Of the 18 or so species of gibbon, only a handful are really common in zoos worldwide (Lar, yellow-cheeked, and siamang). I've also seen northern white-cheeked and Müeller's gibbons. I'm wondering how many of the rest are kept, and where they are. Looking at ZooChat galleries it appears that a lot of gibbon diversity is kept in China and Indonesia. Which gibbon species have you seen?