Gastrophrynoides borneensis has rarely been seen alive, nor is it well represented in scientific collections. 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.
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.
Joint work by scientists from NUS (D. Bickford) and ITB (D. Iskandar, A. Irawan) led to the discovery of more specimens in Kalimantan. Also another specimen was spotted and photographed by Yeo Siew Teck in Sarawak.
Whether there are free swimming larvae or direct development is unknown. The call of a male has been recorded, but has not described scientifically yet.