Reassessment of the taxonomy of Mesopodopsis orientalis (Tattersall, ) (Crustacea, Mysida) and proposal of a new species for the genus with an appendix on M. zeylanica Nouvel,

The Indo‐Australasian mysid Mesopodopsis orientalis (Tattersall, 1908) has been recorded throughout the southwestern coast of India and the Philippines. As a result of its abundance, this mysid is regarded as one of the most important species of the shallow‐water crustacean community. Recent ecological studies of this conventionally identified species have revealed significant differences in certain life history features among populations, in particular between coastal and estuarine populations, which seemed to be associated with some differences in morphology. Following the examination of the syntypes and topotypes, the identity of M. orientalis was redefined, and a new species, M. tenuipes, was subsequently proposed on the basis of the further assessment of morphological and DNA analyses. At several sites, these two species coexist, although M. tenuipes usually inhabits inner estuaries or less haline waters compared with M. orientalis. Our analyses also suggest a possibly higher allopatric diversification within each lineage along their geographical transitions. In addition, earlier records of M. orientalis from India need to be reanalysed to rectify confusion with M. zeylanica Nouvel, 1954.