The morphology of E. paludosa is similar to E. trinacria. Valves of E. trinacria are narrower and have a central undulation on the dorsal margin that is absent in E. paludosa. Valves of E. paludosa are sometimes confused with forms of E. exigua and E. tenella. The apices of E. paludosa are narrowly protracted and are not as strongly dorsally recurved as the capitate, dorsally recurved apices of E. exigua. Valves of E. paludosa have a more evenly curved dorsal margin and a more convex ventral margin than valves of E. tenella, where the dorsal and ventral margins are nearly parallel. The dorsal margin ends in a ‘shoulder’ near the apices and the ventral margin is straighter in E. tenella.