Yesterday I looked at two motets from Rusca's collection that make expressive use of the upper register for "alleluias." The third piece is another four-voice motet: "Gaudete gaudio magno martyres Christi." Here is a familiar separation of roles in the concertato style: upper-register instrumental descant or obbligato and principal (cantus or soprano) choral part. Note the ritornello at the outset and the repetition of it over the chorus's "alleluias" in bars 22 ff. The score in modern notation is by Lorenzo Girodo (2016).
Notwithstanding the above, the three chorus voices end the main text with a firm descent for "in caelis" . . .
. . . after which, the ritornello is repeated . . .
. . . and the alleluias are considerably expanded with antiphonal play before the section from the beginning (22 ff.) is repeated to close.
