Neohelicomyces helicosporus J. Ma, Y. Z. Lu & K. D. Hyde, 2024

Ma, Jian, Gomdola, Deecksha, Boonmee, Saranyaphat, Shen, Hong-Wei, Tang, Xia, Zhang, Li-Juan, Lu, Yong-Zhong & Hyde, Kevin D., 2024, Three new species of Neohelicomyces (Tubeufiales, Tubeufiaceae) from freshwater and terrestrial habitats in China, MycoKeys 105, pp. 317-336 : 317-336

Neohelicomyces helicosporus J. Ma, Y. Z. Lu & K. D. Hyde sp. nov.

Fig. 3

Etymology.

The epithet “ helicosporus ” refers to the helicoid form of conidia.

Holotype.

HKAS 134923 .

Description.

Saprobic on decaying wood in a terrestrial habitat. Sexual morph Unknown from natural habitat. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, effuse, gregarious, white. Mycelium semi-immersed, hyaline to pale brown, septate, branched hyphae, smooth, comprising glistening conidial mass. Conidiophores 105–199 μm long, 3–5.5 μm wide (x ¯ = 160.5 × 4 μm, n = 25), macronematous, mononematous, erect, curved, flexible at the tip, cylindrical, unbranched, septate, hyaline, smooth-, thick-walled. Conidiogenous cells 13–22 μm long, 2.5–4.5 μm wide (x ¯ = 16 × 3.5 μm, n = 20), holoblastic, monoblastic to polyblastic, integrated, sympodial, intercalary or terminal, cylindrical, with a denticulate protrusion, truncate at apex after conidial secession, hyaline, smooth-walled. Conidia solitary, acropleurogenous, helicoid, rounded at the tips, 15.5–18 μm in diameter and conidial filament 2.5–5 μm wide (x ¯ = 16.5 × 3.5 μm, n = 25), 103–170 μm long (x ¯ = 130 μm, n = 30), indistinctly multi-septate, coiled up to 3 ¾ times, becoming loosely coiled in water, guttulate, hyaline, smooth-walled.

Culture characteristics.

Conidia producing germ tubes on PDA within 9 hours of incubation at 25 ° C. Colonies on PDA are irregular with umbonate surface and filiform edge, reaching 43 mm diameter after 48 days of incubation at 25 ° C, top view of colony reddish-brown to black brown, reverse brown to black brown.

Material examined.

China, Guizhou Province, Qianxinan Buyi and Miao Autonomous Prefecture, Lianhuan Town, on decaying wood in a terrestrial habitat, 17 March 2022, Jian Ma, LHX 8 ( HKAS 134923 , holotype; GZAAS 23–0623 , isotype), ex-type living cultures GZCC 23–0633 ; Ibid., LHX 8.1 ( GZAAS 23–0624 , paratype), living culture GZCC 23–0634 .

Notes.

Our isolates ( GZCC 23–0633 and GZCC 23–0634 ) are morphologically similar to Neohelicomyces hainanensis ( Lu et al. 2022) , but the phylogenetic analyses revealed that GZCC 23–0633 and GZCC 23–0634 cluster together and this clade is sister to N. hyalosporus ( GZCC 16–0086 ) with 100 % ML / 1.00 PP support (Fig. 1 ). The polymorphism nucleotides comparison of ITS, LSU, tef 1 α and rpb 2 sequence data between GZCC 23–0633 and Neohelicomyces hyalosporus ( GZCC 16–0086 ), reveals nucleotide base differences of 29 / 527 bp (5.5 %, including thirteen gaps), 2 / 844 bp (0.2 %, including 0 gap), 27 / 892 bp (3.0 %, including 0 gap) and 37 / 893 bp (4.1 %, including 0 gap), respectively. Additionally, our species displays a reddish-brown pigmentation on PDA, but this feature was not observed in N. hainanensis and N. hyalosporus ( Lu et al. 2018 b, 2022). Furthermore, our species differs from N. hainanensis in having longer conidia (103–170 μm vs. up to 136 μm) and from N. hyalosporus in having shorter conidiophores (105–199 μm vs. 210–290 μm) ( Lu et al. 2018 b, 2022). Therefore, based on the phylogenetic and morphological differences, we introduce N. helicosporus herein as a novel species.

Figures

Figure 1. Phylogenetic tree generated from Maximum Likelihood (ML) analysis, based on the combined ITS, LSU, tef 1 α and rpb 2 sequence data. Bootstrap support values of ML equal to or greater than 75 % and Bayesian posterior probabilities (PP) equal to or greater than 0.95 are given near the nodes as ML / PP, respectively. Helicotubeufia hydei (MFLUCC 17–1980) and H. jonesii (MFLUCC 17–0043) were selected as outgroup taxa. The new species are typed in bold red; “ T ” denotes ex-type strains.

Figure 3. Neohelicomyces helicosporus (HKAS 134923, holotype) a, b colonies on the host surface c – f conidiophores and conidiogenous cells g – j conidiogenous cells k germinated conidium l – s conidia t, u surface and reverse colonies on PDA after 48 days of incubation at 25 ° C. Scale bars: 50 μm (c – e); 20 μm (f – h, k – s); 10 μm (i); 5 μm (j).