Shape in Latin-1

Hello all,
I have had a incovenient trouble to read a shapefile that I suspect
was encoded as "latin-1". Since I'm mac user and mac uses UTF-8, some
kind of problem could be happen.
I tryed some comand lines without success:

brasil <- readShapeSpatial(file.choose(),

proj4string=CRS("+proj=longlat"))
Error in getinfo.shape(fn) : Error opening SHP file

brasil <- readShapePoly("/Users/daniel/bases/maps/Brasil/55mu2500gsr.shp", encoding="latin1")

Error in readShapePoly("/Users/daniel/bases/maps/Brasil/55mu2500gsr.shp", ?:
??unused argument(s) (encoding = "latin1")

Somebody know how can I open it?
Daniel