Pestalotiopsis koelreuteriae M. G. Liao & Jian Ma 2026, sp. nov.

Pestalotiopsis koelreuteriae M. G. Liao & Jian Ma sp. nov. Fig. 6 Type. China • Hunan Province, Zhangjiajie City, Zhangjiajie National Forest Park, on diseased leaves of Koelreuteria paniculata, 18 October 2024, M. G. Liao (HJAUP M 2757, holotype), ex-type living culture HJAUP C 2757.1 = HJAUP C 2757.2. Etymology. Named after the genus, Koelreuteria, from which the fungus was isolated. Description. Irregular leaf spots, pale brown in center with brown at margin. Asexual morph on PDA: Conidiomata acervular, globose to clavate, 610–750 μm diam., solitary or aggregated in clusters, black. Conidiophores indistinct and reduced to conidiogenous cells. Conidiogenous cells hyaline, smooth, cylindrical to ampulliform. Conidia fusiform, straight or slightly curved, 18.3–26.9 × 4.1–6.0 μm (x ̄ = 22.7 × 5.3 μm, n = 50), 4 - septate, slightly constricted at the septa; basal cell conical, 2.7–4.6 μm (x ̄ = 3.9 μm), hyaline or sometimes pale brown, smooth, thin-walled, with a single filiform appendage, unbranched, 3.4–6.7 μm (x ̄ = 4.9 μm) long; three median cells doliiform to cylindrical, smooth, thick-walled, 12.8–17.3 μm (x ̄ = 15.2 μm), concolorous, brown, somewhat constricted at the septa, second cell from the base 3.4–6.6 µm (x ̄ = 4.8 μm) long, third cell 3.4–6.5 µm (x ̄ = 5.3 μm) long, fourth cell 3.8–6.6 µm (x ̄ = 5.2 μm) long); apical cell conical to acute, hyaline, smooth, thin-walled, 2.5–5.1 µm (x ̄ = 3.5 μm) long, with 1–3 (mostly 2) filiform appendages, arising from the apex of the apical cell each at a different point, unbranched, 8.1–18.5 µm (x ̄ = 13.2 μm) long. Sexual morph: not observed. Culture characteristics. Colonies on PDA grow fast, filamentous, reaching 50–60 mm diam. after 5–7 days at 25 ° C in light and dark conditions (8 h / 16 h), white, with flocculent mycelium and entire edge, forming black conidiomata, and reverse pale orange. Note. Phylogenetic analyses revealed that the two strains (HJAUP C 2757.1 T and HJAUP C 2757.2) of P. koelreuteriae form a distinct clade sister to P. fraseri (HJAUP C 1693.1 T, HJAUP C 1693.2, HJAUP C 1693.3, and HJAUP C 1693.4) with 100 % ML / 1.00 BI bootstrap support (Fig. 1). The nucleotide divergences and morphological differentiations between P. koelreuteriae and P. fraseri have been delineated in the preceding section. Comparisons of nucleotides showed 13 bp (2.1 %, including three gaps) in the ITS region. Based on the criteria established by Jeewon and Hyde (2016), a divergence of more than 1.5 % in the ITS nucleotide sequence can support the recognition of a novel species. Thus, P. koelreuteriae was proposed as a new species.