This species is known only from two sites in the western corner of Borneo: the type locality on Gunung Damus, near Sambas, in Kalimantan (Indonesia), and Gunung Penrissen, in western Sarawak (Malaysia). It possibly occurs more widely than current records suggest; however it is not likely to occur more widely within Sarawak, as nearby mountains have been surveyed at similar elevations with no records to date (Y.M. Pui pers. comm. March 2018). It occurs from 1,200–1,400 m asl, its extent of occurrence (EOO) is 390 km2 and it occurs at two threat-defined locations.
Habitat and Ecology
This species inhabits primary, hilly montane rainforest. Individuals are entirely arboreal, except juveniles that have been found near permanent streams. It is speculated that this species spawns in streams and have torrent-adapted tadpoles. If it is similar to other members of its genus, it is unlikely to be able to adapt to modified habitats.
Listed as one of the ‘World’s Top 10 Most Wanted Lost Frogs’ by the IUCN/SSC Global Amphibian Specialist Group and Conservation International, it had not been sighted since the 1920s (Inger 1966). In June 2011, an expedition to the higher elevations (>1,000 m asl) of Gunung Penrissen rediscovered three individuals (Pui et al. 2011). The species has been observed at least two additional times on Gunung Penrissen since then (Matsui et al. 2012). There have also been observations of this species in 2017: over two nights for the period of four hours, five to six individuals were observed (Y.M. Pui pers. comm. March 2018). Surveys over the course of one week in April 2017 failed to record the species at Gunung Damus (Mediyansyah pers. comm. May 2017). Due to ongoing decline in the extent and quality of habitat, the population is suspected to be decreasing.
The main threat to this species is habitat loss and degradation primarily as a result of logging. The area of Gunung Penrissen has a long history of agriculture, especially rice, although rubber and pepper are also grown in all except the steepest terrain (Min et al. 2011). The remaining suitable habitat within its range has almost entirely been converted for recreational use (one of the two known sites, Gunung Penrissen, has been converted into an 18-hole golf course and a 25 acre area of ‘flower garden and theme parks’), or converted to cultivated land, but there is still some suitable habitat available. An additional threat is the resultant sedimentation of streams (following logging) which results in the deterioration of breeding habitat.
Gunung Penrissen lies outside the protected area system of Sarawak, but is listed among the Important Bird Areas of the world by BirdLife International.
Effective preservation of hilly rainforest in the regions of the two known localities is essential.
Further survey work in the hilly border area of Sarawak and Kalimantan is necessary to help provide a better indication of the species' distribution, current population status, and natural history.
Red List Status
Listed as Endangered because its extent of occurrence (EOO) of 390 km2, it occurs in two threat-defined locations, and there is a continuing decline in the extent and quality of its primary montane forest habitat in western Borneo.
IUCN SSC Amphibian Specialist Group 2018. Ansonia latidisca. The IUCN Red List of Threatened Species 2018: e.T54471A114916284. http://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T54471A114916284.en .Downloaded on 23 January 2019