The 29-year-old defensive midfielder is available on a cheap deal from Atletico Madrid.
The brother-in-law of former Chelsea and Barelona ace Deco's career has been overshadowed by public rows about his sexuality.
Richarlyson was 'outed' by Palmeiras official Jose Cyrillo.
Cyrillo claimed in a TV interview: “Even though Richarlyson was almost contracted by Palmeiras, Palmeiras will never have a gay player in the squad.”
Richarlyson reacted to the comments by suing Cyrillo. But the case was thrown out by judge Manoel Maximiano Junqueira Filho, who insisted that football is a "virile, masculine sport and not a homosexual one".