Calliobothrium Narsisae n. sp. (Tetraphyllidea: Calliobothriidae) from the Triakid Shark Mustelus mosis Hemprich and Ehrenberg from the Persian Gulf, with a Note on Its Specific Proglottisation Process and a Key to the Species of the Genus.

Abstract

The members of the tetraphyllidean genus Calliobothrium exhibit a high degree of host specificity in the shark genus Mustelus. In the Indian Ocean, where M. mosis occurs dominantly, there is no information on Calliobothrium. The purpose of this study was the evaluation of the Calliobothrium species in M. mosis in the Persian Gulf, northwestern Indian Ocean. Nine specimens of Mustelus mosis were caught from the Persian Gulf. The tapeworms isolated were stained, measured, and the line drawings were made. Calliobothrium narsisae n. sp. is described and differs from C. creeveyae in the intact, rather than the three-lobed, posterior bothridial margins, from C. tylotocephalum in possessing three, rather than one, suckers per bothridial muscular pad, from C. nodosum in possessing the elongated, rather than robust and thorn-like, hooks, from C. shirozame in a maximum number of four, rather than three, dorsal and four, rather than three, ventral laciniations along the strobila, and from its other congeners in possessing three, rather than two, dorsal and three, rather than two, ventral laciniations in the anteriormost immature proglottids. A key to the species of the genus is presented and the proglottisation process, by the germinative zone placed in the terminal part of the worm at least in some stages of growth to maturity, is discussed. The description of C. narsisae n. sp., which brings the total number of valid species of Calliobothrium to 10, also indicates that the germinative zone is not always at the anterior to strobila and in this new species it is placed in the terminal part of the worm at least in some stages of growth to maturity.