This species is known with certainty from the Lang Bian and Tay Nguyen highlands of southern Viet Nam (Smith, 1921 and Inger et al., 1999), and probably also from Tam Dao (northern Viet Nam). It has also been collected from Khao Soi Dao Wildlife Sanctuary, in Chanta Buri Province, southeastern Thailand. The record from Lao People's Democratic Republic (Stuart, 1999) is in error (B. Stuart pers. comm.). It probably occurs more widely than current records suggest, especially in areas between known sites, and it can be expected from both Lao People's Democratic Republic and Cambodia. It has been recorded between 700 and 1,500m asl in Viet Nam, and from 900m asl in Thailand.
Habitat and Ecology
It is known from streams in evergreen forest. It breeds in streams.
Reported collections of this species generally consisted of a single specimen or small series of specimens, indicating a rare or very cryptic frog.
Most of the species' habitat is threatened by forest degradation, clearance for agriculture and logging (Inger et al., 1999 and BirdLife International 2001).
The species' range includes protected areas in Viet Nam and Thailand. Upgrading protected areas to securely encompass the habitats and endemic species of the Tay Nguyen and Lang Bian Plateau regions is a high conservation priority. Clarification of the taxonomic status of northern Lao and Vietnamese records of this species is needed. This species is included in Thailand's OEPP 1997 Red List.
Peter Paul van Dijk, Nguyen Quang Truong 2004. Hylarana montivaga. In: IUCN 2014