Fusarium endophyticum N. Suwannar. 2023, sp. nov.

Fusarium endophyticum N. Suwannar. sp. nov. Figure 2.

MycoBank number: MB848095

Etymology:—“ endophyticum ” is based on the word “endophyte” from where the type strain was isolated.

Holotype:— THAILAND, Skad, Pua District, Nan Province, 19°15′42′′N 101°0′16′′E, elevation 994 m, isolated as an endophyte from leaves of Camellia sinensis var. assamica, 17 September 2017, N. Suwannarach, dried culture: SDBR-CMU465.

Culture characteristics:—Colonies diameters after 7 d at 25 and 30°C on the following agar: PDA 1.8–2.0 and 1.8–2.1 cm; OA 4.3–4.6 and 4.8–5.1 cm; and SNA 3.1–3.4 and 3.5–3.7 cm, respectively. Colonies on PDA grew to 2.8–3.3 and 3.3–3.7 cm, OA 7.7–8.2 and 7.9–8.5 cm, and SNA 5.8–6.1 and 6.2–6.5 cm at 25 and 30°C after two weeks of incubation, respectively. Colonies on PDA were flat with entire edges, yellowish white; reverse pale yellow. Colonies on OA were flat with entire edges, yellowish grey in the center, white at the margin; reverse greyish yellow. Colonies on SNA were white and flat with entire edges; reverse white. Pigment and odor were absent in PDA, OA, and SNA. Sporodochia were not found in PDA, OA, and SNA. Conidia forming were observed on PDA, OA and SNA within two weeks. Conidiophores were formed on aerial mycelium of a size of 8–150 × 1.2–2.9 µm, unbranched, and bearing terminal or lateral phialides. Phialides were mono- and polyphialidic, subulate to subcylindrical, hyaline, smooth and thin-walled, and of a size of 4.9–16.4 × 2.2–3.2 µm (av. ± SD: 10.7 ± 3.1 × 2.8 ± 0.3 µm). Chlamydospores were globose to sub-globose, intercalarily or terminal, hyaline, smooth-walled, solitary, or were present in pairs or formed chains, and a size of 6.7–16.0 × 5.8–12.6 µm (av. ± SD: 11.3 ± 2.5 × 9.0 ± 1.7 µm). Macroconidia ellipsoidal to falcate, straight, slightly curved, smooth to slightly rough, hyaline, apical cell pointed to blunt, basal cell papillate, 1–3-septate; 1-septate conidia 12.8–28.1 × 2.8–6.0 (av. ± SD: 18.8 ± 3.3 × 4.2 ± 0.6 µm); 2-septate conidia 17.5–32.6 × 3.2–5.5 µm (av. ± SD: 23.8 ± 3.1 × 4.3 ± 0.5 µm); 3-septate conidia 32.0–74.2 × 4.2–8.1 µm (av. ± SD: 52.4 ± 9.5 × 6.1 ± 0.8 µm). Microconidia were absent.

Additional specimens examined:— THAILAND, Skad, Pua District, Nan Province, 19°15′42′′N 101°0′16′′E, elevation 994 m, isolated as an endophyte from leaves of Camellia sinensis var. assamica, 17 September 2017, N. Suwannarach, living culture: SDBR-CMU466.

Known distribution:—Known only from northern Thailand.

Note:—The reddish and yellowish-to-orange colonies of F. sarcochroum and F. massalimae differ from those of F. endophyticum (Wollenweber 1917; Cavalcanti et al. 2020).Additionally, 1–3-septated macroconidia of F.endophyticum can be easily distinguished from F. citri-sinensis (3–6-septate macroconidia), F. lateritium (0–7-septate macroconidia), F. massalimae (3–7-septate macroconidia), and F. stilboides (0–16-septate macroconidia) (Gerlach & Nirenberg 1982; Geiser et al. 2005; Cavalcanti et al. 2020; Zhao et al. 2022). The colony characteristics of F.endophyticum also resemble those of F. cassiae and F. magnoliae-champaca. However, due to the indeterminate morphological characteristics of the asexual morph of F. cassiae and F. magnoliae-champaca, we cannot compare their microscopic structures (Perera et al. 2020).

Phylogenetically, F. endophyticum is closely related to F. lateritium Clade IIB. However, F. lateritium Clade IIB produced a red pigment on PDA with pinkish aerial mycelium (Geiser et al. 2005). Additionally, the genetic distance of tef-1 sequences of F. endophyticum to F. lateritium Clade IIB FRC L-120 and FRC L-82 were 1.95% (13/665 bp include gaps) and 2.10% (14/665 bp include gaps), respectively.