Hylarana signata and H. picturata belong to a species group that is not yet fully understood. On the island of Borneo, this group likely comprises more than one distinct species. At present, the two are primarily distinguished by dorsal pattern: H. signata is striped, whereas H. picturata is spotted.

H. signata is typically associated with lowland streams; in most cases we observed the species at streams with soft bottom (preference in H. picturata: rocky bottom). There is also preliminary evidence that the species might also use ponds for reproduction in some areas. 

The body is slender to moderately robust, with moderately long limbs and a relatively narrow head. The snout is moderately long, and the tips of the digits are slightly swollen. Webbing reaches approximately halfway along the toes. The dorsal skin is granular in texture. Males usually reach a snout–vent length of about 40 mm, while females can grow to nearly 70 mm. 

The dorsal coloration of H. signata is black with yellow to orange angular spots or blotches. A distinct stripe runs from the snout to the groin in most individuals, though in some females it may appear pale brown. A colored line also extends from the snout to the eye, continues along the upper eyelid, and reaches posterior to the groin. The upper surfaces of the limbs are banded. The venter is gray, with the thighs slightly darker. The eardrum is distinct and blackish. As in all species of the subgenus Pulchrana, the eyes are big. The iris is coppery, featuring a narrow reddish ring around the pupil and a dense black reticulate pattern.

Tadpoles are black with a bluish shimmer. They have moderately high tail fins and long tails, with numerous skin glands visible under appropriate lighting. The iris shows a distinct red ring around the pupil. Tadpoles inhabit stagnant or slow-moving water and are commonly found in streamside pools or quiet bays containing accumulations of leaf litter. They specialize in using the spaces within submerged leaf packs, hiding during the day and occasionally surfacing at night. At night, their coloration becomes noticeably paler.