Diplodia seriata

Diplodia seriata De Not., Mém. R. Accad. Sci. Torino, Ser. 27: 26 (1845) Figure 1.

Index Fungorum number: IF180468.

Saprobic on dead twigs of Wisteria sinensis L. Sexual morph: Not observed. Asexual morph: Conidiomata 138–245 × 206–240 μm (x̅ = 175 × 228 μm, n = 20), semi-immersed or immersed in the substrate, dark brown to black, solitary, pyriform, initially intraepidermal, visible as black dots on the host when mature, thick-walled, glabrous, centrally ostiolate. Ostiole 16–30 μm diam., centrally located, short papillate. Peridium up to 12–30 μm wide, 3–5 layers, consisting of brown and small-celled textura angularis, becoming hyaline towards the inner region. Conidiophores are reduced to conidiogenous cells. Conidiogenous cells 6–13 × 3–5 μm (x̅ = 8 × 4 μm, n = 20), hyaline, cylindrical, discrete, smooth-walled, slightly swollen at the base, forming a single conidium at the tip. Conidia 18–27 × 9–13 μm (x̅ = 22 × 11 μm, n = 50), brown, aseptate, externally smooth, internally verruculose, subcylindrical to ellipsoid, moderately thick-walled, ends rounded, often with a truncate base.

Culture characteristics: Conidia germinating on PDA within 24 h. Colonies are fast growing at 20–25 °C, becoming ash-grey on the surface after 7 days, and finally black after two weeks, velvety and floccose, dense, convex with papillate surface, aerial.

Material examined: China, Sichuan Province, Chengdu City, High Tech West Zone, Xi Yuan Avenue, University of Electronic Science and Technology of China campus, 30°45’9’’ N, 103°55’31’’ E, on dead twigs of Wisteria sinensis L., 22 November 2020, H.Z. Du, YW297 (GZAAS 23-0583), living culture GZCC 23-0579.

Notes: The sexual morph of Diplodia seriata is linked to Botryosphaeria obtusa Shoemaker [40]. We identified our isolate as Di. seriata based on morphology and phylogeny. This is the first record of Di. seriata found on Wisteria sinensis in China.

Figure 1. Diplodia seriata (GZAAS 23-0583). (a–c) Conidiomata on host substrate. (d,e) Vertical section of conidiomata. (f) Section of peridium. (g–i) Conidiogenous cells and developing conidia. (j–m) Conidia. Scale bars: (d–f) = 20 μm, (g–m) = 10 μm.