When exactly was the ritual of rerum repetitio, the act of declaring war, performed RE the First Punic War? I know that Appius Claudius Caudex pretty much declared it informally on Rome's first mission over to Messina. But doesn't it still involve a fetial priest chucking a spear into enemy territory?
As the Roman demesne expanded throughout Italy, the inconvenience of the fetial ritual necessitated a change in the rite. By "legal fiction", an area near the columna bellica in Rome became the hostile territory on which the ceremony would be performed. This was already done for Pyrrhus, and was therefore almost certainly done for the Punic wars.
Sauce: OCD2, Fetiales.