Neoergasilus japonicus (Harada, 1930): A new non-indigenous copepod for the Italian fauna

Neoergasilus japonicus (Harada, 1930) (Copepoda Ergasilidae) is reported for the first time in Italy. Several specimens of this non-indigenous species were identified in the free-living zooplankton of 11 lakes out of 21 sampled seasonally during a period of 2 years in southern Italy. Adults of both sexes were found, females always without ovisacs. Morphological novelties, such as the bifid inner terminal seta of the furcal rami in females and the plumose terminal setae on either males or females, are reported. Neoergasilus japonicus has been observed only in summer and autumn samples. At present, the geographic distribution of the species is Holarctic, and it is expanding in Europe. Although this is the first record for Italy, the presence in about half of the investigated lakes and the abundance of the found populations suggests that the species distribution should be more extended than we presently know.