A Gram-negative, rod shaped and non-spore-forming bacterium, strain H642(T), was isolated from a desert sample collected from Xinjiang province of China, and subjected to a polyphasic taxonomic investigation. Strain H642(T) grew between 20 and 40 A degrees C (optimal 28-37 A degrees C), pH 6.0-10.0 (optimal 7.0-9.0) and at NaCl concentrations between 1.0 and 20.0 % (optimal 2.0-8.0 %). It was positive for catalase, but negative for oxidase. Ubiquinone-10 was present as the major respiratory ubiquinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, four unknown glycolipids and one unknown lipid. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain H642(T) belongs to the genus Pelagibacterium. Strain H642(T) was most closely related to Pelagibacterium halotolerans (with 98.4 % similarity), Pelagibacterium nitratireducens (97.3 %) and Pelagibacterium luteolum (96.2 %). DNA-DNA reassociation values between strain H642(T), P. halotolerans B2(T) and P. nitratireducens JLT2005(T) were 38.0 and 25.3 %, respectively. The genomic DNA G + C content of strain H642(T) was determined to be 44.4 mol%. Based on genotypic, chemotaxonomic and phenotypic data, strain H642(T) represents a novel species of the genus Pelagibacterium, for which the name Pelagibacterium lixinzhangensis sp. nov is proposed. The type strain is H642(T) (=CGMCC 1.10230(T)=JCM 16597(T)).