We describe a new microhylid frog of the endemic Malagasy subfamily Cophylinae and designate a lectotype for Plethodontohyla notosticta. Plethodontohyla mihanika sp. n. has enlarged terminal disks on all fingers and toes, a distinct border between its dorsal and lateral coloration, and a pointed snout. The new species is recognized by its longer hind limbs, smaller body size (SVL 26–31 mm), and advertisement call. Together with P. notosticta and possibly Plethodontohyla inguinalis, the new species forms a partially arboreal subgroup within the otherwise terrestrial Plethodontohyla. The eggs of the new species are most likely laid in strings, which may be a preadaptation to egg transport by the parents. Males cohabit with eggs, tadpoles, and recently metamorphosed juveniles, suggesting parental care as known from other cophylines.