Ovicillium pseudoattenuatum Y. Wang & D. X. Tang sp. nov.

Fig. 3

Etymology:

“ Pseudoattenuatum ” refers to morphologically resembling Ovicillium attenuatum, but phylogenetically distinct.

Type.

Laos • Vientiane City, Mekong Riverside Park (17.96°N, 102.60°E, 674 m above sea level), from soil on the forest floor, 11 August 2024, Yao Wang (holotype as dried culture GMB 3007); ex-type culture GMBC 3007.

Description.

Sexual morph: Undetermined. Asexual morph: Colonies on PDA reaching 23–25 mm in diameter in 7 days at 25 ° C, white to pinkish; reverse yellowish. Hyphae branched, smooth-walled, septate, hyaline, 1.2–2.8 μm wide. Conidiophores hyaline, smooth-walled, with single phialide or whorls of 2–5 phialides or verticillium-like directly from hyphae, up to 500 μm long. Phialides terminal or lateral, straight, somewhat inflated base, attenuated from the middle, sometimes undulated near the tip, 16.0–37.5 × 1.5–2.4 (X ̄ = 26.8 × 2.0, n = 50) μm. Conidia smooth-walled, hyaline, ellipsoidal to cylindrical, 3.2–4.0 × 1.7–3.2 (X ̄ = 3.7 × 2.3, n = 50) μm, aggregated in large globose to subglobose heads. Crystals absent. Chlamydospores absent.

Other material examined.

Laos • Oudomxay Province, Muang Xay District, Nam Kat Yorla Pa Resort (20.71°N, 102.11°E, 708 m above sea level), from soil on the forest floor, 14 August 2024, Yao Wang (living culture GMBC 3008).

Substrate.

Soil.

Distribution.

Laos.

Notes.

Ovicillium pseudoattenuatum, isolated from forest floor soil, forms a distinct phylogenetic lineage within the Ovicillium genus. Multilocus phylogenetic analyses reveal its close relationship with O. attenuatum and O. sinense, supported by strong statistical values (BS IQ / BS RAx / PP = 82 % / 79 % / 0.93). Morphologically, while sharing the characteristic undulated phialide tips with O. attenuatum, O. pseudoattenuatum differs significantly in microscopic dimensions: it possesses smaller phialides (16.0–37.5 × 1.5–2.4 μm vs 25–50 × 1.7–3.3 μm) and more compact conidia (3.2–4.0 × 1.7–3.2 μm vs 3.5–5 × 2.5–3.8 μm). Distinct from O. sinense, which exhibits even smaller reproductive structures (phialides 16.2–25.8 × 1.7–2.4 μm; conidia 2.1–2.9 × 1.1–1.7 μm), O. pseudoattenuatum is further characterized by its unique ellipsoidal to cylindrical conidial morphology, a diagnostic feature distinguishing it from all known Ovicillium species (Table 3).