Phragmidium potentillae-freynianae 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 potentillae-freynianae J.E. Sun & Yong Wang bis sp. nov.

Fig. 5

Diagnosis.

Different from the related taxa by its urediniospores catenulate, such as Ph. chayuensis , Ph. cibanum and Ph. tormentillae .

Holotype.

China. Guizhou Province;, Guiyang city, 26°44'70"N, 106°59'65"W, 801 m, 27 Mar 2021, on Potentilla freyniana , coll. J.E. Sun, HGUP21033, ITS: OL684826, LSU: OL684837.

Etymology.

Referring to the host, Potentilla freyniana , on which the fungus was first found.

Description.

Spermogonia, aecia and telia not observed. Uredinia produced on the abaxial leaf surface, covering the entire lower surface of the leaves, hypophyllous, nearly oval, powdery, not surrounded by host epidermis, 0.1-1.0 mm diam, on densely orange spot, 0.1-1.0 mm diam. Urediniospores: uredo-type, subglobose to oval, produced in basipetal succession, 19-24 × 18-24 µm (mean 21.5 × 21 μm, n = 30), golden, or bright-yellow; thin-walled, wall 0.4-1.4 µm thick, colorless, densely and minutely echinulate.

Rust diseases symptoms: Large areas of orange powdery uredinia, covering almost the entire lower surface of the leaves, which are aggregated but without obvious boundaries (Fig. 5 ).

Habitat.

Potentilla freyniana .

Known distribution.

China, Guizhou Province.

Notes.

In the phylogenetic tree, Phragmidium potentillae-freynianae formed a well-supported clade allied to Ph. duchesneae-indicae (Fig. 1 ). Morphologically, its urediniospores are bigger than Ph. duchesneae-indicae (21.5 × 21 μm vs. 13-19 × 11-17 µm) ( Zhao et al. 2021). The comparison of DNA base composition supports the morphological separation of this fungus as a new species.

Figures

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

Figure 5. Phragmidium potentillae-freynianae sp. nov. (HGUP 21033, holotype) on Potentilla freyniana. a-c uredinia on leaves d longitudinal section of uredinium e-i urediniospores. Scale bars: 2 mm (b-c); 50 µm (d-e); 25 µm (f-i).