Polycephalomyces chiangraiensis X. Zhang, K. D. Hyde & T. C. Wen 2026, sp. nov.

Polycephalomyces chiangraiensis X. Zhang, K. D. Hyde & T. C. Wen sp. nov. Fig. 6 Etymology. Reference to Mueang Chiang Rai District, Chiang Rai Province, the locality where the type specimen was collected. Type. THAILAND • Chiang Rai Province, Mueang Chiang Rai District, 20°02'48.30"N, 99°49'31.51"E, alt. 410 m, 28 October 2023, Xian Zhang, TX 4-1 (holotype: MFLU 26-0001; ex-type culture: MFLUCC 25-0386). Description. Parasitic on Ophiocordyceps sp. (Ophiocordycipitaceae, Hypocreales). Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on PDA growing slowly, attaining a diameter of 1.4–1.9 cm in 21 days at 25 ° C, powdery, vary in color from yellow to white, reverse yellow to brown. Conidiophores normally with 1–2 phialides. Phialides 8.2–19.8 (x ̄ = 15.2 µm, n = 10) long, base 1.6–2.2 μm wide, neck 0.6–0.7 μm wide, hyaline, smooth, narrowly subulate with a neck. Conidia 2–3.2 × 0.9–1.5 µm (x ̄ = 2.5 × 1.1 µm, n = 30), one-celled, hyaline, ellipsoid. Habitat and distribution. On Ophiocordyceps sp., currently known from northern Thailand. Notes. The newly proposed species, Po. chiangraiensis, forms a sister lineage to Po. myrmecophilus with 100 % ML / 1 PP support (Fig. 1). Morphologically, Po. chiangraiensis differs from Po. myrmecophilus by having a more pronounced difference in width between the base and apex of the phialides and ellipsoid spores. Based on these phylogenetic and morphological distinctions, Po. chiangraiensis is proposed as a novel species within the genus Polycephalomyces.