Wexford emigrees to Assunguy, Brazil?

My father’s great-grandparents on his father’s father’s side -- Thomas Redmond and his first wife, Margaret (maiden name Pierce).   We know from oral history that Thomas and Margaret were originally from Wexford County.Thomas and Margaret Redmond appear to have departed Ireland on a British ship in the early fall of 1864 and reached Brazil in November. Margaret gave birth to a son, Alexander (my father’s future grandfather), on board the vessel as they approached the coast of Brazil. Because Alexander was born on a British ship, he received British citizenship. His early childhood (1864 to 1874) was in the vicinity of Curitiba, Brazil – which appears to coincide with the location of an Irish settlement in Assunguy, Brazil.   

According to 1880 and 1910 US census records, the Redmond family came to the US in 1874. 

Has anyone heard anything about the story behind the Irish settlement in Assunguy, Brazil? Were the settlers all from the same village or parish in Wexford county?    

Although my father’s great-grandparents (Thomas Redmond and Margaret (Pierce) Redmond) were from Wexford County, we have never found any birth or marriage records, or emigration records related to their departure from Ireland in 1864.  Any assistance with locating new information would be greatly appreciated.