A new Callichirus ghost shrimp species from the south-western Atlantic, long confounded with C. major (Say, 1818) (Decapoda: Axiidea: Callichiridae)

Morphological and molecular evidence suggests that the ghost shrimp population in Brazil that had been assigned to Callichirus major (Say, 1818) represents a distinct species. A neotype of C. major is designated in the interest of nomenclature, because the holotype is no longer extant. Based on material from Brazil, a new species, Callichirus corruptus, is described. Differentiating characters between the new species and C. major are discussed and an identification key to species of Callichirus is provided.