Marine tube-dwelling diatoms of the Pacific coast of North America. II. Navicula subg. Navicula and a key to the tube-dwelling diatoms of the region

Abstract

The tube-dwelling cross-lineate Navicula species on the west coast are dominated by a taxon that belongs in or near the N. ramosissima – N. mollis complex. Morphometric data were used to establish that a single, variable population exists. The species was assigned to N. rusticensis. Cells are 28 ± 7 × 5 ± 1 μm and striae number 14 ± 2 in 10 μm; these cells differ from the ramosissima–mollis complex in having 1–3 short central striae that form a narrow rectangular area. The range of size encompasses published limits for both N. ramosissima and N. mollis. A key to tube-dwelling diatoms of the west coast completes this two-part checklist. Key words: diatoms, Pacific, tube-dwelling, Navicula rusticensis, Navicula ramosissima.