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, 1952, resulted in the erection of a new genus, Erudituncus, the new combination Erudituncus musteli (Yamaguti, 1952), and the redescription of the newly combined species. This species exhibits novel hook morphology. Each bothridium bears 2 pairs of hooks, the axial pair comprising 1 medial and 1 lateral 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 homologous to the single prong of the axial hooks of Calliobothrium and the axial prongs of Dicranobothrium, Platybothrium, Phoreiobothrium, and Onchobothrium; the outer prong of the axial hooks of Erudituncus is homologous to the abaxial prongs of Dicranobothrium, Platybothrium, Phoreiobothrium, and Onchobothrium; and the abaxial hooks of Erudituncus and Calliobothrium are homologous. Erudituncus musteli was lacking from 31 individuals of the type host of record, the triakid shark Mustelus manazo Bleeker, 1854, examined for this study, but was obtained from 2 individuals of the triakid shark Hemitriakis japanica (Müller and Henle, 1839). Therefore, H. japanica is proposed as the probable type host of E. musteli.