Aureobasidium floricola Senwanna, Kodchasee, J. Kumla & N. Suwannar. 2026, sp. nov.
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 floricola

<p><i>Aureobasidium floricola</i> Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov.</p><p>Fig. 12</p><p><b>Etymology.</b></p><p>Refers to its association with flowers, the substrate from which this species was isolated.</p><p><b>Type.</b></p><p>THAILAND • Chiang Mai Province, Mueang District, Chang Phueak, isolated from kumquat flower (<i>Citrus japonica</i>; <i>Rutaceae</i>, <i>Sapindales</i>), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, <i>holotype</i> = CMUB 40130 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 829 = GMBCC 2500 = TBRC 21782.</p><p><b>Cultural characteristics.</b></p><p>After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 30–40 mm diam., surface flat, spreading, round with radiating margin, wrinkled, orange white (5 A 2), olive brown (4 E 5: tabby appearance), yellowish white (2 A 2) at margin; on MEA reaching 30–39 mm diam., surface flat, spreading, round with radiating margin, dry, velvety, olive brown (4 E 5) to black, yellowish white (2 A 2) at margin; on OA 26–34 mm diam., surface flat, spreading with irregular margin, yellowish white (2 A 2), orange white (5 A 2: tabby appearance).</p><p><b>Description.</b></p><p><i><i>Anamorph</i> in vitro</i> dematiaceous hyphomycetes. <i>Vegetative hyphae</i> 2.7–7.5 (– 9.0) μm wide, hyaline to brown, branched, septate, smooth, thin-walled, becoming golden brown or dark brown, constricted at the septa, getting darker and thicker with age. <i>Conidiogenous cells</i> (4.0 –) 5.6–8.8 (14.0) × (2.6 –) 3.5–6.1 μm (<i>x ̄</i> = 7.2 × 4.2 μm, <i>n</i> = 25), undifferentiated, intercalary, terminal, producing conidia percurrently from indistinct, short lateral denticles, giving rise to conidia that aggregate in a mucoid mass, or differentiated on hyphae, hyaline to dark brown. <i>Conidia</i> (4.8 –) 7.3–11.0 (– 12.8) × (2.4 –) 3–7.1 μm (<i>x ̄</i> = 8.9 × 4.7 μm, <i>n</i> = 200), obovoid to ellipsoidal, elongate, or subglobose, hyaline to light brown, becoming dark brown with age, aseptate, occasionally with an indistinct truncated base and a hilum, guttulate, smooth-walled. <i>Chlamydospores</i> (4.5 –) 7.5–16.7 (– 19.0) (<i>x ̄</i> = 12.3 μm, <i>n</i> = 40) µm wide, produced in aerial hyphae, intercalary, in branched chains, subglobose to ellipsoidal, hyaline becoming light to dark brown, smooth-, thick-walled, septate, constricted near the septa. <i>Endoconidia</i> (3.9 –) 4.7–7.9 × 1.85–3.0 (– 3.7) μm (<i>x ̄</i> = 6.0 × 2.7 μm, <i>n</i> = 27), obovoid to ellipsoidal, elongate, hyaline, occasionally seen in intercalary hyphal cells.</p><p>Fermentation of glucose is negative. <i>D</i> - glucose, galactose, sorbose, <i>N</i> - acetyl glucosamine, ribose, xylose, <i>L</i> - arabinose, <i>D</i> - arabinose (weak), <i>L</i> - rhamnose, sucrose, maltose, <i>α</i> - <i>α</i> - trehalose, cellobiose, salicin, melibiose, lactose, raffinose, melizitose, glycerol, erythritol, ribitol, glucitol, mannitol, galactitol, <i>myo</i> - inositol, <i>D</i> - glucono- 1, 5 - lactone, <i>D</i> - gluconate, <i>D</i> - glucuronate, <i>D</i> - galacturonic acid, <i>DL</i> - lactate (weak), succinate, citrate, ethanol, and xylitol are assimilated, but methyl- <i>α</i> - <i>D</i> - glucoside, inulin, soluble starch, and methanol are not assimilated. Ammonium sulfate, ethylamine hydrochloride, <i>L</i> - lysine, cadaverine, and creatine are assimilated as sole nitrogen sources. Potassium nitrate and sodium nitrite are not assimilated. After 3 weeks, dark brown sediment formed in <i>D</i> - glucose, <i>D</i> - galactose, <i>L</i> - sorbose, <i>N</i> - acetyl glucosamine, <i>L</i> - rhamnose, maltose, <i>α</i> - <i>α</i> - trehalose, salicin, glycerol, <i>myo</i> - inositol, <i>D</i> - glucuronate, <i>D</i> - galacturonic acid, <i>DL</i> - lactate, and citrate. Black sediment formed in cellobiose, erythritol, <i>D</i> - glucono- 1, 5 - lactone, <i>D</i> - gluconate, and succinate, while white sediment observed in <i>L</i> - arabinose.</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>Additional strains examined.</b></p><p>THAILAND • Phayao Province, Mueang District, isolated from Egyptian star cluster flower (<i>Pentas lanceolata</i>; <i>Rubiaceae</i>, <i>Gentianales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 853.</p><p><b>Habitat and distribution.</b></p><p>Flowers of <i>Citrus japonica</i> and <i>Pentas lanceolata</i>. Known only from northern Thailand.</p><p><b>Notes.</b></p><p>In the multilocus phylogenetic tree, <i>A. floricola</i> SDBR-CMU 829 (ex-type) and SDBR-CMU 853 clustered with <i>A. albui</i> SA 57 and formed a distinct lineage separate from the clade of <i>A. albui</i> NRRL 61482 and SDBR-CMU 866 (Fig. 2). The ITS, LSU, and <i>rpb 2</i> sequences of <i>A. floricola</i> were identical (100 %) to those of <i>A. albui</i> SA 57; however, the ITS, LSU, and <i>rpb 2</i> sequences showed 100 %, 97.90 %, and 96.97 % similarity, respectively, to those of <i>A. albui</i> NRRL 61482 (ex-type), differing by 3.03 % in <i>rpb 2</i> (18 / 594 bp, including gaps). Additionally, the ITS, LSU, <i>rpb 2</i>, <i>tef 1</i>, and <i>tub</i> sequences of <i>A. floricola</i> showed 100 %, 100 %, 96.70 %, 99.64 %, and 100 % similarity, respectively, to those of <i>A. albui</i> SDBR-CMU 866 obtained in this study, differing by 3.30 % in <i>rpb 2</i> (31 / 939 bp, including gaps). However, further analyses of morphological characteristics, growth temperature profiles, and additional genetic loci are required to determine whether <i>A. albui</i> SA 57 represents the same species as <i>A. floricola</i> or a distinct species, warranting further investigation in future studies. <i>Aureobasidium floricola</i> shares micromorphological features similar to those of <i>A. albui</i>; however, it is readily distinguished by its distinct colony morphology. Colonies of <i>A. floricola</i> are orange white to olive brown with a yellowish-white margin on PDA, olive brown to black with a yellowish-white margin on MEA, and yellowish white mixed with orange white on OA, whereas <i>A. albui</i> forms white to pale yellow colonies on PDA, greenish-brown to dark-brown colonies on MEA, and whitish-gray colonies on OA (Jumbam et al. 2025; this study). Furthermore, the PHI test revealed no significant genetic recombination between <i>A. floricola</i> and <i>A. albui</i> (Fig. 4), indicating that they represent distinct species. However, <i>A. floricola</i> differs from <i>A. albui</i> in its ability to assimilate <i>D</i> - arabinose, <i>L</i> - rhamnose, salicin, glycerol, erythritol, ribitol, <i>myo</i> - inositol, ethanol, xylitol, and creatine, while being unable to utilize potassium nitrate or sodium nitrite (Jumbam et al. 2025). Furthermore, <i>A. albui</i> produced pigmentation when grown on <i>L</i> - sorbose, erythritol, <i>D</i> - mannitol, or <i>D</i> - glucono- 1, 5 - lactone, whereas <i>A. floricola</i> did not (Jumbam et al. 2025). Therefore, <i>A. floricola</i> is described herein as a new species.</p>