ALERIA, DIOCESE of. - An ancient bishopric of Corsica, which took its name from an old city, formerly a Phocaean colony, situated on the banks of the Tavignano. The existence of the diocese in 591 is attested by a testimony of St. Gregorio Magno. Initially subject to the immediate jurisdiction of the Pope, the ancient bishopric passed, in the 11th century, under that of Pisa (v. AJACCIO). In the 16th century the bishops of A. established their residence at Bastia, then at Cervione, Campoloco, and Corte.
According to Matteo di Flentin, at the end of the 17th century, the church of S. Erasmo at Cervione served in place of the destroyed cathedral of A., and the diocese consisted of 18 pievi and 3 parishes. Among its ancient bishops were figures such as Gian Andrea Bussi (1466-75; v.), Ardicino della Porta (1475-93), and above all St. Alessandro Sauli (1570-91; v.), who may be regarded as its second founder. The last bishop of A. was Giovanni Giuseppe Maria de Guernes (6 Aug. 1770?), since the Concordat of 1801 reduced the bishops of Corsica to a single one, with his seat at Ajaccio.