The bathymetric distribution of the digenean parasites of deep-sea fishes.

The bathymetric range of 149 digenean species recorded deeper than 200 m, the approximate depth of the continental shelf/slope break, are presented in graphical form. It is found that only representatives of the four families Lepocreadiidae, Fellodistomidae, Derogenidae and Hemiuridae reach to abyssal regions (>4000 m). Three other families, the Lecithasteridae, Zoogonidae and Opecoelidae, have truly deep-water forms reaching deeper than 3000 m. Bathymetric data are available for the Acanthocolpidae, Accacoeliidae, Bucephalidae, Cryptogonimidae, Faustulidae, Gorgoderidae, Monorchiidae and Sanguinicolidae showing that they reach deeper than 200 m. No bathymetric data are available for the members of the Bivesiculidae and Hirudinellidae which are reported from deep-sea hosts. These results indicate that only seventeen out of the 150 or so digenean families are reported in the deep sea.