In February 2010, grapefruit (Citrus paradisi) and Mexican lime (C. aurantifolia) leaves with erumpent callus-like lesions were collected in Senegal in the Sebikotane area between Dakar and Thies. Similar symptoms have been observed by local farmers since 2008, and lesions were morphologically similar to those of citrus canker caused by Xanthomonas citri pv. citri (Asiatic canker) and X. citri pv. aurantifolii (South American canker). Lesions were primarily reported from grapefruit (cv. Shambar), which is the most frequent citrus species produced in this area, and Mexican lime, which is also commonly grown. Both species are very susceptible to X. citri pv. citri pathotype A, and Mexican lime is susceptible to X. citri pv. citri pathotype A* and X. citri pv. aurantifolii (4). Fifteen Xanthomonas-like strains were isolated from disease samples using KC semiselective medium (3). PCR with primer pair 4/7 (2) revealed that all the Senegalese strains and the X. citri pv. citri strain CFBP 2525 from New Zealand, used as a positive control, generated the expected DNA fragment, whereas no fragment was observed for negative controls (distilled water instead of the template). Insertion sequence ligation-mediated (IS-LM)-PCR analysis (1) of X. citri pv. citri strains from Senegal and reference strains of X. citri pv. citri pathotypes A and A* (1), with MspI and four primer pairs (unlabelled MspI primer and four 5?-labelled insertion sequence-specific primers targeting three IS elements), indicated that the strains from Senegal were related to X. citri pv. citri but not to pv. aurantifolii. They were closely related to X. citri pv. citri pathotype A strains, with a broad host range, present in the Indian subcontinent and Mali (C. Vernière, unpublished data). Multilocus sequence analysis of four partial housekeeping gene sequences (atpD, dnaK, efp, and gyrB) confirmed that four Senegalese strains were not related to X. citri pv. aurantifolii and showed a full sequence identity to