Three psychrophilic bacteria,designated as strains SQ149^T,SQ345^T,and S1-1^T,were isolated from deep-sea sediment from the South China Sea. All three strains were the most closely related to Thalassotalea atypica RZG4-3-1^T based on the 16S rRNA gene sequence analysis (similarity ranged from 96.45 to 96.67 %). Phylogenetic analysis based on the 16S rRNA gene and core-genome sequences showed that three strains formed a cluster within the genus Thalassotalea. The average amino acid identity,average nucleotide identity, and digital DNA-DNA hybridization values among the three strains and closest Thalassotalea species were far below the cut-off value recommended for delineating species, indicating they each represented a novel species. All three strains were Gram-stain-negative, rod-shaped, and contained summed feature 3 (C_16:1 omega 7c and/or C_16:1 omega 6c) as the predominant fatty acid, Q-8 as the major respiratory quinone, and phosphatidylethanolamine and phosphatidylglycerol as predominant polar lipids. Based on the genomic,phylogenetic,and phenotypic characterizations,each strain is considered to represent a novel species within the genus Thalassotalea,for which the names Thalassotalea psychrophila sp. nov. (type strain SQ149^T=MCCC 1K04231^T=JCM 33807^T),Thalassotalea nanhaiensis sp. nov. (type strain SQ345^T=MCCC 1K04232^T=JCM 33808^T),and Thalassotalea fonticola sp. nov. (type strain S1-1^T=MCCC 1K06879^T=JCM 34824^T) are proposed.