Xylolentia chishuiensis Y. R. Sun & H Zhang sp. nov.

Fig. 4

Etymology.

The epithet refers to the Chishui River Basin, the location where the taxon was collected.

Holotype.

KUN- HKAS 154381.

Description.

Saprobic on submerged bamboo culms in the Chishui River. Asexual morph: Hyphomycetous. Colonies on natural substrate effuse, white, hairy, visible as solitary, brown conidiophores with white conidial masses at the apex. Mycelium immersed, composed of septate, branched, hyaline hyphae. Conidiophores 80–110 μm long, 3–4 μm wide, macronematous, mononematous, solitary, erect, straight or curved, cylindrical, unbranched, 6–9 - septate, brown, becoming pale brown at the apex, smooth-walled, tapering towards the apex. Conidiogenous cells 20–38 × 2.5–3.5 μm (x ̄ = 28 × 3 μm, n = 15), polyblastic, integrated, terminal, determinate, cylindrical to cylindric-lageniform, pale brown near the base, subhyaline to hyaline towards the apex. Conidia 2.5–4 × 1.5–2.5 μm (x ̄ = 3 × 1.8 μm, n = 50), acrogenous, aggregated in slimy masses, ellipsoidal to subglobose, aseptate, hyaline, smooth-, thin-walled. Sexual morph: Undetermined.

Culture characteristics.

Conidia germinated on PDA within 12 hours at 25 ° C. Germ tubes were produced from both ends. Colonies on PDA reaching 20 mm in diam after 4 weeks at room temperature, circular, entire, moderate mycelial density, raised-convex. Surface dry, velvety-floccose, matte; obverse centrally dark brown, peripherally pale brown; reverse uniformly dark brown, no diffusible pigment. Mycelia woolly, centrally compact, marginally loose-floccose.

Material examined.

China • Guizhou Province, Zunyi City, Renhuai City, Maotai Town, on submerged bamboo culms in the Chishui River, 4 October 2025, H. Zhang, Z 112 (KUN- HKAS 154381, holotype, ex-type culture GZCC 26-0001; ibid., GZAAS 26-0004, isotype).

Notes.

BLAST searches of the newly generated sequences against the NCBI Nucleotide Database confirmed the genetic distinctiveness of the taxon, with sequence identities of 95.46 % (ITS), 99.50 % (LSU), and 99.89 % (SSU) relative to the closest sequences from the same genus. Xylolentia chishuiensis is phylogenetically sister to X. oblongispora (GZCC 18-0054) with high support (ML - BS = 100 %, PP = 1) (Fig. 2). Morphologically, X. chishuiensis can be distinguished from X. oblongispora by its shorter and narrower conidiophores (80–110 × 3–4 μm vs. 91–219 × 3.5–8.5 μm) and its smaller, ellipsoidal to subglobose conidia (2.5–4 × 1.5–2.5 μm vs. 3.6–5.3 × 2.2–3.2 μm) (Lin et al. 2025). In contrast, X. oblongispora produces oblong conidia with obtuse ends and guttules (Lin et al. 2025). Additionally, the two species exhibit a difference of 17 / 502 base pairs (3.4 %, without gap) in the ITS region and 20 / 850 base pairs (2.4 %, without gap) in the tef 1 - α region. Based on this combined molecular and morphological evidence, Xylolentia chishuiensis is described as a new species.