Two Gram-stain-negative, aerobic, motile by a single polar flagellum and rod-shaped strains, designated SCS-49T and SCS-111, were isolated from seawater of the South China Sea. The two strains grew at 4-35 °C, with 0.5-7.5 % (w/v) NaCl and at pH 6.5-9.0 and were able to reduce nitrate. Q-8 was the sole ubiquinone. The major fatty acids of the two strains were C16 : 0, C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The polar lipids included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phospoglycolipid, three unidentified glycolipids, five unidentified phospholipids and two to three unidentified lipids. The isolates formed a stable clade with Pseudohongiella acticola and Pseudohongiella spirulinae based on phylogenetic analysis of 16S rRNA gene sequences. Strains SCS-49T and SCS-111 exhibited 16S rRNA gene sequence similarity values of 97.2 and 96.0 % with respect to the type strains of P. acticola and P. spirulinae, respectively. The average nucleotide diversity and in silico DNA-DNA hybridization values between strain SCS-49T and P. acticola KCTC 42131T were 71.4 and 25.1 %, respectively and the values between strain SCS-49T and SCS-111 were 99.9 and 99.2 %, respectively. Based upon the phenotypic, chemotaxonomic and genetic data, strains SCS-49T and SCS-111 represent a novel species in the genus Pseudohongiella, for which the name Pseudohongiella nitratireducens sp. nov. is proposed. The type strain is SCS-49T (=CGMCC 1.15425T=KCTC 52155T=MCCC 1K03186T).