Arcopilus aureus (Chivers) X. Wei Wang & Samson, Studies in Mycology 84: 217 (2016)

Fig. 18

Description.

Sexual morph: When cultured on PDA medium for approximately 30 days, sporulation begins. Ascomata subglobose to ovate, initially light brown, turning dark brown at maturity, superficial, 92–291 μm diam., and possess an ostiole. Ostiole tubular, dark brown, straight or curved, reaching up to 360 μm in length. Terminal hairs arcuate, with hooked and coiled apices, pale yellowish-brown, 107–341 μm in length. Asci fasciculate, clavate, evanescent, containing eight biseriately arranged ascospores, 15.0–30.4 × 7.6–12.3 µm (av. ± S. D. = 23.7 ± 4.2 × 9.8 ± 1.3). Ascospores unicellular, hyaline, and transparent when immature, becoming brown at maturity, fusiform, reniform, or limoniform, with 1–2 germ pores at each end, 6.9–10.3 × 4.3–6.1 µm (av. ± S. D. = 8.5 ± 0.6 × 5.3 ± 0.4) μm. Asexual morph: Not observed.

Cultural characteristics.

When cultured on PDA medium at 25 ° C in darkness for 7 days, the colonies reached 55 mm in diameter, with abundant white aerial hyphae showing radial growth. After 10 days, the mycelium fully covered the Petri dish, forming concentric rings and continuing to expand outward; the colonies produced purple-red pigments that diffused throughout the agar surface. By 30 days, the colonies turned purple-black, and sporulating structures became visible on the medium surface.

Specimens examined.

China • Beijing City, Changping District, Ming Tombs Reservoir, “ 40°14'57"N, 116°15'54"E ”, on the diseased scale leaves of Platycladus orientalis, 23 February 2025, Z. X. Bi, BJFC -S 2571, living culture CFCC 72639.

Notes.

The genus Arcopilus was introduced by Wang et al. (2016), with Arcopilus aureus designated as the type species. This genus is characterized by colonies producing yellow to orange or red to rust-colored pigments, arcuate perithecial hairs, and ascospores with diverse morphologies (Wang et al. 2016). A. aureus is an endophyte widely associated with various plants (Zimowska and Nicoletti 2023) and also acts as a pathogenic fungus. Reported infections caused by A. aureus include leaf black spot disease in Pseudostellaria heterophylla (Yuan et al. 2021), leaf spot disease in Cucumis melo (Wei et al. 2024), and gray spot disease in tobacco (Yang et al. 2024). Comprehensive phylogenetic and morphological analyses identified the fungal strain CFCC 72639 as A. aureus.