Regina celi
Anonymous:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Source:  TrentC 91, fols. 25r-33r (c.1472).
Philippe Basiron:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Source: VatS 51, fols. 123v-132r.

Requiem eternam
Anonymous:
Credo  
Source:  OxfB Add. C. 87*, fols. 225r-226v.
Edition:  Ernst Apfel, Studien zur Satztechnik der mittelalterlichen englischen Musik, 2 vols. (Heidelberg: Carl Winter, 1959), 2: 142-45. See also Gareth Curtis, ed., Fifteenth-Century Liturgical Music IV: Early Masses and Mass-Pairs, Early English Church Music, 42 (London: Stainer and Bell for The British Academy, 2001), 14-29, for what remains of the Gloria and Sanctus.
Bartolomeo Ramis de Pareia (lost):
Unknown movement  
Excerpt, quoted in a letter from Giovanni Spataro dated 1523. See Bonnie J. Blackburn, Edward E. Lowinsky, and Clement A. Miller, eds., A Correspondence of Renaissance Musicians (Oxford: Clarendon Press, 1991), 273.

Requiem Masses, see: Pro defunctis


Rex dabit mercedem
Anonymous:
Gloria   Credo   Sanctus   Agnus Dei   
Source: VerBC 755, fols. 54v-63r.

Rex seculorum
John Dunstable or Leonel Power
Kyrie*   Gloria   Credo   Sanctus   Agnus Dei
Edition: John Dunstable, Complete Works, 2nd edn., ed. Manfred Bukofzer et al., Musica Britannica, 8 (London: Stainer and Bell, 1970), 47-57 and 172-75.
*Too fragmentary to be recorded here.

Rose playsante
Jacob Obrecht:
Kyrie   Gloria   Credo   Sanctus   Agnus Dei
Edition:  Jacob Obrecht, New Obrecht Edition, gen.ed. C. J. Maas, 18 vols. (Utrecht: Vereniging voor Nederlandse Muziekgeschiedenis, 1983-1999), 9: 47-91.

Rosina
Josquin des Prez:
Credo   
Edition: Tom R. Ward, “A Newly-Discovered Josquin Attribution,” Tijdschrift van de Vereniging voor Nederlandse Muziekgeschiedenis, 33 (1983): 29-48, at 44-47.
The earliest known source for Josquin’s Mass, BasU F.IX.55, was copied c.1507-10. The setting is anonymous there, but it was attributed to Josquin by Heinrich Faber, in 1548. Judging from the style of the Credo, the only complete movement to survive, it is hard to imagine who else would have written this setting in the early 1500s: this is as vintage Josquin as anything I’ve heard. But the editors of the New Josquin Edition have preferred to blunder on the side of caution, and have rejected the work as definitely not by Josquin.
The song Rosina was not necessarily German: it appears as Rozijne hoe is dijn ghestelt with three stanzas of middle-Dutch poetry in the Antwerp Liedboek of 1544. The rhymed psalm Die boose sprack in zijn ghedacht (Ps. 35) in the Dutch Souter Liedekens (Antwerp: Symon Cock, 1540) appears with the designation “after the tune of Rosina waer was v ghestalt,” suggesting that the song was a popular favorite in the Low Countries. Clemens non Papa published a setting of the tune in his Souter Liedekens of 1556. A contrafact of the song also appears under the title O Christe hwor wor thÿn kundskab in Een Ny handbog med Psalmer oc aandelige lofsange (Rostock: Ludowich Dietz, 1529).

Rozel im gortn “andersch franczosel”
Anonymous:
Gloria   Credo   Sanctus   Agnus Dei   
Sources: TrentC 88, fols. 295v-304r (1460-62); PragP 47, fols. 121v-31r and 203v-204r.