A shiny dark yellow pigmented, Gram-stain-negative, rod-shaped, non-motile bacterium, designated as strain JC631(T), was isolated from the sediment ecosystem of Chilika lagoon, India. Strain JC631(T)tolerates up to pH 10 and NaCl up to 3% (w/v). MK6 is the only respiratory quinone. Predominant (> 10%) cellular fatty acids are anteiso-C-11:0, anteiso-C-13:0, and anteiso-C-15:0. Major polar lipids are phosphatidylethanolamine, phosphatidylcholine, a few unidentified phospholipids, and a few unidentified aminolipids. 16S rRNA gene sequencing showed that strain JC631(T)shared the highest sequence identity (98.7%) withArenibacter latericiusKMM 426(T)followed byArenibacter certesiiCCUG 48006(T)(98.6%) and other members of the genusArenibacter(< 97%). The genome size of strain JC631(T)is 4.16 Mb with a GC content of 40.8 mol%. Strain JC631(T)has ANI scores of 78.3% and 78.1%;dDDH values of 22.2% and 21.8%, respectively, with the type strains ofA. latericiusandA. certesii. The genomic distinction is well supported by chemotaxonomic characteristics and differential physiological properties. This supports strain JC631(T)to be described as a new species of the genusArenibacter,named asArenibacter lacussp. nov. The type strain is JC631(T)(= KCTC 72002(T) = NBRC 114071(T)).