Fusarium rubicola M. W. Zhang & C. M. Tian, 2025

Fusarium rubicola M. W. Zhang & C. M. Tian sp. nov.

Fig. 5 View Figure 5

Type.

China • Shaanxi Province, Ningshan County Huoditang Shibazhang Waterfall Park (33°23'56.23"N, 108°22'9.93"E), on leaf of Rubus lambertianus , 19 Jul 2021, S. J. Li, holotype BJFC-H 187 , ex-type living culture CFCC 70819 GoogleMaps .

Etymology.

Named after the host genus from which it was isolated, Rubus .

Description.

Conidiophores in aerial mycelia, 27–90 μm tall, straight or flexuous, smooth- and thin-walled, unbranched, sympodial or irregularly branched, bearing terminal or lateral phialides; aerial phialides polyphialides, subulate to subcylindric, smooth- and thin-walled, periclinal thickening inconspicuous or absent, 5.9–35.8 × 1.9–4.3 μm; aerial conidia hyaline, smooth- and thin-walled, of two types: (a) microconidia ellipsoidal to clavate, aseptate, 7.9–42.7 × 1.7–4.3 μm (av. ± sd. 22.6 ± 7.6 × 3.0 ± 0.6 μm), clustering in discrete false heads at the phialide tips; (b) macroconidia slightly clavate to falcate, straight or gently dorsiventrally curved, with a blunt to slightly papillate apical cell and a blunt to gently notched basal cell, smooth- and thin-walled, 1–3 - septate; 1 - septate conidia: 15.9–41.5 × 2.7–5.1 μm (av. ± sd. 24.9 ± 4.4 × 4 ± 0.5 μm); 2 - septate conidia: 27–51 × 2.9–6.4 μm (av. ± sd. 36.7 ± 5.6 × 4.6 ± 0.8 μm); 3 - septate conidia: 26.9–82 × 2.1–6.3 μm (av. ± sd. 53.7 ± 11.7 × 4.6 ± 0.9 μm). Chlamydospores abundant, globose, subglobose to ovoid, subhyaline, smooth-walled, intercalary, solitary, in pairs or forming chains, 7.4–14.9 μm diam. Sporodochia not observed.

Culture characteristics.

Colonies on PDA growing in the dark reaching 7.8–8.0 cm diam after 7 days at 25 ° C, optimal 25–30 ° C (after 7 days), raised, aerial mycelia dense, colony margin entire, surface pale violet to mauve in the center, pale luteous to white at the margin; reverse livid purple in the center, pure yellow at the margin. Colonies on OA growing in the dark reaching 7.0– 7.2 cm diam after 7 days at 25 ° C, raised, aerial mycelia dense, colony margin crimp, surface pale purple in the center, white at the marginwhite; reverse vinaceous purple in the center, pale luteous at the margin. Colonies on SNA grown in the dark reaching 6.0– 6.2 cm diam after 7 days at 25 ° C, slightly raised, aerial mycelia scant, colony margin entire, white; reverse white. Pigment and odor absent.

Notes.

The isolates of F. rubicola were phylogenetically closely related to F. fractiflexum (ex-type, NRRL 28852 ) isolated from Cymbidium ssp. in Japan (Fig. 2 View Figure 2 ). There were 15 nucleotide position differences between the two species (8 / 667 in tef 1, 2 / 645 in CaM, 5 / 865 in rpb 1). The PHI analysis showed that there was no significant recombination between F. rubicola isolates and its related species (Φw = 1.0) (Fig. 3 B View Figure 3 ). Morphologically, F. fractiflexum forms yellowish colonies, while F. rubicola forms purple colonies on the PDA. Microscopically, the microconidia of F. fractiflexum are 0–3 septate, forming zigzag-like conidial chains, without chlamydospores. Nevertheless, the microconidia of F. rubicola are aseptate, lack zigzag-like conidial chains, and inherence chlamydospores. In conclusion, the phylogenetic and morphological evidence support this fungus being a new species within the FFSC.