Aureobasidium catharanthi Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov.

Fig. 9

Etymology.

Refers to the host genus Catharanthus, from which this species was isolated.

Type.

THAILAND • Phayao Province, Mueang District, isolated from vinca flower (Catharanthus roseus; Apocynaceae, Gentianales), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, holotype = CMUB 40140 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 842 = GMBCC 2503.

Cultural characteristics.

After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 36–44 mm diam., surface flat, spreading, round with radiating margin, velvety, olive brown (4 E 6), with grayish yellow (4 B 6) at the margin; on MEA reaching 55–60 mm diam., surface flat, spreading with lobate margin, velvety, shiny, grayish yellow (4 B 6), with olive brown (4 E 5) mixed with grayish yellow (4 B 6) at the margin; on OA 60–68 mm diam., surface flat, spreading with filiform, entire margin, velvety, slimy, light gray (3 D 1), with dark gray (3 F 1) at the margin.

Description.

Anamorph in vitro dematiaceous hyphomycetes. Vegetative hyphae (3.9 –) 5.0–10.0 (– 16.0) μm, hyaline to brown, branched, septate, smooth, thin-walled, becoming light brown to brown with age, constricted at the septa, thick-walled. Conidiogenous cells (6.8 –) 9.3–13.0 (– 20.1) × 4.0–6.0 μm (x ̄ = 10.2 × 5.3 μm, n = 25), undifferentiated, intercalary, terminal, producing conidia percurrently from short lateral denticles, or differentiated on hyphae, occasionally elongated, solitary, light brown to brown. Conidia obovoid to ellipsoidal, or subglobose, hyaline, aseptate, occasionally with an indistinct truncated base and a hilum, smooth-walled, guttulate, (5.4 –) 6.8–11.5 (– 14.2) × (3.3 –) 4–5.3 (– 6.4) μm (x ̄ = 8.9 × 4.7 μm, n = 150), budding occasionally observed. Chlamydospores (8.0 –) 9.5–14.8 (– 18.1) μm wide (x ̄ = 12.2 μm, n = 30), frequent produced in aerial hyphae, mostly intercalary, solitary or in branched chains, globose to subglobose, light to dark brown, smooth-, thick-walled, septate, 1–2 cells, constricted near the septa. Endoconidia absent.

Fermentation of glucose is negative. D - glucose, galactose, sorbose, N - acetyl glucosamine (weak), ribose, xylose, L - arabinose, D - arabinose, L - rhamnose, sucrose, maltose, α - α - trehalose, methyl- α - D - glucoside (weak), cellobiose, salicin (weak), melibiose, lactose (weak), raffinose, melizitose, glycerol (weak), erythritol (weak), ribitol (weak), glucitol, mannitol, galactitol, myo - inositol, D - glucono- 1, 5 - lactone (weak), D - gluconate, D - glucuronate, D - galacturonic acid (weak), DL - lactate (weak), succinate (weak), citrate (weak), ethanol, and xylitol are assimilated, but inulin, soluble starch, and methanol are not assimilated. Ammonium sulfate, ethylamine hydrochloride, L - lysine, cadaverine, and creatine are assimilated as sole nitrogen sources. Potassium nitrate and sodium nitrite are not assimilated. After 3 weeks, light brown sediment formed in D - glucose, D - galactose, L - sorbose, salicin, D - galacturonic acid, succinate, and citrate, while dark brown sediment formed in N - acetyl glucosamine, ribitol, D - glucono- 1, 5 - lactone, D - gluconate, D - glucuronate, and xylitol. Black sediment formed in methyl- α - D - glucoside, glycerol, and erythritol, while white sediment observed in ethanol.

Cardinal temperatures for growth.

Minimum 10 ° C, optimum in the range of 25 ° C to 30 ° C. No growth at 4 ° C and 37 ° C.

Additional strains examined.

THAILAND • Phayao Province, Mueang District, isolated from vinca flower (Catharanthus roseus; Apocynaceae, Gentianales), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 812.

Habitat and distribution.

Flowers of Catharanthus roseus. Known only from northern Thailand.

Notes.

Phylogenetic analyses showed that A. catharanthi formed a distinct monophyletic lineage and was sister to A. bougainvilleae, with 77 % MLBS and 0.96 BIPP support (Fig. 2). The differences in sequence data, morphological characteristics, and physiological traits between A. catharanthi and A. bougainvilleae are described above. Therefore, A. catharanthi is introduced here as a new species.