Pseudoplagiostoma fagacearum Ning Jiang 2025, sp. nov.

Pseudoplagiostoma fagacearum Ning Jiang sp. nov. Fig. 3 Etymology. Named after the host family, Fagaceae. Diagnosis. Distinct from Ps. castanopsidis by longer conidia; and from Ps. jasmini, Ps. jianfenglingense, Ps. neocastanopsidis and Ps. quercus by wider conidia. Typus. CHINA • Guizhou Province, Zunyi City, Suiyang County, Kuankuoshui Natural Reserve, on diseased leaves of Quercus engleriana, 23 November 2019, Dan-ran Bian (holotype CAF 800039; ex-type culture CFCC 54425). Description. Conidiomata pycnidial, solitary, erumpent, globose to pulvinate, brown, 400–750 μm diam., exuding a brown conidial mass. Conidiophores indistinct, often reduced to conidiogenous cells. Conidiogenous cells hyaline, smooth, lageniform to ampulliform, attenuate towards the apex, phialidic, 13.5–18.5 × 4–5.5 μm. Conidia holoblastic, aseptate, hyaline, smooth, thick-walled, multi-guttulate, ellipsoid, oblong-cylindrical, slightly constricted at the middle, slightly curved, base tapering to a flat protruding scar, (18 –) 18.5–21 (– 22.5) × (10.5 –) 11–13 (– 14) μm (n = 50), L / W = 1.4–2.1, with a prominent hilum. Culture characteristics. Colonies on PDA flat, spreading, with flocculent aerial mycelia and floccose margin, vinaceous buff, reaching 90 mm diam. after 1 week at 25 ° C, forming brown conidiomata with brown conidial masses. Colonies on MEA flat, dense, surface folded, with moderate flocculent aerial mycelia and even margin, lavender gray to buff, reaching 70 mm diam. after 2 weeks at 25 ° C, sterile. Colonies on SNA flat, spreading, with sparse aerial mycelia and smooth margin, white to rosy buff, reaching 70 mm diam. after 2 weeks at 25 ° C, sterile. Additional materials examined. CHINA • Guizhou Province, Zunyi City, Suiyang County, Kuankuoshui Natural Reserve, on diseased leaves of Quercus engleriana, 23 November 2019, Dan-ran Bian (cultures CFCC 54446 and CFCC 54410); • Guizhou Province, Zunyi City, Honghuagang District, Zunyi Normal University, on diseased leaves of Castanopsis choboensis, 24 November 2019, Shang Sun (culture CFCC 54449); • Hainan Province, Changjiang Li Autonomous County, Bawangling National Forest Park, on diseased leaves of Cyclobalanopsis patelliformis, 30 March 2019, Yong Li (culture CFCC 54393). Distribution. China, Guizhou and Hainan Provinces. Ecology. Associated with leaf spot disease of Castanopsis choboensis, Cyclobalanopsis patelliformis and Quercus engleriana. Notes. Five isolates obtained from leaf spots of Castanopsis choboensis, Cyclobalanopsis patelliformis, and Quercus engleriana formed a well-supported clade, which is newly described here as Pseudoplagiostoma fagacearum. This species is phylogenetically closely related to Ps. castanopsidis, Ps. jasmini, Ps. jianfenglingense, Ps. neocastanopsidis and Ps. quercus (Fig. 1). However, Ps. fagacearum (18.5–21 × 11–13 μm) has wider conidia than Ps. jasmini (14–22 × 6.5–11 μm), Ps. jianfenglingense (19–22 × 8.5–11 μm), Ps. neocastanopsidis (19–22 × 9–10 μm), and Ps. quercus (17–21 × 9.5–11 μm), and longer conidia than Ps. castanopsidis (16.5–19.8 × 8.7–12.8 μm) (Gomdola et al. 2023; Zhang et al. 2025).