Aureobasidium kwanphayaoense 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 kwanphayaoense

<p><i>Aureobasidium kwanphayaoense</i> Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov.</p><p>Fig. 14</p><p><b>Etymology.</b></p><p>Refers to Kwan Phayao (Phayao Lake) in Mueang Phayao District, Phayao Province, Thailand, where the flowers containing the new fungus were collected.</p><p><b>Type.</b></p><p>THAILAND • Phayao Province, Mueang District, isolated from chaya spinach flower (<i>Cnidoscolus aconitifolius</i>; <i>Euphorbiaceae</i>, <i>Malpighiales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, <i>holotype</i> = CMUB 40139 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 849 = GMBCC 2506 = TBRC 21784.</p><p><b>Cultural characteristics.</b></p><p>After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 28–30 mm diam., surface flat, spreading, round with radiating margin, velvety, slimy, yellowish white (2 A 2); on MEA reaching 40–48 mm diam., surface flat, spreading, round with radiating margin, velvety, orange gray (5 B 2) at center, grayish brown (7 E 3) at the margin; on OA 42–47 mm diam., surface flat, spreading with filiform, entire margin, powdery, fluffy, light gray (3 D 1).</p><p><b>Description.</b></p><p><i><i>Anamorph</i> in vitro</i> dematiaceous hyphomycetes. <i>Vegetative hyphae</i> 2.8–7.2 (– 9.0) μm wide, hyaline to dark brown, branched, septate, smooth, thin-walled, getting darker and thicker with age, constricted at the septa. <i>Conidiogenous cells</i> 10.0–11.7 × 3.0–3.8 μm (<i>x ̄</i> = 11 × 3.8 μm, <i>n</i> = 25), undifferentiated, intercalary, rarely terminal, producing conidia percurrently from short lateral denticles, giving rise to conidia that aggregate in a mucoid mass, or differentiated on hyphae, hyaline, becoming dark brown. <i>Conidia</i> obovoid to ellipsoidal, elongated, or globose to subglobose, hyaline to brown, becoming dark brown with age, aseptate, occasionally with an indistinct truncated base and a hilum, guttulate, smooth-walled, (4.0 –) 5.8–11.0 (– 14.2) × 2.0–4.4 (– 7.0) μm (<i>x ̄</i> = 8.4 × 3.5 μm, <i>n</i> = 150). <i>Chlamydospores</i> (6.0 –) 7.0–14.5 (– 17.6) (<i>x ̄</i> = 8.9 μm, <i>n</i> = 25) µm wide, produced in aerial hyphae, mostly intercalary, solitary or in branched chains, globose to subglobose, dark brown, smooth-, thick-walled, septate, constricted near the septa. <i>Endoconidia</i> absent.</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, <i>L</i> - rhamnose, sucrose, maltose, <i>α</i> - <i>α</i> - trehalose, methyl- <i>α</i> - <i>D</i> - glucoside, 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, succinate, citrate, ethanol, and xylitol are assimilated, but 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 L-sorbose, salicin, erythritol. Black sediment formed in <i>D</i> - glucose, <i>D</i> - arabinose, methyl- <i>α</i> - <i>D</i> - glucoside, raffinose, glycerol, <i>D</i> - glucitol, <i>myo</i> - inositol, <i>D</i> - glucono- 1, 5 - lactone, <i>D</i> - gluconate, and ethanol.</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 peregrina flower (<i>Jatropha integerrima</i>; <i>Euphorbiaceae</i>, <i>Malpighiales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 839; 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 844; isolated from purslane flower (<i>Portulaca grandiflora</i>; <i>Portulacaceae</i>, <i>Caryophyllales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 860.</p><p><b>Habitat and distribution.</b></p><p>Flowers of <i>Cnidoscolus aconitifolius</i>, <i>Jatropha integerrima</i>, <i>Ocimum tenuiflorum</i>, and <i>Portulaca grandiflora</i>. Known only from northern Thailand.</p><p><b>Notes.</b></p><p>The multilocus phylogenetic tree (Fig. 2) showed that <i>A. kwanphayaoense</i> formed a distinct clade, supported by 100 % MLBS and 1.0 BIPP, and was separated from other <i>Aureobasidium</i> species in the <i>A. thailandense</i> group. <i>Aureobasidium kwanphayaoense</i> formed a sister clade to <i>A. albui</i>, <i>A. anthicola</i>, <i>A. castaneae</i>, <i>A. florale</i>, <i>A. floricola</i>, <i>A. florigenum</i>, <i>A. lannaense</i>, and <i>A. vanuatuense</i>. Morphologically, the colony characteristics of <i>A. kwanphayaoense</i> differed from those of most phylogenetically related sister taxa but were similar to those of <i>A. albui</i>, <i>A. florale</i>, and <i>A. lannaense</i>. However, endoconidia are absent in <i>A. kwanphayaoense</i>, whereas they are present in <i>A. albui</i> and <i>A. florale</i>. In addition, <i>A. kwanphayaoense</i> can be distinguished from these taxa based on multilocus phylogenetic analyses and nucleotide differences in the <i>rpb 2</i> and <i>tef 1</i> loci (Table 2). Moreover, the results of the PHI test further supported the genetic distinctiveness of <i>A. kwanphayaoense</i> within the <i>A. thailandense</i> group (Fig. 4). Furthermore, <i>A. kwanphayaoense</i> can be distinguished from <i>A. anthicola</i>, <i>A. florale</i>, <i>A. floricola</i>, <i>A. lannaense</i>, and <i>A. florigenum</i> by its characteristic pattern of sediment formation in carbon assimilation tests (Table 1). <i>Aureobasidium kwanphayaoense</i> can be distinguished from <i>A. anthicola</i> by the absence of pigmentation on salicin, <i>D</i> - glucono- 1, 5 - lactone, and <i>D</i> - gluconate, which is characteristic of <i>A. anthicola</i> (Table 1). In addition, <i>A. kwanphayaoense</i> also differs from <i>A. floricola</i> in its ability to assimilate methyl-α- <i>D</i> - glucoside. <i>Aureobasidium albui</i> and <i>A. vanuatuense</i> are clearly separated from <i>A. kwanphayaoense</i> by their inability to assimilate <i>L</i> - arabinose, <i>L</i> - rhamnose, salicin, glycerol, ribitol, <i>myo</i> - inositol, ethanol, and xylitol as carbon sources, as well as creatine as a nitrogen source (Jumbam et al. 2025). Based on the combined morphological, physiological, and molecular evidence, <i>A. kwanphayaoense</i> is described herein as a new species.</p><p>“ – ” indicates no result due to unavailable sequence data.</p>