Araphid valves, elongate to elliptical and often undulate and centrally expanded. Occur in filaments, with numerous discoid plastids. Narrow central sternum. Valve with thickened internal transapical costae. Labiate processes may be absent or present (1 or 2). While most araphid genera possess an apical pore field, it is absent in Tetracyclus. Occurs in association with mosses and damp rocks, often in shallow, cold freshwater.

Light Microscope Image(s)

Each image is accompanied by the genus and species, California Academy of Sciences slide number (ie. CAS 612010), location of the specimen on the slide, and dimension in microns.