The former French Catholic diocese of Couserans existed perhaps from the fifth century, to the French Revolution. It covered the former province of Couserans, in south-west France. Its see was in Saint-Lizier a small town to the west of Foix. It was a suffragan of the archdiocese of Auch.
Ancient Diocese of Couserans Wikipedia
Couserans was the fifth of the Novempopulaniae civitates. In the 580's peace and a division of territories was arranged between the Merovingian kings Guntram (561–592) and Childebert II (575–595), in which the territory of Couserans was assigned to Childebert. According to Gregory of Tours, the first bishop was Valerius, before the sixth century. Bishop Glycerius was present at the Council of Agde in 506. According to Louis Duchesne, he should be identified with Lycerius whom the Gallia Christiana places later in the list of bishops. Lycerius was patron saint of St-Lizier, the town in which the bishops of Couserans had their official residence.
The historian Pierre de Marca (1643–52), a native of Béarn and President of the Parliament of Navarre, was subsequently Bishop of Toulouse and Archbishop of Paris.
Up until the administration of Bishop Bernard de Marmiesse (1654–1680), the town of Saint-Lezier had two co-cathedrals, the Cathedral of Notre-Dame-de-la-Sède in the upper town next to the Episcopal Palace, and the Cathedral of St.-Lizier farther down to the south. Each co-cathedral was served by its own Chapter, each Chapter having a Precentor, a Sacristan, an Operarius, six Canons, ten Prebendarii and a priest called the Vicar Perpetuus. Over both Chapters stood the Archdeacon and the Aumonier. Bishop de Marmiesse united the two chapters and based them in the Cathedral of Notre-Dame-de-la-Sède; it was composed of the Archdeacon, two Precentors, two Sacristans, two Operarii, the Aumonier, twelve Canons, and two Vicarii perpetui; there were twenty-four prebends. In 1752 there was one dignity and twelve Canons.