The South American Neritic Copepod Ctenocalanus heronae Vega-Pérez and Bowman (Calanoida) in the Gulf of Mexico, with Comments on the Taxonomy of the Genus

Abstract

A single adult female specimen of the calanoid copepod Ctenocalanus heronae Vega-Perez and Bowman was collected during a zooplankton survey carried out in February 1997 in Campeche Sound, the central-southeastern portion of the Gulf of Mexico. The taxonomy of the genus Ctenocalanus Giesbrecht is still unclear. Characters used to separate the species have been considered rather subtle. In this paper the taxonomic illustrations of the specimen collected are accompanied by a revision of the taxonomic features commonly used to identify the species. New, previously overlooked characters such as the cephalosome/ urosome ratio, the shape of the 5th legs and particularly the structure of legs 1 and 2, are presented and might turn out to be useful to separate some of the species. This record of C. heronae in the Gulf of Mexico also represents the first reported occurrence of the genus in the Northwestern Tropical Atlantic and increases remarkably the known distribution of the species from the 24°S to the 18°N.