A new species of Conidae is described from Brazilian waters. Mitromorpha santosi sp. nov. from the Continental Slope off the state of Rio Grande do Norte (north-east Brazil: 04°50′60″–04°51′40″s, 35°06′01″–35°06′46″W) is compared with M. biplicata (western Atlantic), M. usta (eastern Atlantic), M. dalli (north-eastern Atlantic), M. popeae (West Indies), M. undulate (West Indies) and two unnamed Brazilian species being diagnosed as possessing strong axial ribs, second spiral cord on the body whorl more pronounced and yellowish-brown spiral bands. In addition, a lectotype for Mitromorpha undulata, is designated herein.
