Xylaria tuberculosa Xiao Y. Pan 2025, sp. nov.
Creators: name: Pan, Xiaoyan
name: Chen, Zongzhu
name: Chen, Yiqing
name: Lei, Jinrui
name: Chen, Xiaohua
name: Wu, Tingtian
name: Li, Yuanling
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Fungi
Ascomycota
Sordariomycetes
Xylariales
Xylariaceae
Xylaria
Xylaria tuberculosa

description: Xylaria tuberculosa Xiao Y. Pan sp. nov.
Fig. 3
Holotype.
China • Hainan Province, Diaoluoshan Area of Hainan Tropical Rainforest National Park; 18°43'33"N, 109°52'20"E; elevation 932 m; on fallen leaves, 18 June 2023, Xiaoyan Pan (HAFFR 123). GenBank accession numbers PQ 483148 (ITS), PQ 498330 (TUB 2), and PQ 498327 (RPB 2).
Diagnosis.
Differs from X. acifer, X. hedyosmicola, X. petchii, and X. polysporicola by having smaller ascospores.
Etymology.
“ tuberculosa ” refers to the appearance of the stromata surface, which resembles segmented tubercles formed by the clustered perithecia.
Teleomorph.
Stromata upright, solitary to scattered, cylindrical, unbranched, 5–10 mm total length; acute sterile apex, 0.1 mm; fertile portion 3–6 mm long × 0.3–1 mm wide, cylindrical, composed of tightly packed perithecia; stipe glabrous, 1.8–5 mm long × 0.2–0.5 mm wide, longitudinally striate, the base slightly swollen; surface roughened, black, with half-exposed to fully exposed perithecial mounds; interior white to creamy; texture soft. Perithecia spherical, 180–350 µm diam. Ostioles papillate. Asci with eight ascospores arranged in uniseriate manner, cylindrical, 70–105 µm total length, spore-bearing part 50–70 µm long × 5–7 µm wide, stipe 25–45 µm long, with a bluing apical ring in Melzer’s reagent, tubular to slightly urn-shaped, 1.8–2.6 µm high × 1.2–2.5 µm wide. Ascospores brown, unicellular, ellipsoid, inequilateral, with narrowly rounded ends, smooth, 7–8 (– 9) × 3.3–4.3 µm (M = 7.6 × 3.8 µm, N = 40), with straight germ slit slightly shorter than the spore length on the flattened side, and a hyaline sheath visible in 1 % SDS, swollen at both ends, forming non-cellular appendages.
Remarks.
Xylaria tuberculosa forms a distinct branch in the phylogenetic tree with X. acifer, X. betulicola, X. crinalis, X. filiformis, X. hedyosmicola, and X. simplicissima, but it is morphologically different from these six species. Xylaria acifer has a needle-like stroma with flatter perithecial mounds and larger ascospores (9.3–12 × 3.7–4.7 µm), while X. betulicola, X. crinalis, X. filiformis, X. hedyosmicola, and X. simplicissima all have stromata with long sterile apices and significantly larger ascospores, measuring (9.5–21.5 × 3.5–8.5 µm). The ascospores of X. betulicola, X. crinalis, X. filiformis, X. hedyosmicola, and X. simplicissima measure (11.5 –) 12–14 (– 15) × 5–6 µm, (14 –) 15–16.5 (– 17.5) × (3.5 –) 4–5 (– 6) µm, (9.5 –) 11.5–13.5 (– 14.5) × (4 –) 4.5–5.5 (– 6) µm, (12 –) 13–15 (– 16.7) × (6 –) 6.5–7.5 (– 8.5) µm, and (15 –) 16.5–19 (– 21.5) × (5 –) 5.5–6.5 (– 7.5) µm, respectively (Ma and Li 2018; Pan et al. 2022; Ju and Hsieh 2023).
Xylaria petchii Lloyd and X. polysporicola Hai X. Ma & X. Y. Pan are similar to X. tuberculosa morphologically, as they share cylindrical stromata growing on fallen leaves. Pan et al. (2024) described X. petchii from China, noting that this species has a variable fertile portion of the stromata and ascospores measuring (8.5 –) 10–12.5 (– 15) × (4.5 –) 5–6.5 (– 7) µm, which clearly differentiate it from X. tuberculosa. Xylaria polysporicola differs from X. tuberculosa by having a larger apical ring (2.5–4.5 µm high × 2–3.2 µm broad) and larger ascospores ((11.5 –) 12.5–14.5 (– 15) × 5.5–8 µm) (Pan et al. 2022). Furthermore, X. tuberculosa, X. petchii, and X. polysporicola are clearly separated in the phylogenetic tree.
Xylaria himalayensis Narula & Rawla and X. meliacearum Læssøe also resemble X. tuberculosa in morphology. Xylaria himalayensis can be distinguished by its hairy stipe and larger ascospores ((11.5 –) 13–15 (– 15.5) × (4.5 –) 5–5.5 (– 6) µm) that lack non-cellular appendages (Ju et al. 2018). Xylaria meliacearum can be differentiated by its stromata covered with a sulfur-yellow outer layer and larger ascospores ((19 –) 21.5–27.5 (– 31.5) × (5 –) 5.5–7 (– 8) µm) (Ju and Hsieh 2023). Xylaria tentaculata Ravenel ex Berk. is somewhat similar to X. tuberculosa in morphology, but X. tentaculata has significantly larger ascospores (20.6–24.4 µm × 8.9–10.8 µm) (Kim et al. 2016).
Additional specimen examined.
China • Hainan Province, Diaoluoshan Area of Hainan Tropical Rainforest National Park; 18°43'31"N, 109°52'19"E; elevation 929 m; on fallen leaves, 26 February 2023, Xiaoyan Pan (HAFFR 63). GenBank accession numbers PQ 483149 (ITS) and PQ 498331 (TUB 2).
description: Published as part of Pan, Xiaoyan, Chen, Zongzhu, Chen, Yiqing, Lei, Jinrui, Chen, Xiaohua, Wu, Tingtian & Li, Yuanling, 2025, Two new species of Xylaria (Xylariaceae, Ascomycota) associated with fallen leaves in Hainan Tropical Rainforest National Park, China, pp. 17-34 in MycoKeys 112 on pages 17-34, DOI: 10.3897/mycokeys.112.140487