First Molecular Detection of Neobenedenia girellae (Monogenea: Capsalidae) in Farmed Greater Amberjack (Seriola dumerili) in Greece.

In the present study, we report the first molecular detection and identification of the ectoparasitic monogenean Neobenedenia girellae in the farmed greater amberjack (Seriola dumerili) in Greece. This parasite is considered one of the most economically important ectoparasites affecting marine finfish aquaculture worldwide. The greater amberjack is an emerging species for Mediterranean aquaculture, characterized by rapid growth and high market value. During routine surveillance at a marine fish farm in the Ionian Sea, metazoan ectoparasites were collected from the sampled greater amberjack exhibiting skin and ocular lesions, and thereafter were subjected to molecular identification. Partial sequences of three genetic markers, mitochondrial cytochrome b (cyt b), histone H3, and 28S rDNA, were analyzed. Phylogenetic analyses placed the Greek sequences within N. girellae lineages containing isolates from geographically distant regions, with no clear geographic clustering across the three molecular markers examined. Although these findings indicate genetic affinities with previously characterized isolates, they do not allow for the determination of the geographic origin or route of introduction of the parasite into Greece. Surveillance is therefore warranted to determine its distribution in Mediterranean aquaculture and decrease the risk of further spread.