A Gram-negative, motile, aerobic and rod-shaped bacterial strain designated 119BY6-57T was isolated from spongin. The taxonomic position of the novel isolate was confirmed using the polyphasic approach. Strain 119BY6-57T grew well at 25– 30°C on marine agar. On the basis of 16S rRNA gene sequence similarity, strain 119BY6-57T belongs to the family Xanthomonadaceae and is related to Lysobacter aestuarii S2-CT (99.8% sequence similarity), L. maris KMU-14T (97.5%), and L. daejeonensis GH1-9T (97.3%). Lower sequence similarities (97.0%) were found with all of the other recognized members of the genus Lysobacter. The G + C content of the genomic DNA was 69.9 mol%. The major respiratory quinone was Q-8 and the major fatty acids were C16:0 iso, C15:0 iso, summed feature 9 (comprising C17:1 iso ω9c and/or C16:0 10-methyl), summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c), and C11:0 iso 3-OH. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, three unidentified phospholipids, and an unidentified polar lipid. DNADNA relatedness values between strain 119BY6-57T and its closest phylogenetically neighbors were below 48.0 ± 2.1%. Based on genotypic and phenotypic characteristics, it is concluded that strain 119BY6-57T is a new member within the genus Lysobacter, for which the name Lysobacter spongiae sp. nov. is proposed. The type strain is 119BY6-57T (= KACC 19276T = LMG 30077T).