Erysiphe rosae (Golovin & Gamalitsk.) U. Braun & S. Takam., Schlechtendalia 4: 4, 2000 Fig. 4 ≡ Medusosphaera rosae Golovin & Gamalitsk., Bot. Mater. Otd. Sporov. Rast. Bot. Inst. Komarova Akad. Nauk S. S. S. R. 15: 92, 1962. Type. Holotype: Kyrgyzstan • Tjan-Shan, Kavak-Tau, Tabylgyty, on Rosa albertii, 14 Sep. 1959, Gamalitskaya (LE 193792). Reference collection: China, Xinjiang, Urumqi, on Rosa albertii, 3 Aug. 2009, Z. Y. Zhao & B. Xu (HMAS 242383). Reference sequences: PX 506005 (ITS), PX 506007 (28 S), PX 570626 (IGS). Specimens examined. • HMJAU -PM 92697, HMAS 36517, HMAS 36518, HMAS 44287, and HMAS 138804. Detailed specimen information is presented in Suppl. material 1. Morphological description. Braun and Cook (2012: 501–502). Host range and distribution. on Rosa (albertii, amblyotis, davurica, omeiensis, webbiana), Rosaceae; Asia (China, India, Kyrgyzstan, Russia, Far East). Notes. Erysiphe rosae is characterized by sinuous long appendages and bristle-like short appendages. This taxon has been controversially treated at the generic level. It was first introduced as the type species of the genus Medusosphaera and later transferred to Erysiphe because the morphology of the chasmothecial appendages was no longer recognized as suitable for differentiation at the generic level (Golovin and Gamalitskaya 1962; Braun and Takamatsu 2000). The correct allocation of M. rosae to Erysiphe was confirmed in the present study based on lobed hyphal appressoria and conidiophores with singly formed conidia (Fig. 4), as well as sequences successfully retrieved from specimens of this species, which form a highly supported species clade within Erysiphe (Fig. 1). It should be noted that the sequences of the three examined specimens clustered together according to their host plants, which indicates previously unrecognized diversity within E. rosae, possibly suggesting cryptic formae, a taxonomic unit recently reapplied in Erysiphaceae (Bradshaw et al. 2025 c; Feng et al. 2025 a). However, due to the limited number of specimens available, it was impossible to obtain additional molecular data or to observe potential morphological differences. Therefore, following the species concept proposed by Bradshaw et al. (2022), we provisionally treated these specimens as E. rosae s. lat. Since the holotype of this species from Kyrgyzstan has not yet been sequenced, the Chinese specimen HMAS 242383 on the type host Rosa albertii is selected as the reference collection with reference sequences for the interim.

Published as part of Jin, Dan-Ni, Wang, Shuang-Bao, Guan, Le-Ping, Wu, Xue-Lian, Feng, Jing, Liu, Li, Bradshaw, Michael, Braun, Uwe, Yang, Jing-Han, Yu, Shou-Rong, Li, Yu & Liu, Shu-Yan, 2026, Revision of powdery mildews (Ascomycota, Erysiphaceae) on Rosa in China: unexpected taxonomic complexity with phytopathological implications, pp. e 184484 in IMA Fungus 17 on page e184484, DOI: 10.3897/imafungus.17.184484