Pleosporales » Didymellaceae » Ascochyta

Ascochyta medicaginicola

Ascochyta medicaginicola Qian Chen & L. Cai, Stud. Mycol. 82: 187 (2015)

Index Fungorum number: IF814129; Facesofungi number: FoF 2773 

Replaced synonym: Phoma medicaginis Malbr. & Roum., in Roumeguère, Fungi Selecti Galliaei Exs., Cent. 37: no. 3675 (1886)

Type: USA, Minnesota, from Medicago sativa, September 1953, M.F. Kernkamp, CBS H-16487, ex-type culture CBS 112.53.                                           

Saprobic on dead branch of Scabiosa sp. Sexual morph: Ascomata 143–162 µm high × 144–233 µm diam. (x̄ = 152 × 196 µm, n = 5), semi-immersed to erumpent, visible as raised, dark spots on the host surface, subglobose, solitary or small groups, scattered on the host surface, without papilla, with short ostiole in the centre, thin-walled, carbonaceous, dark brown or usually black. Peridium 17–28 µm wide, thin-walled, inner cells hyaline to pale brown, outer layer cells brown to dark brown, composed of flattened cells of textura angularis. Hamathecium 2.5–3.8 µm wide, comprising numerous, septate, cylindrical, cellular, pseudoparaphyses. Asci 46–67 × 12–15 µm (x̄ = 55 × 14 µm, n = 15), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, short pedicellate, rounded at the apex with acute ends, lacking an ocular chamber. Ascospores 17–22 × 7–9 µm (x̄ = 19 × 8 µm, n = 15), overlapping 1–2-seriate in the ascus, fusiform, 2-celled, narrowly fusoid with rounded ends, the cells above central septum often broader than the lower ones, constricted at the septum, deeply constricted at the septum, enlarged at the first cell, with small guttules in each cell, hyaline, lacking a mucilaginous sheath, smooth-walled. Asexual morph: Undetermined.

Culture characteristics: Colonies on PDA reaching 80 mm diam. after 7 days at 25 °C, circular colony, olivaceous to gray greenish, concentrically zonate, effuse mycelium, entire edge, reverse colony black in middle, grey olivaceous at the edge, without any diffusible pigments. Pycnidia globose to subglobose, without a distinct ostiole, glabrous, conidial matrix off whitish. Conidia sub-cylindrical, aseptate.

Material examined: ITALY, Province of Arezzo, near Moggiona, on dead branch of Scabiosa sp. (Caprifoliaceae), 1 June 2013, Erio Camporesi, IT1314 (MFLU 15-1481, new host record); Ibid. (HKAS 94550 bis).

GenBank Numbers: LSU: KY496720, ITS: KY496741, SSU: KY501111.

Note: We have collected the fungal isolate from dead aerial stem of Medicago sp. and it was identified as Ascochyta medicaginicola with the support from both morphology and phylogeny. Our isolate clustered with A. medicaginicola (CBS 404.65, BRIP450.51, CBS 112.53) and another strain of A. medicaginicola var. medicaginicola Q. Chen & L. Cai (CBS 316.90) in the combined LSU, ITS, RPB2 and TUB2 sequence phylogeny with 98% ML and 0.98 BYPP statistical support. This is the first report of Ascochyta medicaginicola on Scabiosa sp. (Caprifoliaceae) from Italy and the first report of a sexual morph for A. medicaginicola (Tibpromma et al. 2017).