A rare responsory and an even rarer prosula for Pentecost in 13th-century Portuguese fragments

The responsory Erant omnes apostoli is one of the characteristic elements of the Office for Pentecost Sunday adopted in Medieval Portuguese secular uses. This responsory had a limited dissemination. Its earliest sources for both text and music are the early 11th-c. antiphoner E-Tc 44.1, possibly coming from Saint-Orens in Auch; the late 11th- or early 12th-c. antiphoner E-Tc 44.2, likely copied in Moissac; the late 12th-c. noted breviary E-Tc 35.9, probably copied locally; and the mid- to late 12th-c. noted breviary E-H 2, probably copied locally from an exemplar from Auch. In the latter source, the responsory comes with the prosula Alle nunc hodie summa voce. The prose alone and the melisma to which it was composed appear as an addition to a late 10th-c. southern-French manuscript (F-Pn Lat. 94) and, following Erant omnes apostoli, in two 13th-c. Portuguese fragments. This paper will essay to ascertain the origins and routes of this rare responsory and its even rarer prosula.