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Larval development of Etropus longimanus (Paralichthyidae) and Symphurus trewavasae (Cynoglossidae) from Buenos Aires coast, Argentina
Maizuru, Japón
Simposio; Sixth International Symposium on Flatfish Ecology; 2005
Institución organizadora:
University of Kyoto, Japan
On the Southwest Atlantic Ocean, the Pleuronectiformes are represented by more of 20 flatfish species inhabiting mainly between 34º and 47º S, and forming important concentration areas in the Argentinean-Uruguayan Common Fishing Zone (AUCFZ). In this study we described the morphological features of the larval stages (preflexion, flexion and postflexion) of Etropus longimanus and Symphurus trewavasae. Fish larvae were collected in a coastal station situated close to Mar del Plata city and from research cruises conducted by the Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP). The two flatfish larvae species were had a dorsal and ventral row of melanophores along body, more noticeable in E. longimanus. The larval body was elongate in both species at early development stage, with body depth (BD) increasing as body size increased in E. longimanus, but remaining constant in S. trewavasae. In E. longimanus, Head depth (HD) increased until postflexion stage remaining invariable later on, while both predorsal length (PDL) in relation to body length (BL) and eye diameter (ED) with respect to head length (HL) decreased from flexion stages. HL increased in relation to BL, and preanal length (PAL) remained constant during development. In S. trewavasae, ED in relation to HL decreased from preflexion to flexion stages and then remained constant until postflexion stage. BD, HL, HD, PAL and PDL with respect to BL remained constant throughout development. The first 2 dorsal rays in E. longimanus and the first 4 in S. trewavasae appeared to be elongated from preflexion to postflexion stages. The sequence of fin ray formation in E. longimanus comprised: caudal, then dorsal and anal pelvic fins, and finally pectoral fin; in S. trewavasae the sequence was: dorsal and anal fins and then pelvic and caudal fins. Pectoral fin disappeared during metamorphosis. In both species migration of the right eye started at flexion stage. A total of 34-39 vertebrae were recorded in E. longimanus and 46-50 in S. trewavasae during flexion stage. Results of this work were compared with those of other authors.