Iphitus (Depressiphitus) davidei (Caenogastropoda, Epitoniidae): A peculiar new deep-sea subgenus and species from Eastern Atlantic seamounts

The new epitoniid subgenus Depressiphitus, and the new species Iphitus (Depressiphitus) davidei sp. nov., are described upon six shells collected in the north-eastern Atlantic Ocean, from the Coral Patch Seamount (936965 m), and the Atlantis Seamount (795830 m). Compared to species placed in the deep-sea genus Iphitus, being similarly equipped with a protoconch reflecting planktotrophic larval development, the new taxon exhibits unique morphological features. A fragile, very globose-depressed shell, coupled with a faint reticulate sculpture not found in other Iphitus species, motivated the erection of Depressiphitus subgen. nov. to accommodate this new species. So far recorded from two seamounts, we suspect that the geographic range of Iphitus (Depressiphitus) davidei sp. nov. is probably wider, given its larval development mode. The new species was found within time-averaged shelly taphocoenoses rich in scleractinian coral skeletal and other calcareous biogenic remains. The peculiar shape of Iphitus (Depressiphitus) davidei sp. nov. could be possibly taken as an indication that this species lives partially embedded into a still unknown cnidarian host, as is also the case in Iphitus species.