Research Article |
Corresponding author: Kevin D. Hyde ( kdhyde3@gmail.com ) Corresponding author: Ishara S. Manawasinghe ( ishara9017@gmail.com ) Academic editor: Samantha C. Karunarathna
© 2024 Yinru Xiong, Kevin D. Hyde, Li Lu, Dulanjalee L. Harishchandra, Ausana Mapook, Biao Xu, Fatimah Alotibi, Ishara S. Manawasinghe.
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:
Xiong Y, Hyde KD, Lu L, Harishchandra DL, Mapook A, Xu B, Alotibi F, Manawasinghe IS (2024) Novel Helicoma and Neohelicosporium (Tubeufiaceae, Tubeufiales) species and two new host records of Helicoma on tropical palms (Arecaceae) from China. MycoKeys 108: 287-315. https://doi.org/10.3897/mycokeys.108.128889
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Asexual species of Tubeufiaceae are characterised as helicosporous hyphomycetes and are abundantly discovered in tropical and subtropical regions. The present study collected helicosporous fungal samples from rotting tissues of Caryota mitis, Elaeis guineensis and E. oleifera in Xishuangbanna, Yunan Province, China. Fungal isolates were identified, based on the morphological characteristics and multi-gene phylogeny with DNA sequence data of the internal transcribed spacer (ITS), part of the large subunit nuclear rRNA gene (LSU), translation elongation factor 1-alpha gene (tef 1-α) and RNA polymerase II second largest subunit gene (rpb2). Herein, we introduce three new species viz. Helicoma oleifera, Neohelicosporium guineensis and N. xishuangbannaensis. In addition, we introduce two new host records of Helicoma guttulatum and H. rufum on Caryota mitis. The illustrations of all identified species, detailed descriptions and in-depth phylogenetic analyses are provided. Our results add new knowledge of fungal species associated with palm hosts in southern China. Moreover, our data will contribute to the biodiversity of fungi in tropical China.
Caryota mitis, Elaeis guineensis, Elaeis oleifera, helicosporous fungi, phylogeny, saprobic fungi, taxonomy, three new species
Regions in southern China exhibit characteristics of a monsoon climate and its weather patterns are additionally influenced by the geographical distribution and differentiation of land and sea (
Arecaceae species are commonly known as palms and they are common in tropical evergreen forests. These species are available in every ecological habitat in the Tropics and Sub-tropics and regulate the composition and climate in those ecosystems (
Tubeufiaceae was introduced by
Helicoma was proposed by
Neohelicosporium was introduced by
To explore the relationship between Tubeufiaceae associated with various palms, the present study collected terrestrial decaying samples of Caryota mitis, Elaeis guineensis and E. oleifera. A total of 12 isolates were obtained, from which we introduce three new species: Helicoma oleifera, Neohelicosporium guineensis and N. xishuangbannaensis and two new host records: Helicoma guttulatum and H. rufum. Species descriptions, illustrations of macroscopic and microscopic morphology and phylogenetic analyses are provided to delineate new and known species.
Samples were collected in 2023 from an unidentified forest area beside National Highway 219 in Xishuangbanna in Yunnan Province, China (21°93'20"N, 101°24'57"E, 549.6 m elev.). These samples were rotting materials from different palm species namely, Caryota mitis, Elaeis oleifera and E. guineensis. Samples were brought into the laboratory using plastic ziplock bags and relevant macro and micro-characteristics were photographed by a ZEISS SteREO Discovery V20 stereomicroscopy (Germany) and Nikon Eclipse 80i and the industrial DigitaL Sight DS-Fi1 (Panasonic, Japan) microscope. Following the methods of
After the fungal samples were brought into the laboratory, the Cnoptec SZ650 series (Cnoptec, China) stereomicroscope was used to observe the macromorphological characteristics and photographs were taken using SteReo Discovery V20. Nikon Eclipse 80i and the industrial DigitaL Sight DS-Fi1 (Panasonic, Japan) microscope and imaging system were used to take pictures of micromorphological characters. Digital images of micromorphological structures, including shape, size and colour were recorded. The measurement of structures, including spore dimensions for each species was conducted using NIS-Elements BR 5.30.03. Adobe Photoshop CC 2019 and Adobe Illustrator CC 2019 software (Adobe Systems Inc., San Jose, America) were used to develop images and make photo plates. All pure cultures obtained in this study were grown on potato dextrose agar (PDA) at 25 °C in 12 hours of daylight for a week and the diameter of the culture was measured after six weeks. AxioVersion Rel. 4.8 was used to take photos of the cultures.
The pure cultures were cultured on PDA plates for 1–2 weeks and about 500 mg of fresh fungal mycelia were scraped. Total genomic DNA was extracted from the mycelia using MagPure Plant AS Kit (Magen Biotech, China) following the manufacturer’s instructions. Four nuclear gene regions: internal transcribed spacer (ITS), large subunit nuclear rRNA gene (LSU), translation elongation factor 1-α (tef 1-α) and RNA polymerase II second largest subunit gene (rpb2) were amplified using the primers shown in Table
Gene | Primer | Sequence (5’-3’) | Reference |
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ITS | ITS5 | GGAAGTAAAAGTCGTAACAAGG |
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ITS4 | TCCTCCGCTTATTGATATGC | ||
LSU | LR0R | ACCCGCTGAACTTAAGC |
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LR5 | TCCTGAGGGAAACTTCG | ||
tef 1-α | EF1-983F | GCYCCYGGHCAYCGTGAYTTYAT |
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EF1-2218R | TACTTGAAGGAACCCTTACC | ||
rpb2 | fRPB2-5F | GAYGAYMGWGATCAYTTYGG |
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RPB2-7cr | CCCATRGCTTGYTTRCCCAT |
Taxon names, strain numbers and corresponding GenBank accession numbers of the taxa used in the Tubeufiaceae phylogenetic analyses.
Species | Strain numbers | ITS | LSU | tef 1-α | rpb2 |
---|---|---|---|---|---|
Acanthohelicospora aurea | GZCC 16-0060 | KY321323 | KY321326 | KY792600 | MF589911 |
Acanthohelicospora pinicola | MFLUCC 10-0116 | KF301526 | KF301534 | KF301555 | NA |
Aquaphila albicans | BCC 3543 | DQ341096 | DQ341101 | NA | NA |
Aquaphila albicans | MFLUCC 16-0010 | KX454165 | KX454166 | KY117034 | MF535255 |
Berkleasmium fusiforme | MFLUCC 17-1979 | MH558694 | MH558821 | MH550885 | MH551008 |
Berkleasmium longisporum | MFLUCC 17-1990 | MH558697 | MH558824 | MH550888 | MH551011 |
Botryosphaeria agaves T | MFLUCC 10-0051 | JX646790 | JX646807 | JX646855 | NA |
Botryosphaeria dothidea | CBS 115476 | NA | NG_027577 | NA | NA |
Chlamydotubeufia cylindrica T | MFLUCC 16-1130 | MH558702 | MH558830 | MH550893 | MH551018 |
Chlamydotubeufia huaikangplaensis T | MFLUCC 10-0926 | JN865210 | JN865198 | NA | NA |
Chlamydotubeufia krabiensis T | MFLUCC 16-1134 | KY678767 | KY678759 | KY792598 | MF535261 |
Dematiohelicomyces helicosporus T | MFLUCC 16-0213 | KX454169 | KX454170 | KY117035 | MF535258 |
Dematiohelicomyces helicosporus | MFLUCC 16-0003 | MH558703 | MH558831 | MH550894 | MH551019 |
Helicoarctatus aquaticus T | MFLUCC 17-1996 | MH558707 | MH558835 | MH550898 | MH551024 |
Helicodochium aquaticum | MFLUCC 16-0008 | MH558708 | MH558836 | MH550899 | MH551025 |
Helicodochium aquaticum T | MFLUCC 17-2016 | MH558709 | MH558837 | MH550900 | MH551026 |
Helicohyalinum aquaticum T | MFLUCC 16-1131 | KY873625 | KY873620 | KY873284 | MF535257 |
Helicohyalinum infundibulum T | MFLUCC 16-1133 | MH558712 | MH558840 | MH550903 | MH551029 |
Helicoma acropleurogenum T | GZCC 22-2035 | OP806857 | OP806854 | OP821894 | OP821897 |
Helicoma ambiens | UAMH 10533 | AY916451 | AY856916 | NA | NA |
Helicoma ambiens | UAMH 10534 | AY916450 | AY856869 | NA | NA |
Helicoma aquaticum T | MFLUCC 17-2025 | MH558713 | MH558841 | MH550904 | MH551030 |
Helicoma brunneisporum T | MFLUCC 17-1983 | MH558714 | MH558842 | MH550905 | MH551031 |
Helicoma dennisii | NBRC 30667 | AY916455 | AY856897 | NA | NA |
Helicoma freycinetiae T | MFLUCC 16-0363 | MH275062 | MH260295 | MH412770 | NA |
Helicoma fusiforme T | MFLUCC 17-1981 | MH558715 | NA | MH550906 | NA |
Helicoma guttulatum T | MFLUCC 16-0022 | KX454171 | KX454172 | MF535254 | MH551032 |
Helicoma guttulatum | GZCC 22-2004 | OP508739 | OP508779 | OP698090 | OP698079 |
Helicoma guttulatum | GZCC 22-2024 | OP508733 | OP508773 | OP698084 | OP698073 |
Helicoma guttulatum | GZCC 22-2025 | OP508737 | OP508777 | OP698088 | OP698077 |
Helicoma guttulatum | MFLUCC 21-0152 | OL545456 | OL606150 | OL964521 | OL964527 |
Helicoma guttulatum | ZHKUCC 24-0139 | PP860094 | PP860106 | PP858054 | PP858066 |
Helicoma guttulatum | ZHKUCC 24-0140 | PP860095 | PP860107 | PP858055 | PP858067 |
Helicoma hongkongense | MFLUCC 17-2005 | MH558716 | MH558843 | MH550907 | MH551033 |
Helicoma hydei | MFLUCC 18-1270 | MH747101 | MH747116 | MH747100 | NA |
Helicoma inthanonense T | MFLUCC 11-0003 | JN865211 | JN865199 | NA | NA |
Helicoma khunkornensis T | MFLUCC 10-0119 | JN865203 | JN865191 | KF301559 | NA |
Helicoma linderi | NBRC 9207 | AY916454 | AY856895 | NA | NA |
Helicoma liyui | GZCC 22-2033 | OP806858 | OP806855 | OP821895 | NA |
Helicoma longisporum | GZCC 22-2005 | OP508740 | OP508780 | OP698091 | OP698080 |
Helicoma longisporum | MFLUCC 16-0211 | MH558719 | MH558845 | MH550910 | MH551036 |
Helicoma longisporum T | MFLUCC 17-1997 | MH558720 | MH558846 | MH550911 | MH551037 |
Helicoma miscanthi T | MFLUCC 11-0375 | KF301525 | KF301533 | KF301554 | NA |
Helicoma muelleri | CBS 964.69 | AY916453 | AY856877 | NA | NA |
Helicoma muelleri | UBC F13877 | AY916452 | AY856917 | NA | NA |
Helicoma multiseptatum T | GZCC 16-0080 | MH558721 | MH558847 | MH550912 | MH551038 |
Helicoma nematosporum T | MFLUCC 16-0011 | MH558722 | MH558848 | MH550913 | MH551039 |
Helicoma oleifera T | ZHKUCC 24-0121 | PP860086 | PP860098 | PP858056 | PP858068 |
Helicoma oleifera | ZHKUCC 24-0122 | PP860087 | PP860099 | PP858057 | PP858069 |
Helicoma oleifera | ZHKUCC 24-0766 | PP860088 | PP860100 | PP858058 | PP858070 |
Helicoma oleifera | ZHKUCC 24-0767 | PP860089 | PP860101 | PP858059 | PP858071 |
Helicoma rubriappendiculatum T | MFLUCC 18-0491 | MH558723 | MH558849 | MH550914 | MH551040 |
Helicoma rufum T | MFLUCC 17-1806 | MH558724 | MH558850 | MH550915 | NA |
Helicoma rufum | ZHKUCC 24-0143 | PP860096 | PP860108 | PP858060 | PP858072 |
Helicoma rufum | ZHKUCC 24-0144 | PP860097 | PP860109 | PP858061 | PP858073 |
Helicoma rugosum | GZCC 22-2034 | OP806859 | OP806856 | OP821896 | NA |
Helicoma rugosum | ANM 196 | GQ856138 | GQ850482 | NA | NA |
Helicoma rugosum | ANM 953 | GQ856139 | GQ850483 | NA | NA |
Helicoma rugosum | ANM 1169 | NA | GQ850484 | NA | NA |
Helicoma rugosum | JCM 2739 | NA | AY856888 | NA | NA |
Helicoma septoconstrictum | MFLUCC 17-1991 | MH558725 | MH558851 | MH550916 | MH551041 |
Helicoma septoconstrictum T | MFLUCC 17-2001 | MH558726 | MH558852 | MH550917 | MH551042 |
Helicoma siamense T | MFLUCC 10-0120 | JN865204 | JN865192 | KF301558 | NA |
Helicoma sp. | HKUCC 9118 | NA | AY849966 | NA | NA |
Helicoma tectonae T | MFLUCC 12-0563 | KU144928 | KU764713 | KU872751 | NA |
Helicoma vaccinii | CBS 216.90 | AY916486 | AY856879 | NA | NA |
Helicoma wuzhishanense | GZCC 22-2003 | OP508732 | OP508772 | OP698083 | OP698072 |
Helicomyces chiayiensis T | BCRC FU30842 | LC316604 | NA | NA | NA |
Helicomyces hyalosporus | MFLUCC 17-0051 | MH558731 | MH558857 | MH550922 | MH551047 |
Helicomyces torquatus | MFLUCC 16-0217 | MH558732 | MH558858 | MH550923 | MH551048 |
Helicosporium flavum T | MFLUCC 16-1230 | KY873626 | KY873621 | KY873285 | NA |
Helicosporium luteosporum T | MFLUCC 16-0226 | KY321324 | KY321327 | KY792601 | MH551056 |
Helicosporium vesicarium T | MFLUCC 17-1795 | MH558739 | MH558864 | MH550930 | MH551055 |
Helicotruncatum palmigenum | NBRC 32663 | AY916480 | AY856898 | NA | NA |
Helicotruncatum palmigenum | KUMCC 21-0474 | OM102542 | OL985959 | OM355488 | OM355492 |
Helicotubeufia guangxiensis T | MFLUCC 17-0040 | MH290018 | MH290023 | MH290028 | MH290033 |
Helicotubeufia hydei T | MFLUCC 17-1980 | MH290021 | MH290026 | MH290031 | MH290036 |
Helicotubeufia jonesii T | MFLUCC 17-0043 | MH290020 | MH290025 | MH290030 | MH290035 |
Kamalomyces mangrovei | MFLUCC 17-0407 | MH878781 | MH878779 | MH886508 | NA |
Kamalomyces thailandicus | MFLUCC 13-0233 | MF506884 | MF506882 | MF506886 | NA |
Muripulchra aquatica | KUMCC 15-0245 | KY320533 | KY320550 | KY320563 | MH551057 |
Muripulchra aquatica | KUMCC 15-0276 | KY320534 | KY320551 | KY320564 | MH551058 |
Neoacanthostigma fusiforme T | MFLUCC 11-0510 | KF301529 | KF301537 | NA | NA |
Neochlamydotubeufia fusiformis T | MFLUCC 16-0016 | MH558740 | MH558865 | MH550931 | MH551059 |
Neochlamydotubeufia khunkornensis | MFLUCC 16-0025 | MH558742 | MH558867 | MH550933 | MH551061 |
Neohelicomyces aquaticus | KUMCC 15-0463 | KY320529 | KY320546 | KY320562 | MH551065 |
Neohelicomyces grandisporus T | KUMCC 15-0470 | KX454173 | KX454174 | NA | MH551067 |
Neohelicomyces submersus T | MFLUCC 16-1106 | KY320530 | KY320547 | NA | MH551068 |
Neohelicosporium abuense | CBS 101688 | AY916470 | NA | NA | NA |
Neohelicosporium acrogenisporum T | MFLUCC 17-2019 | MH558746 | MH558871 | MH550937 | MH551069 |
Neohelicosporium aquaticum T | MFLUCC 17-1519 | MF467916 | MF467929 | MF535242 | MF535272 |
Neohelicosporium astrictum T | MFLUCC 17-2004 | MH558747 | MH558872 | MH550938 | MH551070 |
Neohelicosporium aurantiellum | ANM 718 | GQ856140 | GQ850485 | NA | NA |
Neohelicosporium bambusicola T | MFLUCC 21-0156 | OL606157 | OL606146 | OL964517 | OL964523 |
Neohelicosporium ellipsoideum T | MFLUCC 16-0229 | MH558748 | MH558873 | MH550939 | MH551071 |
Neohelicosporium fluviatile | MFLUCC 15-0606 | NA | OP377957 | OP473050 | OP473111 |
Neohelicosporium fusisporum T | MFUCC 16-0642 | MG017612 | MG017613 | MG017614 | NA |
Neohelicosporium griseum | CBS 961.69 | AY916474 | AY856884 | NA | NA |
Neohelicosporium griseum | CBS 113542 | AY916475 | AY916088 | NA | NA |
Neohelicosporium guangxiense | GZCC 16-0042 | MF467920 | MF467933 | MF535246 | MF535276 |
Neohelicosporium guangxiense | MFLUCC 17-0054 | MH558750 | MH558875 | MH550941 | MH551073 |
Neohelicosporium guineensis T | ZHKUCC 24-0113 | PP860090 | PP860102 | PP858062 | PP858074 |
Neohelicosporium guineensis | ZHKUCC 24-0114 | PP860091 | PP860103 | PP858063 | PP858075 |
Neohelicosporium hyalosporum T | GZCC 16-0076 | MF467923 | MF467936 | MF535249 | MF535279 |
Neohelicosporium hyalosporum | GZCC 16-0063 | MH558751 | MH558876 | MH550942 | MH551074 |
Neohelicosporium irregulare T | MFLUCC 17-1796 | MH558752 | MH558877 | MH550943 | MH551075 |
Neohelicosporium irregulare | MFLUCC 17-1808 | MH558753 | MH558878 | MH550944 | MH551076 |
Neohelicosporium krabiense T | MFLUCC 16-0224 | MH558754 | MH558879 | MH550945 | MH551077 |
Neohelicosporium laxisporum T | MFLUCC 17-2027 | MH558755 | MH558880 | MH550946 | MH551078 |
Neohelicosporium morganii | CBS 281.54 | AY916468 | AY856876 | NA | NA |
Neohelicosporium morganii | CBS 222.58 | AY916469 | AY856880 | NA | NA |
Neohelicosporium ovoideum T | GZCC 16-0064 | MH558756 | MH558881 | MH550947 | MH551079 |
Neohelicosporium ovoideum | GZCC 16-0066 | MH558757 | MH558882 | MH550948 | MH551080 |
Neohelicosporium panacheum | CBS 257.59 | AY916471 | AY916087 | NA | NA |
Neohelicosporium parvisporum | GZCC 16-0078 | MF467924 | MF467937 | MF535250 | MF535280 |
Neohelicosporium parvisporum | MFLUCC 17-2010 | MH558763 | MH558888 | MH550954 | MH551086 |
Neohelicosporium sp. | CBS 189.95 | AY916472 | AY856882 | NA | NA |
Neohelicosporium sp. | HKUCC 10235 | NA | AY849942 | NA | NA |
Neohelicosporium suae | CGMCC 3.23541 | OP184079 | OP184068 | OP186052 | OP265702 |
Neohelicosporium submersum | MFLUCC 17-2376 | MT627738 | MN913738 | NA | NA |
Neohelicosporium taiwanense T | BCRC FU30841 | LC316603 | NA | NA | NA |
Neohelicosporium thailandicum T | MFLUCC 16-0221 | MF467928 | MF467941 | MF535253 | MF535283 |
Neohelicosporium xishuangbannaensis T | ZHKUCC 24-0119 | PP860092 | PP860104 | PP858064 | PP858076 |
Neohelicosporium xishuangbannaensis | ZHKUCC 24-0120 | PP860093 | PP860105 | PP858065 | PP858077 |
Neotubeufia krabiensis T | MFLUCC 16-1125 | MG012031 | MG012024 | MG012010 | MG012017 |
Parahelicomyces aquaticus T | MFLUCC 16-0234 | MH558766 | MH558891 | MH550958 | MH551092 |
Parahelicomyces chiangmaiensis T | MFLUCC 21-0159 | OL697884 | OL606145 | OL964516 | OL964522 |
Parahelicomyces talbotii | MFLUCC 17-2021 | MH558765 | MH558890 | MH550957 | MH551091 |
Pleurohelicosporium hyalinum T | GZCC 20-0489 | OP377816 | OP377915 | OP472996 | OP473089 |
Pleurohelicosporium parvisporum T | MFLUCC 17-1982 | MH558764 | MH558889 | MH550956 | MH551088 |
Pseudohelicoon gigantisporum | BCC 3550 | AY916467 | AY856904 | NA | NA |
Pseudohelicoon subglobosum T | BCRC FU30843 | LC316607 | LC316610 | NA | NA |
Thaxteriellopsis lignicola | MFLUCC 10-0123 | JN865207 | JN865195 | KF301562 | NA |
Thaxteriellopsis lignicola | MFLUCC 10-0124 | JN865208 | JN865196 | KF301561 | NA |
Tubeufia abundata T | MFLUCC 17-2024 | MH558769 | MH558894 | MH550961 | MH551095 |
Tubeufia aquatica T | MFLUCC 16-1249 | KY320522 | KY320539 | KY320556 | MH551142 |
Tubeufia bambusicola T | MFLUCC 17-1803 | MH558771 | MH558896 | MH550963 | MH551097 |
Tubeufia chlamydospora T | MFLUCC 16-0223 | MH558775 | MH558900 | MH550967 | MH551101 |
Tubeufia cocois T | MFLUCC 22-0001 | OM102541 | OL985957 | OM355486 | OM355491 |
Tubeufia sympodilaxispora T | MFLUCC 17-0048 | MH558808 | MH558932 | MH551001 | MH551135 |
The quality of the DNA sequences was checked from their chromatograms and the sequences generated by forward and reverse primers were combined using Geneious Prime v. 2021.0.3 (Biomatters Ltd., San Diego, CA, USA). The BLASTn tool (Basic Local Alignment Search Tool) in the search engine of the National Center for Biotechnology Information (NCBI) to analyse the sequences is used in this study (https://blast.ncbi.nlm.nih.gov/Blast.cgi). Based on the BLASTn results, we identified that our isolates belong to Helicoma and Neohelicosporium. Phylogenetic analyses for Tubeufiaceae were performed following
Maximum parsimony analysis was performed in PAUP (phylogenetic analysis using parsimony) v.4.0b10 (
Maximum Likelihood analyses were accomplished using RAxML-HPC2 on XSEDE v. 8.2.8 (
Phylogenetic trees were generated by ML, MP and BI of combined ITS (971 bp), LSU (1,172 bp), rpb2 (1,045 bp) and tef 1-α (912 bp) sequence data. The tree topologies generated by these three methods were similar and close to the topology of
Maximum Likelihood majority rule consensus tree for Tubeufiaceae using ITS, LSU, rpb2 and tef 1-α sequence dataset with Botryosphaeria agaves (MFLUCC 10-0051) and B. dothidea (CBS 115476) as the outgroup taxa. Bootstrap support for Maximum Likelihood (ML) and Maximum Parsimony (MP) equal to or greater than 75% and Bayesian Inference posterior probability (BIPP) equal to or greater than 0.90 are indicated above branches as MP/ML/BIPP. The scale bar indicates 0.2 nucleotide changes per site. Isolates from this study are marked in blue and ex-type strains are marked in bold.
Species epithet refers to the host species name “oleifera” from which the fungus was isolated.
MHZU 23-0157.
Saprobic on the rotting petiole of Elaeis oleifera. Sexual morph: Not observed. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, brown. Mycelium composed of partly immersed, partly superficial, hyaline, septate, branched hyphae. Conidiophores 145–360 µm long, 6.5–7.5 µm wide (x̄ = 210 × 6.5 μm, n = 20), macronematous, mononematous, cylindrical, unbranched or branched at base, straight to slightly bent, septate, deep brown at root part, brown at apex, pale brown at middle part mixing with some brown areas, smooth-walled with irregular inclusion. Conidiogenous cells 13–22 µm long, 5–7.5 µm wide (x̄ = 17 × 6.4 μm, n = 20), monoblastic, integrated, sympodial, terminal, cylindrical or fertile at the apex of conidiophores, brown, smooth-walled with irregular inclusion; with denticles, 1.3–2.3 µm long, 1.4–2.5 µm wide (x̄ = 1.6 × 1.8 μm, n = 20), arising from the apex portion of conidiophores as tooth-like and papillate protrusions, exposed or imbedded in the apex of conidiophore, mono- to polyblastic, brown, smooth-wall. Conidia 18–22.5 μm diam. (x̄ = 20.4 μm, n = 40) and conidial filament 6.8–9 μm wide (x̄ = 8.2 μm, n = 40), 45–55 μm long (x̄ = 50.6 μm, n = 40), solitary, acrogenous, helicoid, rounded at tip, tapering towards flat end, conic truncate at base, tightly coiled 1½ times, 8-septate, not becoming loose in water, guttulate, hyaline to pale brown, smooth-walled, the third cell shrinking and producing the root canal.
Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA attaining 2.5 cm diam. after six weeks at 25 °C, irregular, undulate, rough, superficial and partially immersed, brown aerial mycelium mixed with pale brown, deep brown at up and down junction area; reverse brown with pale brown.
China, Yunnan Province, Xishuangbanna City, an unidentified forest beside National Highway 219 (21°93'N, 101°24'E, 549.6 m elev.), rotting petiole of the Elaeis oleifera, 5 February 2023, Y.R. Xiong and Li Lu, XG198 (MHZU 23-0157, holotype); ex-type culture, ZHKUCC 24-0121, other living cultures ZHKUCC 24-0122, ZHKUCC 24-0766, ZHKUCC 24-0767.
Four isolates obtained in this study from the rotting petiole of the Elaeis oleifera clustered in an independent clade in the phylogenetic tree with 78% ML, 76% MP bootstrap support and 1.00 BIPP bootstrap support. The nucleotide differences between Helicoma oleifera and its phylogenetically related species were checked, excluding gaps: H. acropleurogenum (GZCC 22-2035) - ITS: 3.53% (18/510 base pairs), LSU: 0.71% (6/844 base pairs), tef 1-α: 2.85% (26/912 base pairs), rpb2: 3.92% (41/1045 base pairs); H. dennisii (NBRC 30667) - ITS: 4.36% (25/573 base pairs), LSU: 0.35% (2/564 base pairs), tef 1-α and rpb2 sequence unavailable; H. hydei (MFLUCC 18-1270) - ITS: 3.50% (26/744 base pairs), LSU: 0.71% (6/847 base pairs), tef 1-α: 2.74% (25/912 base pairs), rpb2 sequence is unavailable; H. inthanonense (MFLUCC 11-0003) - ITS: 4.56% (26/570 base pairs), LSU: 1.63% (14/860 base pairs), tef 1-α and rpb2 sequence is unavailable. Helicoma oleifera is different from related species not only in the size of conidia and conidiophores (Table
Comparison of asexual morph characteristics of Helicoma species in this study; the names of strains in this study are indicated in bold.
Species names and culture accession numbers | Conidiophores | Conidiogenous cells | Conidia | Septate number | Colour | Coiled times | References |
---|---|---|---|---|---|---|---|
Helicoma acropleurogenum GZCC 22-2035 | 118–389 μm long, 5.5–8.5 μm wide (x̄ = 219 × 6.5 μm, n = 20) | 20–32 μm long, 5–8 μm wide (x̄ = 25 × 6 μm, n = 20) | 21–24 μm diam. and conidial filament 8.5–10.5 μm wide (x̄ = 22.0 × 9.5 μm, n = 20), 48–58 μm long | 6–7 | pale brown | tightly coiled 1½–1¾ times |
|
Helicoma inthanonense MFLUCC 11-0003 | (14.5–)26.5–34(−42) μm in diam., 3 μm wide | NA | (10–)13–20 μm in diam., 4–7 μm wide (x̄ = 14 × 6 μm) | 7 | hyaline to brown | NA |
|
Helicoma hydei MFLUCC 18-1270 | 135–310 μm long, 4.5–7.0 μm wide | 13–37 μm long, 4.5–7.0 μm wide | 19–30 μm diam. (x̄ = 25.0 μm, n = 20), conidial filament 6–12 μm wide (x̄ = 8.1 μm, n = 20) | NA | pale brown to brown | tightly coiled 1–1½ times |
|
Helicoma dennisii NBRC 30667 | 3.5–5 µm wide at the basal part and tapering to 3–3.5 µm wide at the apical part, up to 190 µm long | 1–1.5 × 0.5–1 µm | 10–15 (13.5) µm in diam.; conidial filament hyaline to dilute fuscous, 4–5.5 (4.5) µm thick | 6–9 (8) | Hyaline | tightly coiled 1¼–1¾ (1½) times |
|
Helicoma oleifera ZHKUCC 24-0121 | 145–360 μm long, 6.5–7.5 μm wide (x̄ = 235 × 6.8 μm, n = 20) | 13–22 μm long, 5–7.5 μm wide, tiny tooth–like protrusions (1.3–2.3 μm long, 1.4–2.5 μm wide) | 18–22.5 μm diam. and conidial filament 6.8–9 μm wide (x̄ = 20.4 μm diam., 8.2 μm wide, n = 50), 45–55 μm long | 8 | pale brown to brown | tightly coiled 1½ times | This study |
Helicoma guttulatum MFLUCC 16-0022 | 74–182 (197) μm long, 4–6 μm wide (x̄ = 120 × 5 μm, n = 20) | NA | 18–23 μm diam. and conidial filament 6–8 μm wide (x̄ = 20 × 7 μm, n = 20) | 8–9 | hyaline to pale brown | tightly coiled 1–1½ times |
|
Helicoma guttulatum ZHKUCC 24-0139 | 75–225 μm long, 5.5–6 μm wide (x̄ = 152 × 5.7 μm, n = 20) | 10–29 μm long, 5–8.8 μm wide, tiny tooth–like protrusions (1.6–3.5 μm long, 1.6–2.5 μm wide) | 21–30 μm diam. and conidial filament 7.2–10 μm wide (x̄ = 25 μm diam., 8.4 μm wide, n = 50), 48–69 μm long | 8–9 | pale brown | tightly coiled 1½ times | This study |
Helicoma rufum MFLUCC 17-1806 | 110–210 μm long, 7–8.5 μm wide | 9–14 μm long, 5.5–8.5 μm wide, tiny tooth–like protrusions (2.5–3.6 μm long, 1.5–2 μm wide) | 35–45 μm diam. and conidial filament 4–5.5 μm wide (x = 41 × 4.5 μm, n = 20), 240–410 μm long | 27–37 | hyaline to pale brown | coiled 2–3 times, becoming loosely coiled in water |
|
Helicoma rufum ZHKUCC 24-0143 | 150–270 µm long, 4–7.5 µm thick (x̄ = 225 × 5.9 μm, n = 20) | 7–15 μm long, 4–7 μm wide, tiny tooth–like protrusions (3–6 μm long, 1.5–3 μm wide) | 21–47 μm diam. and conidial filament 2–5 μm wide (x̄ = 36 × 3.8 μm, n = 40), 145–345 μm long | 25–35 | hyaline | tightly coiled 3–4.5 coils | This study |
Neohelicosporium hyalosporum GZCC 16-0076 | up to 540 μm long, 4–5.5 μm wide | 9–13 μm long, 4–5.5 μm wide | 25–33 μm diam. and conidial filament 3–4 μm wide (x̄ = 28 μm diam., 3.5 μm wide, n = 50), 125–225 μm long | NA | hyaline | tightly coiled 2.5–3.5 times, becoming loosely coiled in water |
|
Neohelicosporium ovoideum GZCC 16-0064 | up to 420 μm long, 4–6 μm wide | 10–15 μm long, 4–6 μm wide | 25–35 μm diam. and conidial filament 3–4 μm wide (x̄ = 28 × 3.5 μm, n = 50), 180–230 μm long | multi–septate | hyaline | tightly coiled 2–3 times, becoming loosely coiled in water |
|
Neohelicosporium guineensis ZHKUCC 24-0113 | 50–160 μm long, 4–6 μm wide (x̄ = 120 × 5.2 μm, n = 10) | 11.5–20 μm long, 3.5–5.5 μm wide, tiny tooth–like protrusions (1.4–2.7 μm long, 1.2–2 μm wide) | 16–20 μm diam. and conidial filament 1.8–3 μm wide (x̄ = 18 μm diam., 2.4 μm wide, n = 50), 90–130 μm long | 11–12 | hyaline | tightly coiled 2½–3½ times, loosely coiled in water | This study |
Neohelicosporium fusisporum MFUCC 16-0642 | NA | 12–20 μm long, 1.5–2.5 μm wide | 18–22 μm diam. and conidial filament 1.5–2.5 μm wide (x̄ = 18 μm × 2 μm, n = 50), 100–150 μm long | multi–septate | hyaline | tightly coiled 2½–3¼ times, loosely coiled in water |
|
Neohelicosporium xishuangbannaensis ZHKUCC 24-0119 | 40–125 μm long, 3–6 μm wide (x̄ = 68.4 × 4.4 μm, n = 20) | 7–14 μm long, 2.5–5.5 μm wide, tiny tooth–like protrusions (1.8–3.3 μm long, 1.1–2.3 μm wide) | 16.5–20.5 μm diam. and conidial filament 1.8–3.2 μm wide (x̄ = 18.5 μm diam., 2.4 μm wide, n = 50), 90–125 μm long | 9–13 | hyaline | tightly coiled 2–3¼ times, loosely coiled in water | This study |
Helicoma oleifera (MHZU 23-0157, holotype) a specimen observed b, c colony on decaying Elaeis oleifera d, e conidiophores f, g conidiogenous cell with attached conidia h–l conidiogenous cells m–p conidia q–s conidia produce the tubular structure at the third cell t germinated conidium u, v culture on PDA from above and reverse. Scale bars: 100 μm (d, e); 20 μm (f–t).
Saprobic on the rotting petiole of Caryota mitis. Sexual morph: Not observed. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, brown. Mycelium composed of partly immersed, partly superficial, brown, septate hyphae. Conidiophores 75–225 μm long, 5.5–6 μm wide (x̄ = 152 × 5.7 μm, n = 20), macronematous, crowded, erect, straight to slightly bent, brown, deep brown towards the base, septate, branched, smooth-walled with irregular inclusion. Conidiogenous cells 10–29 μm long, 5–8.8 μm wide (x̄ = 18 × 6.3 μm, n = 20), mono- to polyblastic, integrated, cylindrical, terminal, pale brown to brown, smooth-walled with irregular inclusion; with denticles, 1.6–3.5 μm long, 1.6–2.5 μm wide (x̄ = 2.4 × 2.1 μm, n = 20), arising from the apex portion of conidiophores as tooth-like protrusions, mono- to polyblastic, brown, smooth-wall. Conidia 21–30 μm diam. (x̄ = 25.1 μm, n = 40) and conidial filament 7.2–10 μm wide (x̄ = 8.4 μm, n = 40), 48–69 μm long (x̄ = 57.4 μm, n = 40), solitary, acropleurogenous, tightly coiled 1½ times, guttulate, not becoming loose in water, hyaline to pale brown, tapering towards flat end, 8–9-septate, rounded at the apex, conic truncate at the base, smooth-walled.
Helicoma guttulatum (MHZU 23-0166, new host record) a specimen observed b, c colony on decaying Caryota mitis d conidiophores e–j conidiogenous cells, thereinto j with attached conidia k–o conidia p germinated conidium q, r culture on PDA from above and reverse. Scale bars: 50 μm (d); 20 μm (e–j); 10 μm (k–o); 20 μm (p).
Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA attaining 3 cm diam. after six weeks at 25 °C, irregular, undulate, rough, superficial and partially immersed, brown aerial mycelium mixed with pale brown; reverse brown with pale brown.
China, Yunnan Province, Xishuangbanna City, an unknown forest beside National Highway 219 (21°93'N, 101°24'E, 549.6 m elev.), rotting petiole of the Caryota mitis, 5 February 2023, Y.R. Xiong and Li Lu, XG215 (MHZU 23-0166, new host record; living culture, ZHKUCC 24-0139, ZHKUCC 24-0140).
Two isolates on rotting petiole of the Caryota mitis obtained in this study clustered with the H. guttulatum clade, based on the phylogenetic tree with 100% ML, 100% MP bootstrap support and 0.91 BIPP bootstrap support. The nucleotide differences excluding gaps between H. guttulatum (ZHKUCC 24-0139) and H. guttulatum (MFLUCC 16-0022) in ITS is 3.60% (17/472 base pairs), while there is no difference in LSU and one base pair difference in tef 1-α and rpb2. Our two isolates are similar to H. guttulatum (
Saprobic on the rotting inflorescence of Caryota mitis. Sexual morph: Not observed. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, pale brown. Mycelium composed of partly immersed, partly superficial, hyaline to brown, septate, branched hyphae. Conidiophores 150–270 µm long, 4–7.5 µm wide (x̄ = 225 × 5.9 μm, n = 20), macronematous, mononematous, cylindrical, erect, straight to slightly bent, pale brown to deep brown from top towards the base, apex hyaline, septate, mostly unbranched, smooth-walled. Conidiogenous cells 7–15 μm long, 4–7 μm wide (x̄ = 12 × 5.9 μm, n = 20), mono- to polyblastic, cylindrical, integrated, intercalary, brown, smooth-walled; with denticles, 3–6 μm long, 1.5–3 μm wide (x̄ = 4.6 × 2.5 μm, n = 20), arising from the lower portion of conidiophores as tooth-like protrusions, mono- to polyblastic, pale brown to brown, smooth-walled. Conidia 21–47 μm diam. (x̄ = 36.2 μm, n = 40) and conidial filament 2–5 μm wide (x̄ = 3.8 μm, n = 40), 145–345 μm long (x̄ = 257.7 μm, n = 40), solitary, pleurogenous, tightly coiled 3–4½ times, guttulate, become loose in water, hyaline to pale brown, 25–35-septate, smooth-walled.
Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA attaining 3 cm diam. after six weeks at 25 °C, irregular, undulate, rough, superficial and partially immersed, brown aerial mycelium mixed with pale brown; reverse brown with pale brown.
China, Yunnan Province, Xishuangbanna City, an unidentified forest beside National Highway 219 (21°93'N, 101°24'E, 549.6 m), rotting inflorescence of the Caryota mitis, 5 February 2023, Y.R. Xiong and Li Lu, XG217 (MHZU 23-0168, new host record; living culture, ZHKUCC 24-0143, ZHKUCC 24-0144).
Two isolates on rotting inflorescence of Caryota mitis obtained in this study clustered with the H. rufum clade in the phylogenetic tree with 96% ML, 95% MP bootstrap values and 0.99 BIPP bootstrap support. The nucleotide differences between H. rufum (ZHKUCC 24-0143) and H. rufum (MFLUCC 17-1806) are LSU: 0.09% (1/1171 base pairs), tef 1-α: 0.22% (2/912 base pairs), rpb2 sequence unavailable and no difference in ITS, excluding gaps. Our collection is similar to H. rufum (
Species epithet refers to the host species name “guineensis” from which the fungus was isolated.
MHZU 23-0153.
Saprobic on the rotting petiole of Elaeis guineensis. Sexual morph: Not observed. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, brown. Mycelium composed of partly immersed, partly superficial, pale brown, glistening, septate, branched hyphae. Conidiophores 50–160 µm long, 4–6 µm wide (x̄ = 120 × 5.2 μm, n = 20), macronematous, mononematous, cylindrical, unbranched or branched at apex, straight, septate, pale brown, brown at root part, smooth-walled. Conidiogenous cells 11.5–20 µm long, 3.5–5.5 µm wide (x̄ = 15.5 × 4.8 μm, n = 20), mono- to polyblastic, integrated, sympodial, terminal or intercalary, cylindrical, yellowish to pale brown, smooth-walled; with denticles, 1.4–2.7 µm long, 1.2–2 µm wide (x̄ = 1.9 × 1.6 μm, n = 20), arising from the juncture portion of two conidiogenous cells as tooth-like protrusions, mono- to polyblastic, hyaline, smooth-walled. Conidia 16–20 μm diam. (x̄ = 18 μm, n = 40) and conidial filament 1.8–3 μm wide (x̄ = 2.4 μm, n = 40), 90–130 μm long (x̄ = 112.9 μm, n = 40), solitary, mostly pleurogenous, rarely acrogenous, helicoid, rounded at tip, obvious hump and constricted at septa, coiled 2½–3½ times, 11–12-septate, becoming loose in water, guttulate, hyaline, smooth-walled.
Neohelicosporium guineensis (MHZU 23-0153, holotype) a specimen observed b, c colony on decaying Elaeis guineensis d, e apical branches forming long connected conidiophores f–j conidiogenous cells k–q conidia r germinated conidium s, t culture on PDA from above and reverse. Scale bars: 50 μm (d, e); 10 μm (f–q); 20 μm (r).
Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA attaining 3.5 cm diam. after six weeks at 25 °C, irregular, undulate, umbonate, rough, superficial and partially immersed, white aerial mycelium, deep brown at immersed area; reverse white to deep brown.
China, Yunnan Province, Xishuangbanna City, an unidentified forest beside National Highway 219 (21°93'N, 101°24'E, 549.6 m elev.), rotting petiole of the Elaeis guineensis, 5 February 2023, Y.R. Xiong and Li Lu, XG186 (MHZU 23-0153, holotype); ex-type, ZHKUCC 24-0113, other living culture ZHKUCC 24-0114.
Two isolates from this study formed a separate lineage and clustered with Neohelicosporium hyalosporum and N. ovoideum in the phylogenetic tree with 88% ML, 78% MP bootstrap support and 1.00 BIPP bootstrap support. The nucleotide differences excluding gaps between N. guineensis and its phylogenetically related species were checked: N. hyalosporum (GZCC 16-0076) - ITS: 1.56% (8/513 base pairs), LSU: 0.83% (7/840 base pairs), tef 1-α: 1.32% (12/912 base pairs), rpb2: 3.63% (38/1045 base pairs); N. ovoideum (GZCC 16-0064) - ITS: 1.50% (8/534 base pairs), LSU: 0.48% (4/826 base pairs), tef 1-α: 1.21% (11/912 base pairs), rpb2: 3.16% (33/1045 base pairs). Neohelicosporium guineensis differs from its closely-related species in the size of conidia and conidiophores (Table
Species epithet refers to the location name “Xishuangbanna” from where the holotype was collected.
MHZU 23-0156.
Saprobic on the rotting petiole of Elaeis guineensis. Sexual morph: Not observed. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, brown. Mycelium composed of partly immersed, partly superficial, brown, septate, unbranched hyphae. Conidiophores 40–125 μm long, 3–6 μm wide (x = 68.4 × 4.4 μm, n = 20), macronematous, mononematous, flexuous, long, cylindrical, branched, septate, smooth-walled. Conidiogenous cells 7–14 μm long, 2.5–5.5 μm wide (x̄ = 11.2 × 3.9 μm, n = 20), mono- to polyblastic, integrated, sympodial, terminal or intercalary, cylindrical, pale brown, smooth-walled; with denticles, 1.8–3.3 μm long, 1.1–2.3 μm wide (x̄ = 2.4 × 1.4 μm, n = 20), arising from the juncture portion of two conidiogenous cells as tooth-like and papillate protrusions, mono- to polyblastic, pale brown or hyaline, smooth-walled. Conidia 16.5–20.5 μm diam. (x̄ = 18.5 μm, n = 40) and conidial filament 1.8–3.2 μm wide (x̄ = 2.4 μm, n = 40), 90–125 μm long (x̄ = 107 μm, n = 40), solitary, acropleurogenous, helicoid, rounded at tip, coiled 2–3¼ times, 9–13-septate, becoming loose in water, guttulate, slightly constricted at septa, hyaline to pale brown, smooth-walled.
Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on PDA attaining 2.5 cm diam. after six weeks at 25 °C, irregular, undulate, umbonate, rough, superficial and partially immersed, brown aerial mycelium mixed with pale brown, deep brown at up and down junction area; reverse brown with deep brown.
China, Yunnan Province, Xishuangbanna City, an unidentified forest beside National Highway 219 (21°93'N, 101°24'E, 549.6 m elev.), rotting petiole of the Elaeis guineensis, 5 February 2023, Y.R. Xiong and Li Lu, XG197 (MHZU 23-0156, holotype); ex-type, ZHKUCC 24-0119, other living culture ZHKUCC 24-0120.
Two isolates obtained in this study developed an independent clade in the phylogenetic tree with 77% ML, 79% MP bootstrap support and 0.99 BIPP bootstrap support. The nucleotide differences excluding gaps between Neohelicosporium xishuangbannaensis and N. fusisporum (MFUCC 16-0642) are ITS: 2.81% (15/533 base pairs), LSU: 1.06% (9/852 base pairs), tef 1-α: 2.41% (22/912 base pairs) and rpb2 sequence is unavailable. Neohelicosporium fusisporum was reported as a sexual and asexual morph by
Neohelicosporium xishuangbannaensis (MHZU 23-0156, holotype) a specimen observed b, c colony on decaying Elaeis guineensis d conidiophores e, f intercalary conidiogenous cells g, h terminal conidiogenous cells i–o conidia p germinated conidium q, r culture on PDA from above and reverse. Scale bars: 50 μm (d); 10 μm (e–o); 20 μm (p).
In the present study, we identified and introduced three new species viz. Helicoma oleifera, Neohelicosporium guineensis and N. xishuangbannaensis with two new host records of Helicoma viz. H. guttulatum and H. rufum, which are associated with palms in tropical China. Xishuangbanna forests comprise numerous palm species, including Caryota sp., Calamus sp. and Elaeis sp. This humid tropical area near streams is also an ideal environment for Tubeufiaceae species (
Helicoma is one of the most typical helicosporous genera (
Neohelicosporium was introduced to accommodate helicosporous taxa with distinct conidiophores and is supported by molecular phylogenies, based on ITS, LSU, tef 1-α and rpb2 sequence data (
Yinru Xiong would like to thank Mae Fah Luang University for the award of Tuition fee waiver scholarship for the PhD. Ishara Manawasinghe would like to acknowledge Zhongkai University of Agriculture and Engineering, talent funding (grant number KA210319288) and the Guangzhou Science and Technology Plan Project (2023A04J1427). Biao Xu thanks to the National Natural Science Foundation of China (Nos. 32370021) and the Innovative team program of the Department of Education of Guangdong Province (2022KCXTD015 and 2022ZDJS020). We would like to acknowledge the Innovative team programme of the Department of Education of Guangdong Province (2022KCXTD015 and 2022ZDJS020). The authors also extend their appreciation to the Researchers Supporting Project number (RSP2024R114), King Saud University, Riyadh, Saudi Arabia for funding this work.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This research was funded by the High-level Talents at Zhongkai University of Agriculture and Engineering, grant no: J2201080102 Researchers Supporting Project number (RSP2024R114), King Saud University, Riyadh, Saudi Arabia.
Data curation: LL, YX. Formal analysis: ISM. Funding acquisition: KDH, FA, XB. Investigation: LL, YX. Methodology: YX, LL. Project administration: KDH. Resources: KDH. Supervision: ISM. Visualization: ISM. Writing - original draft: YX. Writing - review and editing: DLH, ISM, AM, KDH.
Yinru Xiong https://orcid.org/0000-0002-4673-606X
Kevin D. Hyde https://orcid.org/0000-0002-2191-0762
Li Lu https://orcid.org/0000-0003-0977-6414
Dulanjalee L. Harishchandra https://orcid.org/0000-0003-1538-4951
Ausana Mapook https://orcid.org/0000-0001-7929-2429
Ishara S. Manawasinghe https://orcid.org/0000-0001-5730-3596
All of the data that support the findings of this study are available in the main text.