Phragmidium parvifolius Q. F. Zhang, Q. Z. Wu & Q. R. Li, 2025

Phragmidium parvifolius Q. F. Zhang, Q. Z. Wu & Q. R. Li sp. nov.

Fig. 4 View Figure 4

Type.

China • Guizhou Province, Guiyang City, Huaxi District (26°43′27.3″N, 106°67′14.4″E), 1,114 m a. s. l., on leaves of Rubus parvifolius ( Rosaceae ), 3 November 2022, Q. Z. Wu and Q. F. Zhang (holotype GMB 4054 , isotype KUN-HKAS 144250 ) .

Etymology.

The epithet refers to the host species, Rubus parvifolius L. , from which the holotype was collected.

Description.

Spermogonia, Aecia and Telia not found. Uredinia 0.3–0.8 mm diam., produced on the abaxial leaf surface, scattered to gregarious, hypophyllous, rounded to irregular, powdery, orange, pulverulent, at first covered by the epidermis, later, not surrounded by host epidermis; Urediniospores 18–32 × 12–24 μm (av. = 22 × 18 μm, n = 30), globose, oblong, orange, wall 1.1–1.7 μm thick (av. = 1.3 μm, n = 30) at sides, regularly echinulate with stout spines; germ pores 2–3, supra-equatorial. Paraphyses 49–83 × 10–19 μm (av. = 65 × 15 μm, n = 30), hyaline, curved.

Additional material examined.

China • Guizhou Province, Guiyang City, Huaxi District (26°43′59.7″N, 106°67′66.5″E), 1114 m a. s. l., on leaves of Rubus parvifolius ( Rosaceae ), 3 November 2022, Q. Z. Wu and Q. F. Zhang ( GMB 4070 ) .

Notes.

Phylogenetically, P. parvifolius formed a sister branch to P. barnardii Plowr. & G. Winter ( HGU 21035), which was also reported on Rubus parvifolius (Fig. 1 View Figure 1 ). Morphologically, P. parvifolius can be easily differentiated from P. barnardii by its larger urediniospores (18–32 × 12–24 μm vs. 16–19 × 15–18 µm) and larger paraphyses (49–83 × 10–19 μm vs. 26–39 × 10–13 µm) ( Winter 1886; McTaggart et al. 2016; Sun et al. 2022). In terms of urediniospore size, P. parvifolius is similar to P. griseum (Dietel) Syd. However , P. parvifolius differs from P. griseum by having relatively larger paraphyses (49–83 × 10–19 μm vs. 34–70 × 7–16 μm) and by its host, Rubus parvifolius vs. Rubus crataegifolius ( Wei 1988; Hiratsuka et al. 1992; Liu et al. 2018; Sun et al. 2024). Additionally, P. parvifolius differs from P. pauciloculare by its larger urediniospores (18–32 μm vs. 13–20 μm) ( Wei 1988; Hiratsuka et al. 1992). Phragmidium parvifolius and P. kanas have the same urediniospores and paraphyses, but P. parvifolius has no teliospores, whereas P. kanas has them ( Zhao et al. 2021).

Furthermore, the morphological comparison between P. parvifolius and P. coreanicola (this study) shows that the urediniospores of P. parvifolius are larger than those of P. coreanicola (18–32 μm vs. 20–29 μm), and P. parvifolius has no teliospores, whereas P. coreanicola has them. The ITS and LSU sequence similarities of P. parvifolius with P. coreanicola are 97.57 % and 99.22 %.