[11] The smallest known Old World frog species prior to the description of Microhyla nepenthicola were Stumpffia pygmaea and Stumpffia tridactyla: S. pygmaea with an SVL of 10–12.5 mm; S. tridactyla with an SVL of 8.6–12 mm.

[7][12] Microhyla borneensis is a very small species with a snout–vent length of about 18 mm (0.71 in) for females and around two thirds of this for males.

The snout is obtusely pointed, the eyes are small and have round pupils and there are no visible tympani.

[13] M. borneensis has less webbing on its feet than most frogs, which may be beneficial when trying to climb the sides of the pitcher plants, which can be slippery.

[3] M. borneensis is found near Mount Serapi in Kubah National Park, Sarawak, Borneo.

It spends much of its life cycle in the traps of the pitcher plant Nepenthes ampullaria, after which it is named.

This is not particularly unusual; in fact, it shares this environment with a species of crab spider, Henriksenia labuanica, which is also commonly found in Nepenthes pitchers.