Longipedia corteziensis sp. nov. (Copepoda, Harpacticoida, Longipediidae) from a coastal lagoon in northwestern Mexico, with the definition of the helgolandica species-group of the genus Longipedia Claus, 1863

A number of specimens of the genus Longipedia Claus, 1863 (Harpacticoida, Longipediidae) were collected during a short-term study of the harpacticoid fauna of Ensenada del Pabellón Lagoon (south-eastern Gulf of California, Mexico). These specimens turned out to belong to a new species closely related to L. helgolandica santacruzensis Mielke, 1979, reported from the Galapagos. The latter is raised to the species level. Both species can only be distinguished by the relative size of the inner seta of the coxa of the second swimming leg, and are closely related to L. americana Wells, 1980, found along the Atlantic coast of North America and the Caribbean Sea, and as far south as Mar de Dentro (Paranaguá, Brazil). The American species is shown to be related to L. helgolandica Klie, 1949, known from the Atlantic coast of northern Europe and south-west Africa. Finally, the helgolandica species-group, composed of L. corteziensis sp. nov., L. santacruzensis, L. americana and L. helgolandica is defined.