Phialoparvum formosanum K. W. Cheng & H. A. Ariyaw. 2025, sp. nov.

Phialoparvum formosanum K. W. Cheng & H. A. Ariyaw. sp. nov. Fig. 36 Typification. TAIWAN • Guanshan Township, Taitung County, 23°02'14.8"N, 121°11'22.6"E, serpentine soil in rice field, 3 rd November 2022, K. W. Cheng, holotype, NTUPPMH 227 (Permanently preserved in a metabolically inactive state), ex-holotype NTUPPMCC 22-301. Etymology. Named after Formosa, the former name of Taiwan, where the type specimen was collected. Description. Sexual morph undetermined. Asexual morph Conidia were observed on WA. Conidiophores solitary, hyaline, straight to slightly flexuous, arising from hyphal ropes or vegetative hyphae. Phialides subulate to ampulliform, hyaline, terminal or lateral, with conspicuous periclinal thickening and cylindrical collarette, 4–18 µm long. Mono-phialides or adelophialides predominant, few poly-phialides with two conidiogenous loci. Conidia cylindrical, hyaline, smooth, thick-walled, 1 - celled, with 1 to 2 guttules, sometimes aggregated in clusters forming a slimy head, 3.6–4.6 µm × 1.7–2.4 µm (x ̄ = 4.2 × 2.1 µm, L / W ratio = 2.04, n = 50). Culture characteristics. Colony exhibit slow growth, reaching 30 mm diam with flat, creamy white, and velvety to powdery at the center, gradually thinning toward the edges with a smooth margin. The reverse side of the colony displayed similar characteristics. Notes. In our multi-locus phylogenetic assessment, Phialoparvum formosanum forms a distinct branch with low statistical support, sister to the clade containing the ex-type strain of Ph. bifurcatum (CBS 299.70 B). Despite the weak nodal support, these taxa exhibit substantial genetic divergence across three loci: ITS (440 / 455 bp, identities 96.7 %, including 7 gaps), rpb 2 (259 / 279 bp, identities 92.8 %), and tef- 1 (761 / 787 bp, identities 96.7 %) (Fig. 37 and Suppl. material 2: figs S 3 – S 5). Ph. formosanum NTUPPMCC 22-301 shares typical characteristics of the genus Phialoparvum, including hyaline, solitary, arising from hyphal ropes or vegetative hyphae of conidiophores and subulate to ampulliform phialides. However, the conidia of Ph. formosanum NTUPPMCC 22-301 are broader than the type strain of Ph. bifurcatum CBS 299.70 B (3.6–4.6 µm × 1.7–2.4 µm versus 2.8–4.4 µm × 1.2–1.8 µm) (Fig. 36; Giraldo and Crous 2019). Additionally, Ph. formosanum exhibits prominent guttules in its conidia, a feature that differentiates it from the other three Phialoparvum species (Fig. 36; Giraldo and Crous 2019; Giraldo et al. 2019).