Phragmidium rubi-coreani 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 rubi-coreani J.E. Sun & Yong Wang bis sp. nov.

Fig. 4

Diagnosis.

Phragmidium rubi-coreani differs to Ph. barclayi by teliospores with fewer cells and shorter pedicels.

Holotype.

China. Guizhou Province: Guiyang city, 26°45'86"N, 106°98'77"W, 970 m, 11 Apr, 2021, on Rubus coreanus , coll. J.E. Sun, HGUP21029, ITS: OL684822, LSU: OL684833.

Etymology.

Referring to the host, Rubus coreanus , on which this species grows.

Description.

Spermogonia: unknown. Aecia golden, produced on the abaxial leaf surface, hypophyllous, and 2.5-3.5 mm diam, subglobose to globose, powdery, 2.5-3.5 mm diam. Aeciospores produced in basipetal succession, subglobose, 14-24 × 10-23 µm (mean 19 × 16 μm, n = 30), bright yellow contents, thick-walled, 1.0-4.0 µm, colorless, echinulate; paraphyses clavate, not or weakly incurved, 38-61 μm long, thick-walled, wall 2.0-2.5 μm thick. Telia hypophyllous, scattered, 0.3-0.5 mm diam, chocolate-brown. Teliospores ellipsoid to cylindrical, 3-5 celled, constricted at the septa, bright orange, chocolate-brown to gray-brown, 29-74 × 14-37 µm (mean 50 × 25 μm, n = 30), thick-walled, wall 1.8-3.5 μm thick, colorless to chocolate-brown; pedicels not swollen at the base, 8-34 μm long, colorless. Uredinia formed on circular lesions on both sides of the leaves, powdery, yellow distinct, hypophyllous scattered, nearly oval, surrounded by host epidermis, 0.5-1.0 mm diam. Urediniospores: uredo-type, subglobose to oval, produced in basipetal succession, golden, or bright-yellow, 19-27 × 15-25 µm (mean 23 × 20 μm, n = 30), thick-walled, wall 0.8-1.5 µm thick, colorless, densely and minutely echinulate.

Rust diseases symptoms: The golden and powdery aecia were first produced on the underside of leaves. Then, scattered uredinia were formed, orange-colored and forming small round spots on the leaves. Chocolate-brown telia were produced on the leaf remnants (Fig. 4 ).

Habitat.

Rubus coreanus .

Known distribution.

China, Guizhou Province.

Additional material examined.

China. Guizhou Province: Guiyang city, 27°10'30"N, 106°99'91"W, 830 m, 09 Apr 2021, on Rubus coreanus , coll. J.E. Sun, HGUP21030 .

Notes.

In the phylogenetic tree, Phragmidium rubi-coreani , Ph. barclayi and Ph. cibanum formed a branch (Fig. 1 ). However in morphology, teliospores of Phragmidium rubi-coreani have fewer septa and shorter pedicels (3-5-celled, 8-34 μm long) than Ph. barclayi (5-8-celled, 60-150 μm long) and Ph. cibanum (5-7-celled, 70-108 μm long) ( Liu et al. 2018). Meanwhile, most reported Phragmidium taxa produce longer teliospores, such as Ph. zangdongii (29-74 × 14-37 µm vs. 82-110 × 23-31 μm); Ph. kanas (29-74 × 14-37 µm vs. 134-198 × 19-31 µm); Ph. potentillae-canadensis (29-74 × 14-37 µm vs. 48.1-86.8 × 30.1-33.3 µm) than the present species ( Yun et al. 2011; Liu et al. 2018; Zhao et al. 2021). Thus, our fungus represented a novel taxon.

Figures

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

Figure 4. Phragmidium rubi-coreani sp. nov. (HGUP 21029, holotype) on Rubus coreanus a gross features of infected leaves b uredinia on a leaf c-d longitudinal section of uredinium e paraphyses f urediniospores g aecia on a leaf h longitudinal section of aecium i-j aeciospores k telia on a leaf l longitudinal section of telium m-n Teliospores. Scale bars: 2 mm (b); 1 mm (g, k); 50 µm (c-e, h, l); 10 µm (f); 25 µm (i-j, m-n).