Abstract
A nematode 22 cm in length was spontaneously expelled from a pond frog, Rana nigromaculata, collected from an irrigation ditch of a paddy field in Kobe, Japan. The worm was identified as a larva belonging to the family Mermithidae on the basis of cephalic structure, presence of six longitudinal cords, and cross fibers in the cuticle. This is the first record of a mermithid from the Amphibia in Japan. This family has also been only rarely recorded from the amphibians outside Japan. Probably the infection is accidental parasitism, because mermithids are mostly parasitic in arthropods.
