I don't agree with all the splits which have been proposed for gibbons (e.g. I certainly don't agree with splitting Mueller's Gibbon into three species as has been done recently) - however the Hoolock Gibbon is now two species, the Bornean population of Agile Gibbon is very probably a distinct species, and the Concolor Gibbon as used on this sign is clearly a complex (perhaps as many as seven or eight species).
