The Primofiore is not a name of cultivar, it means fruits from first flowering.
The primofiore (literally, "first flower") matures from October 1st, has an elliptical shape, skin and flesh which varies from light green to lemon-yellow, and lemon-yellow juice; the bianchetto ripens from April 15th, is ovoid-elliptical, with light yellow skin, yellow flesh and lemon-yellow juice; the verdello matures from July 1st, is an spheroid elliptical shape, light green skin, and lemon-yellow flesh and juice.
The cultivar name is femminello Siracusano aka Limone di Siracusa IGP.