Fusarium semanoti Lin Huang, Jiao He, D. W. Li, sp. nov.

Fig. 8

Etymology.

semanoti, L. insect gen. n. of Semanotus, referring to the association with the cedar longhorned beetle, Semanotus bifasciatus.

Holotype.

China • Shandong Province, Jinan City, Beijiao State-owned Forest Farm, 36°46'03"N, 116°51'46"E, isolated from branch of Taxodium hybrid ‘ Zhongshanshan’, August 2024, Lin Huang, (holotype: CFCC 72663). Holotype specimen is a living specimen being maintained via lyophilisation at the China Forestry Culture Collection Center (CFCC). Ex-type (SG 3-38) is maintained at the Forest Pathology Laboratory, Nanjing Forestry University.

Host / distribution.

From the T. hybrid ‘ Zhongshanshan’ at the Beijiao State-owned Forest Farm, Jinan City, Shandong Province, China.

Description.

Sexual state not observed. Asexual state: sporulation abundant from sporodochia, rarely from conidiophores formed directly on the substrate mycelium. Conidiophores in the aerial mycelium absent. Sporodochia bright orange-coloured, formed abundantly on carnation leaves. Conidiophores in sporodochia (13.9 –) 18.1–25.4 (– 34.3) μm, (mean ± SD = 21.7 ± 3.6 μm, n = 36), irregularly branched and densely packed, bearing apical whorls of 1–2 phialides; sporodochial phialides subulate to subcylindrical, (6.5 –) 9.7–16.8 (– 24.6) × (3 –) 3.2–4.2 (– 4.8) μm, (mean ± SD = 13.3 ± 3.5 × 3.7 ± 0.5 μm, n = 31), smooth, thin-walled. Sporodochial macroconidia colourless, straight or slightly curved, wider at the middle or apical part, tapering towards the base, with a blunt and often curved apical cell and a foot-like to slightly notched basal cell, 3–5 - septate, smooth, thin-walled, (29.9 –) 34.3–44.5 (– 48.5) × (4.3 –) 4.7–5.6 (– 6) μm, (mean ± SD = 39.4 ± 5.1 × 5.2 ± 0.4 μm, n = 35). Chlamydospores developed in large numbers in hyphae, 0 - septate, globose to ellipsoidal, constricted at the septum, intercalary or terminal or solitary with mostly a pale colour and smooth, (6.7 –) 7.4–9.6 (– 11.2) × (6.1 –) 6.6–8.3 (– 9.7) μm, (mean ± SD = 8.5 ± 1.1 × 7.5 ± 0.8 μm, n = 34). Microconidia not observed.

Culture characteristics.

On PDA incubated at 25 ° C in the dark, colonies exhibited an average radial growth rate of 11.3 mm / d. The colony surface appeared white, with a felty to cottony texture. Abundant aerial mycelium was observed, ranging from loosely to densely floccose, with regular margins and fimbriate edges. The reverse side displayed a bright yellow pigmentation. No distinctive odour. On OMA under the same conditions, colonies developed regularly, completely covering the entire 70 - mm OMA plate within five days. The reverse side white with minimal grey pigmentation. On SNA incubated at 25 ° C in the dark, colonies grew uniformly at 10.66 mm / d. The colony surface was pure white, with sparse aerial mycelia that formed regular peripheral rings. The reverse side remained pure white, with no observable diffusible pigments.

Additional materials examined.

China • Shandong Province, Jinan City, Beijiao State-owned Forest Farm, 36°46'03"N, 116°51'46"E, isolated from branch of Taxodium hybrid ‘ Zhongshanshan’, August 2024, Lin Huang, isolates: SG 2-38-1 and SG 2-38-2.

Notes.

The isolates of F. semanoti were phylogenetically closely related to F. odoratissimum InaCC F 822 (ex-holotype) (Fig. 5). Between F. semanoti isolates and ex-holotype of F. odoratissimum InaCC F 822, there were 21 / 1432 differences in RPB 1, 1 / 838 in RPB 2 and 1 / 573 in TEF- 1 α. The PHI analysis showed that there was no significant recombination between F. semanoti isolates and its related species (Φ w = 1.0) (Fig. 6 A). Morphological analysis revealed that macroconidia produced by isolate SG 2-38 of F. semanoti (34.3–44.5 × 4.7–5.6 μm) were much smaller than those of the ex-holotype (InaCC F 822) of F. odoratissimum (44–79 × 6–8 μm), as characterised by Maryani et al. (2019). Another difference is that SG 2-38 of F. semanoti does not develop microconidia, while the ex-holotype (InaCC F 822) of F. odoratissimum does. Thus, F. semanoti is recognised as a new species in F. oxysporum species complex.