Pterobothrioides, a new genus of tapeworms (Cestoda: Trypanorhyncha: Pterobothriidae) from dasyatid stingrays in the Eastern Atlantic and Pacific Oceans
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Two new species of pterobothriid trypanorhynch cestodes representing a new genus are described from dasyatid stingrays taken in Pacific coastal waters off Mexico and Costa Rica and from Atlantic waters off Senegal, West Africa. Pterobothrioides carvajali n. g., n. sp. is described from Dasyatis longus (Garman) from Pacific coastal waters off Mexico and Costa Rica. P. petterae n. g., n. sp. is described from Gymnura altavela (Linnaeus) from Atlantic coastal waters off West Africa. Both species resemble other pterobothriids in their possession of four pedicellate bothridia in a cruciform arrangement, elongated scolex and bulbs, heteroacanthous armature with five hooks per principal row, one or more intercalary rows and a band consisting of irregular files of microhooks on the external tentacular surface. Both new species are unique in the possession of a simple chainette of hooks in addition to a band of microhooks in the tentacle armature. The chainette hooks of P. carvajali are robust, rose-thorn-shaped hooks with large rounded bases. The chainette of P. petterae consists of smaller uncinate hooks that are most distinct in the basal region of the tentacle armature and progressively decrease in size until they become almost indistinguishable from the band microhooks in the distal metabasal region. A new genus, Pterobothrioides, is proposed to accommodate these two new species, combining a chainette, considered characteristic of poeciloacanths, with the band of hooks characteristic of atypical heteroacanths. It is suggested that through changes in hook number and arrangement the typical heteroacanths, having bands of hooks, evolved into poeciloacanths with chainettes and that clades are now apparent in the family Pterobothriidae.
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