This species is widely distributed throughout much of Borneo (Sabah, Sarawak, Brunei and Kalimantan) and Sumatra, Indonesia. In Kalimantan, it occurs Kayan Mentarang National Park (Veith et al. 2004) and Long Binsai Indigenous Forest (Indonesia Red List Assessment Workshop May 2017) in North Kalimantan Province; Bukit Baka-Bukit Raya (Iskandar 2007), Murung Raya (Rahmania 2014), and Mawas (Mistar 2008) in Central Kalimantan Province; PT Intracawood Manufacturing Forest Concession (Utama 2003), Penajam Paser Utara District (Fitrian 2013), Labanan Research Forest, Berau District (Lestari et al. 2013), Sungai Dengan and Sungai Benturak Forestry Concessions (Indonesia Red List Assessment Workshop May 2017), and Mahakam River in East Kalimantan Province. On Sumatra, it is known from scattered localities in Aceh, North Sumatra, West Sumatra, Jambi, South Sumatra Provinces, including Gunung Leuser National Park, Batang Toru Protection Forest, Batang Gadis National Park, and Kerinci Seblat National Park (Kurniati 2008, Teynie et al. 2010, Smart et al. 2017, Indonesia Red List Assessment Workshop May 2017). It occurs up to elevations of 400–1,700 m asl.
Habitat and Ecology
This species occurs along rocky creeks and riverbanks and also wanders widely through primary and secondary forests. Occasionally it is found near isolated houses in hilly terrain near forest and in some types of tree plantations. It breeds in rocky-bottomed, strong flowing streams where the larvae also develop. It will not tolerate habitat disturbance (I. Das pers. comm. March 2018).
It is uncommon in Borneo, but is comparatively rare in Sumatra. Due to ongoing decline in the extent and quality of habitat, the population is suspected to be decreasing.
The principal threat to the species is rapid clear-cutting of lowland tropical rainforest in forest concession land and for oil palm plantations (Indonesia Red List Assessment Workshop May 2017). Local collecting of the species is not taking place in such a way that poses a threat to the species (Indonesia Red List Assessment Workshop May 2017). It occurs in many protected areas throughout its range and is not considered to be majorly threatened (P. Yambun pers. comm. January 2018, I. Das pers. comm. March 2018).
It is present in many protected areas in Borneo and Sumatra.
Continuation of rigorous management of the existing parks to protect forest habitat is the best guarantee for the conservation of this species.
Taxonomic work is needed to compared the specimens from Borneo and Sumatra. Research into this species' population status is needed.
Red List Status
Least Concern (LC)
Listed as Least Concern in view of its wide distribution and large population.
IUCN SSC Amphibian Specialist Group 2018. Phrynoidis juxtaspera. The IUCN Red List of Threatened Species 2018: e.T54676A114917162. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T54676A114917162.en .Downloaded on 18 January 2019