SEA ICE DIATOMS (BACILLARIOPHYCEAE) OF THE CANADIAN ARCTIC .1. THE GENUS STENONEIS

Ice diatom assemblages in the Canadian Arctic are dominated by the Naviculaceae, a family which includes the genus Stenoneis Cleve. A taxonomic history of S. inconspicua var. baculus (Cleve) Cleve (including type material of Navicula baculus Cleve) is presented with morphological data including the first SEM views of the genus. Stenoneis inconspicua var. baculus was compared with S. obtuserostrata (Hustedt) comb. nov. (basionym: Navicula obtuserostrata Hustedt). In the SEM, external, short, flattened siliceous ridges were revealed beside the proximal parts of the raphe branches and central pores. This may be a significant taxonomic feature of the genus. Valves of S. inconspicua var. baculus ranged from 40–103 μm in length, 7–11 μm in width and had 17–20 striae in 10 μm, whereas valves of S. obtuserostrata were shorter (27–53 μm), narrower (6–7.5 μm) and more finely striated (24–30 in 10 μm). Both taxa have a circumpolar Arctic distribution. Copyright © 1990, Wiley Blackwell. All rights reserved