First report on Mermithidae (Mermithida) infection in Ligidium sp. (Isopoda, Ligiidae)

Specimens of Ligidium sp. (Crustacea, Isopoda, Oniscidea) collected from Kanagawa Prefecture in Japan were found to be infected with parasitic nematodes. We have obtained two Mermithidae (Nematoda) by dissecting the fresh specimen and from the dead specimen of Ligidium, which marks the second known discovery of a mermithid infection in the order Isopoda. Herein, a report on the nuclear 28S rDNA and 18S rDNA sequence of the isolated Mermithidae nematodes and on the morphology of the juveniles is provided.