Ascochyta medicaginicola Q. Chen & L. Cai, in Chen et al., Stud. Mycol. 82: 187 (2015)

Index Fungorum number: IF 814129; MycoBank number; MB 814129; Facesoffungi number: FoF 08216; Fig. 1

Pathogenic on living twigs of Prunus cerasifera, noticeable as black, circular dots on the host surface. Asexual morph: Conidiomata 165–190 μm high, 170–210 μm wide, black, scattered or gregarious, superficial to immersed, black, subglobose to globose, uniloculate. Ostiolar neck 25–50 μm long, 3–5 μm wide, covered with 1-celled, thickwalled, dark brown to almost black. Peridium 15–25 μm wide at the base, 30–80 μm wide at the sides, thick, comprising 3–4 layers, outer most layer heavily pigmented, thick-walled, comprising blackish to dark brown loosely packed cells of textura angularis, inner layer composed 3–5 layers, pale brown to hyaline, cells towards the inside lighter, flattened, thick-walled cells of textura angularis. Sexual morph: Not observed.

Material examined – Russia, Rostov region, Shakhty, near a railroad, on dead twigs of Prunus cerasifera Ehrh. (Rosaceae), 11 May 2017, Timur S. Bulgakov, T-1832 (MFLU 17–2138); living culture MFLUCC 18–0453.

Hosts – Medicago albus, Medicago sativa, Medicago sp. (Fabaceae, Hyde et al. 2020), Prunus cerasifera (Rosaceae, this study), Scabiosa sp. (Caprifoliaceae, Tibpromma et al. 2017) and Trichosanthes dioica (Cucurbitaceae, Sarkar et al. 2018-pathogenicity data are available).

Distribution – Canada, Czech Republic, France, Italy, USA (Hyde et al. 2020a, b, c), India (Sarkar et al. 2018), Thailand (this study)

GenBank number – OM235096 (ITS)

Notes – Our collection shares similar morphological characteristics with the ex-type strain of A. medicaginicola (Boerema et al. 2004; Chen et al. 2013). The multigene phylogenetic analysis shows that our specimen groups in the Ascochyta medicaginicola clade with 96/0.90 ML/BYPP support (Fig. 2). Four Ascochyta species have been recorded based on the morphological description from Rosaceae plants in Russia (Melnik 2000; Farr and Rossman 2022): Ascochyta idaei on Rubus idaeus in the Leningrad region, Kursk region, and Stavropol region; A. potentillarum on Potentilla reptans in Arkhangelsk region (Melnik 2000), Lipetsk region (Sarycheva et al. 2009), Republic of Crimea (Ovcharenko 2011) and Voronezh region (Melkumov 2015); A. pruni on Prunus padus in Leningrad region; Ascochyta sorbina on Sorbus torminalis in Stavropol region. As these species were identified based on morphology alone, correct species identification is yet to be done. Our collection provides the first host record of Ascochyta medicaginicola on Rosaceae based on both morphological and phylogenetic data.

Figure 1 – Ascochyta medicaginicola (MFLU 17–2138, new host record) a–c Conidia observed on host substrate. d–e Conidiomata. f–h Conidia i, k–l Conidia j Conidiodenous cell. Scale bars: a=500 µm, b–e, g=100 µm, f, h=50 µm, i–l=10 µm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined, ITS, LSU and tub2 sequence data of selected taxa. Related sequences were obtained from GenBank. Forty-one strains are included in the analyses, which comprise 633 characters including gaps. The tree was rooted with Phoma herbarum (CBS 377.92 and CBS 502.91). The maximum likelihood bootstrap (ML) values>65%) are given above the nodes. The new isolate in red bold