Several species of hydromedusae are reported from material collected by sediment traps placed in the Lacaze-Duthiers submarine canyon, off Banyuls (north-western Mediterranean). Two new taxa Guillea canyonincolae gen. nov. et sp. nov. and Parateclaia euromarge fam. nov., gen. nov. et sp. nov., are described. The existence of highly-specific hydromedusa populations in other Mediterranean canyons which appear to be related via geological history, topography, hydrographic and ecological features peculiar to each canyon, is discussed in relation to these new records.