Botryosphaeriales » Botryosphaeriaceae » Diplodia

Diplodia mutila

Diplodia mutila (Fr.) Mont., Annls Sci. Nat., Bot., sér. 2 1: 302 (1834)

Index Fungorum number: IF201741; Facesofungi number: FoF 05978

Sphaeria mutila Fr., Syst. mycol. (Lundae) 2(2): 424 (1823)

Epitype: PORTUGAL, Beira Litoral, Aveiro, Populus alba, 2012, A. Alves, LISE 96136, MBT176182, ex-epitype culture, CBS 136014.

Saprobic on dead aerial branch of Populus tremula. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 600–680 μm diam., pycnidial, black, initially immersed, raised, becoming erumpent and opening through the host epidermis, sublgobose, uni- to bi-loculate, ostiolate, papillate. Pycnidial walls composed of 3–4 layers, dark brown to black, thick-walled cells of textura angularis, outer layer comprising 1–2 layers, dark brown to black cells, inner layer comprising 1–2 layers of hyaline cells. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 7–10 μm long × 2–5 μm wide, enteroblastic, phialidic, discrete, cylindrical to ampulliform, hyaline, aseptate, smoothwalled, proliferating at the same level giving rise to periclinal thickenings. Conidia 5–10 × 1–4 μm wide (= 8 × 3 μm, n = 20), initially hyaline, becoming dark brown with the age, ellipsoidal to oblong, aseptate thick- and smooth-walled, small granules.

Culture Characteristics: Colonies on PDA covering a 90 mm diam. petri dish before 7 days at 28 °C, circular initially white mycelium, moderately aerial becoming pale grayish to dark and reverse gray to dark grayish green.

Material examined: ITALY, Province of Forlì-Cesena [FC], near Strada San Zeno-Galeata, on dead aerial branch of Populus tremula (Salicaceae), 26 March 2018, E. Camporesi, IT 3784 (MFLU 18–0912), living culture, JZB 3140011.

Known hosts and distribution: On dead aerial branch of Populus tremula (Salicaceae), Previously Diplodia mutila has been reported on Fraxinus excelsior, Olea europaea and Vitis vinifera from Italy (Farr and Rossman 2020).

GenBank Numbers: ITS: MN944415.

Note: The collection obtained from a dead aerial branch of Populus tremula was identified as Diplodia mutila with support from both morphology and phylogeny (Alves et al. 2014). Our strains clustered with the reference strain of Diplodia mutila (CBS 230.30), in the combined ITS and TEF1-α sequence phylogeny with significant support in MP analysis (85% ML). Furthermore, our isolate showed 0.94% and 0.90% base pair difference with Diplodia mutila (CBS 230.30) in ITS and TEF1-α gene regions. This is the first record of Diplodia mutila from Populus tremula from Italy.