Peppermint shrimp resembling Lysmata vittata, a species native to the Indo-West Pacific, were found in the lower Chesapeake Bay and adjacent coastal embayments in 2013, representing the first recorded introduction of this species in the northwestern Atlantic. Conflicting morphological descriptions, inconsistent morphological terminology, and limited molecular data (i.e., unresolved taxonomy), as well as the destruction of the type material of L. vittata, created uncertainty regarding proper identification. We provide the first phylogeny incorporating individuals from across the presumed native and introduced range of L. vittata. Morphological and phylogenetic analyses clearly indicate L. vittata represents a species complex of two widely divergent groups: 1) "Bruce Type" with a uniramous dorsal antennule that agrees with A.J. redescription of L. vittata, and 2) "Rauli Type" with a one-article accessory branch on the dorsal antennule that agrees most closely with the junior synonym L. rauli. Given the taxonomic ambiguity surrounding L. vittata, we designate the individual used by A.J. Bruce to redescribe L. vittata and incorporated in our analyses as a neotype to fix the identity of this species. We therefore identify introduced North American and New Zealand populations as L. vittata sensu stricto and postulate that the native range spans temperate/subtropical East Asia. These data suggest that L. rauli is a valid species, which includes a possible undescribed sister species. We confirm the presence of L. californica in New Zealand, the first non-native record for this species. We also provide data suggesting L. dispar may be more widespread in the Indo-West Pacific than currently known and consider L. lipkei to be a likely junior synonym.