found: Britannica online, Oct. 6, 2015:French Guiana (overseas département of France, situated on the northeastern coast of South America; forms an integral part of the French Republic and sends two elected representatives to the National Assembly and two to the Senate; in text: French Guianese as noun and adjective)
found: Collins English dictionary online, Oct. 6, 2015:French Guianese or French Guianan (noun: a native or inhabitant of French Guiana)
found: Dugas, J.-Y. Dictionnaire universel des gentilés en français, 2006(Guyane: Guyanais, Guyanaise; same terms also used for the country Guyana)
found: Pays et leurs gentilés en français, via Wiktionnaire site, July 14, 2015(Guyane française: Guyanais)