There are several Mountain Horned Dragons, also called Pricklenape Agamas, all native to southeast Asia.
The species shown here, called just the Mountain Horned Dragon or the Green Prinklenape, is native to Cambodia and south Vietnam.
They are diurnal, mainly tree-dwelling, well-camouflaged and eat insects. Both males and females have the horned nape.
They can grow to nearly a foot long.