Setophoma aseptata, Y.T. Cai, L. Zhang & Z.L. Luo, 2025

Setophoma aseptata, Y.T. Cai, L. Zhang & Z.L. Luo , sp. nov. FIGURE 1 View FIGURE 1

Fungal Names number: FN572474

Etymology:— aseptata, referring to the aseptate conidia of this fungus.

Holotype:— KUN-HKAS 146438

Saprobic on decaying submerged wood in freshwater habitat. Asexual morph: Conidiomata 88–106 × 110–140 µm, scattered or gregarious, globose to subglobose, glabrous, papillate, with a small pore-like opening at the center, dark brown to black. Conidiomata wall 17–36 μm thick, consisting of multiple-layers of thick-walled; dark brown cells composed of textura angularis cells in the outer wall, and rectangular hyaline cells in inner the wall. Conidiophores reduced to conidiogenous cells. Conidiogenous cells monophialidic, hyaline, smooth-walled, cylindric-clavate to ampulliform, 5–11 × 1–5 µm (x = 7 × 2.5 μm, n = 20). Conidia 5–6.5 × 3.5–4 µm (x = 5.7 × 3.8 μm, n = 40), solitary, hyaline, ovoid or ellipsoidal, smooth and thin-walled, aseptate, guttulate. Sexual morph: Undetermined.

Culture characteristics: Conidia germinated on PDA medium and germ tubes produced from both ends within 12 h. Colonies grew on PDA, reaching approximately 30 mm in diameter after three weeks at 25°C, colony edge appears irregularly circular, flat, felty, with dense, dark brown mycelium on the surface, with a dark brown elevation in the center; in reverse, brown at the entire margin.

Material examined:— CHINA, Yunnan Province, Yuxi City, on submerged decaying wood in freshwater stream in Yuanjiang River Basin, February 2022, Hong-Wei Shen, H-833 ( KUN-HKAS 146438, holotype), ex-type living culture, CGMCC 3.27726 = KUNCC 24-17665.

Notes: Phylogenetic analyses revealed that Setophoma aseptata ( CGMCC 3.27726) formed a cluster with S. yunnanensis ( CGMCC 3.19529 and LC 6753) and S. yingyisheniae ( CGMCC 3.19527 and LC 13479) ( Figure 2 View FIGURE 2 ). Nucleotide comparison of ITS showed that S. aseptata differs from S. yunnanensis by 28 base pairs out of 508 (5.51%) and from S. yingyisheniae by 41 base pairs out of 509 (8.06%). Setophoma aseptata shows both morphological similarities and differences when compared with S. yunnanensis and S. yingyisheniae ( Liu et al. 2019) . It shares with S. yunnanensis the trait of having hyaline, smooth, globose, and aseptate conidia. Nevertheless, S. aseptata can be distinguished from S. yunnanensis by its larger conidia (5–6.5 × 3.5–4 µm vs. 3.5–5 × 2–3 µm). Similarly, S. aseptata and S. yingyisheniae both possess dark-brown or black, globose or sub-globose conidiomata with an apical opening. However, it differs from S. yingyisheniae by lacking setae. Therefore, based on morphological characteristics and phylogenetic analyses, we introduce Setophoma aseptata as a new species.