Distribution and variation of Carinariidae and Pterotracheidae (Heteropoda, Gastropoda) of the Amsterdam Mid North Atlantic Plankton Expedition 1980

Species of the heteropod families Carinariidae and Pterotracheidae collected in the Mid North Atlantic Ocean in 1980 have been studied. The distribution of the species is given, as well as the morphological variation. It is concluded that two subspecies of Carinaria lamarcki actually have to be considered distinctly recognisable and sympatric species, to be called C. lamarcki and C. challengeri. The vertical distribution of the heteropods studied proves not to be restricted to the photic zone and diurnal vertical migration occurs among the larger species. The horizontal distribution of the two Carinaria species and of at least two populations of the Pterotrachea species coincides with the southern branch of the North Atlantic Current, while others are restricted to the subtropical waters. Consequently, the present heteropods have to be considered good indicators of water masses and currents.