The valves are linear and have a central inflation that is about as wide as, or slightly wider than, the clearly capitate apices. The striae are parallel and alternate in arrangement. The axial area is narrow and linear, and the striae extend to the central part of the valve. The girdle bands are open and have regular septa, with four girdle bands per frustule. Each valve has one rimoportula, typically located within or near the central inflation. There are no rudimentary septa or marginal spines. These cells are connected in colonies that form long, straight chains. When viewed from the side, the frustules have a rectangular shape.