Zoelucasa sablensis n. gen et n. sp. is a small heterotrophic fl agellate housed within a pyriform lorica of relatively large imbricate, circular siliceous scales. It was found in near-shore benthic sand/seawater samples of both the Pacific and Atlantic Oceans (west and east coasts of Canada; salinity = 32–33 ppt). The median length and width of the lorica was 18 and 11 μm, respectively (n = 29). This taxon lacks chloroplasts and swims with a slow zig-zag motion controlled by a short (5–7 μm long), anteriorly-directed flagellum and a longer trailing flagellum, 15–20 μm in length. Its classification within the phylum Cercozoa (most likely, Class Imbricatea) is tentative, as there are no known morphological homologues (discoidal, overlapping siliceous plate-scales forming a test or lorica enclosing a heterotrophic flagellate). Further study of cultured and wild material, including a search for other possible non-flagellate (e.g. amoeboid?) life history stages, TEM examination of cell sections, and rDNA sequencing will most certainly provide more opportunities for a justifi able classifi cation, possibly including a new Order.