Larval anisakid nematodes of Japanese common squid (Todarodes pacificus) from the Sea of Japan.

Two species of third-stage larvae of the family Anisakidae are described from the Japanese common squid (Todarodes pacificus Steenstrup) from the Sea of Japan. The larvae of 1 of them, Anisakis simplex (Rudolphi, 1809), commonly occur encapsulated in the viscera of squid, whereas those of another 1, identified as Lappetascaris sp., are found free in the mantle musculature. The latter, characterized by the presence of a very long ventricular appendix, a conspicuous esophageal gland, and the structure of the cephalic end (presence of sclerotized supports of lip anlagen), previously were reported by various authors as members of the genera Contracaecum, Thynnascaris, or Hysterothylacium. It appears that the larvae form the mantle of squid belong to a hitherto undescribed Lappetascaris species whose adults parasitize an, as yet unknown, predatory marine fish.