South-eastern Brazil (east-central Minas Gerais, southern Espírito Santo and south-western Sío Paulo south to northern and central Rio Grande do Sul), eastern Paraguay (Caaguazú, Alto Paraná, Caazapá, Itapúa) and north-eastern Argentina (Misiones).
 
Population
Estimated population is unknown (2010).
Large-tailed Antshrike (Mackenziaena leachii) [XC353956]
by Bobby Wilcox from Intervales State Park, S\u00e3o Paulo, Brazil (song)
Large-tailed Antshrike (Mackenziaena leachii) [XC244314]
by Jeremy Minns from Itatiaia National Park. Rio Maromba valley, Brazil (call)
Subspecies
Genus presumed related to Thamnophilus on basis of external morphology, especially the strongly hooked bill, but supporting molecular or other evidence unavailable. Relationships uncertain. May not be very closely allied with Tufted Antshrike (Mackenziaena severa).