Aureobasidium tremulum Inamdar, Roh. Sharma & Adhapure
Authors: Senwanna, Chanokned, Kodchasee, Pratthana, Kathongthung, Chirayut, Samarakoon, Milan C., Khunnamwong, Pannida, Kumla, Jaturong, Suwannarach, Nakarin
Type: Taxonomic treatment
Published: 2026-08-03
Keywords: Biodiversity, Taxonomy, Fungi, Ascomycota, Dothideomycetes, Dothideales, Saccotheciaceae, Aureobasidium, Aureobasidium tremulum

<p><i>Aureobasidium tremulum</i> Inamdar, Roh. Sharma & Adhapure, Persoonia 42: 383 (2019)</p><p>Fig. 25</p><p><b>Cultural characteristics.</b></p><p>After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 27–30 mm diam., surface flat, spreading with irregular, lobate margin, orange white (5 A 2), light gray (5 B 2) at the margin; on MEA reaching 24–35 mm diam., surface flat, spreading with irregular margin, velvety, purplish gray (14 D 2) in outer ring, brownish gray (4 E 2) towards to the center; on OA 30–50 mm diam., surface flat, spreading with irregular margin, velvety, aerial mycelium sparse, floccose, light gray (4 B 1) in outer ring, grayish brown (5 E 3) towards to the center, yellowish brown (5 E 8) at center.</p><p><b>Description.</b></p><p><i><i>Anamorph</i> in vitro</i> dematiaceous hyphomycetes. <i>Vegetative hyphae</i> (2.4 –) 4.0–5.8 (– 7.6) μm wide, mostly hyaline, branched, septate, smooth-, thin-walled, getting darker and thicker, constricted at the septa, minutely echinulate with age, anastomosis observed. <i>Conidiogenous cells</i> (8.5 –) 9.5–17.5 (– 20.6) × (3.7 –) 5.2–7.0 (– 8.5) μm (<i>x ̄</i> = 13.9 × 6.1 μm, <i>n</i> = 25), undifferentiated, intercalary, rarely terminal, or producing conidia percurrently from short lateral denticles, giving rise to conidia that aggregate in a mucoid mass, or differentiated from hyphae. <i>Conidia</i> (4.6 –) 6.8–10.0 (– 17.3) × (2.8 –) 3.9–5.5 (– 7.2) μm (<i>x ̄</i> = 8.1 × 4.5 μm, <i>n</i> = 170), fusoid, obovoid to ellipsoid, or oval, or globose, hyaline, becoming light brown to brown with age, aseptate, occasionally with an indistinct truncated base and a hilum, minutely echinulate, budding occasionally observed. <i>Chlamydospores</i> (7.0 –) 8.5–13.0 (– 16) μm wide (<i>x ̄</i> = 10.6 μm, <i>n</i> = 30), frequent produced in aerial hyphae, mostly intercalary, solitary or in branched chains, sub globose to ellipsoidal, pigmented, light to dark brown, smooth-, thick-walled, septate, constricted near the septa. <i>Endoconidia</i> absent.</p><p><b>Cardinal temperatures for growth.</b></p><p>Minimum 10 ° C, optimum in the range of 25 ° C to 30 ° C. No growth at 4 ° C and 37 ° C.</p><p><b>Strains examined.</b></p><p>THAILAND • Chiang Mai Province, Mueang District, Chang Phueak, isolated from Spanish needle flower (<i>Bidens pilosa</i>; <i>Asteraceae</i>, <i>Asterales</i>), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 814; isolated from Carey rose flower (<i>Rosa hybrida</i> ‘ AUSweather’; <i>Rosaceae</i>, <i>Rosales</i>), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 820; isolated from holy basil flower (<i>Ocimum tenuiflorum</i>; <i>Lamiaceae</i>; <i>Lamiales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 856); Chiang Mai Province, Mueang District, Suthep, isolated from American cassia flower (<i>Senna spectabilis</i>; <i>Fabaceae</i>, <i>Fabales</i>), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 816 and SDBR-CMU 834; Phayao Province, Mueang District, isolated from tropical hibiscus flower (<i>Hibiscus rosa-sinensis</i>; <i>Malvaceae</i>, <i>Malvales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 838 F 277.</p><p><b>Habitat and distribution.</b></p><p>From laboratory contaminants in India (Crous et al. 2019); flowers of <i>Bidens pilosa</i>, <i>Hibiscus rosa-sinensis</i>, <i>Ocimum tenuiflorum</i>, <i>Rosa hybrida</i> ‘ AUSweather, ’ and <i>Senna spectabilis</i> in Thailand (this study).</p><p><b>Notes.</b></p><p>Phylogenetically, strains SDBR-CMU 814, SDBR-CMU 816, SDBR-CMU 820, SDBR-CMU 834, SDBR-CMU 838, and SDBR-CMU 856 belonged to the <i>A. tremulum</i> clade (Fig. 2), which formed a sister clade to <i>A. oroxyli</i>. The differences in sequence data and morphological characteristics between <i>A. tremulum</i> and <i>A. oroxyli</i> are mentioned above. However, the morphological characteristics of the strains could not be compared with those of the type strain of <i>A. tremulum</i> because it is known only from its yeast form (Crous et al. 2019). Comparisons of the ITS, LSU, <i>rpb 2</i>, and <i>tub</i> sequences among <i>A. tremulum</i> strains SDBR-CMU 834 and SDBR-CMU 838 and strains SDBR-CMU 816 and SDBR-CMU 820 showed no significant differences. Although strains SDBR-CMU 814 and SDBR-CMU 856 formed a sister clade to <i>A. tremulum</i> and differed by only 3.2 % (9 / 277 bp, including gaps) in the <i>tef 1</i> sequence, their morphological characteristics, growth temperature, and the currently available data do not support recognition as a distinct species. Until morphological data and sequences of reliable genes (<i>rpb 2</i>, <i>tef 1</i>, and <i>tub</i>) from the type strain are obtained and verified, these strains are therefore treated as <i>A. tremulum</i>. This study represents the first report of <i>A. tremulum</i> in Thailand.</p>