Hongkongmyces wuhanensis Y.X. Shu, K.D. Hyde & W. Dong, 2025

Hongkongmyces wuhanensis Y.X. Shu, K.D. Hyde & W. Dong , sp. nov. ( Fig. 2 View FIGURE 2 )

Index Fungorum IF903464; Facesoffungi FoF17378

Etymology:— referring to Wuhan City, from where the holotype was collected.

Holotype:— MHZU 24-0618

Saprobic on decaying wood submerged in freshwater habitats. Sexual morph: Ascomata 180–270 × 170–250 μm, scattered or solitary, semi-immersed, subglobose, black, coriaceous, glabrous, with distinct, ostiolate papilla. Peridium 30–50 μm thick, two-layered, outer layer composed of large, black, thick-walled cells of textura angularis, inner layer composed of subhyaline, thin-walled cells of textura angularis. Pseudoparaphyses 1–3 μm wide, numerous, cellular, hypha-like, hyaline, septate. Asci 115–130(–175) × 14–19 μm (x = 125 × 16 μm, n = 10), 8-spored, bitunicate, clavate, rounded at the apex, short pedicellate. Ascospores 30–40(–70) × 7–8.5(–10) μm (x = 34 × 7.5 μm, n = 30), bi-seriate, overlapping tri-seriate, narrowly fusiform or vermiform, curved, with rounded or sometimes tapered ends, yellowish brown, 0–1-septate when young, slightly constricted at the septum, mostly 5-septate at maturity, occasionally 6- or 9- septate, becoming strongly constricted at the septa, asymmetric, slightly larger at the third to fourth cell from the apex, guttulate, thin-walled, smooth, surrounded by a mucilaginous, nearly ellipsoidal sheath, without appendages. Asexual morph: undetermined.

Culture characteristics: —ascospores germinating on PDA within 48 h at room temperature (~ 28 °C). Colonies on PDA reach 15 mm in 7 days, circular, rough, dry, raised, edge entire, with dense mycelium on the surface, dark brown in the middle, white at the edge; in reverse, dark brown with entire margin.

Material examined: — CHINA. Hubei Province: Wuhan City, Huazhong Agricultural University , on decaying wood submerged in a lake, 1 March 2023, Y.X. Shu, WH4.3 ( MHZU 24-0618 , holotype) ; ex-type culture, ZHKUCC 24-1143.

GenBank accession numbers:— LSU: PP937767, SSU: PP937768, ITS: PV197640, tef1-α: PQ299036

Notes: —in the multi-locus phylogenetic analysis of combined LSU, SSU, ITS and tef1-α sequence data, Hongkongmyces wuhanensis is closely related to H. cylindricisporus ( Fig. 1 View FIGURE 1 ). The comparison of DNA sequence data between H. wuhanensis ZHKUCC 24-1143 (type) and H. cylindricisporus KUNCC 23-16897 (type) reveals a difference of 0.25% (2 out of 817), and 2.50% (20 out of 800, with 2 gaps) in nucleotide variations within the LSU and ITS, respectively. The tef1-α sequence of H. cylindricisporus KUNCC 23-16897 is absent, and the nucleotide difference between H. wuhanensis ZHKUCC 24-1143 (type) and the other two strains HKAS 131480 and HKAS 131742 of H. cylindricisporus is 1.45% (13 out of 895), suggesting that they should not be conspecific ( Jeewon et al. 2016). Hongkongmyces cylindricisporus is a coelomycetous species ( Shen et al. 2024), while H. wuhanensis is an ascomycetous species. No asexual morphs were observed from the culture of H. wuhanensis even after four months. However, H. wuhanensis can be classified under Hongkongmyces due to its morphological similarities with the other five sexual species within the genus, viz., H. aquisetosus , H. brunneisporus , H. hongheensis , H. thailandicus , and H. yunnanensis . Hongkongmyces aquisetosus is distinguished in having ascomata covered by sparse, pale brown, septate hyphae, and mostly uniseriate, oblique, overlapping ascospores ( Yang et al. 2023). Hongkongmyces brunneisporus is distinguished in having ascomata covered by dark brown to black setae near the ostiole, reddish-brown to dark brown, mostly 7-septate ascospores, surrounded by a thin gelatinous sheath ( Bao et al. 2021). Hongkongmyces hongheensis and H. yunnanensis differ from H. wuhanensis in having reddish-brown to black ascospores ( Shen et al. 2024). Hongkongmyces thailandicus is distinguished in having immersed to semi-immersed ascomata within the substrate, and hyaline, 1-septate ascospores surrounded by a relatively well-defined, thin sheath ( Hyde et al. 2017). The six sexual species, including H. wuhanensis , with their main characteristics are summarized in Table 1. Based on the phylogenetic analyses and morphological study, H. wuhanensis is, therefore, introduced as a novel species.