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

Information from the abstract

Aureobasidium floricola Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov. Fig. 12 Etymology. Refers to its association with flowers, the substrate from which this species was isolated. Type. THAILAND • Chiang Mai Province, Mueang District, Chang Phueak, isolated from kumquat flower (Citrus japonica; Rutaceae, Sapindales), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, holotype = CMUB 40130 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 829 = GMBCC 2500 = TBRC 21782. Cultural characteristics. 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). Description. Anamorph in vitro dematiaceous hyphomycetes. Vegetative hyphae 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. Conidiogenous cells (4.0 –) 5.6–8.8 (14.0) × (2.6 –) 3.5–6.1 μm (x ̄ = 7.2 × 4.2 μm, n = 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. Conidia (4.8 –) 7.3–11.0 (– 12.8) × (2.4 –) 3–7.1 μm (x ̄ = 8.9 × 4.7 μm, n = 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. Chlamydospores (4.5 –) 7.5–16.7 (– 19.0) (x ̄ = 12.3 μm, n = 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. Endoconidia (3.9 –) 4.7–7.9 × 1.85–3.0 (– 3.7) μm (x ̄ = 6.0 × 2.7 μm, n = 27), obovoid to ellipsoidal, elongate, hyaline, occasionally seen in intercalary hyphal cells. Fermentation of glucose is negative. D - glucose, galactose, sorbose, N - acetyl glucosamine, ribose, xylose, L - arabinose, D - arabinose (weak), L - rhamnose, sucrose, maltose, α - α - trehalose, cellobiose, salicin, melibiose, lactose, raffinose, melizitose, glycerol, erythritol, ribitol, glucitol, mannitol, galactitol, myo - inositol, D - glucono- 1, 5 - lactone, D - gluconate, D - glucuronate, D - galacturonic acid, DL - lactate (weak), succinate, citrate, ethanol, and xylitol are assimilated, but methyl- α - D - glucoside, inulin, soluble starch, and methanol are not assimilated. Ammonium sulfate, ethylamine hydrochloride, L - 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 D - glucose, D - galactose, L - sorbose, N - acetyl glucosamine, L - rhamnose, maltose, α - α - trehalose, salicin, glycerol, myo - inositol, D - glucuronate, D - galacturonic acid, DL - lactate, and citrate. Black sediment formed in cellobiose, erythritol, D - glucono- 1, 5 - lactone, D - gluconate, and succinate, while white sediment observed in L - arabinose. Cardinal temperatures for growth. Minimum 10 ° C, optimum in the range of 25 ° C to 30 ° C. No growth at 4 ° C and 37 ° C. Additional strains examined. THAILAND • Phayao Province, Mueang District, isolated from Egyptian star cluster flower (Pentas lanceolata; Rubiaceae, Gentianales), Aug 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, living culture = SDBR-CMU 853. Habitat and distribution. Flowers of Citrus japonica and Pentas lanceolata. Known only from northern Thailand. Notes. In the multilocus phylogenetic tree, A. floricola SDBR-CMU 829 (ex-type) and SDBR-CMU 853 clustered with A. albui SA 57 and formed a distinct lineage separate from the clade of A. albui NRRL 61482 and SDBR-CMU 866 (Fig. 2). The ITS, LSU, and rpb 2 sequences of A. floricola were identical (100 %) to those of A. albui SA 57; however, the ITS, LSU, and rpb 2 sequences showed 100 %, 97.90 %, and 96.97 % similarity, respectively, to those of A. albui NRRL 61482 (ex-type), differing by 3.03 % in rpb 2 (18 / 594 bp, including gaps). Additionally, the ITS, LSU, rpb 2, tef 1, and tub sequences of A. floricola showed 100 %, 100 %, 96.70 %, 99.64 %, and 100 % similarity, respectively, to those of A. albui SDBR-CMU 866 obtained in this study, differing by 3.30 % in rpb 2 (31 / 939 bp, including gaps). However, further analyses of morphological characteristics, growth temperature profiles, and additional genetic loci are required to determine whether A. albui SA 57 represents the same species as A. floricola or a distinct species, warranting further investigation in future studies. Aureobasidium floricola shares micromorphological features similar to those of A. albui; however, it is readily distinguished by its distinct colony morphology. Colonies of A. floricola 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 A. albui 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 A. floricola and A. albui (Fig. 4), indicating that they represent distinct species. However, A. floricola differs from A. albui in its ability to assimilate D - arabinose, L - rhamnose, salicin, glycerol, erythritol, ribitol, myo - inositol, ethanol, xylitol, and creatine, while being unable to utilize potassium nitrate or sodium nitrite (Jumbam et al. 2025). Furthermore, A. albui produced pigmentation when grown on L - sorbose, erythritol, D - mannitol, or D - glucono- 1, 5 - lactone, whereas A. floricola did not (Jumbam et al. 2025). Therefore, A. floricola is described herein as a new species.

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Related topics: Plant Pathogens and Fungal Diseases · Advanced Synthetic Organic Chemistry · Plant chemical constituents analysis