Once thought to be a single species, Fukuyama et al. 2021 reexamined the small-sized Kalophrynus frogs of Gunung Mulu and found that they actually represent three distinct species: K. nubicola (sensu stricto), K. puncak, and K. dringi. All three are closely related, forming an ancient lineage within the Kalophrynus tree, and are micro-endemics restricted to Gunung Mulu according to current knowledge. They inhabit distinct elevational zones on Gunung Mulu: K. puncakoccurs near the mountain’s peak (>2100 m), K. dringi is found on the lower slopes (approximately 1300–1800 m), and K. nubicola occupies the zone in between at approximately 2000–2300 m, overlapping with K. puncak at higher elevations. (image)

The snout–vent length ranges from 16 to 19 mm. The species has conspicuous yellow patches extending from the snout to above the eyes. A light dorsolateral stripe is absent. The belly, lower flanks, and ventral side of the thighs bear white blotches. The iris is bluish-grey. The call is less sharp in impulse than those of K. dringi or K. puncak (i.e., it lacks the steep first pulse) and is significantly longer in duration (0.475–0.634 seconds) with many more pulses (43–53).

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