I've only heard of black capped, and white bellied caiques.
I'll write that a bit more precisery: There are 2 species of caiques: black capped (2 subspecies) and white bellied (3 subspecies). Green tighed parrot is one of WBC subspecies. In some classifications each WBC subspecies can be separate species - then there're 4 caigue speciesI've only heard of black capped, and white bellied caiques.
surprisingly enough there's a handful of different subspecies. Most of them just look like the white bellies with slight differences. Green thighed is just one of them.