Alternariaster helianthi – Facesoffungi number: FoF 11565

Pathogenic on leaves of Helianthus annuus L. Sexual morph: undetermined. Asexual morph: Lesions on living leaves starting as dispersed punctiform spots, occurring throughout the leaf blade, becoming subcircular to irregular in shape, yellowish, 3–11 × 2–9 mm, surrounded by a halo of dark green tissue, at the later stages lesions coalesce, resulting in leaf blight and premature plant death. Conidiophores 100–225 × 7.5–10 μm, solitary or in small groups, hypophyllous, straight to slightly sinuous, simple, 3–6-septate, pale to chestnut-brown, smooth. Conidiogenous cells 25–100 × 5–7.5 μm, yellowish to pale brown, tretic, integrated, terminal to intercalary, sympodial, cylindrical. Conidiogenous cellswith conspicuous scars, 1–2 per cell, protuberant, up to 5 μm diam, thickened and darkened. Conidia 60–115 × 11–29 μm, subhyaline to pale brown, dry, solitary, cylindrical to subcylindrical, occasionally with cells of different sizes, apex and base rounded, transversally 5–9-septate (1–2 longitudinal or oblique septa), often deeply constricted at septa, eguttulate, smooth-walled, hilum thickened and darkened. Germ tubes orientated perpendicularly to the main axis of the conidium, and also polar (from Alves et al. 2013).

Fig .Alternariaster helianthi(redrawn from Alternariaster helianthiin Ellis 1971, Fig 319.). Scale bars: 650 μm

Notes: The genus Alternariaster was introduced by Simmons (2007) to accommodate Alternaria helianthi. Alternariaster differs from Alternaria in having cylindrical, ellipsoid or broadly ovoid, subhyaline to greyish brown conidia, rarely forming longitudinal or oblique septa and not formed in chains (Alves et al. 2013). Alves et al. (2013) introduced Alternariaster bidentis which forms a separate clade in the family Leptosphaeriaceae together with the strains of A. helianthi. The collection of a second species in the genus Alternariaster and the multi-gene phylogenetic analysis of these two species, confirmed Alternariaster to be a welldelimited genus in the Leptosphaeriaceae rather than the Pleosporaceae, to which Alternaria belongs (Alves et al. 2013). In this study we illustrate the sexual morph of this genus based on our new species Alternariastercentaureae-diffusae collected from Russia.