Amphibian species diversity in the proposed extension of the Bukit Teraja Protection Forest, Brunei Darussalam

Amphibian species diversity was investigated within the lowland mixed-dipterocarp forest of the proposed extension of the Bukit Teraja Protection Forest (BTPF), Brunei Darussalam in north-west Borneo. A combination of both visual encounter and acoustic sampling techniques were conducted opportunistically as well as in six selected stream transects, each containing five 5x10m plots. A total of 39 species of frogs from seven families (Bufonidae, Ceratobatrachidae, Dicroglossidae, Megophryidae, Microhylidae, Ranidae, and Rhacophoridae) were identified from the BTPF. Most notably, four new records for Brunei were discovered: Hylarana nicobariensis, Kaloula baleata, Limnonectes malesianus, and Microhyla perparva. This brings the total number of amphibian species in Brunei Darussalam to 84. Canonical correspondence analysis showed that out of 13 measured environmental variables maximum stream depth and % soil/sand of ground cover were significantly correlated with anuran assemblage composition. Species overlap between the proposed extension of the Bukit Teraja Protection Forest and the Ulu Temburong National Park (UTNP) determined by the coefficient of biogeographic resemblance (CBR) showed low species complementarity between these two regions. This emphasizes the need to upgrade the proposed extension of the BTPF to a protection forest to ensure the conservation of regional amphibian biodiversity.