The family of Firebelly Toads contains only nine species worldwide. Two of these occur in the Sunda Region (Barbourula), while the remaining seven belong to the genus Bombina, which is distributed across mainland Eurasia.

The only Barbourula recorded from Borneo is Barbourula kalimantanensis. This species was once thought to be the only lungless frog in the world; however, more recent studies have demonstrated that lungs are indeed present.

Until recently, the reproductive of Barbourula species have been unknown and much speculated about. Miñarro et al. (2024), however, discovered and described the tadpoles of Barbourula busuangensis from the Philippines, significantly expanding our understanding of the reproductive biology of the species—and likely of the entire genus.

Miñarro et al. (2024) wrote that B. busuangensis "exhibits characteristics of a K-strategist, with large, unpigmented eggs in small number relative to body size." Their field observations suggest "a prolonged reproductive period, with gravid females present across seasons, and possible egg retention for at least up to two months." They found that tadpoles were rheophilous, endotrophic (non-feeding), and nidicolous (not leaving the nest site). The tadpoles lacked keratinized mouthparts and had a large sucker-like oral disc with which they for adhered to the rock face in crevices in river-bed cave systems. The team successfully made camera recordings at nest sites that revealed the presence of an adult with the larvae, suggesting parental care. These reproductive features were proposed to be a "new, undescribed reproductive mode for anurans, thus contributing to our knowledge on the evolution of reproductive strategies of tropical species in different ecological contexts."