A new, montane species of Ansonia is described from the state of Pahang in central, peninsular Malaysia on the basis of having a unique combination of head, body, digit, and color pattern characteristics. This new species is similar to A. malayana, to which it is closest geographically, but differs greatly in aspects of head morphology and body tuberculation. A review of Ansonia from the Malay Peninsula demonstrates that the population of A. malayana from Tasan, Chumphon Province, Thailand is A. kraensis and A. penangensis from Ulu Tahan, Pahang in peninsular Malaysia is not conspecific with A. penangensis from Pulau Penang but an additional, undescribed species ranging throughout northwestern, peninsular Malaysia.