Amphilochidae comprises 92 species of small and colourful amphipods that live associated with sessile marine organisms. Hourstonius is one of the most diverse genera with 17 described species, most of the species are recorded from North Temperate Pacific and Tropical Atlantic and live in shallow waters. Only three species of Amphilochidae are recorded in Brazil, and from the genus Hourstonius, there is a single species, H. wakabarae. In the present work, we describe a new species of Hourstonius from Todos-os-Santos Bay, the second species of the genus to the country and the first record of this genus from Bahia State. A taxonomic key and an overview of the genus across the globe are also provided.
