Phaeoseptum biyangense W. X. Su, R. Xu & X. Li, 2025

Phaeoseptum biyangense W. X. Su, R. Xu & X. Li sp. nov.

Fig. 5 View Figure 5

Etymology.

Refers to the type locality, Biyang County.

Description.

Saprobic on dead branches of Fagaceae . Sexual morph: Ascomata 415–445 × 467–606 μm (x ̄ = 432 × 525 µm, n = 5), solitary to gregarious, depressed, immersed, globose to subglobose, irregular, convex, without ostiole. Peridium 18–25 μm (x ̄ = 23.5 μm, n = 10) wide, multi-layered, comprising 5–9 layers of cells of textura angularis, thick-walled, dark brown to brown cells of outer layers, and hyaline cells of inner layers. Hamathecium comprising 1–2.2 μm (x ̄ = 1.4 µm, n = 20) wide, dense, numerous, branched, cellular pseudoparaphyses, extending above the asci, embedded in a gelatinous matrix. Asci 152–170 × 25–32 μm (x ̄ = 164 × 27 μm, n = 20), 8 - spored, bitunicate, fissitunicate, cylindrical to clavate, apically rounded, with an ocular chamber, long pedicellate. Ascospores 34–47 × 9–12 μm (x ̄ = 39 × 11 μm, n = 30), overlapping, 1–2 - seriate, oblong to broadly fusiform, slightly curved, initially hyaline, becoming pale to yellowish brown, smooth-walled, muriform, with 9–18 - transverselly septa, 0–4 longitudinal septa in each row, slightly constricted at septum, cell above median septum slightly enlarged, tapering towards both ends, broadly rounded or truncate at apex and base, guttulate, without sheath or appendages. Asexual morph: undetermined.

Culture characteristics.

Single ascospores germinate on PDA within 24 h. Colonies growing on PDA at 25 ° C, dark, reaching 37 mm diam after four weeks. Cultures from above, circular, dense, gray, curled, floccose, umbonate, dentate, and iron gray at the margins; reverse was dark gray, with white, sparse hyphae radiating outward.

Material examined.

China, • Henan Province, Biyang , from the branches of Fagaceae , 12 June 2023, Wenxin Su, HN 02 ( HMJAU 70076 , holotype); ex-type living culture, EMFCC 0045 ; ex-isotype living culture, EMFCC 0048 .

GenBank accession number.

EMFCC 0045 : ITS = PQ 686747, SSU = PQ 686299, LSU = PQ 686300, tef 1 - α = PQ 724421. EMFCC 0048 : ITS = PV 463748, SSU = PV 490598, LSU = PV 490600, and tef 1 - α = PV 670038.

Notes.

Morphological comparisons revealed that the ascomata of Phaeoseptum biyangense are considerably larger than those of related species, P. zhujiangyuanense , P. mali , and P. manglicola (415–445 × 467–606 μm vs. 215–470 × 150–320 μm vs. 320–375 × 320–360 μm vs. 210–420 × 170–374 μm) ( Phukhamsakda 2019; Dayarathne 2020; Zhang et al. 2024). The ascospores of P. biyangense possess more septa (9–18 vs. 7–13 vs. 11–14 vs. 9–13) and wider dimensions compared to P. zhujiangyuanense , P. mali , and P. manglicola (34–47 × 9–12 vs. 35–42 × 9–15 vs. 27–38 × 8–13 vs. 27–36 × 7.5–13). Notably, P. biyangense lacks distinct ostioles ( Zhang et al. 2017, 2024; Phukhamsakda 2019; Dayarathne 2020; Jayawardena et al. 2022). In the multi-locus phylogeny, P. biyangense showed close affinity to P. manglicola ( NFCCI 4666 ). The ITS, LSU, SSU, and tef 1 - α base pair differences between two species (excluding gaps) are 3 / 413 bp (0.61 %), 3 / 790 bp (0.38 %), 198 / 1034 bp (11.91 %), and 3 / 757 bp (0.40 %), respectively. Thus, we describe P. biyangense as a novel species.