Xenosporidesmium yilonghuense H. W. Shen & Z. L. Luo 2026, comb. nov.

Xenosporidesmium yilonghuense (H. W. Shen & Z. L. Luo) H. W. Shen & Z. L. Luo comb. nov. Fig. 3 ≡ Sporidesmium yilonghuense H. W. Shen & Z. L. Luo, Fungal Diversity 134: 853 (2025). Chinese name. 异龙湖异葚孢 (Pinyin: yì lóng hú yì shèn bāo). Description. Saprobic on submerged decaying wood in freshwater habitats. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on superficial substratum, effuse, dark brown, hairy. Mycelium mostly superficial, partly immersed, composed of branched, septate, hyaline to pale brown, smooth-walled hyphae. Conidiophores (16 –) 21–40 (– 54) × 3.5–5 μm (x ̄ = 31 × 4 μm, n = 40), macronematous, mononematous, solitary or fascicular, cylindrical, straight to slightly flexuous, brown to dark brown, 2–4 - septate, slightly swollen at the base, truncate at the apex, smooth-walled, sometimes percurrently proliferating. Conidiogenous cells 9–14 × 3–4.7 μm (x ̄ = 11 × 3.8 μm, n = 30), holoblastic, monoblastic, terminal, integrated or percurrently proliferating, cylindrical, slightly narrowing at the tip, brown, smooth-walled. Conidia (28 –) 33–40 (– 43) × 7.5–9 μm (x ̄ = 36.5 × 8.4 μm, n = 30), acrogenous, solitary, obclavate, pale brown to brown, hyaline at apex, straight or slightly curved, 7–9 - distoseptate, truncate at the base, rounded at the apex, guttulate, smooth-walled, apical 1–2 cells surrounded by a mucilaginous sheath. Culture characteristics. Conidia germinated on PDA within 24 h. Germ tubes produced from the basal cell of conidia. Colonies growing on PDA for one month at room temperature in the dark. Circular, wrinkled, white to pale yellow from above, yellow brown and paler towards the margin from below. Material examined. China, Yunnan Province, Dulongjiang River, 28.033444°N, 98.317358°E (elevation 1702 m), on submerged decaying wood, 1 May 2023, Ying Wang, S 5266 (HKAS 135964), living culture, KUNCC 23-16467. Notes. Phylogenetic analyses showed that the newly collected strain, KUNCC 23-16467, clustered stably with previously reported strains of X. yilonghuense (HKAS 131420 and HKAS 132083) collected from freshwater lakes (Fig. 1). Xenosporidesmium yilonghuense has been reported from unknown submerged decaying wood in Dujuanhu Lake and Yilonghu Lake, Yunnan Province, China (Shen et al. 2025). In the present study, strain, KUNCC 23-16467, was re-collected from a lotic freshwater habitat. Based on detailed morphological comparisons and multi-locus phylogenetic analyses, this strain was identified as X. yilonghuense. Morphologically, the new collection is characterized by macronematous, mononematous, cylindrical conidiophores that are 2–4 - septate; conidiogenous cells are holoblastic, monoblastic, terminal, and integrated; and conidia are acrogenous, solitary, obclavate, and distoseptate, with the apical 1–2 cells surrounded by a mucilaginous sheath. These characters are consistent with the original description of X. yilonghuense (Shen et al. 2025). Molecular sequence comparisons revealed nucleotide differences of 13 bp (ITS), 9 bp (LSU), and 2 bp (tef 1 - α) between strain KUNCC 23-16467 and the type material HKAS 131420. Therefore, based on morphological congruence and phylogenetic placement, the newly collected specimen is confirmed as X. yilonghuense. This new record extends the known distribution of X. yilonghuense and provides additional morphological and molecular data supporting species delimitation within Xenosporidesmium.