First report of the parasitic copepod Lernaea cyprinacea (Copepoda: Lernaeidae) on gobioid fishes (Teleostei: Gobonellidae) in southern Europe

Lernaea cyprinacea is a non host-specific parasitic copepod known to infest many freshwater fish species. Outbreaks of infestations by this ectoparasite may cause mass mortality of parasitized fishes. L. cyprinacea has been found mostly on pelagic species. Records on small benthic fish species are less common. Especially rare are infestations of Gobioidei adapted to a benthic life style, with reports restricted to Asia and, in Europe, to the Ponto-Caspian region. Although it is cosmopolitan, L. cyprinacea has rarely been found in Italy. One of the few Italian localities with documented infestations is Lake Trasimeno, a lake with an economically important fishery. Although endoparasites of commercially interesting fish species in this lake are well documented, information about ectoparasites is rare. In May 2015, specimens of two gobioids Knipowitschia panizzae and Pomatoschistus canestrinii infested with L. cyprinacea were sampled at the south shore of Lake Trasimeno. Both gobies are not native to the lake. This is the first documentation of gobioid fishes as hosts of L. cyprinacea in Italy and in Europe (outside of the Ponto-Caspian region). Although both gobies are not optimal hosts (small size, short life expectancy) they have the potential to carry and to transmit the parasite in freshwater habitats, e.g. by unintentional introduction with fry of other fish species.