Microsporomyces rubellus Q.M. Wang, F.Y. Bai & A.H. Li, 2020

Li, A. - H., Yuan, F. - X., Groenewald, M., Bensch, K., Yurkov, A. M., Li, K., Han, P. - J., Guo, L. - D., Aime, M. C., Sampaio, J. P., Jindamorakot, S., Turchetti, B., Inacio, J., Fungsin, B., Wang, Q. - M. & Bai, F. - Y., 2020, Diversity and phylogeny of basidiomycetous yeasts from plant leaves and soil: Proposal of two new orders, three new families, eight new genera and one hundred and seven new species, Studies In Mycology 96, pp. 17-140 : 115

Microsporomyces rubellus Q.M. Wang, F.Y. Bai & A.H. Li sp. nov. MycoBank MB828819. Fig. 15G, H.

Etymology: the specific epithet rubellus refers to the pale red colony colour of this species.

Culture characteristics: In YM broth, after 7 d at 17 °C, cells are ovoid and ellipsoidal, 3.8 –6.2 × 5.1–8.1 μm and single, budding is polar ( Fig. 15G), a sediment is formed. After 1 mo at 17 °C, a ring and a sediment are present. On YM agar, after 1 mo at 17 °C, the streak culture is pale-red, butyrous, smooth and semi-glossy. The margin is entire. In Dalmau plate culture on corn meal agar, pseudohyphae are not formed. Sexual structures are not observed on YM, PDA, V8 and CM agar. Ballistoconidia are allantoid, reniform or cylindrical, 2.1 –5.7 × 5.0– 11.4 μm ( Fig. 15H).

Physiological and biochemical characteristics: Glucose fermentation is absent. Glucose, galactose, sucrose, maltose, trehalose, melibiose, raffinose, melezitose, glycerol (delayed and weak), ribitol, galactitol, D-mannitol (delayed and weak), D-glucitol (weak), salicin (variable) and DL-lactate (variable) are assimilated as sole carbon sources. L-sorbose, cellobiose, lactose, inulin, soluble starch, D-xylose, L-arabinose, D-arabinose, Dribose, L-rhamnose, D-glucosamine, methanol, ethanol, erythritol, Methyl-α- D-glucoside, succinate, citrate, myo-inositol and hexadecane are not assimilated. Ammonium sulfate, potassium nitrate (variable) and L-lysine (variable) are assimilated as sole nitrogen sources. Sodium nitrite, ethylamine hydrochloride and cadaverine dihydrochloride are not assimilated. Maximum growth temperature is 32 °C. Growth in vitamin-free medium is negative. Starch-like substances are not produced. Growth on 50 % (w/w) glucose-yeast extract agar is negative. Urease activity is positive. Diazonium Blue B reaction is positive.

Physiologically, Mi. rubellus differs from its three closely related species Mi. ellipsoideus in its inability to assimilate soluble starch and Methyl-α- D-glucoside and its ability to assimilate melezitose, ribitol and galactitol ( Table S1.24).

Typus: China, Taiwan province, obtained from a leaf of an unidentified plant, Aug. 2009, Q.-M. Wang (holotype CGMCC 2.4444 T preserved in a metabolically inactive state, ex-type CBS 15622 = TW1.3F-017).