Occurrence of (Monogenea: Capsalidae) in Gilthead Seabream (Actinopterygii: Sparidae) Cultured in Portugal.

Monogenean capsalids of the genus are widespread parasites of wild and farmed marine fish, and represent a potential threat to mariculture due to their pathogenicity and ability to cause mortality in fish maintained in controlled conditions. The identification of species and, consequently, the definition of their host specificity is often problematic due to their highly conserved morphology; therefore, in order to establish their specific identity, microscopic observation should be complemented with molecular analysis. The present work aims at characterizing specimens infecting the skin of cage reared gilthead seabream from Portugal. Parasite samples obtained from caged fish were processed for morphological analysis, through observation in light and scanning electron microscopy, and for molecular analysis, through amplification and sequencing of 28S rDNA and , aimed at identifying them to the species level. Our results showed that the collected parasites belonged to the species ; the susceptibility of towards this pathogenic capsalid monogenean highlighted in the present work represents an important risk in the farming of this valuable fish species.