Nyctixalus pictus is a striking medium-sized frog found in lowland and hillside rainforests. It was originally described from Sarawak, although the precise locality was not specified. We encountered the species at elevations up to 1350 m a.s.l., and Inger & Stuebing (2005) report records from as high as 1650 m. Its distinctive coloration and pattern make it unlikely to be confused with any other Bornean frog.

Males and females reach approximately 30–35 mm in snout–vent length (SVL).

Specimens are very slender, giving the head a relatively broad and flat appearance, with a moderately long snout. The limbs, fingers, and toes are long and slender. The toes are half-webbed, while the fingers are unwebbed. Both toes and fingers end in expanded, terminally truncated tips, each adorned with two lateral white spots on the pads. The dorsal skin is covered with numerous small, pointed tubercles.

The coloration of N. pictus is distinctive. The dorsum ranges from red to reddish-brown and is marked with conspicuous white spots scattered across the body. Some spots unite to form a line from the snout to the upper eyelid, and occasionally continue behind the eye as a broken line down the flank. The iris is strikingly unique: the upper sector is bright white, while the remaining portions are reddish brown.

Nyctixalus pictus is a phytotelma breeder, with tadpoles developing in tree holes or similar structures. The tadpoles are highly distinct among Bornean species. They are dorsoventrally flattened and broadly oval when viewed from above. The relatively small eyes are positioned dorsally. The body coloration is dark brown to black, and the tail ends bluntly with a relatively low fin. Tadpoles can exceed 50 mm in total length.