The cells are linked together in chains that exhibit a slight twist around the central axis. These cells have a rectangular shape with slightly rounded corners, and they do not touch at the corners. The valves are slightly convex, and the apertures are wide and elliptical with a slight constriction in the middle. Setae originate inside the valve margin, cross at the edge of the chain, and are generally perpendicular to the chain axis. Terminal setae diverge at a wide angle.Resting spores have primary valves that are uniformly vaulted and adorned with 2-12 dichotomously branched spines. The secondary valve is smooth and inflated.