Erudituncus n. gen. (Tetraphyllidea : Onchobothriidae) with a redescription of E-musteli (Yamaguti, 1952) n. comb. and comments on its hook homologies

Examination of type and new material of Platybothrium musteli Yamaguti, 195 2, resulted in the erection of a new genus, Erudituncus, the new combinatio n Erudituncus musteli (Yamaguti, 1952), and the redescription of the newly combined species. This species exhibits novel hook morphology. Each bothrid ium bears 2 pairs of hooks, the axial pair comprising 1 medial and 1 latera l bipronged hook and the abaxial pair comprising a lateral unipronged hook and a medial, simple hook element. Based on the position of the hook talons , we suggest that the inner prong of the axial hooks of Erudituncus is homo logous to the single prong of the axial hooks of Calliobothrium and the axi al prongs of Dicranobothrium, Platybothrium, Phoreiobothrium, and Onchoboth rium; the outer prong of the axial hooks of Erudituncus is homologous to th e abaxial prongs of Dicranobothrium, Platybothrium, Phoreiobothrium, and On chobothrium; and the abaxial hooks of Erudituncus and Calliobothrium are ho mologous. Erudituncus musteli was lacking from 31 individuals of the type h ost of record, the triakid shark Mustelus manazo Bleeker, 1854, examined fo r this study, but was obtained from 2 individuals of the triakid shark Hemi triakis japanica (Muller and Henle, 1839). Therefore, H. japanica is propos ed as the probable type host of E. musteli.