Some anisakid nematodes from marine fishes of Japan and the North Pacific Ocean

Abstract

A recent collection of anisakid nematodes from marine fishes from Japan and the North Pacific Ocean comprised a total of seven species of two genera; six of them (Raphidascaroides nipponensis Yamaguti, 1941, Hysterothylacium aduncum aduncum (Rudolphi, 1802), H. auctum (Rudolphi, 1802), H. cornutum (Stossich, 1904), H. marinum (Linnaeus, 1767) and H. physiculi sp. n.) parasitize fishes as adults, whereas one (Hysterothylacium sp.) occurred as larvae encapsulated in the host's abdominal cavity. Hysterothylacium physiculi sp. n. from the intestine of the gadiform fish Physiculus maximowiczi (Herzenstein) (family Moridae) from the western North Pacific (Kamaishi Bay, Honshu) is characterized mainly by shape of the lips, presence of well developed lateral alae starting some distance posterior to base of the lips, a short caecum, and markedly short (324-416mum) spicules. SEM study of R. nipponensis, type species of the genus, did not confirm the presence of dentigerous ridges on the lips. All species are briefly described and illustrated and some taxonomic problems are discussed. Several new host and geographical records are presented.

Keywords:

• Parasites Anisakid Nematodes Hysterothylacium Raphidascaroides Marine Fishes Japan North Pacific Ocean