Scientific classification
Kingdom:Animalia
Phylum:Mollusca
Class:Gastropoda
(unranked):clade Caenogastropoda
clade Hypsogastropoda
clade Littorinimorpha
Family:Ovulidae
Subfamily: Simniinae:
Genus:Cyphoma
Species:C. macumba

Ilha de Itaparica, Salvador da Bahía, Brazil

From my collection

Endemic to Brazil – from Ceará to Rio de Janeiro State
This species has become a synonym of C. gibbosum (Linnaeus, 1758)

Research: Cyphoma macumba Petuch 1979 (Gastropoda: Ovulidae): a versatile predator of the Brazilian Octocorallia
bit.ly/2RLt9AU

Regarding the inclusion of this species in C. gibbosum, the morphological and mantle differences, you can read the following:
Coat of many colours—DNA reveals polymorphism of mantle patterns and colouration in Caribbean Cyphoma Röding, 1798 (Gastropoda, Ovulidae)
peerj.com/articles/3018/

via Flickr https://flic.kr/p/2iS8pRm