A Gram-stain-positive, non-spore-forming actinobacterium, strain 9H-4T, isolated from the choana of a garden warbler (Sylvia borin) was studied to examine its taxonomic position. On the basis of 16S rRNA gene sequence analysis it was shown that strain 9H-4T belongs to the genus Aeromicrobium with Aeromicrobium flavumTYLN1T (98.7 % similarity) and Aeromicrobium tamlenseSSW1-57T (98.4 %) as the nearest neighbours and forms a separate branch in a neighbour-joining phylogenetic tree based on 16S rRNA gene sequences. DNA-DNA hybridizations confirmed its novel species identity based on 39 and 46 % DNA-DNA relatedness with A. flavum DSM 19355T and A. tamlense DSM 19087T, respectively. The predominant menaquinone of strain 9H-4T was MK-9(H4). The peptidoglycan contained ll-diaminopimelic acid as the diagnostic diamino acid. The major fatty acids (C18 : 1ω9c, 10-methyl C18 : 0, C16 : 0, C18 : 0, C16 : 0 2-OH) were consistent with the fatty acid patterns reported for members of the genus Aeromicrobium. The DNA G+C content of strain 9H-4T was 70.8 mol%. The distinct genotypic, chemotaxonomic, physiological and biochemical characteristics support the classification of strain 9H-4T as a representative of a novel species of the genus Aeromicrobium, for which the name Aeromicrobium choanae sp. nov. is proposed. The type strain is 9H-4T (=ZIM B1021T=LMG 29165T=CCM 8650T).