A powdery mildew was found on Leontopodium leontopodioides (Asteraceae) in China. Phylogenetic analyses using a combination of internal transcribed spacer and 28S rDNA sequences showed that this species, which clusters as sister to Neoerysiphe joerstadii, is allied to N. galii, N. geranii, and N. nevoi. This species differs from the closely allied N. joerstadii in the number and size of asci (3-10 asci, 55-75 × 20-40 µm versus 16-32 asci, 40-60 × 20-30 µm). This species is morphologically very similar to N. gnaphalii, but clearly differs from this species in having larger chasmothecia and colorless appendages. Therefore, the powdery mildew on L. leontopodioides is described as N. leontopodii sp. nov.
Keywords: Asteraceae; Erysiphaceae; Molecular phylogeny; Morphology; New species.
2024, by The Mycological Society of Japan.