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Calliobothrium spp. (Eucestoda: Tetraphyllidea: Onchobothriidae) in Mustelus schmitti (Chondrichthyes: Carcharhiniformes) from Argentina and Uruguay

2002; American Society of Parasitologists; Volume: 88; Issue: 6 Linguagem: Inglês

10.2307/3285494

1937-2345

Verónica A. Ivanov, Daniel R. Brooks,

Bird parasitology and diseases

Three species of Calliobothrium inhabit the spiral intestine of Mustelus schmitti in Argentina and Uruguay.Calliobothrium verticillatum australis is redescribed and its taxonomic status modified to species as C. australis.Calliobothrium barbarae n. sp.can be distinguished from all other species of Calliobothrium, which are small bodied, nonlaciniate, and without accessory piece between the bases of axial hook, by worm length, number of segments, cocoon morphology, and hooks shape.Calliobothrium lunae n. sp. is different from other Calliobothrium spp., which are small bodied, nonlaciniate, and have an accessory piece, by the number of segments and testes, hook shape, cocoon morphology, and the presence of ciliumlike projections on the distal surface of muscular pads.Calliobothrium australis is clearly distinguished from other large-bodied, laciniate species of the genus by worm length, number of testes, ovary shape, cocoon morphology, hook shape, and in being hyperapolytic.The oioxenous specificity involving Calliobothrium spp.and Mustelus spp.described by previous authors is confirmed in this study. Eucestodes of the onchobothriid tetraphyllideanCalliobothrium van Beneden, 1850, are common inhabitants of sharks, i.e., Mustelus Linck, 1790; in fact, only 1 species of the genus (C.creeveyae Butler, 1987) inhabits a host other than Mustelus spp.Moreover, most of the Calliobothrium spp.show specificity for a single species of Mustelus, even when other congeneric host species are sympatric with the preferred host (Nasin et al., 1997).Ostrowski de Nunfiez (1973) presented a strikingly different view of host specificity patterns among Calliobothrium spp., when she reported C. verticillatum australis Ostrowski de Nunifez, 1973, C. eschrichti van Beneden, 1850, and C. lintoni Euzet, 1954, in the narrownose smooth-hound shark, M. schmitti Springer, 1939, from Argentine waters.These species were previously reported inhabiting other species of Mustelus in the Mediterranean Sea, northeastern Atlantic Ocean, and Japan.The unusual nature of the report by Ostrowski de Nuniez (1973) prompted us to make new collections from the same and new localities, to reexamine the taxonomic status of the Calliobothrium spp.inhabiting M. schmitti. MATERIALS AND METHODSA total of 52 specimens of M. schmitti was obtained from catches of commercial trawlers in the following localities: 7 specimens off La Paloma (Uruguay) in July 1993, 30 specimens off Mar del Plata (Provincia de Buenos Aires, Argentina) in December 1995, and 15 specimens off Puerto Quequen (Provincia de Buenos Aires, Argentina) in February 2000.The mucosal surface of some spiral intestines of hosts from Argentina was examined fresh, and the worms were removed and placed directly into fixative (10% hot formalin).Other spiral intestines were fixed in 10% formalin for later examination for worms and transferred to 70% alcohol for storage after 48 hr.Specimens prepared for light microscopy were hydrated in a graded ethanol series, stained with Harris' hematoxylin, dehydrated in a graded ethanol series, cleared in methyl salicylate, and mounted in Canada balsam.Specimens recovered from elasmobranchs off Uruguay were relaxed in seawater, killed with hot water, fixed with AFA, and stored in 70% ethanol.Whole mounts were stained with Mayer's hematoxylin.