The anatomy of Brazilian and African specimens of Pugilina morio, a supposedly amphi-Atlantic species, is described in detail in this paper. Two different entities are recognised. The first is the true Pugilina morio, which is now restricted to the western African coast, from Senegal to Congo. The remaining species is Pugilina tupiniquim sp. n., described herein as the single Brazilian melongenid species known so far, distributed from the Caribbean to Brazil (Pará to Santa Catarina states). The two species showed important anatomical discrepancies, and differ in the position of the tentacles, size of the neck, diameters of the aortas, diameter of the posterior oesophagus, and other features described below. A bursa copulatrix and rachidian teeth bearing a central cusp are both exclusive to P. morio.