Despite the English name, this frog belongs to the Microhylidae and not to toads (Bufonidae) in a zoological sense. Gastrophrynoides assumes the most basal position of the Australian-New Guinean subfamily Asterophryinae. This means that its closes relatives are microhylid frogs from the Australopapuan realm. 

Gastrophrynoides borneensis has rarely been seen alive, nor is it well represented in scientific collections. So far, encounters with this species have been reported from sites in the lowlands below 900 m a.s.l. The reason likely is a very secretive way of life, possibly subterrestrial. Little is know about this frog. Once we learn more about it, it might turn out that it is not as rare as previously thought. Particularly because this species is not limited to pristine habitats but tolerates anthropogenic habitat alterations to some extent. 

The body is dark brown, with or without white spots. The head is conical and has a long snout. The eyes are small and black. The appearance is very unique as shown in the images. 

Whether there are free swimming larvae or direct development is unknown, however, due to its phylogenetic position as sister-taxon to other Asterophryinae (all direct developers) and the large eggs found in female specimens, direct development likely is the mode of reproduction in this species. Matsui et al. (2017) described two calls: one with notes in intervals and one whistle-like call.