A titular see in Mauretania Casariensis
Tubunae, a titular see in Mauretania Casariensis, according to the "Gerarchia cattolica", or in Numidia according to Battandier, "Annuaire pontifical catholique" (Paris, 1910), 345. The official list of the Roman Curia does not mention it. The confusion is explained by the fact that it was located at the boundary of the two provinces. Bocking, in his notes to the "Notitia dignitatum" (Bonn, 1839), 523, and Toulotte ("Geog. de l'Afrique chret., Mauretanies", Montreuil, 1894, p. 171), speak of two distinct cities, while Muller ("Notes to Ptolemy", IV, 12, ed. Didot, I, 611) admits only one, and his opinion seems the more plausible. It was a municipium and also an important frontier post in command of a prcepositus limitis Tubuniensis. St. Augustine and St. Alypius sojourned there as guests of Count Boniface (Ep. ccxx). In 479 Huneric exiled thither a large number of Catholics. Its ruins, known as Tobna, are in the Department of Constantine, Algeria, at the gates of the Sahara, west of the Chott el-Hodna, the "Salinae Tubunenses" of the Romans. They are very extensive, for three successive towns occupied different sites, under the Romans, the Byzantines, and the Arabs. Besides the remains of the fortress, the most remarkable monument is a church now used as a mosque.
Three bishops of Tubunae are known. St. Nemesianus assisted at the Council of Carthage in 256. St. Cyprian often speaks of him in his letters, and we have a letter which he wrote to St. Cyprian in his own name and in the name of those who were condemned with him to the mines. An inscription testifies to his cult at Tixter in 360, and the Roman Martyrology mentions him on September 10. Another bishop was Cresconius, who usurped the see after quitting Bulla Regia, and assisted at the Council of Carthage in 411, where his rival was the Donatist Protasius. A third, Rearatus, was exiled by Huneric in 484.