Cytospora cotini Norph., Bulgakov & K.D. Hyde, in Hyde et al., Fungal Diversity 80: 176 (2016)
Index Fungorum number: IF 552231; Facesofungi number: FoF 02365
Saprobic on the bark. Sexual morph: Stromata 1190–2098 µm wide, with the poorly developed interior, solitary to gregarious, immersed, becoming raised to erumpent by the ostiolar canal, dark brown to black, glabrous, circular in shape, arranged with conspicuous, clustered, roundish to cylindrical prominent ostioles. Ascomata (excluding necks) 183–386 μm high, 364–613 µm diam. (x̄ = 284 × 489 μm, n = 15), perithecial, immersed in a stroma, brown to dark brown, globose to subglobose, glabrous, individual ostiole with the neck. Ostiolar canal 250–310 μm high, 120–155 μm diam. (x̄ = 276 × 139 μm, n = 10), cylindrical, sulcate, periphysate. Peridium 49–84 μm wide, composed of two section layers, outer section comprising 5–10 layers, of relatively small, brown to dark brown, thick-walled cells, arranged in textura angularis, the inner part comprising 3–5 layers of hyaline cells of textura angularis. Hamathecium comprising only asci. Asci (56–)61–71(–85) × (6.5–)7.5–9.5(–11) μm (x̄ = 66 × 8.4 μm, n = 50), 8-spored, unitunicate, clavate, short stalks, apically rounded to truncate, with a J-, refractive apical ring. Ascospores (10.5–)12.5–15(– 17) × (2.5–)3–4(–4.5) μm (x̄ = 14 × 3.5 μm, n = 250), overlapping 1–2-seriate, hyaline, allantoid, aseptate, smooth-walled. Asexual morph: Undetermined.
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 7 days at room temperature, colonies circular to irregular, medium dense, flat or effuse, slightly raised, with edge fimbriate, fluffy to fairy fluffy, white from above, white to yellow from below; not producing pigments in agar
Material examined: ITALY, Corniolo, Santa Sofia (Province of Forlì-Cesena [FC]), on a dead land branch of Ostrya carpinifolia (Betulaceae), 29 March 2017, E. Camporesi, IT 3294 (MFLU 17-0864, KUN-HKAS 100919), living culture, MFLUCC 18-1203.
Notes: The phylogenetic result of Shang et al. (2020) reveals the strain of MFLUCC 18-1203 clusters together with a Cytospora cotini strain (MFLUCC 14-1050, holotype) and they share a sister relationship to Cytospora ampulliformis (MFLUCC 16-0583, holotype), Cytospora ceratosperma (MFLUCC 16-0625) and Cytospora gelida (MFLUCC 16-0634, holotype) with 46% ML, 60% MP and 0.80 PP support. The specimen of C. cotini (MFLU 17-0864) differs from C. ceratosperma by its larger stromata, shorter ostiolar canal and its asci with J-, refractive apical ring (Tibpromma et al. 2017). The taxa of C. ampulliformis, C. cotini and C. gelida were only reported in their asexual morph, and it is impossible to compare with C. cotini in this study which are sexual morphs (Norphanphoun et al. 2017, Tibpromma et al. 2017). Considering the unresolved phylogenetic result and the incomparable morphology, Shang et al. (2020) compared the single gene regions of ITS, LSU and RPB2 for these taxa, which displayed the highest nucleotides sequence similarity between strains MFLUCC 18-1203 and MFLUCC 14-1050. Based on the guidelines of Jeewon & Hyde (2016), Shang et al. (2020) identify their new isolate as C. cotini and provide the first sexual morph description of this species. However, the study indicates that taxonomic revision of C. ampulliformis, C. ceratosperma, C. cotini and C. gelida in Cytospora is needed based on type studies and further analyses from other informative genes and with more taxon sampling (Jeewon & Hyde 2016).