[4] Edward Dickinson and Leslie Christidis placed it in Tachurisidae in the fourth edition of the Howard and Moore Complete Checklist of the Birds of the World.

Adult males of the nominate subspecies T. r. rubrigastra have a black crown with a slight crest and a partly hidden red patch in the middle.

They have a large golden supercilium and glossy blue to black lores whose color extends onto the ear coverts giving a masked appearance.

Their wings are black with white edges on the coverts and tertials that form a large bar when closed.

[9][10][11] Subspecies T. r. alticola is slightly larger than the nominate, with a paler yellow supercilium and a darker, more blackish green back.

[9][10][11][12][excessive citations] The many-colored rush tyrant almost exclusively inhabits large reedbeds in lakes and marshes; it also infrequently occurs slightly into adjoining grassy edges.

[9][10][11][12][excessive citations] The many-colored rush tyrant is partially migratory though the exact pattern is not well understood.

It reaches Brazil north of Rio Grande do Sul, Paraguay, and possibly northern Uruguay and far northeastern Argentina only in the austral winter.

[9][12] The many-colored rush tyrant's breeding season has not been fully defined but includes September and October in Peru and Brazil.

It makes a distinctive deep cone-shaped cup nest from wet reed leaves that harden as they dry; their consistency has been likened to cardboard.

The many-colored rush tyrant's song is "a quiet, mellow, pleasant series of noes with a short buzz near the start and ending with a loose musical rattle: kachup-brrr-kachup'yp'a'trrrrl.