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Coryneum heveanum sp. nov. (Coryneaceae, Diaporthales) on twigs of Para rubber in Thailand
expand article infoChanokned Senwanana§, Kevin D. Hyde|§, Rungtiwa Phookamsak§|, E.B. Gareth Jones, Ratchadawan Cheewangkoon
‡ Chiang Mai University, Chiang Mai, Thailand
§ Mae Fah Luang University, Chiang Rai, Thailand
| Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
¶ World Agroforestry Centre, Kunming, China
Open Access

Abstract

During studies of microfungi on para rubber in Thailand, we collected a new Coryneum species on twigs which we introduce herein as C. heveanum with support from phylogenetic analyses of LSU, ITS and TEF1 sequence data and morphological characters. Coryneum heveanum is distinct from other known taxa by its conidial measurements, number of pseudosepta and lack of a hyaline tip to the apical cell.

Keywords

1 new species, Ascomycota, Hevea brasiliensis, Phylogeny, Taxonomy

Introduction

The para rubber tree (Hevea brasiliensis) is a tropical plant belonging to family Euphorbiaceae (Priyadarshan et al. 2009). Para rubber tree is the major commercial source of natural rubber, which is used in all kinds of manufactured products, including tyres, medical appliances and agricultural equipment, in addition, rubber-wood is used in the furniture industry (Priyadarshan et al. 2009, Rippel and Galembeck 2009, Häuser et al. 2015, Herrmann et al. 2016). The total para rubber tree plantation area in South East Asia exceeds more than 5 million hectares (Vongkhamheng et al. 2016). In Thailand, para rubber tree plantation area covers more than 3 million hectares and this number has increased every year (Kromkratoke and Suwanmaneepong 2017, Romyen et al. 2018). This important perennial crop is currently often affected by plant pathogenic fungi which can substantially decrease the quality and quantity of rubber yield (Liu et al. 2018). Many taxa have proven to be serious pathogens worldwide, causing severe leaf spot formation, defoliation, shoot die-back and stem cankers (Jayasinghe 2000, Nyaka Ngobisa et al. 2015, Trakunyingcharoen et al. 2015, Liyanage et al. 2016, Liu et al. 2018). Nonetheless, information about the diversity of phytopathogenic taxa on para rubber from Thailand is generally lacking and currently there are only thirteen reports (Farr and Rossman 2018). Thus, the main objective of our project is to survey and study the diversity of microfungi associated with para rubber trees in Thailand. During the survey, we found a Coryneum species associated with canker disease on twigs of para rubber. This work is based on a combination of morphology and molecular data for identification this taxon.

Many Coryneum species have been reported as phytopathogens causing tree canker (Strouts 1972, Gadgil and Dick 2007, Horst 2013, Senanayake et al. 2017). This genus was introduced by Nees von Esenbeck (1817) to accommodate C. umbonatum as the type species. Historically, Coryneum species have relied on morphological studies and only a few species are supported by sequence data in GenBank. Many species causing tree canker, previously known as Coryneum were transferred to other genera e.g. Seiridium, Seimatosporium and Wilsonomyces (Sutton 1980, Raddi and Panconesi 1981, Marin-Felix et al. 2017). Recently, research has clarified the taxonomic position of the family Coryneaceae based on morphological and molecular data (Rossman et al., 2015; Senanayake et al., 2017; Wijayawardene et al., 2018). Currently 123 Coryneum species are listed in Index Fungorum (2018). Molecular analyses, using sequence data of LSU, ITS and TEF1 regions, has supplemented traditional taxonomic methods, enabling a more precise and rapid identification of species in the genus Coryneum (Senanayake et al. 2017, 2018, Fan et al. 2018). The correct identification of pathogenic fungi is necessary to implement appropriate quarantine decisions, suitable control strategies and to promote an understanding of the evolution of new pathogens and the movement of fungi between continents.

Material and methods

Collections, morphological studies and isolation

Fresh materials were collected from Chiang Rai, Thailand in 2016. Specimens were taken to the laboratory in zip lock bags and observed with a Motic SMZ 168 series stereomicroscope and photographed with an Axio camera on a Zeiss Discover V8 stereomicroscope. Sections of the conidiomata were mounted in double-distilled water (ddH2O) for morphological structures and photography. Images were taken using a Canon 600D camera on a Nikon ECLIPSE 80i microscope. All measurements were calculated using Tarosoft® Image Framework programme v.0.9.0.7. Photoplates were made using Adobe Photoshop CS6 version 13.0 (Adobe Systems U.S.A.). The specimens were deposited in the Mae Fah Luang University Herbarium, Chiang Rai, Thailand (MFLU). Living cultures were deposited in Mae Fah Luang University Culture Collection (MFLUCC) in Thailand and duplicated at the Kunming Culture Collection (KUMCC). Faces of Fungi and Index Fungorum numbers are registered as described in Jayasiri et al. (2015) and Index Fungorum (2018).

DNA extraction, PCR and DNA sequencing

Genomic DNA was extracted from mycelium using Biospin Fungus Genomic DNA Extraction Kit (BioFlux®, Hangzhou, P.R. China) following the manufacturer’s protocol. The DNA product was kept at 4 °C for the DNA amplification and maintained at -20 °C for long term storage. The DNA amplification was carried out by polymerase chain reaction (PCR) using three genes, the 28S large subunit (LSU), internal transcribed spacer (ITS) and translation elongation factor 1 alpha gene (TEF1). The LSU gene was amplified by using the primers LROR and LR5 (Vilgalys and Hester 1990), the ITS gene was amplified by using the primers ITS5 and ITS4 (White et al. 1990) and the TEF1 gene was amplified using the primers EF1-728F (Carbone and Kohn 1999) and EF2 (O’Donnell 1998). The amplification reactions were performed in 25 μl final volumes contained of 8.5 μl of sterilized ddH2O, 12.5 μl of 2 × Easy Taq PCR Super Mix (mixture of Easy Taq TM DNA Polymerase, dNTPs and optimised buffer (Beijing Trans Gen Biotech Co., Chaoyang District, Beijing, PR China), 1 μl of each forward and reverse primers (10 pM) and 2 μl of DNA template. The PCR thermal cycle programme for LSU and ITS gene amplification was provided as initially 94 °C for 3 mins, followed by 35 cycles of denaturation at 94 °C for 1 min, annealing at 55 °C for 50 secs, elongation at 72 °C for 1 min and final extension at 72 °C for 10 mins. The PCR thermal cycle programme for TEF1 gene amplification was provided as initially 94 °C for 5 mins, followed by 40 cycles of denaturation at 94 °C for 45 secs, annealing at 52 °C for 30 secs, elongation at 72 °C for 1.30 mins and final extension at 72 °C for 6 mins. PCR products were sequenced by Sangon Biotech Co., Shanghai, China. Nucleotide sequences were deposited in GenBank (Table 1).

Phylogenetic analysis

Phylogenetic analyses were conducted based on a combined gene of LSU, ITS and TEF1 sequence data. Sequence data of Coryneaceae from previous studies and representative strains of major classes in Diaporthales were downloaded from GenBank to supplement the dataset (Table 1). The combined dataset consisted of 45 sequences including our newly generated sequences. Phaeoacremonium aleophilum (CBS 63194) and P. vibratile (CBS 117115) were selected as the outgroup taxa. The combined LSU, ITS and TEF1 gene dataset were initially aligned by using MAFFT version 7 (Katoh et al. 2017; http://mafft.cbrc.jp/alignment/server/) and improved manually, where necessary, in BioEdit v.7.0.9.1 (Hall 1999) and MEGA7 (Kumar et al. 2015). The final alignment of the combined LSU, ITS and TEF1 sequence datasets was analysed and inferred the phylogenetic tree based on maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference analyses (BI).

Isolates utilized in the phylogenetic tree and their GenBank and culture accession numbers.

Taxa Culture AC no. GenBank Accession number
ITS LSU TEF1
Asterosporium asterospermum KT2125 _ AB553743 _
Asterosporium asterospermum KT2138 _ AB553744 _
Chaetoconis polygoni CBS 405.95 _ EU754141 _
Coryneum castaneicola 43-1 _ MH683551 _
Coryneum castaneicola 43-2 MH683560 MH683552 _
Coryneum depressum AR 3897 _ EU683074 _
Coryneum heveanum MFLUCC 17-0369 MH778707 MH778703 MH780881
Coryneum heveanum MFLUCC 17-0376 MH778708 MH778704 _
Coryneum modonia AR 3558 _ EU683073 _
Coryneum perniciosum CBS 130.25 MH854812 MH866313 _
Coryneum umbonata CBS 199.68 MH859114 MH870828 _
Coryneum umbonatum AR 3541* _ EU683072 _
Coryneum umbonatum MFLUCC 13-0658* MF190120 MF190066 MF377574
Coryneum umbonatum MFLUCC 15-1110* MF190121 MF190067 MF377575
Crinitospora pulchra CBS 138014 KJ710466 KJ710443 _
Cytospora centravillosa MFLUCC 17-1660 MF190122 MF190068 _
Cytospora centravillosa MFLU 17-0887 MF190123 MF190069 _
Cytospora melanodiscus Jimslanding2 JX438621 _ JX438605
Cytospora translucens CZ320 FJ755269 FJ755269 _
Diaporthe azadirachtae TN 01 KC631323 _ _
Diaporthe eres AR 5193* KJ210529 _ KJ210550
Diaporthe eres MFLUCC 17-1668 MF190138 MF190081 MF377595
Diaporthe maytenicola CBS 136441 KF777157 KF777210 _
Hyaliappendispora galii MFLUCC 16-1208 MF190150 MF190095 MF377587
Lamproconium desmazieri MFLUCC 15-0870* KX430134 KX430135 MF377591
Lamproconium desmazieri MFLUCC 15-0872 KX430138 KX430139 MF377593
Macrohilum eucalypti CPC 10945* DQ195781 DQ195793 _
Macrohilum eucalypti CPC 19421* KR873244 KR873275 _
Pachytrype princeps Rogers s.n.* _ FJ532382 _
Pachytrype rimosa FF1066 _ FJ532381 _
Phaeoacremonium aleophilum CBS 631.94 AF266647 AB278175 KF764643
Phaeoacremonium vibratile CBS 117115 KF764573 DQ649065 KF764645
Phaeoappendispora thailandensis MFLUCC 13-0161* MF190157 MF190102 _
Phaeoappendispora thailandensis MFLU 12-2131 MF190158 MF190103 _
Phaeodiaporthe appendiculata CBS 123821* KF570156 KF570156 _
Prosopidicola mexicana CBS 113529* AY720709 KX228354 _
Prosopidicola mexicana CBS 113530* AY720710 _ _
Rossmania ukurunduensis AR 3484* _ EU683075 _
Stegonsporium acerophilum CBS 117025 EU039982 EU039993 EU040027
Stegonsporium pyriforme CBS 117023 EU039971 EU039987 EU040001
Stilbospora ellipsosporum WJ 1840 _ AY616229 _
Stilbospora macrosperma CBS 121883* JX517290 JX517299 _
Sydowiella depressula CBS 813.79 _ EU683077 _
Sydowiella fenestrans CBS 125530* JF681956 EU683078 _
Valsella salicis AR 3514 _ EU255210 EU222018

The estimated evolutionary model of Bayesian inference and maximum likelihood were performed independently for each locus using MrModeltest v. 2.3 (Nylander 2004) implemented in PAUP v. 4.0b10 (Swofford 2002). The best-fit model resulted as GTR+I+G model for each locus under the Akaike Information Criterion (AIC).

Maximum likelihood analysis was performed by Randomized Accelerated Maximum Likelihood (RAxML) (Stamatakis 2008) version 7.4.2 (released by Alexandros Stamatakis on November 2012) implemented in raxmlGUI v.1.0 (Stamatakis et al. 2008, Silvestro and Michalak 2011). The search strategy was set to rapid bootstrapping at 1,000 replicates.

Maximum parsimony analysis was performed using PAUP v 4.0b10 (Swofford 2002). Trees were inferred using the heuristic search function with 1,000 random stepwise addition replicates and tree bisection-reconnection (TBR) as the branch-swapping algorithm. All informative characters were unordered and of equal weight. The consistency index (CI), retention index (RI), rescaled consistency index (RC) and homoplasy index (HI) were calculated. Statistical supports for branches of the most parsimonious tree were estimated using maximum parsimony bootstrap (BS) analysis with 1,000 bootstrap replicates.

Bayesian inference was performed in MrBayes v. 3.2.2 (Ronquist and Huelsenbeck 2003) with the best-fit model of sequences evolution under the Akaike Information Criterion (AIC). Bayesian posterior probabilities (BY) (Rannala and Yang 1996, Zhaxybayeva and Gogarten 2002) were determined by Markov Chain Monte Carlo Sampling (BMCMC). Six simultaneous Markov chains were run from random trees for one million generations and trees were sampled every 100th generation. The first 20% of generated trees representing the burn-in phase of the analysis were discarded and the remaining trees were used for calculating posterior probabilities (BY) in the majority rule consensus tree.

The phylogenetic tree was shown in FigTree V.1.4.3 (Rambaut 2016) and drawn and converted to tiff file in Microsoft PowerPoint 2013 and Adobe Photoshop CS6 version 13.0 (Adobe Systems U.S.A.). The final alignment and tree were deposited in TreeBASE (http://www.treebase.org/) under the submission ID 23550.

Results

Phylogenetic analysis

The dataset consisted of 45 taxa including the new taxa (Figure 1). The combined LSU, ITS and TEF1 sequence data including 2040 total characters, were analysed based on Bayesian inference, maximum likelihood and maximum parsimony analysis. RAxML analysis of the combined dataset had 996 distinct alignment patterns and 39.23% of undetermined characters or gaps. Maximum parsimony had 1191 constant characters, 151 variable parsimony-uninformative characters and 690 parsimony-informative characters. The most parsimonious tree is shown where TL = 2336, CI = 0.607, RI = 0.716, RC = 0.435, HI = 0.393. Bayesian posterior probabilities (BY) from MCMC were evaluated with the final average standard deviation of split frequencies = 0.005452. Phylogenetic analysis from ML, MP and BI gave trees with similar overall topologies of the generic placement and in agreement with previous studies (Senanayake et al. 2017, Fan et al. 2018, Yang et al. 2018). The final RAxML tree of the combined dataset is shown in Figure 1, with a final ML optimisation likelihood value of -13004.6966291. The phylogeny shows that Coryneum heveanum forms a distinct lineage in Coryneum with strong support (94% ML, 95%MP and 1.00 BY) and in a sister clade to C. umbonatum, C. depressum, C. modonium, C. perniciosum and C. castaneicola.

Figure 1. 

Maximum likelihood (RAxML) based on analysis of a combined dataset of LSU, ITS and TEF1 sequence data representing Diaporthales. Bootstrap support values for maximum likelihood (ML, left), maximum parsimony (MP, middle) greater than 70% and Bayesian posterior probabilities (BY, right) equal to or greater than 0.95 are indicated at the nodes. The tree is rooted to Phaeoacremonium aleophilum (CBS 63194) and P. vibratile (CBS 117115). The newly generated sequences are in blue. The strains from generic type species are in black bold.

Taxonomy

Coryneum heveanum Senwanna, Cheewangkoon & K.D. Hyde, sp. nov.

Figure 2

Etymology

Named after the host on which it occurs, Hevea brasiliensis.

Type

THAILAND, Chiang Rai Province, Wiang Chiang Rung District, on twigs (attached on tree) of Hevea brasiliensis, 1 November 2016, C. Senwanna, RBCR003 (MFLU 18-0936, holotype), ex-type living culture MFLUCC 17-0369, KUMCC 18-0106; Dry culture from ex-type MFLU 18-0936); ibid., RBCR016 (MFLU 17-1982, living culture MFLUCC 17-0376, dry culture MFLU 18-0937, MFLU 18-0938)

Description

Associated with canker on twigs of Hevea brasiliensis. Asexual morph: Conidiomata acervular, solitary, erumpent through the outer periderm layers of host, scattered, surface tissues above slightly dome-shaped, black, velvety, formed of brown cell, thick-walled textura angularis, 145–540 µm diam. Conidiophores short, cylindrical, apically pale brown, paler at the base, smooth, septate, branched at the base, arising from basal stroma, 22–37 × 4–8 μm (x‒ = 28.5 × 5.6 μm, n = 15). Conidiogenous cell annellidic, integrated, terminal, cylindrical, medium brown, truncate apex, with 1-3 slightly percurrent proliferations, 6–17 µm long (x‒ = 10.7 μm, n = 20). Conidia curved, clavate to fusiform, dark brown, smooth-walled, 4–6-pseudo-septa, sometimes with apical and basal cells darker than other cells, rounded or sometime truncate at apex, truncate and black at the base, (40–)43–53(–68) × (14–)15–20 μm (x‒ = 48.7 × 17.3 μm, n = 85). Appressoria hyaline, globose to sub globose, thick-walled, 4–11 μm wide (x‒ = 7.1 μm, n = 20).

Cultural characteristics

Conidia germinated on MEA within 24 h with germ tubes produced from one or both end cells, mostly from basal cell of conidia. Colonies on MEA reaching 20–25 mm diam. after 4 weeks at 25–30 °C, colonies circular, medium dense, cottony, margin wavy, superficial, slightly effuse, radially striated; colony from above, white, edges with more aerial mycelium than centre in the beginning and later become white grey, smooth with edge entire; from below: white to cream at the margin, yellowish-green in the centre in the beginning and later become dark green; not producing pigmentation in agar. Colonies on PDA reaching 10–15 mm diam. after 4 weeks at 25–30 °C, colonies circular, medium dense, cottony, slightly effuse, dark green with brown aerial mycelium on surface; not producing pigmentation in agar. Conidial masses were observed in PDA culture after 6 months at 25–30 °C. Mass of conidia dark brown to black, extruding on colony or tip of mycelium (Figure 2 q, r). Mycelium superficial and immersed, dark brown, hyphae branched, septate, constricted at septa, thick, smooth-walled (Figure 2 s).

Figure 2. 

Coryneum heveanum (MFLU 18-0936). a−d Conidiomata on host surface e−f Acervuli g Conidiogenesis (annellidic; red arrow, proliferation; blue arrow) h−j Conidiophores, conidiogeneous cells with conidia k Conidia l Germinated spores m−p Appressoria q−r Mass of conidia on PDA after 6 months s Mycelium on PDA after 6 months. Scale bars: 5 mm (a), 1000 µm (b), 200 µm (c, d, r), 100 µm (e, f, q), 20 µm (g−k), 50 µm (l, s), 5 µm (m−p).

Additional GenBank number

SSU (primer NS1 and NS4; White et al. 1990) MH778705; MFLUCC 17-0369, MH778706; MFLUCC 17-0376, TEF1 (primer EF1-983F and EF1-2218R; Rehner 2001) MH780882; MFLUCC 17-0376.

Notes

Phylogenetically, Coryneum heveanum clustered in the same clade with C. umbonatum, C. depressum, C. modonium, C. perniciosum and C. castaneicola with high statistical support. Based on morphological characters, the conidia of C. castaneicola, C. depressum, C. elevatum, C. modonium and C. umbonatum have slightly curved conidia with an apical cell with a hyaline tip, while C. heveanum, C. castaneicola and C. perniciosum lack a hyaline tip (Table 2) (Briosi and Farneti 1908, Sutton 1980, Gadgil and Dick 2007, Senanayake et al. 2017, 2018). Coryneum heveanum is similar to C. betulinum, C. perniciosum, C. psidi and C. pyricola in having broadly fusiform or clavate conidia but differs in size of conidia and number of pseudosepta (Table 2).

Discussion

Fungi on para rubber (Hevea brasiliensis) can be pathogens, saprobes or endophytes (Rocha et al. 2011, Seephueak et al. 2011, Ghazali 2013, Nyaka Ngobisa et al. 2015, Hyde et al. 2018, Senwanna 2017, 2018). Fungal endophytes on para rubber have been comparatively well-studied (Gasiz and Chaverri 2010, Rocha et al. 2011, Déon et al. 2012, Martin et al. 2015), while few studies have investigated saprobic fungi or fungi associated with para rubber (Cai et al. 2013, Trakunyingcharoen et al. 2015). However, previous studies reporting saprobic taxa based on morphology, are available (Seephueak et al. 2011, Seephueak 2012). In this study, we introduced a new species, Coryneum heveanum, found on twigs of para rubber, based on morphological characters and phylogenetic analyses.

Synopsis of recorded Coryneum species (asexual morph) (Related to this research).

Taxa Size (µm) Host records
Conidiomata Conidiophores Conidia; Number of pseudo-septate
Coryneum betulinum (Sutton 1980) 31–36 × 14–17; 4–5 Betula rubrum (Betulaceae)
C. castaneicola (Sutton 1980) 57–80 × 10–13; apical cell with a hyaline tip; 6–7 Castanea dentata (Fagaceae)
C. depressum (Sutton 1980) 44–53 × 19–23; apical cell with a hyaline tip; 4–5(–6) Quercus spp. (Fagaceae)
C. elevatum (Sutton 1980) 56–70 × 24–32; apical cell with a hyaline tip; 6–7 Quercus spp. (Fagaceae)
C. heveanum This study 145–540 22–37 × 4–8 (40–)43–53(–68) × (14–)15–20; 4–6 Hevea brasiliensis (Euphorbiaceae)
C. modonium (Sutton 1980) 50–71 × 14–19; apical cell with a hyaline tip; 5–8 Castanea spp. (Fagaceae)
C. perniciosum (Briosi and Farneti 1908) 40–50 × 13–15; 5–7 Castanea sp. (Fagaceae)
C. psidi (Sutton 1980) 25–40 × 14–17; 5–6 Psidium guajava (Myrtaceae)
C. pyricola (Sutton 1980) 61–70 × 24–32; 5–7 Pyrus sp. (Rosaceae)
C. umbonatum (Pseudovalsa longipes) (Wehmeyer 1926) 47–104 × 10–14; 3–8 Quercus coccinea (Fagaceae)
C. umbonatum (Gadgil and Dick 2007, Sutton 1980) 1500–2200 (10–) 27.5–47 57–72 × 14–16; apical cell with a hyaline tip; 5–7 Quercus spp. (Fagaceae), Castanea sativa (Fagaceae)
C. umbonatum (Senanayake et al. 2017) 1000–1300 × 500–550 20–35 × 4–7 42–56 × 13–16; apical cell with a hyaline tip; 4–6 Quercus sp. (Fagaceae)
C. umbonatum (Senanayake et al. 2018) 450 × 700 20–30 × 3–6 35–45 × 8–10; apical cell with a hyaline tip; 4–6 Quercus petraea (Fagaceae)

Coryneum species are phytopathogenic fungi associated with twig blight, canker and dieback disease with some species reported as saprobes (Carter 1914, Strouts 1972, Gadgil and Dick 2007, Senanayake et al. 2018). Host-specificity of Coryneum has not yet been clarified and species have been recorded from various plant families worldwide (i.e. Betulaceae, Clusiaceae, Cupressaceae, Fagaceae, Hippocastanoideae, Malvaceae, Myrtaceae, Rosaceae, Ulmaceae) (Wehmeyer 1926, Strouts 1972, Sutton 1980, Senanayake et al. 2017, 2018, Farr and Rossman 2018). Until recently, these taxa have primarily been identified by their morphology i.e. Sutton (1980) and only a few species are supported by molecular data with nine sequences from six species available in GenBank. However, we do not include Coryneum foliicola (CBS 153.32) sequence data in our analyses as its phylogenetic affinities are distant from Coryneaceae (data not shown). Therefore, we use reliable sequences from GenBank to determine the taxonomic placement of our new species.

Based on morphological characters, there are some similarities between Coryneum heveanum and related Coryneum species, such as acervular conidiomata, fusiform or clavate conidia with pseudosepta (Sutton 1980, Maharachchimbura et al. 2016, Senanayake et al. 2017, 2018). However, C. heveanum is distinct from other known taxa including Coryneum umbonatum (type species) by conidial measurements, number of pseudosepta and lack of a hyaline tip to the apical cell (Table 2) (Briosi and Farneti 1908, Sutton 1980, Gadgil and Dick 2007, Senanayake et al. 2017, 2018).

Current phylogenetic analyses of combined LSU, ITS and TEF1 alignment are used to clarify the species relationships in Coryneum (Figure 1), following Senanayake et al. (2017) and Fan et al. (2018). The phylogenetic tree shows that our species clearly groups with Coryneum. In addition, pairwise dissimilarities of DNA sequences of ITS regions between C. heveanum and other Coryneum species also provide further evidence to justify C. heveanum as a new species (Jeewon & Hyde, 2016). Comparison of 599 nucleotides of the ITS nucleotides between C. heveanum and C. umbonatum (MFLUCC 13-0658 and MFLUCC 15-1110) reveals 90 base pair differences. Comparison of 536 nucleotides of the ITS nucleotides between C. heveanum and C. castaneicola (43_2) reveals 90 base pair differences. Comparison of 620 nucleotides of the ITS nucleotides between C. heveanum and C. umbonatum (CBS 199.68) reveals 91 base pair differences. Comparison of 598 nucleotides of the ITS nucleotides between C. heveanum and C. perniciosum (CBS 130.25) reveals 77 base pair differences. Coryneum umbonatum strains (AR3541, MFLUCC 13-0658 and MFLUCC 15-1110) form a distinct lineage, which is in agreement with the results of Fan et al. (2018). However, Coryneum umbonatum (CBS 199.68) forms a separate clade with C. umbonatum strain AR 3541, MFLUCC 13-0658 and MFLUCC 15-1110 and we cannot verify this taxon based on morphological characters. Previous studies have described the morphological features of Coryneum umbonatum but conidial dimensions and number of pseudosepta reported varies significantly from each other (Sutton 1980, Gadgil and Dick 2007, Senanayake et al. 2017, 2018) (Table 2). In addition, some of the Coryneum sequences deposited in GenBank (i.e. C. castaneicola, C. depressum, C. foliicola, C. monodia and C. perniciosum, C. umbonatum) lack morphological characteristics and their identities cannot be confirmed. Therefore, these taxa need to be recollected, described and sequenced to determine their taxonomic placement in this family.

Acknowledgements

We would like to thank the Thailand Research Fund (TRF) grant no. MRG5580163, DGB6080013 and Chiang Mai University for financial support. C. Senwanna would like to thank the Key Research Program of Frontier Sciences, CAS (grant no. QYZDY-SSW-SMC014 and 973 key project of the National Natural Science Foundation of China (grant no. 2014CB954101) for supporting DNA molecular experiments of this study. R. Phookamsak expresses appreciation to the Research Fund from China Postdoctoral Science Foundation (grant no. Y71B283261), the Yunnan Provincial Department of Human Resources and Social Security (grant no. Y836181261), the National Nature Science Foundation of China (NSFC; grant no. 31850410489) and Chiang Mai University for financial support. We thank Milan C. Samarakoon and Sirinapa Konta for their valuable suggestions and helping in phylogenetic analyses. Dr. Shaun Pennycook is thanked for his essential nomenclatural review.

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