Tapeworms of the Mangrove Whipray, Himantura granulata Macleay, and an Investigation of Host Size as it Relates to Tapeworm Faunal Composition

Abstract

Since its description by Macleay in 1883, only three tapeworm species have been reported to parasitize the mangrove whipray, Himantura granulata. These are the rhinebothriideans Rhinebothrium himanturi and a presumably new species referred to as “Rhinebothrium sp.”, and the trypanorhynch Prochristianella clarkeae. Elasmobranch collection efforts in the Solomon Islands and northern Australia from 1997 to 2012 yielded ten specimens of H. granulata, all of which were examined for tapeworms. Morphological and molecular data indicate that at least 31 additional species of tapeworms in 13 genera from five orders parasitize H. granulata from these localities, bringing the total number of tapeworm species known from this host to 34 species. Included in these 34 species are three new species representing two new lecanicephalidean genera, and at least six new species in the rhinebothriidean genus Anthocephalum. Of the ten specimens of H. granulata examined, six were small juvenile rays (disk width less than 35 cm) and four were large mature rays (disk width greater than 100 cm), presenting the unique opportunity to assess differences in tapeworm faunal diversity between two size classes of the same host species. Not unexpectedly, host size appears to play an important role, as conspicuous disparities in tapeworm faunal diversity at the specific, generic and ordinal levels were noted between the two host size classes. Ultimately, a combination of variation in both host diet and habitat use between different size classes, as well as the specificity of larval tapeworms within their intermediate hosts, will likely be necessary to explain these observed differences.