Among Italian Baroque music theorists recognizing the tuoni ecclesiastici
as modal categories in their own right (including Banchieri, Angleria,
Penna, and Tevo) or as a subset of the twelve modes (including most notably
Bononcini), some present them with, and others without, reference to the
specific psalm-tone cantus firmi from which they derive.
Writers who present them in the context of the psalm tones usually represent
them as a set of signatures and finals (crucial cues to transposition level
and psalm-tone termination for an organist accompanying or alternating
with psalmody), as well as common interior cadential degrees. Theorists
who address the tuoni ecclesiastici quite apart from psalmody, however,
typically adopt the apparatus of traditional modal theory, namely mediated
octave species. These differences in representation echo a tension
between concepts of tonus and modus extending back to the
Middle Ages and highlight the role of the tuoni ecclesiastici in
mediating between vocal and instrumental ways of organizing tonal space.