This species has been recorded mainly from Borneo, where there are records from Sarawak (Malaysia), Kalimantan (Indonesia) and Brunei Darussalam. In peninsular Malaysia, records from two mountain peaks (Gunung Tahan and Gunung Benom) have been assigned to this species (Grandison 1972; Berry 1975). In Peninsular Thailand there are records from Thong Pha Phum Forest, in Kanchanaburi Province, but these require verification. It probably occurs more widely on Borneo than current records suggest. It has an altitudinal range of 150 to above 1,500m asl.
Habitat and Ecology
It is confined to primary and old secondary rainforests. Adults and juveniles live in the floor litter and in the herb and shrub strata. Breeding occurs in streams with clear water and sandy to rocky bottoms. Larvae live amid the rocks on the bottom of the watercourse.
In Borneo it appears to be abundant at some sites in some years and much less common in others, while in Peninsular Malaysia it appears to be an uncommon species.
Deforestation is the principal threat to this species, while siltation of streams following deforestation is a threat to the larval habitat.
In mainland Southeast Asia one population is securely protected in Taman Negara National Park, and this species is also found in at least three protected areas in Borneo.
Red List Status
Near Threatened (NT)
Listed as Near Threatened since although this species is still relatively widely distributed, it depends on streams in areas of undisturbed forest habitat, and so its Area of Occupancy is probably not much greater than 2,000 km2, and the extent and quality of its habitat is declining very rapidly due to widespread forest loss within its range, thus making the species close to qualifying for Vulnerable.
Dubois (1983) suggested that the Peninsular Malaysian populations might be taxonomically distinct from Bornean Leptolalax gracilis.
Peter Paul van Dijk, Robert Inger, Jeet Sukumaran, Yodchaiy Chuaynkern 2004. Leptolalax gracilis. The IUCN Red List of Threatened Species 2004: e.T57565A11658693. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T57565A11658693.en .Downloaded on 16 January 2019