Once thought to be only one species, Fukuyama et al. 2021 reexamined it and found that the small-sized Kalophrynus of Gunung Mulu represent actually three distinct species: K. nubicola (sensu stricto), K. puncak, and K. dringi. All three are closely related and form an ancient line in the the tree of Kalophrynus and all three are Gunung Mulu micro-endemics according to current knowledge. They inhabit certain elevantional zones at Gunung Mulu with K. puncak being the one around the moutain's peak (>2100 m) and K. dringi the species at the low slopes (approximately. 1300-1800 m). Kalophrynus nubicola settles in between at approximately. 2000-2300 m, overlapping with K. puncak at the upper elevation. 

The snout-vent length is 16-19 mm. The species has conspicuous yellow patches from the snout to above the eyes. A light dorsolateral stripe is absent. The belly, lower flanks and ventral side of thighs bear white blotsches. The iris is blueish-grey. The call is less sharp in impulse than in K. dringi or K. puncak (i.e., steep first puls) and relative to them significantly longer in duration (yet only 0.475-0.634 s) and with far more pulses (43-53). 

Little is know about their biology, however, all three species in this clade of Kalophrynus will likely feed on small arthropods such as mites, termites, ants etc. Although positive evidence existst only for K. puncak (Fukuyama et al. 2021), we expect terrestrial clutches and most possibly non-feeding tadpoles in all three species.