We describe a new species of arboreal narrow-mouthed frog, genus Platypelis, from Ambodivoangy near Maroantsetra in northeastern Madagascar. The new species, Platypelis ando sp. nov., is characterised by small body size (under 19 mm), a generally rather slender body, yellowish finger and toe tips, and a dark brown dorsal chevron. Its advertisement call is a single, moderately long, high-pitched whistle repeated at regular intervals. It is the sister species of P. ravus from Marojejy National Park, but differs from that species by considerable pairwise genetic distances (7.9%) in a fragment of the mitochondrial 16S rRNA gene, and also in bioacoustic and morphological features, especially the absence of yellow on the posterior abdomen. It is also surprisingly similar in external appearance to Cophyla occultans and C. maharipeo, to which it is not, however, closely related; these species are most easily discerned based on their calls. Platypelis ando sp. nov. joins the ranks of several species recently described from Ambodivoangy with close affiliations to species in the nearby Marojejy National Park, that are still divergent at species level. The species qualifies as Critically Endangered according to the IUCN Red List criteria, in line with other species recently assessed from this area, but we urge that more research be conducted in the nearby forests to extend the range of this and other species known only from Ambodivoangy.