Phragmidium rosae-laevigatae J.E. Sun & Yong Wang bis, 2022

Sun, Jing-E, Zhang, Qian, Luo, Wen-Mei, Yang, Yuan-Qiao, An, Hua-Ming & Wang, Yong, 2022, Four new Phragmidium (Phragmidiaceae, Pucciniomycetes) species from Rosaceae plants in Guizhou Province of China, MycoKeys 93, pp. 193-213 : 193

Phragmidium rosae-laevigatae J.E. Sun & Yong Wang bis sp. nov.

Fig. 6

Diagnosis.

Different from Ph. Jiangxiense mainly because of bigger urediniospores.

Holotype.

China. Guizhou Province: Panzhou city, 25°64'56"N, 104°84'35"W, 1800 m, 19 Jul 2021, on Rosa laevigata , coll. J.E. Sun, HGUP21036, ITS: OL684829, LSU: OL684840.

Etymology.

Referring to the host, Rosa laevigata , on which the fungus was first found.

Description.

Spermogonia and aecia not observed. Uredinia produced on the abaxial leaf surface, hypophyllous, subglobose to globose, powdery, 0.1-0.5 mm diam, yellow, peripherally parphyses, hyaline, 20-31 × 10-17 µm. Urediniospores square to diamond-shaped, oval to nearly spherical, 23-35 × 16-30 µm (mean 29 × 23 µm, n = 30), orange-colored, thick-walled 0.5-2.0 µm thick, colorless, regularly echinulate with stout spines on the surface. Telia scattered compact, hypophyllous, golden, 0.1-0.5 mm diam. Teliospores (immature) oval, 24-60 × 8-20 µm (mean 50.5 × 25.5 μm, n = 30), with apical papillae (4.0-7.0 μm high, n = 10), too immature to know how many cells, orange-yellow; pedicels swollen at the base, 15-26 μm long, colorless, disconnected easily; wall 0.5-2.0 μm thick.

Rust diseases symptoms: As shown in Fig. 6 , Uredinia and telia, which are bright-yellow and powdery are produced almost simultaneously on the lower surface of the yellowing and wilting leaves.

Habitat.

Rosa laevigata .

Known distribution.

China, Guizhou Province.

Additional material examined.

China. Guizhou Province: Panzhou city, 25°61'81"N, 104°83'61"W, 1790 m, 19 Jul 2021, on Rosa laevigata , coll. J.E. Sun, HGUP21037 .

Notes.

Phylogenetically, Phragmidium rosae-laevigatae kept a close relationship to Ph. leucoaecium , Ph. japonicum and Ph. jiangxiense (Fig. 1 ). Morphologically, Phragmidium rosae-laevigatae has bigger urediniospores than Ph. jiangxiense (23-35 × 16-30 µm vs. 15-23 × 11-18 μm), but the uredinia and urediniospores of Ph. leucoaecium and Ph. japonicum were not observed ( Liu et al. 2020). The comparison of DNA base composition also supported morphological conclusion. Thus, this fungus was also introduced as one novel taxon herein.

Figures

Figure 1. The maximum parsimony tree of 42 Phragmidium taxa based on ITS and LS U genes; host plants are also given.

Figure 6. Phragmidium rosae-laevigatae sp. nov. (HGUP 21036, holotype) on Rosa laevigata a gross features of infected leaves b uredinia and telia on a leaf c longitudinal section of telium d immature teliospores e longitudinal section of uredinium f-h urediniospores. Scale bars: 1 mm (b); 50 µm (c, e); 12.5 µm (d, f - h).