Symbionts of invasive and native crabs, in Argentina: The most recently invaded area on the Southwestern Atlantic coastline

•Invasive green crabs, Carcinus spp., are infected by more microparasites than native crabs (Cyrtograpsus angulatus, C. altimanus) (5:3).•A new species of Agmasoma-like microsporidium was isolated from Carcinus aestuarii.•Carcinus spp. have escaped their macroparasites on the Southwestern Atlantic coast.•Green crabs are not susceptible to Maritrema madrynense (Trematoda).