Recent surveys of the herpetofauna in the rainforest of the Forêt d'Ambre Special Reserve, northern Madagascar, revealed a distinctive fossorial microhylid anuran species of the genus Rhombophryne. The new species is characterized by medium size (snout–vent length up to 49 mm in males), a stout body, short legs, and tuberculate skin on dorsal surfaces. It is most similar and closely related to R. testudo from the Sambirano region, but differs mainly by the absence of barbels on the lower lip, a different advertisement call, and a pairwise total sequence divergence of 8.5% the mitochondrial 16S RNA gene. We consider this species to be at particular risk from a conservation perspective because it appears to be endemic to a relatively small area of lowland transitional forest heavily altered by human activities. According to the International Union for Conservation of Nature criteria, its threat status is classified as “Endangered.”