Diplodia seriata De Not., Micr. Ital. Dec. 4: 6. 1942.
≡Botryosphaeria obtusa (Schwein.) Shoemaker, Canad. J. Bot. 42: 1298. 1964.
Index Fungorum number: IF 180468; MycoBank number: MB 180648; Facesoffungi number: FoF 03596; Fig. 1
Saprobic on Tilla sp. Sexual morph: Undetermined. Asexual morph: Conidiomata 240–380 μm high×235–275 μm diam. (x=285×245 μm, n=10), solitary or aggregated, immersed in the host, partially emergent at maturity, dark brown to black, ostiolate, apapillate, thickwalled, outer layers composed of dark brown textura angularis, inner layers of thin-walled hyaline textura angularis. Conidiogenous cells 8–15×3–6 μm, lining the pycnidial cavity, hyaline, thin-walled, smooth, cylindrical, swollen at the base, discrete, producing a single conidium at the tip, indeterminate, proliferating internally giving rise to periclinal thickenings or proliferating percurrently forming 2–3 annellations. Conidia 18–21(–22) × 15–18(–20), initially hyaline, becoming dark brown, moderately thick-walled (ca. 0.5 μm thick), wall externally smooth, roughened on the inner surface, aseptate, globose to ovoid, widest in the middle, apex rounded, base truncate or rounded.
Culture characteristics – Colonies on PDA, reaching 5–6 cm after 12 days in the dark at 25 °C; circular, initially white, after 7 days becoming greyish brown to black; reverse grey to dark grayish green.
Material examined – Italy, Forlì-Cesena Province, on dead twigs of Tilla sp. (Malvaceae), 30 September 2014, E. Camporesi (MFLU 15-2952); living culture MFLUCC 17-0942.
Hosts and distribution – Plurivorous and cosmopolitan (Dissanayake et al. 2016).
Notes – In the combined gene analyses of ITS and tef1-α (Fig. 2) showed that, our isolate is phylogenetically closely related to the ex-type isolate of Diplodia seriata. The conidia of our isolate are shorter than 25 μm in length than conidia of ex-type isolate of D. seriata that are longer than 25 μm (Phillips et al. 2013). Diplodia seriata has been recorded on various hosts worldwide (Phillips et al. 2013; Dissanayake et al. 2016) and this is the first record of D. seriata on Tilla sp.
Figure 1 – Diplodia seriata (MFLU 15-2952). a Examined material. b Appearance of conidioma on host surface. c Vertical section through conidioma. d Close-up view of conidiogenous cells and conidia in conidioma. e–i Immature, hyaline conidia and mature, brown conidia. Scale bars: c=100 μm, d=50 μm, e–i=20 μm
Figure 2 – The best scoring RAxML tree for combined dataset of ITS and tef1-α sequence data. The tree is rooted to Lasiodiplodia theobromae (CBS 164.96). The matrix had 283 distinct alignment patterns with 10.52% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.207698, C=0.297682, G=0.261769, T=0.232852; substitution rates AC=0.990412, AG=3.569134, AT=0.786115, CG=1.635193, CT=4.459105, GT=1.0; gamma distribution shape parameter α=0.169845 with a final likelihood value of − 3366.787048. Ex-type strains are in bold and newly generated sequences are in blue. Bootstrap support for ML equal to or greater than 60% and BI equal to or greater than 0.80 are given near the nodes