Neoroussoella guizhouensis S. Q. Guo, K. D. Hyde & Yong Wang bis 2025, sp. nov.

Neoroussoella guizhouensis S. Q. Guo, K. D. Hyde & Yong Wang bis sp. nov. Fig. 3 Etymology. The name refers to Guizhou Province, where the fungus was collected. Type. China • Guizhou Province, Guiyang City, 26°6'N, 106°7'E, 1071 m, 7 September 2023, from dead wood culms, coll. S. Q. Guo, HGUP 24-0071 (holotype), ex-type culture GUCC 24-0197 (ITS: PQ 404886, LSU: PP 949847, rpb 2: PQ 438557, ef 1 - α: PQ 438560). Description. Saprobic on dead wood culms. Sexual morph: undetermined. Asexual morph: On the natural substrate: Pycnidia 81–137 × 65–1198 µm (x ̄ = 108.5 × 81.9 µm, n = 10), ellipsoidal to nearly circular, inlaid on the surface of the substrate with a black ring at the edge, transparent in the center, and smooth in surface texture. On PDA: Conidiophores reduced to conidiogenous cells. Conidiogenous cell 9–35 × 1–6 µm (x ̄ = 20 × 3.8 µm, n = 10), enteroblastic, indeterminate, discrete, unbranched, clavate or ampulliform to lageniform, hyaline, aseptate, smooth-walled. Conidia (2.9 –) 3.4–3.5 (– 4) × (2 –) 2.4–2.5 (– 2.6) µm (x ̄ = 3.5 × 2.5 µm, n = 50), oblong to ellipsoid, with rounded to obtuse ends, hyaline, aseptate, smooth-walled. Culture characteristics. Under dark conditions at 25 ° C, the colony diameter can reach 80 mm within seven days on PDA medium. Center of the colony is light gray, accompanied by a white ring. Hyphae at the edge are sparse, slightly irregular, and lace-like, and several vertical stripes spread out at the center. Reverse side is black to light red, and the edge is yellowish. Material examined. China • Guizhou Province, Guiyang City, 26°6'N, 106°7'E, 1071 m, 7 September 2023, from dead wood culms, coll. J. E. Sun, HGUP 24-0071 (holotype), living culture GUCC 24-0197, GUCC 24-0196, and GUCC 24-0198. Notes. Neoroussoella guizhouensis is a saprobic fungus found on dead wood culms. According to the multi-gene phylogenetic analysis (Fig. 1), our isolates formed a distinct clade, sister to Neoroussoella leucaenae, which was previously reported from decaying pods of Leucaena sp. and Pterocarpus sp. in Thailand (Jayasiri et al. 2019). This relationship is supported by statistical values of 79 % MLBS and 0.78 BIPP (Fig. 1). On PDA, colonies of N. guizhouensis display a light gray center surrounded by a white ring, distinguishing it from N. solani, which exhibits white to lavender-gray colonies and produces rosy buff to grayish-rose pigments (Mochizuki et al. 2017). Morphological data for N. leucaenae and N. entadae on PDA are unavailable in the literature. However, on MEA, N. leucaenae shows gray to brown hyphal growth with a radially arranged brown edge and a two-layered reverse side, dark brown and brown. In contrast, N. entadae displays irregular edges with a thin, light-colored outer layer embedded in the medium, a three-layered reverse side of dark brown with distinct boundaries, and scattered pycnidia throughout the culture medium (Jayasiri et al. 2019). Phylogenetically, the new species was grouped with N. guizhouensis, N. leucaenae, N. solani, and N. entadae. However, the morphological distinctions are evident among those species, particularly in the conidiogenous cells. Although all species exhibit bottle-shaped sporogenic structures, N. leucaenae is characterized by flask- to cylindrical-shaped cells with a thicker neck and nearly round base. In contrast, N. guizhouensis has a narrow-necked bottle shape, whereas N. solani shows a broader base, with some cells appearing nearly oval. N. entadae displays phialidic, ampulliform to cylindrical conidiogenous cells. The dimensions of the conidiogenous cells differ significantly among the species: N. guizhouensis (9–35 × 1–6 µm), N. leucaenae (5.5–9 × 3–4 µm), N. solani (5–10 × 3.5–5 µm), and N. entadae (3.5–5.6 × 0.7–1.8 µm). Conidia size comparisons also highlight differences: N. guizhouensis (2.9–4 × 2–2.6 µm), N. leucaenae (3.5–4.5 × 1.9–2.6 µm), N. solani (3.9–5.3 × 1.9–2.2 µm), and N. entadae (3–4 × 1.7–1.9 µm). While N. guizhouensis and N. leucaenae are similar in spore size, they have shorter lengths and narrower widths compared to N. solani and exhibit similar lengths but narrower widths compared to N. entadae. Additionally, nucleotide sequence comparisons of the ef 1 - α and rpb 2 loci revealed differences between N. guizhouensis (GUCC 24-0197) and N. leucaenae (MFLUCC 17-0927), with 2 - bp and 16 - bp discrepancies, respectively. Based on these findings, N. guizhouensis is established as a new species.