Hypomontagnella hibisci

Hypomontagnella hibisci Rathnayaka, K.D. Hyde & Chethana, MycoKeys 120:35-117 (2025)

Index Fungorum number: IF903886; Facesofungi number: FoF17290

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 (x̄ = 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 (x̄ = 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 (x̄ = 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, AZ01 (MFLU 24-0532, holotype); ex-type culture MFLUCC 24-0613.

GenBank numbers: PV459061 (ITS), PV476727 (rpb2), PV469695 (β-tub)

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. 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. 2021a). 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. 2021a). With the evidence of unique morphology and distinct phylogeny, we introduce H. hibisci as a new species.