This species formerly occurred along the north (right) margin of the Rio Paranapanema, west as far as the Rio Paraná, and between the upper Rios Paranapanema and Tieté in the state of São Paulo (Coimbra-Filho 1976a,b; Hershkovitz 1977). Today, it is known only from 11 widely separated forest patches covering 444 km². L. chrysopygus occurs in two state protected areas, the Morro do Diabo State Park, municipality of Teodoro Sampaio, and the Caetetus State Ecological Station, municipality of Gália, (Coimbra-Filho 1970a,b, 1976a,b; Coimbra-Filho and Mittermeier 1973, 1977; Valladares-Padua et al. 1994). All surviving populations are in the central to western part of its former range and concentrated in the region called the Pontal de Paranapanema, except for Buri, municipality of Buri, discovered in recent surveys in the eastern part, approximately 200 km east of the Caetetus Ecological Station, by Valladares-Padua et al. (2000). Rylands et al. (2002b) reviewed the distributions of all four lion tamarins.