Phyllosticta rhododendri M. Y. Zhang, Z. X. Zhang & X. G. Zhang 2025, sp. nov.

Phyllosticta rhododendri M. Y. Zhang, Z. X. Zhang & X. G. Zhang sp. nov. Fig. 4 Etymology. The specific epithet “ rhododendri ” refers to the host plant Rhododendron × pulchrum Sweet. Type. China • Yunnan Province, Hongta District, Yuxi City, Longma Mountain Scenic Area, on diseased leaves of Rhododendron × pulchrum, 13 May 2024, M. Y. Zhang (holotype HSAUP 8342), ex-type living culture CGMCC 3.28673. Description. Leaf endogenic and associated with leaves of Rhododendron × pulchrum. Sexual morph: Not observed. Asexual morph: Conidiomata pycnidial, mostly aggregated in clusters, black, erumpent. In PDA culture, exuding white conidial masses within 10 days or longer. Pycnidial wall multi-layered, textura angularis, brown to dark brown. Conidiophores indistinct, often reduced to conidiogenous cells. Conidiogenous cells 7–16 × 1.4–5.2 μm, subcylindrical, ampulliform, hyaline, smooth. Conidia 8.5–11.5 × 6.8–9.4 µm (L / W 1.33 –1.53), ovoid, ampulliform, ellipsoidal to subglobose, hyaline, aseptate, thin and smooth walled, multi-guttulate, or with a single large central guttule, surrounded by a mucilaginous sheath. Sheath 0.8–1.5 μm thick, thicker on both sides, and bearing a hyaline, apical mucoid appendage. Appendages 3–7.5 × 1–1.2 μm, flexible, unbranched, tapering towards an acutely rounded tip. Spermatia 6.3–8.2 × 1–1.5 μm, occurring in conidioma with conidia, hyaline, smooth, guttulate to granular, bacilliform. Culture characteristics. Colonies on PDA 19–22 mm in diameter after 14 days at 25 ° C in darkness, with a growth rate of 1.4–1.6 mm / day, greenish black with white edge on obverse and reverse. Additional specimens examined. China • Yunnan Province, Hongta District, Yuxi City, Longma Mountain Scenic Area, on diseased leaves of Rhododendron × pulchrum, 13 May 2024, Z. X. Zhang (HSAUP 8346), living culture SAUCC 8346–1. Notes. Phylogenetic analysis showed that Phyllosticta rhododendri formed an independent clade that is sister to a large clade comprising over ten species (P. anhuiensis, P. aucubae-japonicae, P. citribraziliensis, P. citrichinaensis, P. concentrica, P. cussonia, P. elongata, P. elliptica, P. ericarum, P. fujianensis, P. gardeniicola, P. gwangjuensis, P. hypoglossi, P. iridigena, P. kerriae, P. ophiopogonis, and P. spinarum) (Fig. 1). In morphology, Phyllosticta rhododendri was found to produce spermatia, a structure that is rarely observed within this genus. Therefore, we establish this fungus as Phyllosticta elliptica sp. nov.