Colonies can be straight, curved, or slightly twisted, of moderate length. Cells are rectangular when viewed from the girdle, with a low mantle and narrow foramina. Setae are long and slender without a basal part, with capilli (long spines) exclusively on the intercalary setae. Both intercalary and terminal setae diverge nearly perpendicular to the colony axis and cross over at the colony margin. Each cell contains one chloroplast.In SEM, valves are broad and flat, with radiating costae from an eccentric annulus. The rimoportula is a flattened-tube structure externally, and a slit along the apical axis internally. Setae are circular in cross-section with random spines of varying length, except at the base, which has small poroids.Resting spores come in pairs with dome-shaped, smooth primary valves and flattened, smooth secondary valves. Sibling setae of resting spores fuse at a short distance after bending around the cell.