SYSTEMATICS, DISTRIBUTION AND ECOLOGY OF COMMERCIALLY IMPORTANT PARALICHTHYID FLOUNDERS OCCURRING IN ARGENTINEAN-URUGUAYAN WATERS (PARALICHTHYS, PARALICHTHYIDAE) - AN OVERVIEW

Species of Paralichthys Girard are the most important flatfishes to co mmercial fisheries in nearshore waters of Argentina and Uruguay. Recen t commercial catches increased from 3000 tonnes (t) in 1984 to 11000 t in 1995, representing more than $65 million in export income for 1995 . Although their commercial importance has long been recognized, paral ichthyid flounders in this region are not well studied, either from a systematic or an ecological viewpoint. Six nominal species have been r eported from Argentinean and Uruguayan waters: Paralichthys bicyclopho rus, P. brasiliensis, P. isosceles, P. orbignyanus, P. patagonicus and P. simulans. However, species descriptions are often vague and incomp lete, and reported distributions are dubious. Variations in scale morp hology, meristic and morphometric characters were used to differentiat e among the Paralichthys species co-occurring in this area. Of six spe cies previously reported from this region, only three, P. isosceles, P . orbignyanus and P. patagonicus, are valid. P. bicyclophorus is regar ded as a junior synonym of P. patagonicus; P. simulans is a junior syn onym of P. orbignyanus; while P. brasiliensis, although reported from coastal waters of Argentina and Uruguay for many years, does not occur there. Paralichthys spp. were collected on the continental shelf and in estuaries in the south Atlantic between 34-55 degrees S. P. orbigny anus and P. patagonicus inhabit marine and estuarine locations and ext end as far south as 43 degrees S. The former is a shallow-water, euryh aline species occurring to about 20 m. In contrast, P. patagonicus has higher densities between 36-40 degrees S at 70-100 m depth. P. isosce les occurs mainly on the inner continental shelf between 43-45 degrees S at 70-100 m depth, and reaches its southern Limit at about 47 degre es S. (C) 1998 Elsevier Science B.V. All rights reserved.