Naviculaceae are typically composed of lineate areolae, one of the many forms of areolae. Some of the other areolae are punctate (Gomphoneis) and loculate (Diploneis).[1] These can be found among other families of diatoms including Thalassiosiraceae. The areolae found in Naviculaceae tend to be uniseriate. Some Naviculaceae tend to have a pseudoseptum which is a silica plate extending internally from the apical portion of the valve. To contrast, a pseudoseptum is part of a valve while a septum is part of a copula, or girdle band. For example, the pseudoseptum occurs in some species of Gomphonema, Gomphoneis, Stauroneis and Navicula. The plural is pseudosepta.[2]
