Magnusiomyces pitmudophilus Y. H. Wei, H. Y. Zhu, P. J. Han & F. Y. Bai, 2025

Zhu, Hai-Yan, Wei, Yu-Hua, Guo, Liang-Chen, Wen, Zhang, Hu, Shuang, Wang, Di-Qiang, You, Xiao-Long, Fan, En-Di, Yao, Shang-Jie, Bai, Feng-Yan & Han, Pei-Jie, 2025, Two new arthroconidial yeast species from bark and pit mud in China, MycoKeys 113, pp. 57-72 : 57-72

Magnusiomyces pitmudophilus Y. H. Wei, H. Y. Zhu, P. J. Han & F. Y. Bai sp. nov.

Fig. 3

Etymology.

The species is named after the isolation source, pit mud.

Holotype.

China • Guizhou Province, Zunyi City , Xishui County, from a pit mud sample, on May 8, 2023, X. L. You and E. D. Fan, (holotype CGMCC 2.7496 T permanently preserved in a metabolically inactive state, ex-holotype JCM 36982 = 682-Y-2 ).

Description.

Culture characteristics: After 10 days on YPD agar at 30 ° C, colonies are 28 mm in diameter, white, dry, and powdery, with finely hairy and irregular margins (Fig. 3 A ). Hyphae soon disarticulate into cubic arthroconidia measuring 3.3–7.7 × 8.1–29.0 μm (Fig. 3 B-C ). Hyphae and arthroconidia produce oblong blastoconidia measuring 5.3–8.3 × 7.2–15.2 μm on PDA agar after one month at 25 ° C (Fig. 3 D ). Sexual structures were not observed on YCB, PDA, V 8, YM, and CMA agar. Physiological and biochemical characteristics: Glucose is not fermented. Glucose, D-galactose, L-sorbose, ethanol, glycerol, D-glucitol, D-mannitol, and DL-lactic acid (weak) are assimilated as sole carbon sources. Trehalose, ribitol, succinic acid, citric acid, sucrose, D-maltose, cellobiose, lactose, melibiose, raffinose, melezitose, inulin, starch soluble, D-xylose, L-arabinose, D-arabinose, D-ribose, L-rhamnose, D-glucosamine, methanol, erythritol, galactitol, α-methyl-D-glucoside, salicin, D-glucuronic acid, inositol, hexadecane, N-acetyl-D-glucosamine, and xylitol are not assimilated as sole carbon sources. Ethylamine, cadaverine, ammonium sulfate, L-lysine, potassium nitrate (weak), and sodium nitrite (weak) are assimilated as sole nitrogen sources. Urease activity is positive. Diazonium Blue B reaction is negative. Extracellular starch compounds are not produced. No growth occurs in 10 % (w / v) sodium chloride plus 5 % (w / v) glucose medium. Growth occurs on 50 % (w / v) glucose-yeast extract agar. No growth occurs on 60 % (w / v) glucose-yeast extract agar. Growth in vitamin-free medium is positive. Growth occurs on YPD agar at 35 ° C, but not at 37 ° C.

Materials examined.

China • Guizhou Province, Zunyi City , Xishui County, a pit mud sample, on May 8, 2023, X. L. You and E. D. Fan, living culture 735-8 = CGMCC 2.7774 = JCM 36984 ; • ibid. living culture 735-10 = CGMCC 2.7775 .

Notes.

Physiologically, M. pitmudophilus sp. nov. differs from its closely related species M. fungicola and M. japonica in its inability to assimilate succinic acid, from M. suaveolens and M. saccharophilus in its inability to ferment glucose, from M. gigas in its inability to ferment both glucose and galactose, from M. magnusii in its inability to ferment glucose, galactose, and sucrose, and from M. tetraspermus in its inability to ferment glucose and grow at 37 ° C (Table 2 ). The three strains representing M. pitmudophilus sp. nov. are from pit mud collected in China, suggesting the unique niche of the new species.

Figures

Figure 3. Morphology of M. pitmudophilus sp. nov. (Strain CGMCC 2.7496 T) A colonies on yeast extract peptone dextrose (YPD) after 10 days B cylindrical arthroconidia on yeast extract – malt extract (YM) C cylindrical arthroconidia on V 8 agar D blastoconidia on potato dextrose agar (PDA). Scale bars: 10 μm (B-D).