A novel Gram-negative, obligate aerobic, non-motile, and both coccobacillus- and bacillus-shaped bacterium, designated strain HYN18(T), was isolated from the intestinal tract of a honey bee (Apis mellifera). The isolate was oxidase-negative and catalase-positive. Strain HYN18(T) showed optimum growth at 25°C, pH 6-7, and in the presence of 1% (w/v) NaCl in trypticase soy broth medium. The isolate was negative for hydrolyses of starch, casein, gelatin and urea, indole production from tryptone and hemolysis on sheep blood agar. A phylogenetic analysis based on the 16S rRNA gene and rpoB gene sequence showed that strain HYN18(T) was most closely related to Acinetobacter nectaris SAP 763.2(T) and A. boissieri SAP 284.1(T) with 98.3% and 98.1% similarity (16S rRNA gene), respectively, and 84.4% similarity with Acinetobacter nectaris SAP 763.2(T) (rpoB gene). The major cellular fatty acids were summed features 3 (comprising C16:1ω7c /C16:1ω6c ), C12:0 and C16:0. The main isoprenoid quinone was ubiquinone-9 (Q-9). The polar lipids of strain HYN18(T) were phosphatidylethanolamine, three unidentified lipids, an unidentified phospholipid and an unidentified glycolipid. The DNA G+C content was 40.6 mol%. DNA-DNA hybridization experiments indicated less than 33 ± 10% relatedness to the closest phylogenetic species, Acinetobacter nectaris SAP 763.2(T). Thus, the phenotypic, phylogenetic and genotypic analyses indicate that strain HYN18(T) is a novel species within the genus Acinetobacter, for which the name Acinetobacter apis is proposed. The type strain is HYN18(T) (=KACC 16906(T) =JCM 18575(T)).