On a recent expedition to eastern Madagascar, we discovered a distinct new species of the genus Calumma that we describe here using an integrative approach combining morphology, coloration, osteology and molecular genetics. Calumma roaloko sp. n. has a dermal rostral appendage and occipital lobes, and belongs to the C. boettgeri complex, within the Madagascar-endemic phenetic C. nasutum species group. It is readily distinguished from other species of the C. boettgeri complex by a characteristic two-toned body coloration and small body size with a snout-vent length of 45.6 mm in an adult male. The osteology of the skull, with a prominent maxilla and broad parietal, is similar to the closest related species, C. uetzi. Analysis of uncorrected genetic distances within the C. nasutum group using the mitochondrial gene ND2 shows a minimum pairwise distance of 11.98% to C. uetzi from the Sorata massif and Marojejy National Park >500 km north of the type locality of C. roaloko sp. n.. Given an apparently small range (potentially <300 km²), located entirely outside of any nationally-protected areas, we recommend this new species be classified as Endangered under criterion B1ab(iii) of the IUCN Red List. The discovery of clearly distinct species like C. roaloko sp. n. in an area of Madagascar that is comparatively thoroughly surveyed highlights the critical role of continued field surveys for understanding the true extent of Madagascar's spectacular biodiversity.