A Gram-stain-negative, facultatively aerobic, motile and ovoid- to rod-shaped bacterium, designated as FT324T, was isolated from a surface mangrove sediment sample from Shenzhen, PR China. The taxonomic position of strain FT324T was determined by a combination of phylogenetic, physiological, biochemical and chemotaxonomic analyses. Strain FT324T grew at 20–40 °C (optimum, 30–37 °C), pH 5.0–9.0 (optimum, pH 8.0) and in the presence of 0–3 % (w/v) NaCl (optimum, 1 %). Its full-length 16S rRNA gene sequence was the most similar to
Frigidibacter oleivorans
XJ4T (97.4 %), followed by
Defluviimonas denitrificans
DSM 18921T (96.62 %),
Pseudothioclava arenosa
CAU 1312T (96.54 %) and
Defluviimonas nitratireducens
DL5-4T (96.47 %). The major fatty acids (>10 %) of FT324T were C19 : 0 cyclo ω8c (51.9 %) and summed feature 8(29.6 %). The predominant respiratory quinone was Q-10. Its polar lipid profile contained phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified aminolipid, one unidentified lipid and two unidentified phospholipids. Its estimated genome size was 4 294 115 bp and the genomic DNA G+C content was 69.6 mol%. Based on its distinct phenotypic, chemotaxonomic and phylogenetic characteristics, strain FT324T should represent a novel species of the genus
Defluviimonas
, for which the name Defluviimonas sediminis sp. nov. is proposed (=MCCC 1K07685T=KCTC 92477T).