| Characteristics |
Lesions commonly present on leaves and stems, causing discoloration of the affected tissues, initially pale green to yellow, later becoming purplish, polyangular, vein-limited, frequently covering larger areas by coalescing. Down hypophyllous, whitish, dense, felt-like. Haustoria filling the host cell partly to almost completely, lobate. Conidiophores emerging through stomata, up to 30 in a fascicle, hyaline, somewhat stout, straight, (270.0–)332.7–390.6–448.5(–490.0) µm; trunk straight, (100–)200–350(–400) µm long, (9–)10–13(–17) µm wide (n = 30). Ultimate branchlets mostly in pairs, curved to sigmoid, (5.1–)6.7–9.4–12.2(–17.7) µm long, (1.0–)1.5–1.9–2.4(–2.7) µm wide at the base; tip obtuse or subtruncate (n = 30). Conidia hyaline, broadly ellipsoidal to subglobose, (13.3–)14.5–15.9–17.4(–19.2) µm long, (9.3–)11.2–12.2–13.2(–14.2) µm wide, a length to width ratio of (1.12–)1.21–1.31–1.40(–1.50), the greatest width median, rarely sub- or supra-median, tip and base rounded; pedicel mostly present as a scar. Resting organs rarely present and visible as yellow to brown spots on leaves. Oogonia irregular in shape, 36–57 µm diameter (n = 30); wall wrinkled, yellowish, 2–5(–7) µm thick. Oospores plerotic to aplerotic, globose, (22–)25–30 µm diameter, yellowish, 2–3.5 µm thick wall (n = 30). |
| Notes |
Hyaloperonospora dentariae was originally described from Cardamine heptaphylla and was historically applied to downy mildews on several Cardamine species. Multilocus analyses showed that this broad concept included several distinct species; H. dentariae is currently confirmed on C. heptaphylla, C. pentaphyllos, C. impatiens, and C. bulbifera (Voglmayr et al., 2014). Korean collections from C. impatiens clustered within H. dentariae, but formed a distinct, well-supported cox2 subclade separated from European isolates from the same host, suggesting geographic or host-associated differentiation (Lee et al., 2017). |
