Xenodidymella guizhouensis S. Q. Guo, K. D. Hyde & Yong Wang bis, 2025

Guo, Shi-Qi, Norphanphoun, Chada, Hyde, Kevin D., Fu, Sha-Min, Sun, Jing-E, Wang, Xing-Chang, Wu, Jiao-Jiao, Al-Otibi, Fatimah & Wang, Yong, 2025, Three novel species and a new record of Pleosporales (Didymellaceae, Roussoellaceae) from China, MycoKeys 113, pp. 295-320 : 295-320

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

Fig. 5

Etymology.

The name refers to Guizhou Province, where the fungus was collected.

Type.

China • Guizhou Province, Guiyang City , 26°6'N, 106°6'E, 1071 m, 7 September 2023, from dead wood culms, coll. S. M. Fu, HGUP 24-0073 (holotype), ex-type culture GUCC 24-0205 (ITS: PQ 404876 , rpb 2: PQ 399763, β-tubulin: PQ 399760) .

Description.

Saprobic on dead wood culms. Sexual morph: undetermined. Asexual morph: Stromata grow above the epidermis and become hemispherically raised when mature. Stromata 61–587 µm high, 67–489 µm wide, fattened at the base, those stromata distributed singly, in groups, or scattered, and their color ranges from dark brown to black. On PDA medium, grows on epidermis and bulges when matures. Conidiophores degenerated into sporogenous cells. Conidiogenous cells 8–17 × 1–5 µm (x ̄ = 17.9 × 2.6 µm, n = 10) wide, phialidic, ampulliform, or lageniform, hyaline, smooth-walled, and have two types of spore-producing structures: one type, long, thin tentacles that extend irregularly outward, other type, short and wide, and twisted together to form knots, and the ends of both rounded. Conidia (1.7 –) 2.7–2.8 (– 3) × (0.7 –) 0.9–1 (– 1.5) µm (x ̄ = 2.5 × 1 µm, n = 50) oblong, hyaline, aseptate, with two small polar guttules at both ends, smooth, thin-walled.

Culture characteristics.

Colonies on PDA reached a diameter of 20 mm after seven days at 25 ° C. Hyphae white at the center, radiating outward from a pale-yellow inner ring to a light yellowish-brown periphery with a milky white outer ring. The colony reverse exhibited a dark yellow to bright yellow pigmentation.

Colonies on OA reached 32 mm after seven days at 25 ° C. Initially, it was a small circle formed by uniform and sparse white hyphae. After 14 days, it grew into slightly sparse hyphae with white clutter inside and dense white hyphae at the edge in a slightly regular circle. On the surface, hyphae balls with uneven sizes from orange to white and tiny black spots were scattered, and sporogenous structures could be observed.

Material examined.

China • Guizhou Province, Guiyang City , 26°6'N, 106°6'E, 1071 m, 7 September 2023, from dead wood culms, coll. S. M. Fu, HGUP 24-0073 (holotype), living culture GUCC 24-0205 , GUCC 24-0206 , and GUCC 24-0207 .

Notes.

Phylogenetic analyses (Fig. 2 ) revealed that the three isolates ( GUCC 24-0205 , GUCC 24-0206 , and GUCC 24-0207 ) formed an independent branch. In morphology, they can be distinguished from Xenod. clematidis by their smaller conidiogenous cells (10–17 (– 20) × 1–2 µm vs. 2–6 (– 12) × 2.3–3.3 µm), although the conidiogenous cell size for Xenod. saxea remains undetermined. Additionally, Xenod. guizhouensis produces smaller conidia than both Xenod. clematidis and Xenod. saxea (2.9–4.3 × 1.7–2.4 µm vs. 4–8 × 2–5 µm and 3.5–7.5 × 2.5–4 µm), respectively.

Figures

Figure 2. The phylogenetic tree generated from maximum likelihood analysis based on combined ITS, β-tubulin, and rpb 2 sequence data for 22 strains of Xenodidymella. This tree is rooted with Didymella subrosea (CBS 733.79) and D. subglobispora (CBS 364.91). Maximum likelihood bootstrap values ≥ 50 % and Bayesian posterior probabilities ≥ 0.80 (MLBS / BIPP) are given at the nodes. The species obtained in this study are blue, and the ex-type taxa are bold. Bar: 0.03 represents the estimated number of nucleotide site substitutions per branch.

Figure 5. Xenodidymella guizhouensis (GUCC 24-0205, holotype) a cultures on PDA from above and below b appearance on host surface c, d black ascostromata on host surface e – h conidiophores, conidiogenous cells, conidia. Scale bars: 500 µm (c); 100 µm (d); 2.5 µm (e); 12.5 µm (f); 5 µm (g); 2.5 µm (h).