Two new families of copepods (Copepoda : Siphonostomatoida) parasitic on echinoderms

The description of Dichelina phormosomae is supplemented by study of new ma terial from a deep-water echinoid collected in the North Atlantic, and the homology of some mouthparts is reinterpreted. The phylogenetic relationship s between Dichelina and other echinoderm-inhabiting siphonostomatoids are a nalysed. Based on inferences from the phylogenetic analysis, two new famili es of siphonostomatoid copepods parasitic on echinoderms are established, t he Dichelinidae and the Codobidae. The hitherto unplaced genus Stephopontiu s is formally assigned to the family Nanaspididae.