Actinobacillus pleuropneumoniae causes pleuropneumonia, an economically significant, lung disease of pigs. Recently, isolates of A. pleuropneumoniae that were serologically distinct from the previously characterized 15 serovars were described, and a proposal put forward that they comprised a new serovar 16. Here we used whole genome sequencing of the proposed serovar 16 reference strain A-85/14 to confirm presence of a unique capsular polysaccharide biosynthetic locus. For molecular diagnostics, primers were designed from the capsule locus of A-85/14 and a PCR formulated that differentiated serovar 16 isolates from all 15 known serovars, and other common respiratory pathogenic/commensal bacteria of pigs. Analysis of the capsule locus of strain A-85/14 combined with the previous serological data, show the existence of a sixteenth serovar – designated serovar 16 - of A. pleuropneumoniae.