A Review of the Genus Pedibothrium Linton, 1909 (Tetraphyllidea: Onchobothriidae) with Description of Two New Species and Comments on the Related Genera Pachybothrium Baer and Euzet, 1962 and Balanobothrium Hornell, 1912

Abstract

A review of the genus Pedibothrium Linton, 1909, is based on type and voucher specimens. The type species, Pedibothrium globicephalum Linton, 1909, is redescribed; descriptions of Pedibothrium brevispine Linton, 1909, and Pedibothrium longispine Linton, 1909, are emended; 2 new species are described; the generic diagnosis is emended; and a key is provided. The bothridia of all species were found to possess a pair of symmetrical bipronged hooks, each with 2 separate channels and 2 pores, a single loculus and an apical muscular pad. Pedibothrium lintoni n. sp. from the spiral valve of Ginglymostoma cirratum (Bonnaterre) collected at Dry Tortugas, Florida, is most like P. globicephalum but differs in having fewer testes (mean number 145 rather than 252), larger testes (mean diameter 65 rather than 16 ,um), abaxial prongs of hooks no longer than bases, and narrow inconspicuous longitudinal excretory ducts. Pedibothrium maccallumi n. sp. from the spiral valve of G. cirratum, locality unknown, is unique in possessing flat, ovoid, non-contiguous loculi with hooks approximately one-sixth the length of the loculus. A diagnosis for Pachybothrium Baer and Euzet, 1962, is provided, and the description of the type and only species, Pachybothrium hutsoni (Southwell, 1911) Baer and Euzet, 1962, is emended. Species of Balanobothrium Hornell, 1912, possess bipronged hooks with 2 separate channels and 2 separate pores like the hooks of Pedibothrium spp., but the morphology of the Balanobothrium scolex has not been thoroughly elucidated. The bothridial hooks of most onchobothriids possess a single internal channel (branched or unbranched) with a single pore. Judging from the published figures (Linton, 1909; Baer and Euzet, 1962), the bothridial hooks of Pedibothrium globicephalum Linton, 1909 and Pedibothrium longispine Linton, 1909 have two separate channels and two pores. To investigate these unusual onchobothriid hooks, as many as possible of the type and voucher specimens of Pedibothrium spp.