The　poles　of　the　Earth　harbour　many　novel　micro-organisms　that　have　not　yet　been　isolated　and　identified.　Here,　a　Gram-stain-negative,　motile,　aerobic　and　rod-shaped　bacterial　strain,　designated　as　wDCs-4T,　was　isolated　from　surface　seawater　collected　from　the　Weddell　Sea　in　Antarctica.　It　grows　at　4–40　°C　(optimum　10–15　°C),　pH　4–8　(optimum　7)　and　in　the　presence　of　0–4%　NaCl　(w/v,　optimum　0.5–1%).　The　complete　16S　rRNA　gene　of　strain　wDCs-4T　had　maximum　sequence　identity　with　Oceanobacter　mangrovi　SM2-42T　(97.2%),　followed　by　Thalassolituus　oleivorans　MIL-1T　(96.5%)　and　Oceanobacter　kriegii　197T　(96.2%).　Phylogenetic　analyses　based　on　the　16S　rRNA　gene　and　genome　sequences　showed　that　strain　wDCs-4T　was　closely　clustered　with　the　members　of　the　genus　Oceanobacter　and　formed　an　independent　clade,　which　could　be　considered　a　mono-phyletic　taxon.　The　average　nucleotide　identity　values　between　strain　wDCs-4T　and　the　members　of　the　genera　Oceanobacter　and　Thalassolituus　were　77.7–78.1　and　77.4–80.5%,　respectively.　The　corresponding　digital　DNA‒DNA　hybridization　values　are　19.5–20.1　and　20.5–22.4%,　respectively.　The　major　fatty　acids　(＞5%)　of　strain　wDCs-4T　comprised　summed　feature　5　(C18:0　ante/C18:2　ω6,9c　or　C18:2　ω6,9c/C18:0　ante)　and　C16:0.　The　predominant　respiratory　was　Q-8.　The　polar　lipid　profile　consisted　of　phosphatidylethanolamine,　phosphatidylglycerol,　aminolipids　and　unknown　polar　lipids.　The　draft　genome　size　was　4.58　Mbp,　with　a　DNA　G+C　content　of　53.4　mol%.　On　the　basis　of　polyphasic　analyses,　strain　wDCs-4T　represented　a　novel　species　in　the　genus　Oceanobacter,　for　which　the　name　Oceanobacter　antarcticus　sp.　nov.　was　proposed.　The　type　strain　was　wDCs-4T　(=MCCC　1A20726T=KCTC　8314T).　©　2025　The　Authors.