Fusoidigranularius dongtingensis Z. Y. Wang, K. D. Hyde & Q. Zhao 2026, sp. nov.

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Fusoidigranularius dongtingensis Z. Y. Wang, K. D. Hyde & Q. Zhao sp. nov. Fig. 3 Etymology. The epithet “ dongtingensis ” refers to the collecting site where the fungus was collected. Holotype. HKAS 150454. Description. Saprobic on submerged wood. Sexual morph: Ascomata 240–410 µm high × 210–400 µm diam. (x ̄ = 321 × 271 µm, n = 10), scattered to gregarious, immersed, ostiolate, black, coriaceous, subglobose to obpyriform. Ostiole 130–200 µm long × 80–110 µm wide (x ̄ = 168 × 93 µm, n = 10), central, black, subcylindrical, straight, periphysate. Peridium 22–70 µm wide (x ̄ = 42 µm, n = 30) with 6–11 layers, a dark brown outer part composed cell of textura angularis, inner part composed of 2–4 layers, pale brown to hyaline textura angularis to textura prismatica cells. Paraphyses 3.5–8.4 µm wide × 150–250 µm length (x ̄ = 5.7 × 196 µm, n = 30), hyaline, numerous, unbranched or rarely branched, septate, constricted or not at the septa, tapering distally. Asci 306–413 × 8–10 µm (x ̄ = 360 × 9 µm, n = 10), 8 - spored, unitunicate, cylindrical, apex rounded, with up to 200 μm long or rarely short pedicel and a large, refractive, wedge-shaped, apical ring, 2.6–3.7 μm high × 4.5–5.4 μm wide (x ̄ = 3.1 × 4.9 µm, n = 10). Ascospores 33–40 × 7.5–9 µm (x ̄ = 36.5 × 8.5 µm, n = 30), hyaline, 3 - septate or occasionally 4 - septate, constricted at the septa, fusoid, both ends rounded, straight to slightly curved, guttulate, smooth-walled. Asexual morph: Undetermined. Culture characteristics. Ascospore germinate on PDA within 24 h at 25 ° C in a dark incubator. Germ tubes are produced from both ends. Colonies reach 3.4 cm diam after one month at 25 ° C, circular, rough surface, umbonate, filiform edge, dense hyphae, white from above, yellow-white around brown spot in the center from below, no pigment. Material examined. China • Hunan Province, Yiyang City, Dongting Lake (28°53'58.58"N, 112°20'14.88"E, 10 m), submerged wood in shoreline of Dongting Lake, 20 December 2024, D 3 S 3-1 (HKAS 150454, holotype); ex-type KUNCC 25-20200; ibid., D 3 S 5-1 (HKAS 150457, isotype), living culture KUNCC 25-20203. GenBank numbers. KUNCC 25-20200 = ITS: PZ 174006, LSU: PZ 174010, SSU: PZ 174014; KUNCC 25-20203 = ITS: PZ 174007, LSU: PZ 174011, SSU: PZ 174015. Notes. In the phylogenetic analysis, Fusoidigranularius dongtingensis clustered with F. nilensis (Fig. 1). Although morphologically similar, the new species can be distinguished from F. nilensis by several characters. Fusoidigranularius dongtingensis has smaller ostioles (130–200 × 80–110 µm vs. 240–360 × 96–112 µm), narrower asci (360 × 9 µm, L / W ≈ 40.0 vs. 322.5 × 12.2 µm, L / W ≈ 26.4), and fewer septa per ascospore [3 (– 4) - septate vs. 5–9 (– 11) - septate] (Abdel-Wahab et al. 2011). In addition, the position and orientation of the ostiolar neck differ between the two species: in F. dongtingensis, the neck is straight and projects vertically through the host substrate, whereas in F. nilensis, it is oriented horizontally and lies along the substrate surface (Abdel-Wahab et al. 2011; Zhang et al. 2017; Dong et al. 2021). The base pair comparisons (excluding gaps) of LSU show that F. dongtingensis differs from F. nilensis by 1.98 % (16 / 807 bp). Therefore, Fusoidigranularius dongtingensis is introduced as a novel species based on morphological and phylogenetic analyses.

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Related topics: Plant Pathogens and Fungal Diseases · Mycorrhizal Fungi and Plant Interactions · Fungal Biology and Applications