Copulabyssia riosi, a new deep-sea limpet (Gastropoda : Pseudococculinidae) from the continental slope off Brazil with comments on the systematics ofthe genus

A new bathyal species of the family Pseudococculinidae is described from sa mples dredged in 1987 along the continental slope of southeastern-eastern B razil by the French research vessel Marion-Dufresne. The new species, alloc ated in the ge nus Copulabyssia, differs from the 4 other known congeners b y characters of shell, external morphology, mantle cavity, and radula. Desc riptions of internal morphology based on micro-dissections are provided, in cluding the digestive system and the complex muscular apparatus of the odon tophore. The distribution of characters of taxonomic significance at the sp ecies level in Copulabyssia is given in tabular format and discussed.