Wikipedia may not be your bag, it does have an entry for portuguese personal names, with an appendix on Brazilian usage.
Dear PCCLIST readers,
For Portuguese-language names: What do you do when you have a separately written prefix followed by a compound surname?
In AACR2 we're instructed "If the person’s language is Portuguese, enter under the last element." (11.5C4). However I don't see this AACR2 rule carried over into RDA.
RDA has: F.11.8 Portuguese. Record the part of the name following the prefix as the first element.
That would result in this name
Renato Fontoura de GusmaÞo Cerqueira
being formulated as
GusmaÞo Cerqueira, Renato Fontoura de
Cerqueira, Renato Fontoura de GusmaÞo
as AACR2 would have it.
Following the direction in 184.108.40.206.2 to go by IFLA's Names of Persons, I've looked here
but don't see which example, if any, matches the situation I'm dealing with.
One caveat: The person is a Brazilian. But this document http://www.ifla.org/files/
assets/cataloguing/pubs/ifla_didn't seem to have a match either. names_of_persons_brazil_1994.
I am in communication with authors of the book in hand – five of them, all Brazilian, three of them having compound surnames, three with the prefix de, two with both! Hopefully they’ll tell me their preferences (two have already responded). The Brazil National Library doesn’t appear to be a NACO member, and its practice differs from NACO for at least one author.
All advice gratefully received! I look forward to hearing from you.
Sincerely - Ian
Cataloging and Metadata Services Librarian
George Mason University