Four new Phragmidium (Phragmidiaceae, Pucciniomycetes) species from Rosaceae plants in Guizhou Province of China Author Sun, Jing-E Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China Author Zhang, Qian Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China Author Luo, Wen-Mei Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China Author Yang, Yuan-Qiao Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China Author An, Hua-Ming Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China & Agricultural College, Guizhou University, Guiyang, 550025, China Author Wang, Yong Department of Plant Pathology, Agricultural College, Guizhou University, Guiyang, 550025, China yongwangbis@aliyun.com text MycoKeys 2022 2022-11-10 93 193 213 http://dx.doi.org/10.3897/mycokeys.93.90861 journal article http://dx.doi.org/10.3897/mycokeys.93.90861 1314-4049-93-193 DBF89CE4A6B7518BA94F6B181158D1D7 Phragmidium rosae-roxburghii J.E. Sun & Yong Wang bis sp. nov. Figs 2 , 3 Diagnosis. Phragmidium rosae-roxburghii easily to be distinguished by its unique square to diamond-shaped urediniospores. Holotype. China. Guizhou Province, Panzhou city, 25°89'61"N, 104°56'07"W , 750 m, 21 Mar 2021, on Rosa roxburghii , coll. J.E. Sun & Y.Q. Yang, HGUP21025, ITS: OL684818, LSU: OL684831. Etymology. Referring to the host, Rosa roxburghii , on which the fungus was first found. Description. Spermogonia : unknown. Aecia formed on gold distinct, circular lesions on both sides of the stems, petioles and leaves, rarely produced on the abaxial leaf surface, scattered, flat oval to subglobose, powdery, 1.0-5.0 mm diam. Aeciospores formed in basipetal succession, oval o subglobose, 22-30 x 14-22 µm (mean 26 x 18 µm , n = 30), inclusions golden, to bright-yellow; wall 1.8-3.1 µm thick, colorless, mostly with irregularly elongated verrucae on the surface. Uredinia produced on the abaxial leaf surface, scattered to gregarious, hypophyllous, orange-colored or white, powdery, oval to rounded, 0.1-1.0 mm diam, paraphysis in the periphery of the uredinia, curved, 30-55 x 9-20 µm , colorless thin-walled. Urediniospores generally angular, square to diamond-shaped, yellowish to orange-colored, 20-30 x 16-21 µm (mean: 25 x 19 µm , n = 30), thick-walled, 0.5-2.0 µm thick, colorless, regularly echinulate with stout spines. Rust diseases symptoms: In the early stage (March) of rust disease yellowish-orange powdery aecia formed on the stems and petioles on Rosa roxburghii and Rosa sp., the aecia were scattered, flat oval or nearly round and bordered (Fig. 2 ). In middle of June (Fig. 3 ), the upper surface of the lower leaves was turning yellow and orange spots gradually appeared on the under surface caused by uredinia, which are powdery, aggregated but without obvious boundaries. Figure 2. Phragmidium rosae-roxburghii sp. nov. (HGUP21025, holotype) on Rosa roxburghii a-c aecia on stem and leaf pieces. d longitudinal section of aecium e-h aeciospores. Scale bars: 2 mm ( b-c ); 50 µm ( d ); 10 µm ( e-h ). Figure 3. Phragmidium rosae-roxburghii sp. nov. (HGUP21026) on Rosa roxburghii a appearance of infected plants b uredinia on a leaf c longitudinal section of uredinium d paraphyses e-i urediniospores. Scale bars: 5 mm ( b ); 50 µm ( c ); 25 µm ( d ); 12.5 µm ( e-i ). Habitat. Rosa roxburghii , Rosa sp. Known distribution. China, Guizhou Province. Additional material examined. China . Guizhou Province : Duyun city, 26°45'88"N, 106°98'42"W, 820 m , 22 Jun 2021 , on Rosa roxburghii , coll. J.E. Sun , HGUP21026; Tongren city, 28°14'09"N , 108°34'03"W , 810 m , 04 Sep 2021 , on Rosa roxburghii , coll. J.E. Sun , HGUP21027; Guiyang city, 26°44'74"N, 106°58'67"W, 960 m , 27 Mar , 2021, on Rosa sp., coll. J.E. Sun , HGUP21028 . Notes. Phragmidium rosae-roxburghii was the first species of Phragmidium described on Rosa roxburghii . It is easily to distinguish species by its unique square to diamond-shaped urediniospores, since in other Phragmidium species the urediniosporas are oval to nearly spherical ( Yun et al. 2011 ; Ono 2012 ; Zhuang et al. 2012 ; Yang et al. 2015 ; Liu et al. 2018 , 2019 , 2020 ; Ono and Wahyuno 2019 ). In phylogeny, this species only kept a close relationship to Ph. warburgiana (Fig. 1 ) but its urediniospores are yellowish to orange-colored different to Ph. warburgiana with colorless urediniospores ( Ono 2012 ). We proposed Ph. rosae-roxburghii as a new taxon.