Unravelling the conoidean gastropods assigned to the genus ??????? (Gastropoda: Mangeliidae) from south-western Atlantic deep waters

A new genus of conoidean gastropods of the family Mangeliidae, Notopropebela gen. nov., is herein described to include N. profunda (Castellanos and Landoni, 1993) previously in the genus Propebela Iredale, 1918, and two new species from the deep waters off south-western Atlantic Argentine. This new genus is characterised by small rhomboid shells with axial riblets and spiral cords, absent operculum, and radula of semi-enrolled marginal teeth. Both new species are distinguished from N. profunda by the presence of pustules covering the shell. Notopropebela pustulata sp. nov. was collected at depths ranging from 530 to 2845 m off Argentina within the Mar del Plata Submarine Canyon in the north and Burdwood Bank surroundings in the south. Notopropebela petu sp. nov., distinguished from N. pustulata by a larger spire and subsutural ramp, was described from material collected from 210 m off Buenos Aires province. The radula and details of the shell and protoconch of both new species were studied from material deposited in the collections of Museo Argentino de Ciencias Naturales (MACN) and Museo de La Plata (MLP). We conclude that the genus Propebela is absent from the south-western Atlantic.