Westerdykella aquatica H. Y. Song & D. M. Hu 2020

Westerdykella aquatica H. Y. Song & D. M. Hu (2020) Fig. 12 Description. Sexual morph Cleistothecia superficial or submerged on central region of PDA, 150–291 µm diam, globose to subglobose, glabrous, dirty gray when immature, black when mature. Peridium single-layered, brown, translucent, membranous, angular cells. Asci subglobose to ovoid, hyaline when immature, brown when mature, 32 - spored, 12.2–16.3 µm × 10.7–14.7 µm (x ̄ = 14.3 × 12.6 µm, L / W ratio = 1.15, n = 30). Ascospores ellipsoidal, smooth, subhyaline to light brown, 1 to 2 guttules, no germ-slits, 4.7–5.9 µm × 2.2–3.3 µm (x ̄ = 5.1 × 2.8 µm, L / W ratio = 1.87, n = 50). Asexual morph undetermined. Culture characteristics. Colony exhibits rapid growth, reaching 90 mm daim with a slightly diffused edge, flat and fluffy, predominantly creamy white, with a central region transitioning to pale yellow, reverse yellow to dark yellow in the central region due to the presence of cleistothecia. Material examined. TAIWAN • Guanshan Township, Taitung County, 23°02'17.6"N, 121°11'26.3"E, serpentine soil in rice field, 3 rd November 2022, K. W. Cheng, living culture NTUPPMCC 22-248 to 251. Notes. Westerdykella aquatica has been reported from rice field mud and stems of Acorus calamus in China (Song et al. 2020), river sediment in Korea (Goh et al. 2021), and Polygonum acuminatum Kunth root in Brazil (Pietro-Souza et al. 2017; Senabio et al. 2023). In the present study, multi-gene phylogeny indicated that our strains NTUPPMCC 22-248 to 251 grouped with the clade representing W. aquatica (Fig. 13). Especially, similar to previous studies (Song et al. 2020; Goh et al. 2021), only the sexual stage was observed for all the strains identified as W. aquatica in the present study (Fig. 12). Distinguishing W. aquatica from its phylogenetically closely related species, W. purpurea based solely on sexual-stage morphology can be challenging. This is the first report of W. aquatica in Taiwan.