Rosettozyma petaloides Q.M. Wang, F.Y. Bai & A.H. Li sp. nov.

MycoBank number: MB 828832; Index Fungorum number: IF 828832; Facesoffungi number: FoF; Figs 11G, H and 16A, B.

Etymology: the specific epithet petaloides refers to the vegetative cells forming a petale morphology of the type strain.

Culture characteristics: In YM broth, after 7 d at 17 °C, cells are elongate fusiform, either singly or in rosettes, 2.2 – 3.2 × 9.8 – 18.7 μm, budding is polar (Fig. 16A), a sediment is formed. After 1 mo at 17 °C, a pellicle and a sediment are present. On YM agar, after 1 mo at 17 °C, the streak culture is whitish to cream, butyrous, slightly wrinkled 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 cylindrical or falcate, 1.3 – 1.6 × 9.3 – 12.0 μm (Fig. 16B).

Physiological and biochemical characteristics: Glucose fermentation is absent. Glucose, sucrose, maltose, cellobiose (variable), trehalose, lactose (variable), raffinose (variable), melezitose, D- xylose, L-arabinose, D-arabinose (variable), D-ribose (variable), ethanol (variable), glycerol, ribitol (variable), D-mannitol, D-glucitol, Methyl-α-D-glucoside, salicin (delayed and weak), DL-lactate (variable), succinate (delayed and weak) and citrate (delayed and weak) are assimilated as sole carbon sources. Galactose, L-sorbose, melibiose, inulin, soluble starch, L-rhamnose, D-glucosamine, methanol, erythritol, galactitol, myo-inositol and hexadecane are not assimilated. Ammonium sulfate, potassium nitrate (variable), sodium nitrite (variable), L-lysine (variable), ethylamine hydrochloride (delayed and weak) and cadaverine dihydrochloride (delayed and weak) are assimilated as sole nitrogen sources. Maximum growth temperature is 26–27 °C. Growth in vitamin-free medium is delayed and weak. 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, Ro. petaloides and its two closely related species, Ro. cystopteridis and Ro. motuoensis, can be distinguished from one another by the assimilation of D-xylose, L- arabinose, D-arabinose, glycerol and succinate. Ro. petaloides differs from the other species in its ability to assimilate D-xylose and glycerol (Table S1.28).

Typus: China, Wuzhishan mountain, Hainan province, obtained from a leaf of an unidentified plant, Nov. 2006, Q.-M. Wang (holotype CGMCC 2.3446T preserved in a metabolically inactive state, ex-type CBS 15480 = WZS29.14).

Fig. 11. SEM image of vegetative cells grown in YM broth for 5 d at 17 °C. (A) Fi. mali CGMCC 2.4012T, Bars = 4 μm; (B) Boe. sterigmata CGMCC 2.4539T, Bars = 5 μm; (C) St. layueensis CGMCC 2.5817T, Bars = 5 μm; (D) Pse. motuoensis CGMCC 2.5816T, Bars = 2 μm; (E) Me. layueensis CGMCC 2.5818T, Bars = 5 μm; (F) Beg. foliicola CGMCC 2.3164T, Bars = 1 μm; (G, H) Ros. petaloides CGMCC 2.3446T, G Bars = 10 μm, H Bars = 3 μm.

Fig. 16.