The colonies are linear in length. Rectangular cells with a concave valve face and a high mantle in girdle view. Nausea is narrow. Setae are straight, long, thick, and lack a basal portion. The proximal parts of sibling intercalary setae merge, and they diverge at an angle of more than 10–25 degrees from the colony axis. In general, terminal setae depart from cell angles and curve parallel to the colony axis. They are shorter and thicker than intercalary setae. Setae transition near the edge of the colony. There are several tiny chloroplasts.