Diphyllobothrium fayi n.sp.(Cestoda: Diphyllobothriidae) from the Pacific Walrus, Odobenus rosmarus divergens

摘要

An independent species of cestode of the genus Diphyllobothrium Cobbold, 1858, known only from the Pacific walrus, Odobenus rosmarus divergens Illiger, has been incorrectly designated Diphyllobothrium cor datum (Leuckart, 1863) in the literature since 1955. That cestode is described in this study as Diphyllobothrium fayi n. sp. on the basis of specimens obtained from walruses from the northern Bering Sea and the Arctic Ocean. It is distinguished readily from D cor datum by its much larger strobila of different form and by a range of morphological characteristics of taxonomic significance in the reproductive organs. Comparisons were made with specimens of D cor datum from the bearded seal, Erignathus bar hiatus (Erxleben), its typical host, Diphyllobothrium fayi has been recorded only from the Pacific walrus. Although that mammal feeds mainly on mollusks and other benthic invertebrates, records of cestodes from it suggest that fishes potentially harboring plerocercoids are frequently consumed.