Taxonomic Status of Nominal Species of the Genus Pellona Previously Regarded as Synonyms of Pellona ditchela Valenciennes, 1847 (Teleostei: Clupeiformes: Pristigasteridae)

Pellona is a genus of pristigasterid longfin herrings that are widespread in different marine habitats in Asia, Africa, and South America. While this genus is abundant and economically important, the taxonomy and biogeography of its highly similar species remain poorly understood due to a lack of morphological and genetic data from most populations. New molecular and trait data suggest that Indo-West Pacific populations assigned to one species, Pellona ditchela, may represent several different taxa, leading to re-examination of all records and type specimens for this species. Based on the examination of the holotype and original description, Pellona ditchela (Clupeiformes: Pristigasteridae) is shown to be a member of the similar related genus Ilisha and a senior synonym of Ilisha striatula. Two other valid species of the genus Pellona are found in separate populations previously identified as Pellona ditchela and resurrected based on past descriptions and type material. The species distributed in Southeast Asia (Pellona hoevenii) differs from the species from the eastern coast of Africa (Pellona natalensis) in the numbers of fin rays of the dorsal, anal, and pectoral fins, some morphometric characters, and scale ornamentation. We used the mitochondrial cytochrome oxidase I (COI) gene to infer the relationship among these species and five other Indo-West Pacific pristigasterids. We confirmed that Pellona hoevenii and P. natalensis formed a monophyletic sister group to all other pristigasterid species, including I. ditchela. These two species diverge from each other by a mean uncorrected COI-based distance of 15.1%. Neotypes of P. hoevenii and P. ditchela are newly designated.