Current distribution data suggests that this species occurs at lowland sites in Sarawak with evidence from Sibu and Lanjak Entimau (250 m a.s.l.). It is sympatric with L. kong and L. abanghamidi in Lanjak. Matsui et al. (2024) did not specify helpful distinguishing features between L. lanjakensis and L. abanghamidi, the ones they mention with respect to L. kong refer to the relatively wider disk at the fourth toe and a larger ration of disk to base of third finger, characters that will be difficult to assess in the field. 

The species is medium in size, both sexes are similar, approximately 53 mm snout-vent length in males and 52 mm in females on average.

The new species can be distinguished from other similar species by the combination of the first finger being either as long as or shorter than the second finger. The outer edges of the second and third fingers possess freely movable ridges of skin. The inner and outer webbing of the fourth toe is moderately excised. Its head is relatively long, and its forelimb, hindlimb, and tibia are also relatively long in comparison. The dorsal skin is extremely folded, with networks of wrinkles originating from small warts and running in all directions. Yet the wrinkles are very weak on the head. The tibia has small, low warts scattered coarsely on the dorsal surface.The tip of the third finger forms a large disk, with a width much wider than the basal phalanx. Similarly, the tip of the fourth toe is swollen into a large disk, with a width much wider than the basal phalanx. The fourth toe disk is much wider than the third finger disk, and the fourth toe is broadly webbed to the disk. The dorsal skin is light brown, with dark brown markings on the interorbital, upper eyelid, and canthus (edge from eye to nostil).

Natural history and ecology remain unknown.