Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.
Northern and eastern Colombia and northern and central Venezuela east to Trinidad and the Guianas, southern irregularly to eastern Ecuador, north-eastern Peru, northern and eastern Bolivia, northern Argentina, Paraguay and south-eastern Brazil.
 
Population
Estimated population is unknown (2010).
White-headed Marsh Tyrant (Arundinicola leucocephala) [XC720937]
by Dante Buzzetti from Inaj\u00e1, State of Paran\u00e1, Brazil (flight call)
White-headed Marsh Tyrant (Arundinicola leucocephala) [XC185783]
by Caio Brito from Pirassununga, S\u00e3o Paulo, Brazil (call)
Subspecies
No subspecies.
Genus related to Fluvicola and sometimes merged with it. However, anatomical evidence and behaviour suggest that separate generic treatment is more appropriate.