Golovinomyces sordidus  

Mycelium white or cream-coloured, on leaves, dense. Hyphae 3-8 μm diam. Appressoria nipple-shaped.
Conidiophores erect, 90-140 μm long (fresh material), foot-cells straight or with a curved basal half, cylindrical, 35-70 × 11-14 μm, followed by 1-3 shorter cells. Conidia in chains, ellipsoidal to ovoid, after drying cylindric-ellipsoidal to doliiform, 25-38 × 12-20 μm (dry material), 30-40 × 17-25 μm (fresh material).
Ascomata cleistothecial, 70-150 μm diam., gregarious, hemispherical to almost spherical, the peridial cells irregularly shaped, 6-18 (–20) μm diam. Appendages in the lower part of the ascoma, numerous, 0.5-1.5 times as long as the ascoma diameter, 3-10 μm diam., thin-walled, smooth or somewhat rough, septate, brown throughout when mature. Asci numerous, 6-16 (–20), 40-67 (–75) × 20-35 (–40) μm, ellipsoidal to ovoid, stalked, 2- (rarely 3-) spored. Ascospores 20-30 × 10-18 μm, ellipsoidal to ellipsoid-ovoid, aseptate, hyaline, thin-walled.

Description adapted from Voytyuk et al. (2006).