Ansonia guibei is a highland species of stream toads, commonly encountered breeding in the Mesilau River of Kinabalu Park. The specimens on this page are from the East Mesilau River, Gunung Kinabalu, Sabah. The full extent of its distribution on the mountains of Borneo is unknown. 

Adult males reach approx. 30 mm snout-vent length, females up to 34 mm. The altitudinal distribution is 1500–2000 m asl.

Ansonia guibei tadpoles are quite distinct. The body shape (viewed from above) is more "angular" than that of other Ansonia species. Ansonia guibei tadpoles are dark brown to black on the upper side. Tadpoles of this species can be seen grazing by day and at night on the algae growing on rocks in the cold Mesilau River. Particularly at night, dozens of tadpoles may be observed grazing in a group.