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

Information from the abstract

Aureobasidium siamense Senwanna, Kodchasee, J. Kumla & N. Suwannar. sp. nov. Fig. 24 Etymology. Refers to Siam (the former name of Thailand), where the new species was found. Type. THAILAND • Phayao Province, Mueang District, isolated from butter daisy flower (Melampodium divaricatum; Asteraceae, Asterales), Jul 2024, P. Kodchasee, C. Senwanna, J. Kumla and N. Suwannarach, holotype = CMUB 40127 (preserved in metabolically inactive state), living culture (ex-type) = SDBR-CMU 847 = GMBCC 2504 = TBRC 21792. Cultural characteristics. After 14 days of incubation at 25 ° C in the dark, colonies on PDA reaching 45–53 mm diam., surface flat, spreading, round with radiating margin, velvety, shiny, light brown (6 D 4) to brown (6 E 8), with brownish gray (4 E 2) to black at the margin; on MEA reaching 48–59 mm diam., surface flat, spreading with lobate margin, velvety, shiny, wrinkled, light brown (6 D 4) to brown (6 E 8) or grayish brown (6 E 3), with brownish gray (4 E 2) to black at the margin; on OA 60–69 mm diam., surface flat, spreading with entire margin, velvety, gradient from light to dark grayish yellow (4 B 4), with grayish brown (6 E 3) to dull red (11 C 4) at the margin. Description. Anamorph in vitro dematiaceous hyphomycetes. Vegetative hyphae 4.0–8.0 (– 10.2) μm wide, hyaline to dark brown, branched, septate, smooth, thin-walled, getting darker and thicker, constricted at the septa with age. Conidiogenous cells (8.9 –) 9.5–14.8 (– 16.1) × 4.8–6.0 (– 7.2) μm (x ̄ = 11.9 × 6.2 μm, n = 25), undifferentiated intercalary, terminal, producing conidia percurrently from indistinct lateral denticles, giving rise to conidia that aggregate in a mucoid mass, or differentiated from hyphae, occasionally elongated, solitary, hyaline to light brown, becoming golden brown to dark brown with age. Conidia (5.1 –) 7.4–11.0 (– 16.2) × (2.1 –) 3.6–5.9 (– 8.2) μm (x ̄ = 9.3 × 5.0 μm, n = 200), obovoid to ellipsoidal, hyaline to light brown, aseptate, occasionally with an indistinct truncated base and a hilum, guttulate, smooth-walled, becoming light brown to brown with age, 0–1 - septate. Chlamydospores 6.6–10.6 (– 12.7) μm wide (x ̄ = 9.0 μm, n = 25), produced in aerial hyphae, mostly intercalary, solitary or in branched chains, subglobose, dark brown, smooth-, thick-walled, septate, constricted near the septa. Endoconidia absent. Fermentation of glucose is negative. D - glucose, galactose, sorbose, N - acetyl glucosamine, ribose, xylose, L - arabinose, D - arabinose, L- rhamnose, sucrose, maltose, α-α- trehalose, methyl- α - D - glucoside (weak), cellobiose (weak), salicin, melibiose (weak), lactose (weak), raffinose (weak), melizitose (weak), glycerol, erythritol (weak), ribitol, glucitol, mannitol (weak), galactitol, myo - inositol (weak), D - glucono- 1, 5 - lactone, D - gluconate (weak), D - glucuronate (weak), D - galacturonic acid (weak), DL - lactate (weak), succinate (weak), citrate (weak), ethanol (weak), and xylitol (weak) are assimilated, but 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, light brown pigmentation and dark brown sediment were observed in D - glucono- 1, 5 - lactone. Dark brown sediment formed in D - galactose, L - sorbose, and salicin, whereas light brown sediment presented in D - glucose. Back sediment formed in D - ribose, D - arabinose, and D - gluconate, while white sediment preformed in N - acetyl glucosamine, D - xylose, L - arabinose, L - rhamnose, sucrose, maltose, α - α - trehalose, methyl- α - D - glucoside, cellobiose, melibiose, lactose, raffinose, melizitose, glycerol, erythritol, ribitol, D - glucitol, D - mannitol, galactitol, myo - inositol, D - glucuronate, D - galacturonic acid, DL - lactate, succinate, citrate, ethanol, and xylitol. 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 837. Habitat and distribution. Flowers of Melampodium divaricatum and Pentas lanceolata. Known only from northern Thailand. Notes. Phylogenetic analyses showed that A. siamense strains SDBR-CMU 837 and SDBR-CMU 847 (ex-type) formed a distinct lineage with strong support (100 % MLBS and 0.99 BIPP) and were sister to A. motuoense (Fig. 2). The ITS and LSU sequences of A. siamense showed 98.77 % and 100 % similarity, respectively, to those of A. motuoense strains XZY 411-4 (ex-type), E 26-4, E 31-4, and E 82-2. However, the rpb 2, tef 1, and tub sequences could not be compared because sequences of A. motuoense were unavailable. Morphologically, A. siamense is distinguishable from A. motuoense based on differences in colony characteristics. Colonies of A. siamense on PDA are light brown to brown with brownish-gray to black margins; those on MEA are light brown to grayish brown with brownish-gray to black margins; and those on OA are light to dark grayish yellow with grayish-brown to dull-red margins. In contrast, colonies of A. motuoense on PDA are dark brown with black zones; those on MEA are brownish olivaceous; and those on OA are pitch black. Aureobasidium siamense is distinguished from A. motuoense by the production of endoconidia. In addition, A. siamense differs from A. motuoense in having longer conidiogenous cells [(8.9 –) 9.5–14.8 (– 16.1) × 4.8–6.0 (– 7.2) μm vs. 6.4–12.2 × 3.6–4.5 μm] (Wu et al. 2023). However, because of the lack of available physiological characteristics of A. motuoense, a direct comparison between A. siamense and A. motuoense could not be made. Thus, A. siamense is described herein as a new species based on morphological and multilocus phylogenetic analyses.

Why this record is monitored

This record has an Impact Signal of 85/100 based on recency, source, collaboration, and bibliographic signals. It prioritizes monitoring and is not a judgment of research quality.

Related topics: Plant Pathogens and Fungal Diseases · Plant chemical constituents analysis · Microbial Natural Products and Biosynthesis