Seriascoma oblonga H.J. Zhao & W. Dong [as ‘Seriascoma oblongum‘], in Cao et al., (2025)

Index Fungorum number: IF 902893; MycoBank number: MB 902893; Facesoffungi number: FoF 16780; Figs. 1, 2

Etymology – refers to oblong conidia.

Holotype – MHZU 24–0622.

Asexual morph: coelomycetous. Conidiomata 160–200 µm high, 315–400 µm diam., coriaceous, erumpent, semi immersed in cortex layers, solitary to gregarious, subglobose, dark gray, uni-loculate, glabrous. Wall of conidiomata 15–80 µm thick, thin- to thick walled, of unequal thickness, thick at the sides, comprised of host and fungi tissue, with several layers of brown to dark brown, pseudoparenchymatous cells of textura angularis. Conidiophores arising from the base of the cavity reduced to conidiogenous cells. Conidiogenous cells 4–9.5 × 2–4.5 µm (x̄ = 6.0 × 3.1 µm, n = 30), enteroblastic, phialidic, determinate, discrete, ampulliform or lageniform, hyaline, aseptate, apically attenuated, with distinct periclinal thickening, smooth-walled. Conidia 5.5–8 × 2.2–3.2 µm (x̄ = 6.4 × 2.8 µm, n = 30), oblong, with rounded to obtuse ends, hyaline, aseptate, guttulate, verrucose, smooth-walled.

Culture characters – Conidia germinating on PDA within 12 h, colonies growing on PDA, reaching 20–26 mm diam. in 4 weeks at 25–28 °C, circular, dense, flat, slightly raised, smooth with entire white edge, velvety to floccose, slightly radiating, aspect smooth, slightly raised at the center, pale brown from above, dark green from below.

Material examined – CHINA, Sichuan Province, Weiyuan County, Zhenxi Town, Huaci Village. Isolated from decaying bamboo, 31 January 2023, J. Hu, SC024 and SC025 (MHZU 24–0622, holotype; ZHKUCC 24–1168, ex-type).

GenBank – ZHKUCC 24–1168: PQ475789 (ITS), PQ475790 (LSU), PQ474276 (tef1).

Notes – In the phylogenetic analysis, Seriascoma oblonga forms a sister branch with S. yunnanense (Fig. 2). Regarding DNA sequence data comparison, there is a discrepancy of 2.1% (10 out of 476, 3gaps) and 0.2% (1 out of 424, no gaps) in nucleotide variations within the ITS and tef1 sequence, respectively, between S. oblonga ZHKUCC 24–1168 and S. yunnanense SICAU 22–0059. However, morphologically, S. yunnanense have no asexual morph (Rathnayaka et al. 2019; Zeng et al. 2022). Seriascoma oblonga fit in the asexual morph of Seriascoma. Seriascoma oblonga was isolated from decaying bamboo. Seriascoma didymospora was found from on bamboo pieces on WA culture. Seriascoma oblonga can be distinguished from S. didymospora by differences in the shape of conidiogenous cells. Seriascoma oblonga lacks of the cylindric conidiogenous cells than S. didymospora. In addition, S. oblonga has conidia that are larger (5.5–8 × 2.2–3.2 µm) compared to those of S. didymospora (4–5.5 × 1.5– 2 µm). Seriascoma oblonga has conidiomata that are higher and wider (160–200 µm high, 315–400 µm diam.) compared to those of S. didymospora (110–170 µm high, 250– 470 µm diam.) (Dai et al. 2017).

Figure 1 – Seriascoma oblonga (MHZU 24–0622, holotype). a, b Conidiomata on host surface. c, d Section through conidiomata. e Conidiomata wall. f–l Conidiogenous cells. m–t Conidia. u, v Colonies on PDA from above and reverse. Scale bars: c = 100 µm, e = 20 µm, f–t = 10 µm.

Figure 2 – Maximum Likelihood tree based on ITS sequences, bootstrap support values for ML equal to or greater than 75% and PP equal to greater than 0.95 are indicated at the nodes as ML/PP. New species are shown in red. The ex-type strains are in bold.