Ophiostoma guttiferum H. G. Woo, D. Hyeon Lee & S. E. Cho 2026, sp. nov.

Ophiostoma guttiferum H. G. Woo, D. Hyeon Lee & S. E. Cho sp. nov. Fig. 4 Etymology. The specific epithet guttiferum is derived from the Latin gutta (drop) and - ferum (bearing), referring to the characteristic mucilaginous spore drops formed at the apices of the synnemata. Type. Republic of Korea • Gyeongsangnam-do, Sancheong-gun, Danseong-myeon, Baegun-ri, Mt. 254; 35°16'44.0"N, 127°51'47.0"E. Wounds, Quercus variabilis. 13 May 2025. D. Hyeon Lee. CDH 139 (Holotype. KA 25-1573, ex-holotype culture KACC 411104). Description. Colonies hyaline at first, becoming dark brown in center with age. Mycelium appressed with scarce aerial. Optimal temperature for growth 25 ° C, reaching 60 mm diam in 14 d at 25 ° C. Sexual morph not observed. Asexual morph synnematous, macronematous, erect, hyaline, pigmented at the base, (440 –) 497.6–527.1 (– 550) µm long, (32 –) 49.1–60.5 (– 63) µm wide at base; conidiogenous cells annellated, discrete, terminal, cylindrical, tapering towards apex, hyaline, smooth, (16.8 –) 21.1–31.6 (– 34) µm; conidia hyaline, 1 - celled, smooth, oblong to ellipsoidal, obovoid, (2.9 –) 3.5–4.0 (– 4.1) × (1.2 –) 1.7–2.0 (– 2.1) µm aggregating into a cream-white mucilaginous spore drop. Additional specimen examined. Republic of Korea • Gyeongsangnam-do, Sancheong-gun, Danseong-myeon, Baegun-ri, Mt. 254; 35°16'44.0"N, 127°51'47.0"E. Wounds, Quercus variabilis. 13 May 2025. D. Hyeon Lee. (CDH 139-1). Habitat. Fresh wounds (less than one-month-old) on Quercus variabilis trees. Notes. Ophiostoma guttiferum is phylogenetically closely related to O. quercus. Both species share similar rapid growth characteristics and form colonies that become dark brown in the center with age. While the sexual morph has not been observed in O. guttiferum, in contrast to O. quercus, which readily produces ascomata, their asexual morphs provide subtle but notable morphological distinctions. O. guttiferum produces oblong to ellipsoidal, obovoid conidia measuring 2.9–4.1 × 1.2–2.1 μm. Conversely, the conidia of O. quercus (typically from its Pesotum anamorph) can be slightly larger, frequently reaching up to 4.7–4.8 μm in length and 2.4 μm in width. Furthermore, while O. guttiferum conidia are generally oblong to ellipsoidal, the conidia of O. quercus often exhibit a distinctly truncate base or present as purely elliptical, offering a useful micro-morphological trait to differentiate the two species (Grobbelaar et al. 2009).