A Gram-stain-negative, aerobic, non-motile and coccoid, ovoid or rod-shaped bacterial strain, designated MYP11T, was isolated from seawater around Jeju island, Republic of Korea and identified by polyphasic taxonomic study. A neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strain MYP11T joined the cluster comprising the type strains of Shimiaabyssi, Shimiaaestuarii and Shimiaaquaeponti, showing 16S rRNA gene sequence similarities of 96.3-96.8 %. Strain MYP11T exhibited 16S rRNA gene sequence similarity values of 94.2-94.9 % to the type strains of other Shimia species. In the upgma dendrogram based on the average nucleotide identity values of genomic sequences, strain MYP11T formed an evolutionary lineage independent of those of Shimia species and other taxa. Strain MYP11T contained Q-10 as the predominant ubiquinone and C18 : 1 ω7c and cyclo C19 : 0 ω8c as the major fatty acids. The major polar lipids of strain MYP11T were phosphatidylcholine, phosphatidylglycerol, two unidentified lipids and one unidentified aminolipid. The DNA G+C content of strain MYP11T was 63.1 or 61.5 mol%. The differences in the fatty acid and polar lipid profiles and DNA G+C contents made it reasonable to distinguish strain MYP11T from the type strains of S. abyssi, S. aestuarii and S. aquaeponti and those of other Shimia species. On the basis of the polyphasic data presented here, strain MYP11T is considered to constitute a new genus and species within the class Alphaproteobacteria, for which the name Aliishimia ponticola gen. nov., sp. nov. is proposed. The type strain is MYP11T (=KCTC 62899T=NBRC 113544T).