Pseudochaetosphaeronema heveae R. F. Xu, K. D. Hyde & Tibpromma sp. nov. Fig. 4 Etymology. Refers to the host genus Hevea. Holotype. GMB-W 1222 Description. Saprobic on a decaying branch of Hevea brasiliensis. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 125–170 × 140–225 μm (x ̄ = 148 × 190 μm, n = 10), solitary to aggregated, globose to subglobose or pyriform, immersed to semi-immersed, unilocular, dark brown to black, appearing as black dots on the host surface. Conidiomatal wall 20–70 μm wide, brown to dark brown, textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3–8 × 2–6 μm (x ̄ = 6 × 4.4 μm, n = 10), monophialidic, cylindrical or ampulliform, hyaline, smooth-walled, with guttules. Conidia 8–14 × 3–4 μm (x ̄ = 11.25 × 3.23 μm, n = 50), fusiform or fusoid, slightly curved, 1–2 - septate, constricted at septum, cell swollen sometimes, rounded at both ends, hyaline, smooth, thin-walled, without a mucilaginous sheath. Culture characteristics. Conidia germinating on PDA within 12 hours. Colonies irregular, umbonate, white to cream, with a central brown droplet, undulate margin; reverse dark brown with pale brown edge, producing brown pigment on PDA media. Material examined. China, • Yunnan Province, Dehong Dai and Jingpo Autonomous Prefecture, Mang City, on a decaying branch of Hevea brasiliensis, 18 April 2024, Rui-Fang Xu, DHR 27 (GMB-W 1222, holotype), ex-type living culture GMBCC 2333 = GMBCC 2334. Notes. In the phylogenetic analyses, GMBCC 2333 and GMBCC 2334 formed a distinct lineage, sister to P. siamensis (MFLUCC 17–2287, ex-type) and P. bruguierae (MFLUCC 24–0515, ex-type) (Fig. 1). Sequence comparisons showed that GMBCC 2333 differs from P. siamensis by 13 / 510 bp (ITS, 2.55 %), 3 / 810 bp (LSU, 0.20 %), 2 / 1,005 bp (SSU, 0.19 %), and 99 / 645 bp (tef 1 - α, 15.35 %); differences with P. bruguierae included 8 / 497 bp (ITS, 1.61 %), 2 / 810 bp (LSU, 0.25 %), and 28 / 893 bp (tef 1 - α, 3.14 %). Morphologically, P. heveae (GMB-W 1222, holotype) can be distinguished from P. coffeae (MHZU 23–0081, holotype) by smaller conidiomata (125–170 × 140–225 μm vs. 150–190 × 180–240 μm) and conidiogenous cells (3–8 × 2–6 μm vs. 6–9 × 3–6 μm), as well as shorter conidia (8–14 × 3–4 μm, 1–2 - septate vs. 12–16 × 3–5 μm, 1–3 - septate) (Lu et al. 2025). It also differs from P. bruguierae (MFLU 24–0192, holotype), which has larger conidiomata (230–400 × 300–370 μm), narrower conidiogenous cells (7–10 × 1–2.7 μm), and smaller conidia (5–10 × 2–3 μm), 2–3 - septate with guttules (Apurillo et al. 2025). Based on molecular and morphological evidence, we introduce our new collection as a new species, P. heveae.

Published as part of Xu, Rui-Fang, Karunarathna, Samantha C., Hyde, Kevin D., Kakumyan, Pattana, McKenzie, Eric H. C., Elgorban, Abdallah M., Yu, Fu-Qiang, Alfagham, Alanoud T., Phukhamsakda, Chayanard & Tibpromma, Saowaluck, 2026, Taxonomy and phylogeny of Pseudochaetosphaeronema associated with rubber trees from Yunnan Province, China, pp. 301-322 in MycoKeys 128 on pages 301-322, DOI: 10.3897/mycokeys.128.182163