This Bornean endemic is known only from a few localities in western and central Sarawak (Malaysia) and scattered areas of Kalimantan (Indonesia), although it probably occurs more widely than current records suggest (Inger et al. 2017). All known localities lie between 200–1,000 m asl.
Habitat and Ecology
This is a terrestrial species of lowland moist tropical forest, which breeds in small, clear, rocky streams where the larvae also develop. It has not been found in modified habitats.
In Sarawak, it is considered to be common in most localities, such as Gunung Penrissen (Y.M. Pui pers. comm. March 2018). 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). The subsequent siltation of streams is an additional threat. 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). More recently, 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. The subpopulation from Pelagus National Park occurs in good, intact forest and is not presently threatened (Y.M. Pui pers. comm. March 2018).
This species is known from Gunung Nyuit Nature Reserve, Gunung Bondang Protected Forest, Bukit Baka Bukit Raya National Park, Bukit Batikap Protected Forest, and the Kayan Mentarang protected area. In Sarawak, it is known from Pelagus National Park (Y.M. Pui pers. comm. March 2018). Outside of protected and national park areas, this species is known from conservation areas in forest concessions in Ketapang Regency, West Kalimantan Province (Mediyansyah pers. comm. May 2017). No conservation actions are currently in place for this species.
Sustainable management of conservation areas within the forest and oil palm concessions need to be improved and continued (Mediyansyah pers. comm. May 2017). Effective preservation of lowland forest is needed to conserve this species because oil palm plantations are encroaching into protected areas. Some oil palm companies and forestry companies designate High Conservation Value areas, which is required by some financial institutions providing loans. However, not all lenders require these areas to be set aside and the habitat within the HCVs could disappear if the lender or requirements change (Indonesia Red List Assessment Workshop May 2017).
Taxonomic studies is necessary to determine the identity of many specimens assigned to this species (D. Iskandar pers. comm. May 2017). More information is needed on this species' distribution and population status.
Red List Status
Near Threatened (NT)
Listed as Least Concern in view of its wide distribution and presumed large population. However, since this species depends on streams in areas of undisturbed forest habitat and there is ongoing decline in the extent and quality of its habitat is declining due to widespread forest loss within its range, its population should be monitored.
There is uncertainty around the identity of many specimens and further work is required to clarify the taxonomy of these records (D. Iskandar pers. comm. May 2017).
IUCN SSC Amphibian Specialist Group 2018. Ansonia minuta. The IUCN Red List of Threatened Species 2018: e.T54476A114916512. http://dx.doi.org/10.2305/IUCN.UK.2018-1.RLTS.T54476A114916512.en