Xenoroussoella triseptata Mapook & K. D. Hyde

Xenoroussoella triseptata Mapook & K. D. Hyde, Fungal Diversity 101: 93 (2020) Fig. 6 Description. Saprobic on dead wood culms. Sexual morph: see Mapook et al. (2020). Asexual morph: Pycnidia on natural host, stromatic, developing above the epidermis and becoming raised when mature. Stromata 60–786 × 43–306 µm (x ̄ = 320.8 × 172.0 µm, n = 10), with a color ranging from dark brown to black, rough surface with tiny protrusions, some exhibit a certain degree of gloss. and exhibit circular, oval, or irregular shapes, adhering tightly to the surface of decaying wood. On PDA medium, Conidiophores reduced to conidiogenous cells. Conidiogenous cell 8–17 × 2–5 µm (x ̄ = 11.5 × 3 µm, n = 10), enteroblastic, indeterminate, discrete, unbranched, clavate or ampulliform, aseptate, hyaline, smooth-walled. Conidia (3.3 –) 3.7–3.8 (– 4.7) × (2.8 –) 3.1–3.2 (3.6) µm (x ̄ = 3.8 × 3.2 µm, n = 50), oblong to ellipsoid or rounded to obtuse ends, aseptate, hyaline to pale yellow, smooth-walled. Culture characteristics. Under dark conditions at 25 ° C, the colony reaches a diameter of 15 mm within seven days on PDA medium. The colony is dense, smooth, and irregularly shaped, with a lace-like margin and compact structure. The center is grayish-white, bordered by a white lace-like margin, while the outer edge is grayish-black. The reverse side of the colony is black, producing a dark pigment. Distribution. China, Korea, Thailand. Material examined. China • Guizhou Province, Guiyang City, 26°6'N, 106 ° 73 ' E, 1071 m, 7 September 2023, from dead wood culms, coll. J. E. Sun, HGUP 24-0074 (holotype), ex-type: GUCC 24-0202 (ITS: PQ 404879, LSU: PQ 475839, rpb 2: PQ 399766, ef 1 - α: PQ 438566), living culture: GUCC 24-0203 and GUCC 24-0204. Notes. Phylogenetic analyses (Fig. 1) revealed that the newly isolated strains (GUCC 24-0202, GUCC 24-0203, and GUCC 24-0204) clustered closely with two strains of Xenoroussoella triseptata (MFLUCC 17-1438 and KNUF-20-NI 009). This species was initially reported from dead stems of Chromolaena odorata in Thailand, with its sexual morph documented by Mapook et al. (2020). Subsequently, Ryu et al. (2022) described an asexual morph of this species isolated from soil in Korea. In the current study, sequence data from the ITS, LSU, ef 1 - α, and rpb 2 loci of newly isolated strains were identical to those of X. triseptata, confirming their conspecific status. The morphological characteristics of the asexual morph of the new strains were consistent with those previously described by Ryu et al. (2022) based on observations from the PDA medium. Conidiogenous cells were ampulliform to doliiform, producing unicellular conidia. Conidia were globose to ellipsoid with a blunt apex containing one or two guttules. The conidia contained one or two guttules, measuring 2.7–5.1 × 1.6–3.3 µm (Ryu et al. 2022). Thus, GUCC 24-0202, GUCC 24-0203, and GUCC 24-0204 were identified as Xenoroussoella triseptata, marking the first recorded occurrence in China.