From 12°S to 9°N -140°W on the benthic cruise of the US Joint Global Ocean Flux Studies (JGOFS), horizontal near-surface net tows (n = 18) and vertical net hauls (n = 15,200-0 m) yielded high relative abundances of small, bicapitate, intact Nitzschia valves (average 59.0 and 56.0% of total diatoms, respectively), although >90% of them were too small to have been caught effectively with the net used. This complex was much less common (average 3.2% of diatoms) in the surface sediment samples (n =

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... 7,12°S-9°N, below water depths of 4269-4991 m). Examination under the light microscope showed concentrations of cells associated with organic detritus, planar and cylindrical membranous structures, fecal pellets, and occasionally on other diatoms (e.g. Asterolampra), i.e. on or within particles large enough to be collected in the net. Although Nitzschia bicapitata Cleve has been considered to have a characteristic range of shapes, and has often been cited from open-ocean habitats in nano-and microplanktonic studies, a scanning electron microscopic study revealed several species in our material. Examples of larger and smaller species are given, and Nitzschia ikeanae G.Fryx. & H.Lee, sp. nov., is described here. Ecologically, these observations indicate that although some are grazed and have been seen aggregated in fecal pellets, these small pennate diatoms can affix to and grow on substrates, termed 'pseudo-benthic habitats' in the open ocean, resulting in unexpected concentrations that have implications for their life histories and sexual cycles, selection or avoidance by grazers, sinking on substrates, and roles in the recycling of nutrients in near-surface waters.