Corynespora septata J. Y. Zhang, Y. Z. Lu & K. D. Hyde, 2025

Corynespora septata J. Y. Zhang, Y. Z. Lu & K. D. Hyde sp. nov.

Fig. 4 View Figure 4

Etymology.

Named after the presence of eu-septate conidia.

Holotype.

HKAS 129839 View Materials .

Description.

Saprobic on dead rachis of an unidentified fern in terrestrial habitats. Sexual morph undetermined. Asexual morph Colonies on natural substrate superficial, effuse, gregarious, hairy, brown to black. Mycelium partly superficial, partly immersed, composed of branched, septate, pale brown to brown, smooth-walled hyphae. Conidiophores 490–671 µm long, 3.5–6.5 µm wide at the base (x ̄ = 600 × 5 µm, n = 15), macronematous, mononematous, erect, straight or flexible, unbranched, or occasionally branched, septate, smooth, dark brown at the base, pale towards the apex. Conidiogenous cells 21–60 × 3–5.5 µm (x ̄ = 36.3 × 3.8 µm, n = 15), integrated, terminal, monotretic, cylindrical, smooth, pale brown to brown. Conidia 42–74 × 4.5–7.5 µm (x ̄ = 54 × 5.7 µm, n = 25), acrogenous, solitary, up to 7 - distoseptate with one true septum, straight or slightly curved, subcylindrical to obclavate, rounded at the apex, base short obconically truncate, somewhat thickened and darkened, sometimes with percurrent proliferation which forms another conidium from the conidial apex, hyaline to pale brown.

Culture characteristics.

Conidia germinating on WA within 15 h and germ tube produced from conidia. Colonies growing on PDA, reaching 55 mm diameter in 10 days at 26 ° C, circular, flat with entire margin, velvety, fluffy, white from above, reverse dark brown at center, paler to light yellow towards margin, and not producing pigmentation in culture.

Material examined.

China • Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Mengla County, Menglun Town, Xishuangbanna Tropical Botanical Garden , Chinese Academy of Sciences (21°55'39"N, 101°15'15"E), on dead rachis of an unidentified fern, 16 November 2019, J. Y. Zhang, Y 159 ( HKAS 129839 View Materials , holotype; GZAAS 23–0769 , isotype), ex-type living culture, GZCC 23–0741 GoogleMaps .

Notes.

A BLASTn search in NCBI-GenBank revealed that the LSU and ITS sequences of our newly collected strain of Corynespora septata exhibited 99 % similarity to C. encephalarti ( NG _067878 ) and 95.62 % similarity to C. cassiicola ( MN 648322 View Materials ), respectively. Phylogenetic analysis confirmed that C. septata formed a distinct clade within Corynespora and shared a sister relationship with C. pseudocassiicola Crous & M. J. Wingf. (Fig. 3 View Figure 3 ). There are 10 bp (10 / 841 bp with 0 gap, 1 %) and 38 bp (38 / 527 bp with 13 gaps, 7 %) differences between the C. pseudocassiicola and C. septata in the LSU and ITS gene regions, respectively. Morphologically, C. septata has longer conidiophores (490–671 µm vs. 200–400 µm), and smaller conidia (42–74 × 4.5–7.5 µm vs. 95–160 × 9–10 µm) compared to C. pseudocassiicola ( Crous et al. 2018) . Similarly, C. septata is most similar to C. lignicola Z. L. Luo, H. Y. Su & K. D. Hyde in the shapes of conidiophores, conidiogenous cells, and conidia ( Capital and Lao 2020). However, C. septata differs from C. lignicola in having narrower conidiophores (3.5–6.5 µm vs. 9–13 µm) and notably smaller conidia (42–74 × 4.5–7.5 µm vs. 110–156 × 7–9 µm).