Hypomontagnella hibisci Rathnayaka, K. D. Hyde & Chethana, 2025

Rathnayaka, Achala R., Chethana, K. W. Thilini, Manowong, Areerat, Bhagya, Amuhenage T., Win, Hsan, Tun, Zaw L., Mapook, Ausana & Hyde, Kevin D., 2025, Taxonomy, phylogeny, and bioactive potential of Xylariales (Sordariomycetes, Ascomycota) from Thailand: novel species discovery, new host and geographical records, and antibacterial properties, MycoKeys 120, pp. 35-117 : 35-117

Hypomontagnella hibisci Rathnayaka, K. D. Hyde & Chethana sp. nov.

Fig. 15

Etymology.

In reference to the host genus from which the fungus was collected

Holotype.

MFLU 24-0532

Description.

Saprobic on a dead branch of Hibiscus sp. Sexual morph: Stromata effused-pulvinate, with conspicuous to inconspicuous perithecial mounds, surface blackish, carbonaceous tissue immediately beneath the surface and between the perithecial surface and perithecia. Ascomata 157–300 × 133–218 μm (x ̄ = 223 × 178 μm, n = 5), globose to spherical, ostioles higher than the stromatal surface. Peridium 13–26 μm diam., composed of thin-walled, brown to dark brown cells of textura angularis. Paraphyses 2–3 μm wide, hyaline, filamentous, long, branched, aseptate, arising from the base of ascomata. Asci 78–100 × 5–6 μm (x ̄ = 90 × 5.4 μm, n = 25), the spore-bearing parts 46–53 µm long, 8 - spored, cylindrical, with J-, apical ring and a stipe of 28–36 µm long. Ascospores 7–9 × 3–5 μm (x ̄ = 8 × 4 μm, n = 30), unicellular, uni-seriate, slightly overlapping, ellipsoid, with narrowly rounded ends, slightly curved, hyaline to dark brown, smooth to finely roughened, guttulate. Asexual morph: Undetermined.

Culture characteristics.

Ascospores are germinated on the PDA within 24 hours at 25 ° C. Germ tubes are produced from one side of the ascospore. Colonies on the PDA reach 1.5–2.5 cm diam. after seven days at 25 ° C, circular in shape, flat, cottony, slightly less dense towards the edge, white color in the front view, and pale yellow in the reverse view.

Material examined.

Thailand • Chiang Rai, Mae Fah Luang University premises , on a decaying branch of Hibiscus sp. ( Malvaceae ), 08 March 2024, Zaw Lin Tun, AZ 01 ( MFLU 24-0532 , holotype); ex-type culture MFLUCC 24-0613 .

Notes.

Hypomontagnella hibisci ( MFLUCC 24-0613 ) is similar to Hypomontagnella in having stromata with conical, papillate ostioles and cylindrical asci with a short pedicel ( Lambert et al. 2019). According to the multi-gene phylogenetic analyses, our strains ( MFLU 24-0532 and MFLUCC 24-0613 ) formed a separate lineage sister to H. monticulosa ( MUCL 54604 and MFLUCC 24-0613 ) with 100 % ML bootstrap and 1.00 PP support (Fig. 13 ). However, H. hibisci has globose to spherical perithecia and asci with J-, apical rings, whereas H. monticulosa has spherical to obovoid perithecia and asci with J + discoid apical rings ( Chethana et al. 2021 a). Additionally, H. monticulosa differs from H. hibisci by having ascospores with a straight, spore-length germ slit, which is not observed in H. hibisci ( Chethana et al. 2021 a). With the evidence of unique morphology and distinct phylogeny, we introduce H. hibisci as a new species.

Figures

Figure 13. Phylogram generated from ML analysis based on the combined dataset of ITS, LSU, rpb 2, and β-tub. The tree is rooted to Graphostroma platystomum (CBS 270.87), Natonodosa speciosa (CLM RV 86), Xylaria arbuscula (CBS 126415), and X. hypoxylon (CBS 122620). Bootstrap support values for ML ≥ 70 % and Bayesian posterior probabilities (PP) ≥ 0.90 are noted at the nodes. Strain numbers are noted after the species names. Strains isolated in this study are represented in blue, and type strains are in bold.

Figure 15. Hypomontagnella hibisci on a decaying branch of Hibiscus sp. (MFLU 24-0532, Holotype). a. Substrate; b. Mature stroma on the bark; c. Stromatal surface showing papillate and ostiolar discs (indicated by white arrows); d – f. Stromata in vertical sections; g. Peridium; h. Paraphyses; i – m. Asci; n. Apical apparatus with Melzer’s reagent; o – r. Ascospores; s, t. Colony on the PDA (s upper, t lower). Scale bars: 2 mm (b); 1 mm (c); 200 μm (d); 100 μm (e); 50 μm (f); 10 μm (g, n); 20 μm (h – m); 5 μm (o – r).