Dimorphiseta serpentinicola K. W. Cheng & H. A. Ariyaw. 2025, sp. nov.

Dimorphiseta serpentinicola K. W. Cheng & H. A. Ariyaw. sp. nov. Fig. 31 Typification. TAIWAN • Wanrung Township, Hualien County, 23°42'40.3"N, 121°24'48.2"E, serpentine soil in rice field, 2 nd November 2022, K. W Cheng, holotype, NTUPPMH 22-225 (Permanently preserved in a metabolically inactive state), ex-holotype NTUPPMCC 22-292. Etymology. Named for the serpentine soil from which the species was isolated. Description. Sexual morph undetermined. Asexual morph No sporulation on PDA and MEA, conidiomata produced on carnation leaves. Conidiomata 258–548 µm diam, 70–225 µm deep, randomly scattered, superficial, sporodochial, stromatic, globose to subglobose, smooth outline, dark green to black, agglutinated slimy, mucoid mass of conidia. Setae thick-walled, hyaline, smooth, septate, straight to slightly curved, tapering to sharp apices, 180–280 µm long, 5–7 µm wide at broadest part. Conidiophores unbranched, hyaline to green, smooth to lightly verrucose, arising from basal stroma. Conidiogenous cells phialidic, hyaline, cylindrical, smooth, with collarette at tip, 18.3–23.5 µm × 1.6–2.2 µm (x ̄ = 21.0 × 1.9 µm, n = 25). Conidia aseptate, hyaline, fusiform, smooth, funnel-shaped apical appendage, 7.4–8.7 µm × 2.2–3.1 µm (x ̄ = 8.1 × 2.7 µm, L / W ratio = 3.07, n = 50). Culture characteristics. Colony reaching 38 mm diam with abundant white, cotton-like mycelium and slightly irregular margin. A mustard pigment developed, and the reverse side of the medium appeared pale yellow. Notes. The new taxon D. serpentinicola proposed in the present study forms a distinct clade with strong statistical support (97 / 1.00) based on multi-locus phylogenetic analysis (Fig. 30). Moreover, D. serpentinicola exhibits significant genetic divergence from its closest relative, the ex-type strain of D. acuta (CGMCC 3.19208), with 90.7 % identity in the cmd A gene (526 / 580 bp, including 11 gaps) and 93.8 % identity in the rpb 2 gene (676 / 721 bp). The colony color and texture on PDA were similar to D. acuta CGMCC 3.19208, but pigment diffusion into the medium was observed in PDA (Fig. 31; Liang et al. 2019). D. acuta was previous recorded in Taiwan, isolated from the dead leaves of Celtis formosana by (Tennakoon et al. 2021). However, our species exhibited smaller conidia (8.1 × 2.7 µm versus 10.5 × 2.5 µm) and longer setae (up to 280 µm versus 150 µm) compared to D. acuta (Tennakoon et al. 2021).