A thermotolerant, Gram-strain-negative, non-spore-forming and strictly aerobic bacterium, designated GU51T, was isolated from Guhai hot spring in Jimsar county, Xinjiang province, north-west China. Each cell of strain GU51T consisted of an oval body and two symmetrical long (3–6 µm) prosthecae. The strain moved by polar flagellum. Oxidase and catalase were produced. Strain GU51T grew within the ranges of 37–65 °C (optimum 48–50 °C), 0.5–7.5 % (w/v) NaCl (optimum 2–3 %) and pH 6.0–9.0 (optimum pH 7.5). The major respiratory quinone detected was ubiquinone 10 (U-10) and the genomic DNA G+C content was 66.7±0.4 mol%. Major fatty acids (>5 %) were C16 : 0, C18 : 1ω7c and 11-methyl C18 : 1ω7c. The polar lipids consisted of diphosphatidylglycerol, five glycolipids, phosphatidylglycerol and an unknown phospholipid. Phylogenetic analysis showed the closest relatives of strain GU51T were members of the genus
Parvularcula
with 92.3 % 16S rRNA gene sequence similarity. On the basis of this polyphasic taxonomic characterization, it is suggested that strain GU51T represents a novel species of a new genus in the family ‘
Parvularculaceae
’, for which the name Amphiplicatus metriothermophilus gen. nov., sp. nov. is proposed. The type strain of the type species is GU51T ( = CGMCC 1.12710T = JCM 19779T).