The species has been recorded from Gunung Mulu NP and Crocker Range NP at elevations from 155 m to 1450 m asl. 

The name "separatus" refers to the fact that this species has been recorded from two separated areas, that is Mulu and Crocker Range.

In the description by Matsui et al. (2024), I (AH) could not find a morphological comparison section that compares specifically L. separatus and the sympatric L. mocquardi. This could indicate that the two species have basically been established on genetic evidence and are morphologically not significantly different (note some differences in size). For the time being, please cross-check with L. mocquardi. 

The species can be diagnosed by a combination of features (adjusted from Matsui et al 2024): Adults of this species reach 48 mm in males and 50 mm snout-vent-length in females. The first finger is slightly longer than the second. Both edges of the second and third fingers, as well as the inner edge of the fourth finger, have freely movable dermal fringes. The tip of the third finger forms a large disk, significantly wider than the basal phalanx. The inner and outer webbing of the fourth toe is shallowly excised. It has a long head and forelimbs, but relatively short hindlimbs and tibiae. The dorsal skin is highly folded, forming a network of wrinkles in all directions, and is scattered posteriorly with small warts. Wrinkles are weak on the eyelids and the top of the snout. The dorsal side of the tibia is coarsely covered with small, conical warts. The tip of the fourth toe is swollen into a large disk, which is much wider than the basal phalanx. This disk is also wider than that of the third finger. The fourth toe is broadly webbed to the base of the disk. The dorsum is dark brown and lacks any darker markings.