Aureobasidium albui Jumbam & Aime, Persoonia 54: 171 (2025)

Fig. 5

Cultural characteristics.

After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 32–40 mm diam., surface flat, spreading, round with radiating, irregular margin, velvety, slimy, fluffy, yellowish white (2 A 2), paler at the margin; on MEA reaching 40–50 mm diam., spreading, round with radiating, irregular margin, velvety, slimy, grayish brown (7 F 3) at center, becoming yellowish brown (5 E 4) to smoke brown (4 E 2) and white at the margin; on OA 35–47 mm diam., surface flat, spreading with entire margin, velvety, fluffy, whitish gray, light gray at the margin.

Description.

Anamorph in vitro dematiaceous hyphomycetes. Vegetative hyphae (2.6 –) 3.5–7.5 (– 9.6) μm wide, mostly hyaline, branched, septate, smooth, thin-walled; become light brown to brown with age, constricted at the septa, thick-walled. Conidiogenous cells (4.4 –) 6.0–11.0 (– 16.2) × 2.5–5.4 (– 6.7) μm (x ̄ = 8.6 × 4.3 μm, n = 25), mostly undifferentiated, intercalary, rarely terminal, producing conidia percurrently from indistinct, short lateral denticles, or differentiated on hyaline hyphae, occasionally elongated, solitary, becoming light brown to dark brown with age. Conidia (4.3 –) 5.9–9.8 (– 13.6) × (2.3 –) 3.2–5.6 (– 7.0) μm (x ̄ = 8.0 × 4.4 μm, n = 180), fusoid, obovoid to ellipsoidal or occasionally elongate, hyaline to light brown, aseptate, guttulate, smooth-walled, becoming brown with age, budding occasionally observed. Chlamydospores (5 –) 6.5–9.5 (– 11.2) μm wide (x ̄ = 8.1 μm, n = 35), produced in aerial hyphae, mostly intercalary, solitary or in branched chains, subglobose to ellipsoidal, pigmented, light to dark brown, smooth-, thick-walled, septate, 1–2 cells, constricted near the septa. Endoconidia (3.7 –) 4.2–5.8 × 2.3–3.5 μm (x ̄ = 4.9 × 2.9 μm, n = 20), obovoid to ellipsoidal, hyaline, occasionally seen in intercalary hyphal cells.

Cardinal temperatures for growth.

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

Strain examined.

THAILAND • Chiang Mai Province, Mueang District, Suthep, isolated from white cheesewood flower (Alstonia scholaris; Apocynaceae, Gentianales), Sep 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 866.

Habitat and distribution.

Phylloplane of Cyrtomium falcatum and unidentified leaf in the USA (Jumbam et al. 2025); flowers of Alstonia scholaris in Thailand (this study).

Notes.

In the phylogenetic tree, strain SDBR-CMU 866 formed a well-supported clade with A. albui NRRL 61482 (ex-type), with 100 % MLBS and 1.0 BIPP support (Fig. 2). Morphologically, strain SDBR-CMU 866 is generally consistent with the type description of A. albui by Jumbam et al. (2025); however, detailed observations of some structures (e. g., conidiophores and conidiogenous cells) were not provided. Therefore, strain SDBR-CMU 866 was identified as A. albui, and an updated morphological description of the species is provided herein. Prior to this study, A. albui had been reported only from the leaf phylloplane in the USA (Jumbam et al. 2025). This study represents the first report of A. albui in Thailand.