This floor plan of the PECO Primate Reserve appears to show the original inhabitants, as it no longer matches up with what's actually there.
The Aye-aye, Orangutan, Gibbons, and Gorillas are still in the enclosures as noted in the plan.
The Aye-aye is also in the enclosure directly next to it. They also have Slow Lorises in there, but I did not see them.
The "Squirrel Monkey" enclosure now holds Black-and-white Ruffed Lemurs.
The "Spectacled Langur" enclosure now holds Coquerel's Sifaka.
The "Lemur" exhibit below the Gorillas now holds Mantled Guerezas.
The "Coquerel's Sifaka" enclosure to the right of the outdoor Orangutan/Gibbon exhibit is now signed for Colombian Spider Monkey (although they have not actually moved in there yet, but they were exhibited near the Southern Ground Hornbills just south of the Backyard Kitchen restaurant).