﻿AbstractUncertainties regarding the taxonomic status and biogeographical distribution of some species of the genusEmeritafrom the western Atlantic led to thorough examination of the subtle morphological differences between two coexistent species (E.brasiliensisSchmitt, 1935 andE.portoricensisSchmitt, 1935) along the Brazilian coast and compare them using two genetic markers. The molecular phylogenetic analysis based on sequences of the 16S rRNA andCOIgenes showed that individuals identified asE.portoricensiswere clustered into two clades: one containing representatives from the Brazilian coast and another containing specimens distributed in Central America. Our molecular-based phylogeny, combined with a detailed morphological analysis, revealed the Brazilian population as a new species, which is described here asEmeritaalmeidaiMantelatto & Balbino,sp. nov.The number of species in the genusEmeritais now raised to 12, with five of them occurring in the western Atlantic, five in the Indo-Pacific, and two in the eastern Pacific.