Pelophryne guentheri has only been seen a few times since its description in 1882. It must be considered a rare species, known at this point only from the Matang range of Sarawak. However, further research might discover it elsewhere. 

This species grows larger than P. api, P. saravacensis, and P. signata. Size of adults: approx. 25 mm snout-vent length. It has very long arms and a small head. Note the extend of webbing between toes and fingers and the truncated, nearly rectangular finger tips. The dorsal surface is warty, some of them black in color, some other bigger ones yellow to red. Lightly colored bands form at the limbs. The general tone is brown with yellow or orange hues in the lighter parts and dark marbling on the back of head and trunk.

Where this species deposits its eggs, how many eggs there are in a clutch and whether the development is through a feeding or non-feeding tadpole... All these questions remain unanswered and need further research.

We observed males calling from trunks of large trees 1-5 m above ground in a kerangas-dipterocarp transition zone. This species is very similar to Pelophryne saravacensis, which, however, calls from saplings.