Fusarium pascuum Dewing, Visagie & Yilmaz, 2025

Fusarium pascuum Dewing, Visagie & Yilmaz sp. nov.

Fig. 5 View Figure 5

Etymology.

Latin, pascuum , meaning pasture, referring to the species isolated from grass pastures.

Type.

South Africa • Eastern Cape, from mixed pasture samples, May 2020, collected by A. Davis (holotype: PRU (M) 4600 , dried specimen in a metabolically inactive state; ex-type strain: CBS 151772 View Materials = CMW 58653 View Materials = CN 159 G 4 = CN 071 C 4 ) .

Description.

Conidiophores borne on aerial mycelium, 15.5–101 μm tall, unbranched, sympodial or irregularly branched, bearing terminal or lateral phialides, often reduced to single phialides; aerial phialides mono- and polyphialidic, subulate to subcylindrical, proliferating percurrently, smooth- and thin-walled, 4–43 × 1–4.5 μm, with inconspicuous periclinal thickening; aerial conidia fusiform, falcate, slender, curved dorsiventrally and more pronounced on the apical half, tapering towards both ends, with a blunt to conical and straight to slightly curved apical cell and a blunt to papillate basal cell, 0–3 - septate conidia; 0 - septate conidia: 7–17 × 2–5 μm (av. 11.7 × 3.2 μm) (n = 34); 1 - septate conidia: 12–26 × 3–6 μm (av. 19.2 × 3.8 μm) (n = 14); 2 - septate conidia: 23–32 × 4–6 μm (av. 26.9 × 4.5 μm) (n = 7); 3 - septate conidia: 27–32 × 3–5 μm (av. 29.5 × 4.4 μm) (n = 2). Sporodochia and chlamydospores not observed.

Culture characteristics.

Colonies on PDA incubated at 25 ° C in the dark with an average radial growth rate of 3–10 mm / d, reaching 80 mm diam at 25 ° C; surface white, flat, felty to velvety, radiate, with abundant aerial mycelium, margin irregular, filiform. Additional colony diam (after 7 d, in mm): PDA at 10 ° C 13–15; PDA at 15 ° C 36–42; PDA at 20 ° C 63–65; PDA at 30 ° C 34–39; PDA at 35 ° C no growth. Odour absent. Reverse yellowish white (3 A 2). Diffusible pigments absent. On OA in the dark, occupying an entire 90 mm Petri dish in 7 d; surface white, flat, felty to velvety, radiate, with abundant aerial mycelium, margin irregular, filiform. Reverse yellowish white (3 A 2). Diffusible pigments absent. On SNA with sparse aerial mycelium, sporulation moderate on the surface of the medium.

Additional materials examined.

South Africa • Eastern Cape, from mixed pasture samples, May 2020, collected by A. Davis, isolated by C. Dewing, Humansdorp area : CMW-IA 003320 = CMW 61364 View Materials = CN 056 A 8 , CMW 58649 View Materials = CN 070 E 7 , CMW 58650 View Materials = CN 070 F 7 , CMW-IA 002133 = CMW 60931 View Materials = CN 070 I 3 , CMW 58651 View Materials = CN 070 I 4 , CMW 58652 View Materials = CN 071 B 8 , CMW 58654 View Materials = CN 071 D 3 , CMW 58655 View Materials = CN 071 E 9 , CMW 58662 View Materials = CN 104 D 6 , CMW 58663 View Materials = CN 104 D 7 , close to Kou-Kamma : CMW 58656 View Materials = CN 071 F 9 , Outside Humansdorp, close to Clarkson : CMW 58657 View Materials = CN 071 G 8 , CMW 58660 View Materials = CN 071 I 9 , CMW 58661 View Materials = CN 072 A 1 , close to Tsitsikamma on Sea : CMW 58658 View Materials = CN 071 I 3 , CMW 58659 View Materials = CN 071 I 5 .

Notes.

Fusarium pascuum belongs to the Camptoceras - clade (as introduced by Han et al. (2023)) and is closely related to F. fecundum . Both F. pascuum and F. fecundum produce aerial mono- and polyphialides. Aerial conidia from F. pascuum (0–3 - septate; 7–32 × 2–6 μm) are comparably smaller than those of F. fecundum (( 1 –) 2–4 (– 6) - septate; 3.6–35.8 × 3.6–6.8 μm) ( Han et al. 2023). Sporodochia and chlamydospores are absent in both F. pascuum and F. fecundum . Colony colour on PDA differs between F. pascuum and F. fecundum , where the former is completely white across the surface and the latter is greyish yellow in the centre, while the reverse of F. pascuum is yellowish white and F. fecundum is just white ( Han et al. 2023). The growth rate after 7 d on PDA in F. pascuum (reaching 80 mm) is slightly slower than that of F. fecundum (84–90 mm) ( Han et al. 2023). Pairwise comparisons revealed that F. pascuum differs from other species by at least 8, 8 and 23 bp for CaM, RPB 2 and TEF, respectively.