A new species of parasitic copepod, Chondracanthus hoi sp. n. (Copepoda: Chondracanthidae), is described based on specimens of both sexes collected from the buccal cavity and gill arches of the silvery john dory, Zenopsis conchifer (Lowe) (Zeiformes: Zeidae), from waters off northern Argentina (35-36 degrees S, 53-54 degrees W). Female of C. hoi differs from its congeners by the following combination of characters: presence of five pairs of trunk processes, antennule with four knobs tipped with small setae and absence of denticles on the terminal process of maxilla. Chondracanthids and zeiform fishes have been proposed as an example of co-speciation; this assumption is derived from a series of analyses based on incomplete records of both geographical distribution and host range of some parasite species, as well as misidentification offish hosts. These inconsistences observed during our bibliographical analyses are also discussed.

Laboratorio de Parasitología Instituto de Investigaciones Marinas y Costeras Universidad Nacional de Mar del Plata CONICET Mar del Plata Argentina

Laboratorio de Parasitología Instituto Nacional de Investigaciones y Desarrollo Pesquero Mar del Plata Argentina