The expansion of antibiotic resistant Acinetobacter baumannii lineages has prompted investigation into effective epidemiological markers. Sequence diversity observed at the genomic K locus (KL) for synthesis of the highly variable capsular polysaccharide (CPS) and the OC locus (OCL) for synthesis of the outer-core component of the lipooligosaccharide have proven valuable in epidemiological studies of the major global clonal lineages [1]. However, little is known about these regions in the increasingly antibiotic resistant, global sequence type 25 (ST25). A total of 3,417 public genome sequences were subjected to multilocus sequence typing (MLST), revealing 81 isolates belonging to ST25. These genomes were evaluated for quality and assessed for KL and OCL types using Kaptive [2], and our database of KL and OCL reference sequences [3]. 50 dated ST25 isolates were then subjected to time-measured phylogenomic analysis and ancestral state reconstruction using Bayesian analysis software, BEAST2 [4]. 19 KL and 5 OCL gene clusters were identified, with 5 KL and 1 OCL being novel gene cluster arrangements. The gene cluster variation observed in ST25 was more extensive than previously seen in other global clonal lineages [5]. The results obtained indicate that recombination events over 50 years have established significant diversity in loci encoding outer surface components. While some loci combinations were global, other locus combinations were restricted to geographical regions, indicating viability of KL and OCL as epidemiological markers. Tracing these genomic locus and their evolution enables more thorough discrimination between strains belonging to the same clonal lineage, allowing for delineation of sub-lineages and mapping of global distribution patterns.