Three Gram-stain-negative, strictly aerobic, motile bacterial strains, designated IMCC44359^T, IMCC44632^T, and IMCC44653, were isolated from coastal surface seawater collected near Jangbong Island in the Yellow Sea. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences assigned the isolates to the genus Aliikangiella. Strains IMCC44632^T and IMCC44653 shared identical 16S rRNA gene sequences and exhibited high genomic relatedness (99.0% average nucleotide identity and 92.0% digital DNA-DNA hybridization), indicating that they represent a single species. In contrast, strain IMCC44359^T showed low genomic relatedness to these strains and to previously validly published Aliikangiella species, supporting its recognition as a distinct species. The genome of IMCC44359^T (5.95 Mbp; 36.5 mol% G + C) is substantially larger than those of IMCC44632^T and IMCC44653 (~3.75 Mbp; 40.1–40.2 mol% G + C), and all genomes encode aerobic chemoorganotrophic metabolism and biochemical capacities consistent with adaptation to marine environments. The isolates grew under mesophilic and moderately halophilic conditions typical of coastal seawater bacteria, with growth occurring at ranges at 10–40℃, pH 6.0–9.0, and 0.5–7.5% NaCl (optimum, 30℃, pH 7.0–8.0, and 2.0–3.0% NaCl). All strains contained ubiquinone-8 (Q-8) as the sole respiratory quinone, and phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were the major polar lipids. The dominant cellular fatty acids were iso-C_15:0 and summed feature 9 (iso-C_17:1 ω9c and/or C_16:0 10-methyl). Integrated phylogenetic, genomic, phenotypic evidence supported the recognition of two novel species within the genus Aliikangiella, for which the names Aliikangiella litoralis sp. nov. (type strain IMCC44359^T = KCTC 18089^T = JCM 37879^T = HNIBRBA19635^T) and Aliikangiella aequoris sp. nov. (type strain IMCC44632^T = KCTC 18090^T = JCM 37880^T = HNIBRBA19636^T) are proposed.

Two Gram-stain-negative, aerobic, non-motile, rod-shaped bacterial strains, designated IMCC43444^T and IMCC44478^T, were isolated from surface seawater collected off Deokjeok Island and Jangbong Island, respectively, in the Yellow Sea. The two strains shared 100% 16S rRNA gene sequence similarity with each other but exhibited ≤ 96.2% similarity to validly published species of the genus Robiginitalea. Complete whole-genome sequences of IMCC43444^T and IMCC44478^T were 3.21 Mb and 3.30 Mb in size, with DNA G + C contents of 46.5% and 46.4%, respectively. Genome-based relatedness analyses revealed average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values of 90.7% and 42.9% between the two strains, which are well below the accepted species-level thresholds. Furthermore, ANI (≤ 70.2%) and dDDH (≤ 17.8%) values relative to type strains of Robiginitalea species supported the conclusion that strains IMCC43444^T and IMCC44478^T each represent novel species within the genus. Chemotaxonomic characterization showed that iso-C_15:0, iso-C_17:0 3-OH and iso-C_15:1 G were the major fatty acids of both strains; menaquinone-6 (MK-6) was the sole isoprenoid quinone; and the major polar lipids comprised phosphatidylethanolamine, glycolipids, aminolipids, phospholipids, and other unidentified lipids. Based on phylogenetic, genomic, and phenotypic evidence, strains IMCC43444^T and IMCC44478^T are proposed as two novel species, Robiginitalea rubriflava sp. nov. and Robiginitalea insularis sp. nov., respectively. The type strains are IMCC43444^T (= KCTC 102397^T = JCM 37893^T) and IMCC44478^T (= KCTC 102398^T = JCM 37894^T).