On the status of the Cestode Order Diphyllidea following a National Science Foundation funded Planetary Biodiversity and Inventory (PBI) of Cestodes Globally

CAIRA, JANINE N.; IVANOV, VERONICA; JENSEN K

Sao Sebastiao

Workshop; VIII Workshop for Cestode Systematic and Phylogeny; 2014

The new collections conducted over the course of the PBI have done much to increase the total number of valid diphyllidean genera and species. Reconfiguration of generic boundaries to bring them into line with the results of the phylogenetic analyses conducted resulted in the erection of 3 new genera; catsharks yielded a fourth novel genus, increasing the number of valid genera from 2 to 6. The geographic distribution of the order was expanded only slightly (i.e., to include South Africa, Indonesia, Taiwan, and Brazil), for it was already known to be cosmopolitan at the initiation of the project. Morphological novelty within the order is related to the elements that constitute the scolex armature, since most of them appear to be able to evolve independently. The host range of the order was expanded to include many additional host species and 10 new genera of elasmobranchs, most in families already known to host diphyllideans; however, the Proscylliidae and Anacanthobatidae were added to the list of families serving as hosts. Unstudied catsharks (Scyliorhinidae) and houndsharks (Triakidae) are the most potentially productive sources of diphyllidean specific and potentially even generic novelty. We predict that the global fauna of diphyllideans will be found to reach a total of somewhere around 470 species. The interrelationships among diphyllideans are fairly well understood, although the family-level classification would benefit from additional attention. That diphyllideans are monophyletic and, as an order, have affinities with the other bothriate eucestode orders is also clear; their exact affinities among these groups remain to be definitively resolved.