PORTUNALIA. - A festival on 17 August in the oldest Roman calendar, dedicated to the god Portuno, whose character is described by literary evidence in uncertain and vague terms (god of gates or of ports). The god’s ancient importance is shown by the fact that he had his own flamen, called Portunalis, of whose functions, however, nothing is known except the duty of anointing, on certain occasions, the sacred arms of the god Quirino.
The P. were celebrated on the bank of the Tiber, near the Pons Amilus, where the god’s temple stood: in a late calendar the day is called, instead of P., Tiberinalia. This connection with the river or with waters seems to emerge from the mythological identification of Portuno with the Greek Melikertes-Palaimon. On the other hand, Portuno is inseparable from the sphere of Giano: the P. are the dedication day of an ancient temple of Giano;
and one rite of the P. consisted in burning keys, while the key is known as an attribute of Giano.