Two new species of Neohelicomyces (Tubeufiaceae, Tubeufiales) from Hainan Province, China

75 Two new species of Neohelicomyces (Tubeufiaceae, Tubeufiales) from Hainan Province, China Fan Gao1, Ting-Hong Tan1,2 , Song Bai3, Chun-Fang Wu1, Ning-Ning Zhao1, Na Qiu1, Min Zhou1, Jian Ma3,4 1 School of Agriculture and Forestry Engineering and Planning, Tongren University, Tongren, Guizhou 554300, China 2 Guizhou Provincial Key Laboratory for Biodiversity Conservation and Utilization in the Fanjing Mountain Region, Tongren University, Tongren, Guizhou 554300, China 3 Guizhou Industry Polytechnic College, Guiyang, Guizhou 550008, China 4 School of Food and Pharmaceutical Engineering, Guizhou Institute of Technology, Guiyang, Guizhou 550003, China Corresponding authors: Ting-Hong Tan ([email protected]); Song Bai ([email protected]); Jian Ma ([email protected]) Copyright: © Fan Gao et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract During a survey of helicosporous hyphomycetes in tropical regions, four fungal strains were isolated from decaying wood in terrestrial habitats of Hainan Province, China. Based on combined phylogenetic analyses of LSU, ITS, tef1-α, and rpb2 sequence data, together with morphological evidence, two novel species, Neohelicomyces terrestris and N. tropicus, are herein proposed. Comprehensive descriptions, illustrations, taxonomic notes, and phylogenetic analyses are provided to confirm the taxonomic placement. The newly described species were found in tropical rainforests, thereby expanding the known distribution of Neohelicomyces in tropical terrestrial habitats. Key words: Dothideomycetes, helicosporous hyphomycetes, phylogeny, taxonomy, two new species Introduction Helicosporous hyphomycetes are a group of asexual fungi characterized by helicoid or spiral conidia (Lu and Kang 2020; Ma et al. 2024b). To date, reported helicosporous hyphomycetes belong to three phyla (Ascomycota, Basidiomycota, and Zoopagomycota), 10 classes (Agaricomycetes, Atractiellomycetes, Dothideomycetes, Eurotiomycetes, Exobasidiomycetes, Leotiomycetes, Orbiliomycetes, Sordariomycetes, Tremellomycetes, and Zoopagomycetes), 20 orders (Agaricales, Atractiellales, Chaetosphaeriales, Exobasidiales, Helotiales, Hypocreales, Lulworthiales, Microascales, Microthyriales, Mycosphaerellales, Mytilinidiales, Orbiliales, Pleosporales, Pleurotheciales, Sclerococcales, Torpedosporales, Tremellales, Tubeufiales, Venturiales, and Zoopagales), 25 families, 103 genera, and nine fossil genera (Morgan 1892; Moore 1957; Rao and Rao 1964; Goos 1985; Tsui et al. 2006; Boonmee et al. 2011, 2014, 2021; Hyde et al. 2016; Singh and Singh 2016; Chaiwan et al. 2017; Dai et al. 2017; Doilom et al. 2017; Tibpromma et al. 2018; Li et al. 2022; Tian et al. 2022). Academic editor: Xinlei Fan Received: 7 October 2025 Accepted: 19 November 2025 Published: 4 December 2025 Citation: Gao F, Tan T-H, Bai S, Wu C-F, Zhao N-N, Qiu N, Zhou M, Ma J (2025) Two new species of Neohelicomyces (Tubeufiaceae, Tubeufiales) from Hainan Province, China. MycoKeys 126: 75–91. https://doi.org/10.3897/ mycokeys.126.174186 MycoKeys 126: 75–91 (2025) DOI: 10.3897/mycokeys.126.174186 76 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Among them, the Tubeufiaceae (Tubeufiales, Dothideomycetes) is the most species-rich and morphologically diverse group of helicosporous hyphomycetes (Lu et al. 2017, 2018a, 2018b, 2022, 2023b; Luo et al. 2017; Ma et al. 2023, 2024b, 2025). Helicosporous genera within Tubeufiaceae, such as Helicoma, Helicomyces, Helicosporium, Neohelicomyces, Neohelicosporium, and Tubeufia, represent important fungal resources capable of producing secondary metabolites with novel chemical structures and notable bioactivities (Lu et al. 2018b; Lu and Kang 2020; Zeng et al. 2022; Qian et al. 2023; Zhang et al. 2023a, 2023b, 2024; Zheng et al. 2023). These compounds show considerable potential in drug development, including antitumor, anticancer, and antibacterial applications (Ma et al. 2024b). Neohelicomyces Z.L. Luo, D.J. Bhat & K.D. Hyde was established by Luo et al. (2017) with N. aquaticus as the type species, based on phylogenetic analyses of combined LSU, ITS, and tef1-α sequence data and morphological characteristics. Currently, Neohelicomyces comprises 32 accepted species (Luo et al. 2017; Lu et al. 2018b, 2022; Tibpromma et al. 2018; Crous et al. 2019a, 2019b; Dong et al. 2020; Hsieh et al. 2021; Yang et al. 2023; Ma et al. 2024b; Lin et al. 2025; Peng et al. 2025; Sun et al. 2025). Species of Neohelicomyces are distributed across China, the Czech Republic, Germany, Italy, Japan, the Netherlands, Thailand, and the USA, occurring as saprobes on various substrates such as bamboo culms, Deschampsia cespitosa, Fraxinus excelsior, Melaleuca styphelioides, Miscanthus floridulus, Pandanus sp., Quercus robur, and decaying wood in both freshwater and terrestrial habitats (Linder 1929; Goos 1986, 1989, 1990; Tsui et al. 2006; Zhao et al. 2007; Ruibal et al. 2009; Luo et al. 2017; Lu et al. 2018b, 2022; Tibpromma et al. 2018; Crous et al. 2019a, 2019b; Dong et al. 2020; Hsieh et al. 2021; Yang et al. 2023; Ma et al. 2024b; Lin et al. 2025; Peng et al. 2025; Sun et al. 2025). The asexual morph of Neohelicomyces is characterized by gregarious, white, grayish-brown, yellowish-green, and pinkish colonies; macronematous, mononematous, erect, septate, pale brown, branched and/or unbranched conidiophores; monoto polyblastic, integrated, terminal or intercalary conidiogenous cells with denticles; and acropleurogenous or pleurogenous, aseptate or septate, guttulate, hyaline, helicoid conidia (Yang et al. 2023; Ma et al. 2024a, 2024b; Peng et al. 2025). The sexual morph is characterized by superficial, solitary, scattered, reddish brown to brown, subglobose ascomata; eight-spored, bitunicate, cylindric-clavate, rounded-at-apex, short-pedicellate asci; and multiseriate, narrowly cylindrical, straight to slightly curved, hyaline to pale brown, septate, rough ascospores (Sun et al. 2025). In this study, four isolates of helicosporous hyphomycetes, representing two distinct taxonomic lineages, were collected from terrestrial environments in Hainan Province, China. Comprehensive analyses, including detailed morphological observations, illustrations, and multigene phylogenetic assessments, were conducted to accurately characterize these isolates. Based on the integrative evidence, two previously undescribed species are proposed and formally introduced here: Neohelicomyces terrestris and N. tropicus. These findings not only expand the current understanding of the genus Neohelicomyces but also provide valuable insights into its diversity in tropical terrestrial habitats. 77 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Materials and methods Sample collection, specimen examination, and isolation Decaying wood was collected from Hainan Province, southwestern China. Samples were taken to the laboratory in plastic bags with the collection details, including localities and dates (Rathnayaka et al. 2024). The microscopic features were examined and photographed using a stereomicroscope (SMZ-168, Nikon, Japan) and an ECLIPSE Ni compound microscope (Nikon, Tokyo, Japan) with a Canon 90D digital camera (Canon, China). Measurements were made using Tarosoft (R) Image Frame Work software. Photo plates were assembled using Adobe Photoshop CC 2019 (Adobe Systems, USA). Single-spore isolation was performed following the methods described by Senanayake et al. (2020), and the germinated conidia were aseptically transferred to fresh PDA plates. Morphological characters of fungal colonies, including color, shape, and size, were documented. Dried specimens were deposited in the Herbarium of the Kunming Institute of Botany, Chinese Academy of Sciences (Herb. HKAS), Kunming, China, and the Herbarium of the Guizhou Academy of Agriculture Sciences (Herb. GZAAS), Guiyang, China. Pure cultures were deposited in the Guizhou Culture Collection (GZCC), Guiyang, China. MycoBank numbers of the newly obtained species were registered in the MycoBank database (https://www.mycobank.org/). DNA extraction, PCR amplification, and sequencing Fresh fungal mycelia were scraped from colonies grown on PDA plates and transferred to a 1.5 mL microcentrifuge tube using a sterilized lancet for genomic DNA extraction. Genomic DNA was extracted using the Biospin Fungus Genomic DNA Extraction Kit (BioFlux, China). LR0R/LR5, ITS5/ITS4, EF1-983F/ EF1-2218R, and fRPB2-5F/fRPB2-7cR were employed to amplify the large ribosomal subunit (LSU; Vilgalys and Hester 1990), internal transcribed spacer (ITS; White et al. 1990), translation elongation factor 1-alpha (tef1-α; Rehner and Buckley 2005), and RNA polymerase II second-largest subunit (rpb2; Liu et al. 1999) sequence fragments, respectively. DNA preparation was conducted in a 25 μL mixture, which included 1 μL DNA, 1 μL each of the forward and reverse primers, and 22 μL of 1.1× T3 Super PCR Mix (including 8.5 μL distilled-deionized water; Tsingke Biotech, Chongqing, China). The conditions for the polymerase chain reaction (PCR) correspond to those reported by Ma et al. (2023). The PCR products were purified and sequenced with the same primers at Beijing Tsingke Biotechnology Co., Ltd. Phylogenetic analyses The newly obtained sequences were checked and assembled using BioEdit v.7.0.5.3 (Hall 1999) and SeqMan v.7.0.0 (DNASTAR, Madison, WI, USA; Swindell and Plasterer 1997), respectively. The sequences incorporated in this study were downloaded from GenBank (Table 1; https://www.ncbi.nlm.nih.gov/). Multiple sequences were aligned using MAFFT v.7.473 (https://mafft.cbrc.jp/alignment/ server/; Katoh et al. 2019). The dataset was trimmed using trimAl v.1.2rev59 78 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Table 1. Taxa used in this study and their GenBank accession numbers. Taxon Strain GenBank Accessions LSU ITS tef1-α rpb2 Helicotubeufia hydei MFLUCC 17-1980TMH290026 MH290021 MH290031 MH290036 Helicotubeufia jonesii MFLUCC 17-0043TMH290025 MH290020 MH290030 MH290035 Neohelicomyces acropleurogenus CGMCC 3.25549TPP639450 PP626594 PP596351 PP596478 Neohelicomyces aquaticus MFLUCC 16-0993TKY320545 KY320528 KY320561 MH551066 Neohelicomyces aquisubtropicus GZCC 23-0080TPQ098537 PQ098499 PV768327 PV768336 Neohelicomyces aseptatus CGMCC 3.25564TPP639451 PP626595 PP596352 PP596479 Neohelicomyces astrictus HKAS 105122TPQ898796 PQ898760 PV040811 N/A Neohelicomyces brunneus HKAS 105147TPQ898805 PQ898768 PV040818 N/A Neohelicomyces dehongensis MFLUCC 18-1029TMN913709 NR_171880 MT954393 N/A Neohelicomyces denticulatus GZCC 19-0444TMW133855 OP377832 N/A N/A Neohelicomyces deschampsiae CPC 33686TMK442538 MK442602 N/A N/A Neohelicomyces edgeworthiae CGMCC 3.25565TPP639453 PP626597 PP596354 PP596481 Neohelicomyces grandisporus KUMCC 15-0470TKX454174 KX454173 N/A MH551067 Neohelicomyces guizhouensis GZCC 23-0725TPP512973 PP512969 PP526727 PP526733 Neohelicomyces guttulatus CGMCC 3.25550TPP639454 PP626598 PP596355 N/A Neohelicomyces hainanensis GZCC 22-2009TOP508774 OP508734 OP698085 OP698074 Neohelicomyces helicosporus GZCC 23-0633TPP512975 PP512971 PP526729 PP526735 Neohelicomyces hyalosporus GZCC 16-0086TMH558870 MH558745 MH550936 MH551064 Neohelicomyces hydei GZCC 23-0727TPP512977 N/A PP526731 PP526737 Neohelicomyces lignicola CGMCC 3.25551TPP639456 PP626600 PP596357 PP596483 Neohelicomyces longisetosus NCYU-106H1-1-1TN/A MT939303 N/A N/A Neohelicomyces macrosporus CGMCC 3.25552TPP639457 PP626601 PP596358 PP596484 Neohelicomyces maolanensis GZCC 23-0079TPQ098529 N/A PQ490683 PQ490677 Neohelicomyces melaleucae CPC 38042TMN567661 MN562154 MN556835 N/A Neohelicomyces pallidus CBS 271.52 AY856887 AY916461 N/A N/A Neohelicomyces pallidus CBS 962.69 AY856886 AY916460 N/A N/A Neohelicomyces pandanicola KUMCC 16-0143TMH260307 MH275073 MH412779 N/A Neohelicomyces qixingyaensis CGMCC 3.25569TPP639458 PP626602 PP596359 PP596485 Neohelicomyces sexualis HGUP 24-0021TPQ570861 PQ570844 N/A N/A Neohelicomyces sp. GMBCC 2225 PX308848 PX308843 PX314510 PX314514 Neohelicomyces sp. GMBCC 2217 PX308846 PQ737369 PX314508 PX314512 Neohelicomyces submersus MFLUCC 16-1106TKY320547 KY320530 N/A MH551068 Neohelicomyces subtropicus GZCC 23-0076TPQ098530 PQ098492 PQ490685 PQ490679 Neohelicomyces terrestris GZCC 23-0399TPX575662 PX575639 PX512845 PX512836 Neohelicomyces terrestris GZCC 25-0660 PX575663 PX575640 PX512846 PX512837 Neohelicomyces thailandicus MFLUCC 11-0005TMN913696 NR_171882 N/A N/A Neohelicomyces tropicus GZCC 25-0661TPX575664 PX575641 PX512847 PX512838 Neohelicomyces tropicus GZCC 25-0662 PX575665 PX575642 PX512848 PX512839 Neohelicomyces wuzhishanensis GZCC 23-0410TPQ098532 PQ098494 PV768325 PV768334 Neohelicomyces xiayadongensis CGMCC 3.25568TPP639460 PP626604 PP596361 PP596487 Neohelicomyces yunnanensis GZCC 23-0735TPP664113 PP664109 N/A N/A Tubeufia guttulata GZCC 23-0404TOR030834 OR030841 OR046678 OR046684 79 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Taxon Strain GenBank Accessions LSU ITS tef1-α rpb2 Tubeufia hainanensis GZCC 22-2015TOR030835 OR030842 OR046679 OR046685 Tubeufia javanica MFLUCC 12-0545TKJ880036 KJ880034 KJ880037 N/A Tubeufia krabiensis MFLUCC 16-0228TMH558917 MH558792 MH550985 MH551118 Tubeufia latispora MFLUCC 16-0027TKY092412 KY092417 KY117033 MH551119 Tubeufia laxispora MFLUCC 16-0232TKY092408 KY092413 KY117029 MF535287 Tubeufia mackenziei MFLUCC 16-0222TKY092410 KY092415 KY117031 MF535288 Tubeufia muriformis GZCC 22-2039TOR030836 OR030843 OR046680 OR046686 Tubeufia nigroseptum CGMCC 3.20430TMZ853187 MZ092716 OM022002 OM022001 Tubeufia pandanicola MFLUCC 16-0321TMH260325 MH275091 N/A N/A Note: “T” indicates ex-type strains. Newly generated sequences are in bold. “N/A” indicates unavailable data in GenBank. software (Capella-Gutiérrez et al. 2009). A combined sequence dataset was created using SequenceMatrix-Windows-1.7.8 software (Vaidya et al. 2011). The maximum likelihood (ML) analysis was carried out using RAxML-HPC v.8 on XSEDE (8.2.12) with a GTRGAMMA approximation and rapid bootstrap analysis followed by 1,000 bootstrap replicates (Stamatakis 2014). The substitution model was automatically tested by the server. Bayesian Inference (BI) analysis was performed using MrBayes on XSEDE (3.2.7a) via CIPRES (Stamatakis 2014). The aligned FASTA file was converted to a Nexus format file using AliView (Daniel et al. 2010). The best-fit evolutionary model for the individual datasets was determined using MrModeltest v.2.3.10 (Nylander et al. 2008). The GTR+G+I substitution model was selected for LSU, ITS, and tef1-α, whereas the SYM+I+G model was applied to rpb2. The posterior probabilities (BYPP) were determined based on Bayesian Markov chain Monte Carlo (BMCMC) sampling (Huelsenbeck and Ronquist 2001). Four simultaneous Markov chains were run for 10,000,000 generations, and trees were sampled every 1,000th generation. The burn-in phase was set at 25%, and the remaining trees were used for calculating posterior probabilities (BYPP). Phylogenetic trees were visualized using FigTree v.1.4.4 and edited with Adobe Illustrator CC 2019 (v.23.1.0; Adobe Systems, USA). Phylogenetic results The phylogenetic positions of the four novel strains were assessed using a multi-locus phylogenetic approach. The concatenated sequence matrix comprised 3,431 characters (LSU: 1–856, ITS: 857–1,450, tef1-α: 1,451–2,362, and rpb2: 2,363–3,431) across 51 taxa. Base frequencies and rates were A = 0.249274, C = 0.247026, G = 0.255949, and T = 0.247750; substitution rates were AC = 1.139215, AG = 5.117176, AT = 2.501758, CG = 1.050796, CT = 8.734543, and GT = 1.000000. The distribution shape parameter α equaled 0.181304. Based on the multi-gene phylogenetic tree (Fig. 1), our collections are identified as two distinct Neohelicomyces species within the family Tubeufiaceae (Tubeufiales, Dothideomycetes). The isolates GZCC 23-0399 and GZCC 250660 formed a sister clade to N. wuzhishanensis (GZCC 23-0410), with robust support of 87% ML and 1.00 BYPP. Furthermore, isolates GZCC 25-0661 and GZCC 25-0662 clustered together and formed a sister clade to N. hainanensis (GZCC 22-2009), with 95% ML and 1.00 BYPP support (Fig. 1). 80 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Figure 1. Phylogenetic tree generated from maximum likelihood (ML) analysis based on the combined LSU, ITS, tef1-α, and rpb2 sequence data. Bootstrap support values for ML (≥ 70%) and BYPP (≥ 0.95) are indicated near their respective nodes. Both Maximum Likelihood (ML) and Bayesian Inference (BYPP) analyses produced congruent topologies. A hyphen (“-”) indicates a value lower than 70% for ML and a posterior probability lower than 0.95 for Bayesian inference. The tree is rooted with Helicotubeufia hydei (MFLUCC 17-1980) and H. jonesii (MFLUCC 17-0043). Ex-type strains are denoted with “T,” and newly obtained strains are in bold black fonts. 81 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Taxonomy Neohelicomyces terrestris T.H. Tan & J. Ma, sp. nov. MycoBank No: 904429 Fig. 2 Etymology. The species epithet “terrestris’’ refers to the terrestrial habitat of this fungus. Holotype. HKAS 128950. Description. Saprobic on decaying wood in a terrestrial habitat. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, effuse, gregarious, with masses of crowded, glistening conidia, white to brown. Mycelium partly immersed, partly superficial, composed of hyaline to pale brown, branched, septate, smooth hyphae. Conidiophores 106–212 × 3–4.5 μm (xˉ = 176 × 4 μm, n = 25), macronematous, mononematous, erect, cylindrical, flexuous, widest at the base, tapering towards narrow apex, branched or unbranched, septate, brown at base, subhyaline towards apex, thick-walled. Conidiogenous cells 7.5–25 × 2–4 μm (xˉ = 13.5 × 3.5 μm, n = 25), holoblastic, monoblastic, or polyblastic, integrated, terminal or intercalary, cylindrical, with denticles, subhyaline to pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, developing on tooth-like protrusion, 15–21 μm diam. and conidial filament 2.5–3.5 μm wide (xˉ = 17.5 × 3 μm, n = 20), 107–143 μm long (xˉ = 128.5 μm, n = 30), loosely coiled 21/2–3 times, becoming loosely coiled in water, septate, guttulate, hyaline, smooth-walled. Culture characteristics. Conidia germinated on PDA and produced germ tubes within 11 h. Colonies on PDA reached 27 mm in diameter after 40 days of incubation at 25 °C, with an irregular shape, raised surface, and undulate margin, pale brown to brown; the reverse was brown to dark brown. Material examined. China • Hainan Province, Wuzhishan City, Shuimanhe tropical rainforest scenic area in Wuzhishan, 18°92′N, 109°63′E, on decaying wood in a terrestrial habitat, 4 November 2024, Ting-Hong Tan & Jian Ma, WZ66 (HKAS 128950, holotype), ex-type living cultures GZCC 23-0399 • ibid., WZ67 (GZAAS 23-0403, paratype), living culture GZCC 25-0660. Notes. Morphologically, Neohelicomyces terrestris (HKAS 128950) resembles Parahelicomyces laxisporus (HKAS 128943) in having macronematous, mononematous, erect, widest-at-the-base, tapering-towards-a-narrow-apex, brown-at-base, subhyaline-towards-apex, flexuous conidiophores; holoblastic, monoblastic or polyblastic, integrated, cylindrical conidiogenous cells with denticles, subhyaline to pale brown; and acropleurogenous, helicoid, aseptate, guttulate, hyaline conidia (Ma et al. 2024b). However, N. terrestris (HKAS 128950) differs from Pa. laxisporus (HKAS 128943) by its wider conidial diameter (up to 21 μm vs. 14.5–16 μm) and longer conidia (up to 143 μm vs. 80.5–124 μm) (Ma et al. 2024b). Phylogenetically, our isolates (GZCC 230399 and GZCC 25-0660) form a sister clade to N. wuzhishanensis (GZCC 23-0410), with 87% ML and 1.00 BYPP support (Fig. 1). Comparison of the LSU, ITS, tef1-α, and rpb2 sequence data between Neohelicomyces terrestris (GZCC 23-0399) and N. wuzhishanensis (GZCC 23-0410) revealed nucleotide base differences of 5/486 bp (1%, including three gaps), 26/484 bp (5.4%, 82 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species Figure 2. Neohelicomyces terrestris (HKAS 128950, holotype). a, b. Colonies on the host surface; c–e. Conidiophores and conidiogenous cells; f–h. Conidiogenous cells; i–n. Conidia; o, p. Colonies on PDA from above and below. Scale bars: 50 μm (c–e); 10 μm (f–n). 83 MycoKeys 126: 75–91 (2025), DOI: 10.3897/mycokeys.126.174186 Fan Gao et al.: Introduce two new species including 10 gaps), 25/937 bp (2.7%, including seven gaps), and 33/926 bp (3.6%, with no gaps), respectively. Therefore, based on both multi-gene phylogenetic analyses and morphological differences, we introduce Neohelicomyces terrestris as a novel species. Neohelicomyces tropicus T.H. Tan & J. Ma, sp. nov. MycoBank No: 904430 Fig. 3 Etymology. The species epithet “tropicus” refers to the tropical climate in which the species occurs. Holotype. GZAAS 25-0675. Description. Saprobic on decaying wood in a terrestrial habitat. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, gregarious, with a little of crowded, glistening conidia, white. Mycelium partly immersed, partly superficial, composed of hyaline to pale brown, branched, septate, smooth hyphae. Conidiophores 139–175 × 4–5.5 μm (xˉ = 154 × 4.5 μm, n = 25), macronematous, mononematous, erect, cylindrical, straight or slightly flexuous, branched or unbranched, septate, subhyaline to pale brown, thick-walled. Conidiogenous cells 10–17 × 3–4 μm (xˉ = 14 × 3.5 μm, n = 25), holoblastic, monoblastic or polyblastic, integrated, terminal or intercalary, cylindrical, with denticles, subhyaline to pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, tapering towards the rounded ends, developing on tooth-like protrusion, 15.5–20 μm diam. and conidial filament 2–3.5 μm wide (xˉ = 17.5 × 2.5 μm, n = 20), 95–140 μm long (xˉ = 116 μm, n = 20), tightly coiled up to 3 times, becoming loosely coiled when the conidia are young and not becoming loose when mature in water, aseptate, guttulate, hyaline, smooth-walled. Culture characteristics. Conidia germinated on PDA and produced germ tubes within 14 h. Colonies on PDA reached 25 mm in diameter after 38 days of incubation at 25 °C with a circular shape, flat surface, and entire margin, pale brown to brown; the reverse was pale brown to brown. Material examined. China • Hainan Province, Baoting Li and Miao Autonomous County, Qixianling Hot Spring National Forest Park, on decaying wood in a terrestrial habitat, 2 November 2024, Ting-Hong Tan & Jian Ma, Q45 (GZAAS 25-0675, holotype), ex-type living culture GZCC 25-0661 • ibid., Q47 (GZAAS 250690, paratype), living culture GZCC 25-0662. Notes. In the phylogenetic analyses (Fig. 1), our isolates (GZCC 25-0661 and GZCC 25-0662) formed a well-supported sister clade to Neohelicomyces hainanensis (GZCC 22-2009), with 95% ML and 1.00 BYPP values. Morphologically, N. tropicus (GZAAS 25-0675) and N. hainanensis (GZAAS 22-2009) are nearly identical in their conidiophores, conidiogenous cells, and conidia (Lu et al. 2022). 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