A new species of Acanthochondria (Copepoda: Chondracanthidae) parasitizing the flounder Xystreurys rasile (Pleuronectiformes: Paralichthyidae) from Argentina.

A new copepod species, Acanthochondria sagitta sp. n., is described based on specimens collected from the flounder Xystreurys rasile (Jordan) (Pleuronectiformes, Paralichthyidae), caught in the coastal waters off Necochea, Buenos Aires Province, Argentina. The new species differs from its congeners by the following combination of characters: presence of three pairs of cephalic outgrowths; the triangular shape of the trunk with diverging postero-lateral processes; leg 2 of an intermediate shape between Types C and D, which projects laterally from the trunk, and Type B-V antennule bearing two proximal processes (one ventral and one dorsal) on the swollen basal portion.

Parasite assemblages of estuarine-dependent marine fishes from Mar Chiquita coastal lagoon (Buenos Aires Province, Argentina).

The estuarine-dependent marine fish includes marine species that inhabit, at some stage of their life cycle, the Mar Chiquita coastal lagoon, Buenos Aires Province, Argentina. In the present study, we examined for parasites a total of 209 fishes belonging to following the estuarine-dependent marine species: Brevoortia aurea, Odontesthes argentinensis, Mugil platanus, Paralichthys orbignyanus, Micropogonias furnieri, and Pogonias cromis. The parasite fauna in the six host species comprised 43 parasite species, the majority of which represented new locality and new host records. A high percentage of fish was parasitized with at least one parasite species. The greatest values of prevalence were registered for M. furnieri, B. aurea, and P. cromis, at the component community level, followed by P. orbignyanus, O. argentinensis, and M. platanus. On the other hand, B. aurea, O. argentinensis, M. furnieri, and P. cromis showed similar percentages of both larval and adult stages of parasites. In the case of M. platanus, adult stages dominated the total number of parasites, whereas P. orbignyanus harbored mainly larval stages. Out of the six fish species herein studied, M. platanus seems to generally act only as definitive host in the local parasite's life cycle. From a parasitological point of view, the expression "estuarine-dependent marine fishes" remains valid, although the contribution of the fish species in the lagoon to the maintenance of parasite populations is relatively minor.