brevisporum is more brownish as compared to the grey Tylocinum griseolum. In addition, Wu et al. (2016) mentioned no discolouration in the context of Tylocinum griseolum. The context of Tylocinum brevisporum becomes slightly brown when bruised. The hymenophore of T. brevisporum changes to greyish-orange to brownish-orange when bruised as compared to the unchanging hymenophore of T. griseolum. Moreover, T. griseolum has relatively larger pores (up to 1.5 mm) than that of T. brevisporum (< 0.5 mm). The tubes in T. griseolum are also shorter than those of T. brevisporum.

The basidiospores of Tylocinum brevisporum [(6.7–)7.5–10–11.7(–11.8) × (3.1–)3.5–4.7–5.8(–5.9) µm, Q = (1.7–)1.79–2.15–2.5(–2.61)] are shorter and narrower than those of Tylocinum griseolum [(11)12.0–14.5(16) × 4.5–5.5 µm Q = 2.60–3.22] from China. The basidia of T. brevisporum [(27–)27–37.4–54(–54) × (9–)9–12.3–19(–19) µm] are also slightly longer and broader than T. griseolum [30–45 × 10–12 µm]. Wu et al. (2016) reported that, for T. griseolum, the pleurocystidia and cheilocystidia are similarly-sized. In T. brevisporum, the pleurocystidia are longer than the cheilocystidia. Phylogenetically, T. brevisporum clusters with T. griseolum, together forming a well-supported clade (MLB/BPP = 93/1.00) i.e. the genus Tylocinum.

Analysis

Phylogenetic analysis

The concatenated gene dataset comprised 47 terminals. The final alignment contained 121 sequences (38 for atp6, 46 for tef1, 37 for rpb2) and was 2,676 characters long, including gaps. Both ML and Bayesian analyses produced the same tree topology; thus, only the ML tree is shown with both Maximum Likelihood Bootstrap (MLB) and Bayesian Posterior Probabilities (BPP) values. In the analyses, the new species Tylocinum brevisporum shared a sister relationship with the type species Tylocinum griseolum (Fig. 3), providing strong statistical support (MLB = 93 and BPP = 1.00) for the genus Tylocinum (Leccinoideae). The atp6 sequence of the holotype (BR 137) was 100% identical to OR622.

Figure 3.  

Maximum Likelihood phylogenetic tree inferred from the three-gene dataset (atp6, rpb2, tef1). The three Lanmaoa and three Baorangia species were used as outgroup taxa. Maximum Likelihood Bootstrap (MLB, left) ≥ 70% and Bayesian Posterior Probabilities (BPP, right) ≥ 0.95 are shown above supported branches. The new species is in bold.

Discussion

Boletales is a globally-distributed order of fungi, comprising morphologically diverse groups (Binder and Hibbett 2006, Wu et al. 2016), with ECM, ligninolytic, saprobic and mycoparasitic members (Binder and Hibbett 2006, Kirk et al. 2008). Thorough morphological and phylogenetic analyses of the order has led to the discovery of new genera and other taxa (e.g. Binder and Bresinsky 2002, Wu et al. 2014, Zhu et al. 2015, Wu et al. 2016, Orihara et al. 2016, Vadthanarat et al. 2019, Zhang et al. 2019). Boletaceae Chevall. 1826 is a morphologically diverse family currently comprising of 94 genera distributed amongst seven subfamilies (Binder and Hibbett 2006, Wu et al. 2014, Wu et al. 2016). The subfamily Leccinoideae was revealed by the phylogenetic analyses of Wu et al. (2014). Currently, this subfamily comprises fifteen genera, viz. Binderoboletus T.W. Henkel & M.E. Sm. 2016, Borofutus Hosen & Z.L. Yang 2012, Chamonixia Rolland 1899, Ionosporus Khmeln. 2018, Kaziboletus Iqbal Hosen & Zhu L. Yang 2021, Leccinum Gray 1821, Lecinellum Bresinsky & Manfr. Binder 2003, Pseudoaustroboletus Y.C. Li & Zhu L. Yang 2014, Octavania, Retiboletus Manfr. Binder & Bresinsky 2002, Rossbeevera T. Lebel & Orihara 2012, Rhodactina Pegler & T.W.K. Young 1989, Spongiforma Desjardin, Manfr. Binder, Roekring & Flegel 2009, Spongispora G. Wu, S.M.L. Lee, E. Horak & Z.L. Yang 2018, Turmalinea Orihara & N. Maek. 2015 and Tylocinum. Only ten of these genera are stipitate-pileate.

Our survey on the diversity of boletes in northern Thailand led to the discovery of a second species of Tylocinum (the focus of the present study), being found in tropical forests dominated by Dipterocarpaceae, which have been reported as ECM hosts for Boletaceae (Desjardin et al. 2009, Halling et al. 2014, Wu et al. 2018, Vadthanarat et al. 2019). According to Wu et al. (2016), the white to dirty white hymenophore of Tylocinum is similar to that of Tylopilus Karst. 1881 when young, while the verrucose stipe surface is similar to Leccinum. The stipe surface of Tylocinum is dotted-verrucose, which may give a more or less rough touch, but it does not produce markedly projecting scabers like in Leccinum. Tylocinum is also similar to Tylopilus, but there are some morphological differences between the two genera. Tylopilus species usually produce larger basidiomata and have minutely and densely tomentose to dotted-tomentose, but never dotted-verrucose, stipitipellis. Moreover, some Tylopilus species have reticulate stipe, whereas, in Tylocinum, the stipe is at most longitudinally venose near the apex. As the diversity of Boletaceae in Thailand is high and remains understudied (e.g. Vadthanarat et al. 2021), further studies may uncover additional species of Tylocinum or related taxa.

Acknowledgements

B. Raghoonundon appreciates the kind support given by the Mushroom Research Foundation (MRF), Thailand. The authors thank the Thailand Science Research and Innovation (TSRI) (Grant No. DBG6280009) entitled “Macrofungi diversity research from the Lancang-Mekong Watershed and surrounding areas”. The authors are also grateful to Amy Choong for loaning her collection of Spongispora tamasekensis, Changlin Zhao for sequencing of Tylocinum specimens and to the reviewers for their comments.

References