Abstract
A new marine diatom genus and species, Nephroneis macintirei Amspoker, has been identified from the epipsammon of Scripps Beach, La Jolla, California, U.S.A. This taxon is reniform in valve outline with a rimoportula at one or both poles. Poroid areolae are arranged in transapical striae over a broad mantle, but this organization is lost over the valve face, the areolae here being scattered. The valve lacks an axial area, raphe, apical pore fields, elevations, costae, pseudosepta, and a marginal ring of processes. Elements of the cingulum lack ligulae, antiligulae and septa. The genus is tentatively assigned to the heterogeneous araphid family, Diatomaceae sensu Simonsen 1979.