Cytospora prunicola

Cytospora prunicola Norph., Camporesi, T.C. Wen & K.D. Hyde, in Hyde et al., Mycosphere 9(2): 378 (2018)

Index Fungorum number: IF 554078; Facesofungi number: FoF 04097

Saprobic on the bark. Sexual morph: Stromata 622–908 µm wide, with the poorly developed interior, solitary to gregarious, immersed, becoming raised to erumpent the bark by the ostiolar canal, dark brown to black, glabrous, circular in shape, arranged with conspicuous, roundish to cylindrical prominent ostioles. Ascomata (excluding necks) 187–270 μm high, 159–289 µm diam. (x̄ = 229 × 224 μm, n = 15), perithecial, immersed in a stroma, dark brown to brown, globose to subglobose, glabrous, individual ostiole with the neck. Ostiolar canal 215–250 μm high, 57–122 μm diam., cylindrical, sulcate, periphysate. Peridium 29–48 μm wide, composed of two section layers, outer section comprising 2–5 layers, of relatively small, brown to dark brown, thick–walled cells, arranged in textura angularis, the inner part comprising 2–3 layers of hyaline cells of textura angularis. Hamathecium composed of 6–9 μm wide, dense, cylindrical, septate, hyaline, paraphyses. Asci (45–)55–68(–78) × (7.5–)8.5–10.5(–12) μm (x̄ = 62 × 9.5 μm, n = 50), 8-spored, unitunicate, clavate, with short stalks, apically rounded to truncate, with a J^- apical ring. Ascospores (9.5–)10.5–13.5(–15.5) × (3–)3–4.5(–5) μm (x̄ = 12 × 3.7 μm, n = 80), overlapping 1–2-seriate, hyaline, allantoid, aseptate, smooth-walled. Asexual morph Coelomycetous. Conidiomata 259–535 μm, pycnidial, appearing as brown to black, watery, rounded, conidial masses, superficial, solitary or aggregated, subglobose, shiny, with white to brown mycelium covering the surface. Pycnidial walls 23–34 μm wide, comprising several layers of brown to dark brown, compressed hyphae, arranged in a textura angularis. Conidiogenous cells (6–)6.5–11(–13) × (1–)1.5–2.5(–3) (x̄ = 8.7 × 2 μm, n = 15), cylindrical to clavate, holoblastic, straight or curved. Conidia (4–)5–6.8(–8.2) × (0.8–)1–1.5(–2) (x̄ = 6 × 1.2 μm, n = 130), hyaline, allantoid, slightly curved ends, unicellular, smooth-walled.

Culture characteristics: Ascospores germinating on PDA within 24 hrs. Germ tubes produced from all sides. Colonies on PDA reaching 5–5.5 cm diam. after 5 days at room temperature, colonies circular to irregular, medium dense, flat or effuse, slightly raised, with edge fimbriate, initially fluffy to fairy fluffy, white from above, light yellow to brown from below; After 10 days, white to brown from above, brown to dark brown from below; not producing pigments in agar.

Material examined: Italy, Predappio Alta, Predappio (Province of Forlì-Cesena [FC]), on a dead land branch of Ostrya carpinifolia (Betulaceae), 22 November 2016, E. Camporesi, IT 3162 (MFLU 16-2900, KUN-HKAS S100888), living culture, MFLUCC 18-1200

Notes: The phylogenetic result by Shang et al. (2020) revealed that their strain of MFLUCC 18-1200 clusters together with Cytospora prunicola (MFLU 17-0995) with 54% ML, 84% MP and 0.82 PP support and they share the sister relationship to Cytospora gutnerae (214) and Cytospora terebinthi (227). The conidia of the strain of MFLUCC 18-1200, on PDA, are similar in size to C. prunicola and smaller in size than C. gutnerae and C. terebinthi (Shang et al. 2020). Therefore, this collection is identified as C. prunicola and the first sexual morph description of this species is provided.