We report the discovery of a population of the exotic North African Water Frog Pelophylax saharicus around the Etang de Berre, on the Mediterranean coast of France, about 25 km north-west of Marseille. The animals had been originally identified as P. perezi or P. kl. grafi by a combination of acoustic and morphological characters and their true identity was not revealed until three samples from one locality were included in a large-scale genomic work dedicated to the genus Pelophylax. Mitochondrial barcoding of the samples from other areas around Etang de Berre did not detect any native P. perezi or P. kl. grafi and confirmed that P. saharicus has spread to several localities, does reproduce and has been present since 2011 at least. We suggest that dedicated field work is needed as soon as possible to i) map the extant of P. saharicus’s distribution around the Etang de Berre, ii) establish if populations of the native P. perezi – kl. grafi system still persist around the Etang de Berre or not and iii) check if P. saharicus has spread to neighboring areas or not. Depending on the answers to these three questions, local conservationists will need to evaluate the feasibility and relevance of any action to control the spread of this new invasive species and attempt to eradicate it.