SAN TOMMASO, DIOCESI di. — Diocese and island of the same name in Portuguese Guinea (Africa). The diocese has an area of 964 sq. km. and a population of 60,540 inhabitants, of whom 36,149 are Catholics; it has 10 parishes served by 8 religious priests and 1 diocesan priest (Ann. Pont. 1952, p. 367).
The territory of this diocese consists of the Portuguese islands of S. T. and Principe in the Gulf of Guinea, and it is suffragan to Loanda (bull Solemnibus conventionibus, 4 Sept. 1940). Vacant since the 19th century, but not suppressed, it is provided for in the person of the archbishop of Loanda, who governs it through a vicar general.
On 17 June 1532, Giovanni III, king of Portugal, commissioned d. Martino del Portogallo to ask the Holy Father for the erection of the diocese of S. T., which was to comprise the islands of S. T., S. Antão, Ferdinando del Pò, S. Elena, and Buon Anno (Ano Bom), and the mainland from S. Giorgio della Mina, where the diocese of Cape Verde ended, to the Cape of Good Hope. The King further asked the Holy See to annex to the episcopal mensa of the new diocese the Cistercian monastery of S. Giovanni di Tarauca. On 31 January 1533, Clement VII granted the King’s request, but, only in part, the bulls were not dispatched in time. However, Paul IV, by the bull Aepuam reputamus (3 Nov. 1534), carried out all the determinations of his predecessor concerning the erection of the cathedral of S. T. The diocese comprised the mainland territory from the river of S. Andrea, near Cape Palmas, on the coast of Guinea, where the diocese of Cape Verde ended, to the Cape of Good Hope and, moreover, as far as Cape Agulhas; the islands of S. T., S. Antão, Ferdinando del Pò, S. Elena, and Buon Anno (Ano Bom); and the part of the Ocean lying to the west between two parallels, one drawn from the mouth of the river of S. Andrea and the other from Cape Agulhas, together with all the islands already discovered or that might be discovered in the future. The diocese was suffragan to Funchal and had 12 canons and 5 dignities. Later, the bishoprics of Congo and Angola were detached from this diocese, having by then been suppressed through the establishment of the new dioceses (bull Solemnibus conventionibus).