sp. nov. and sp. nov., and reclassification of , , and as later heterotypic synonyms of , , and .

Two Gram-negative, obligately aerobic, rod-shaped bacteria, strains G1-22 and G1-23, were isolated from the phycosphere of a marine brown alga. Both strains exhibited catalase- and oxidase-positive activities. Strain G1-22 displayed optimal growth at 25 °C, pH 8.0, and 2.0-3.0% (w/v) NaCl, while strain G1-23 exhibited optimal growth at 25 °C, pH 8.0, and 4.0% NaCl. Ubiquinone-8 was identified as the sole isoprenoid quinone in both strains. As major fatty acids (> 5%), strain G1-22 contained C, summed feature 3 (C 7 and/or C 6), summed feature 8 (C 7 and/or C 6), C 3-OH, and C 3-OH, while strain G1-23 contained C, summed feature 3 (C 7 and/or C 6), and C. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were major polar lipids in both strains. Strains G1-22 and G1-23 had DNA G+C contents of 40.2 and 38.9 mol%, respectively. Phylogenetic analyses based on 16S rRNA and genome sequences revealed that strains G1-22 and G1-23 formed distinct phylogenetic lineages within the genera and , respectively. Strain G1-22 showed closest relatedness to MTZ26 with 97.8% 16S rRNA gene sequence similarity, 70.2% average nucleotide identity (ANI), and a 21.5% digital DNA-DNA hybridization (dDDH) value, while strain G1-23 was most closely related to KCTC 32108 with 95.6% 16S rRNA gene sequence similarity, 74.6% ANI, and a 20.1% dDDH value. Based on phenotypic and molecular characteristics, strains G1-22 and G1-23 are proposed to represent two novel species, namely sp. nov. (type strain G1-22=KACC 22486=JCM 34971) and sp. nov. (type strain G1-23=KACC 22490=JCM 34972), respectively. Additionally, based on the comparison of whole genome sequences, it is proposed that , , and are reclassified as later heterotypic synonyms of , , and , respectively.