Aureobasidium phayaoense 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 phayaoense

<p><i>Aureobasidium phayaoense</i> Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov.</p><p>Fig. 19</p><p><b>Etymology.</b></p><p>Refers to Phayao Province, where the flowers containing the new fungus were collected.</p><p><b>Type.</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, <i>holotype</i> = CMUB 40126 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 852 = GMBCC 2508 = TBRC 21787.</p><p><b>Cultural characteristics.</b></p><p>After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 39–45 mm diam., surface flat, spreading with entire margin, velvety, concentric, gradient from gray (4 B 1), brownish gray (4 E 2) to grayish brown (7 E 3), with yellowish white (2 A 2) at the margin; on MEA reaching 40–48 mm diam., surface flat, spreading with entire margin, wrinkled, velvety, concentric, gradient from dull yellow (3 B 3) to grayish yellow (4 B 6), with yellowish white (2 A 2) at the margin; on OA 55–65 mm diam., surface flat, spreading with entire margin, wrinkled, brownish orange (6 C 8), grayish brown (6 E 3) with light gray (6 B 1) to brownish gray (4 E 2) at the margin.</p><p><b>Description.</b></p><p><i><i>Anamorph</i> in vitro</i> dematiaceous hyphomycetes. <i>Vegetative hyphae</i> (2.0 –) 3.0–9.0 (– 12.0) μm wide, hyaline, light to brown with age, branched, septate, smooth, thin-walled, becoming dark melanized, getting darker and thicker with age, constricted at the septa, minute echinulate. <i>Conidiogenous cells</i> (7.5 –) 8.7–13.8 (– 17.4) × (3.6 –) 4.5–6.5 (– 7.5) μm (<i>x ̄</i> = 10.9 × 5.5 μm, <i>n</i> = 25) µm, 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, occasionally elongated, solitary, light to dark brown. <i>Conidia</i> (4.0 –) 5.5–9.6 (– 11.8) × (1.9 –) 2.8–6.0 (– 7.4) μm (<i>x ̄</i> = 7.6 × 4.3 μm, <i>n</i> = 170), oval, obovoid to ellipsoidal or elongated, or subglobose, hyaline, becoming light brown to brown with age, aseptate, occasionally with an indistinct truncated base and a hilum, guttulate, smooth-walled, budding occasionally observed. <i>Chlamydospores</i> (9.0 –) 10.4–14.0 (– 17.5) µm wide (<i>x ̄</i> = 12.6 μm, <i>n</i> = 30), frequent produced in aerial hyphae, mostly intercalary, solitary, subglobose to ellipsoidal, pigmented, light to dark brown, septate, smooth-, thick-walled. <i>Endoconidia</i> absent.</p><p>Fermentation of glucose is negative. <i>D</i> - glucose, galactose, sorbose, <i>N</i> - acetyl glucosamine (weak), ribose, xylose, <i>L</i> - arabinose, <i>D</i> - arabinose, <i>L</i> - rhamnose, sucrose, maltose, <i>α-α-</i> trehalose, methyl- <i>α</i> - <i>D</i> - glucoside, cellobiose, salicin, melibiose (weak), 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 (weak), citrate, ethanol, and xylitol are assimilated, but inulin, soluble starch, <i>DL</i> - lactate, succinate, 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>N</i> - acetyl glucosamine, <i>D</i> - xylose, <i>L</i> - arabinose, <i>D</i> - arabinose, <i>L</i> - rhamnose, sucrose, maltose, methyl- <i>α</i> - <i>D</i> - glucoside, cellobiose, salicin, melibiose, lactose, raffinose, melizitose, glycerol, erythritol, ribitol, D-glucitol, galactitol, <i>D</i> - glucono- 1, 5 - lactone, <i>D</i> - gluconate, <i>D</i> - glucuronate, <i>D</i> - galacturonic acid, and citrate, while light brown sediment formed in <i>α</i> - <i>α</i> - trehalose. Black sediment formed in <i>D</i> - glucose, <i>D</i> - galactose, <i>L</i> - sorbose, <i>D</i> - ribose, <i>D</i> - mannitol, <i>myo</i> - inositol, and xylitol, while white sediment observed in ethanol.</p><p><b>Cardinal temperatures for growth.</b></p><p>Minimum 10 ° C, optimum in the range of 25 ° C to 30 ° C, maximum 37 ° C. No growth at 4 ° C.</p><p><b>Additional strains examined.</b></p><p>THAILAND • Phayao Province, Mueang District, isolated from bush clock vine flower (<i>Thunbergia erecta</i>; <i>Acanthaceae</i>, <i>Lamiales</i>), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 811 and SDBR-CMU 857.</p><p><b>Habitat and distribution.</b></p><p>Flowers of <i>Pentas lanceolata</i> and <i>Thunbergia erecta</i>. Known only from northern Thailand.</p><p><b>Notes.</b></p><p>Phylogenetic analyses showed that <i>A. phayaoense</i> SDBR-CMU 852 (ex-type) and SDBR-CMU 857 formed a distinct lineage sister to <i>A. pollinicola</i>, with 80 % MLBS and 0.90 BIPP support (Fig. 2). Comparisons of ITS, LSU, <i>rpb 2</i>, <i>tef 1</i>, and <i>tub</i> nucleotide sequences showed that <i>A. phayaoense</i> differed from <i>A. pollinicola</i> by 1.01 % (6 / 592 bp, including gaps), 0.33 % (3 / 901 bp, including gaps), 4.85 % (46 / 948 bp, including gaps), 7.83 % (21 / 268 bp, including gaps), and 2.93 % (12 / 409 bp, including gaps), respectively. Although comparisons of the ITS, LSU, and <i>tub</i> loci indicated that <i>A. phayaoense</i> was not markedly different from <i>A. pollinicola</i>, the <i>rpb 2</i> and <i>tef 1</i> sequences revealed clear differences. Morphologically, the colony colors of <i>A. phayaoense</i> and <i>A. pollinicola</i> differed across culture media. On PDA, <i>A. phayaoense</i> produced gray to grayish-brown colonies with a yellowish-white margin, whereas <i>A. pollinicola</i> formed light- to dark-yellowish colonies with a yellowish-white margin. On MEA, colonies of <i>A. phayaoense</i> were dull yellow to grayish yellow with a yellowish-white margin, compared with the grayish-yellow colonies with a light-gray margin of <i>A. pollinicola</i>. On OA, <i>A. phayaoense</i> produced brownish-orange to grayish-brown colonies with a light-gray to brownish-gray margin, whereas <i>A. pollinicola</i> formed yellowish-white colonies with a light-gray margin. The micromorphological features of <i>A. phayaoense</i> and <i>A. pollinicola</i> are similar in size; however, <i>A. phayaoense</i> can be distinguished from <i>A. pollinicola</i> by the absence of endoconidium production. Moreover, PHI analyses revealed no evidence of significant recombination between <i>A. phayaoense</i> and <i>A. pollinicola</i> (Fig. 3). <i>Aureobasidium phayaoense</i> can be distinguished from <i>A. pollinicola</i> by its inability to assimilate <i>DL</i> - lactate and succinate (Table 1). Hence, <i>A. phayaoense</i> is introduced as a new species based on combined morphological and phylogenetic evidence.</p>